Sony 100-400 f/4.5
p.6 #1Sony 100-400 f/4.5
My first use of the Rolanpro's was with a previous 400 f/2.8GM. Never had an issue, fit like a glove.
Jun 17, 2026 at 12:55 PM
p.6 #2Sony 100-400 f/4.5
hyken wrote:
For those of you who are thinking about a cover for this lens, I have always liked the RolanPro covers. This was a straightforward install, I will adjust a little once I use it for a month or so. Ordered off of Amazon from China, fast shipment, 4 days via FedEx.
The hood was the most difficult, more or less. Just had to realign the release 5x or so. Everything else is velcro.
https://www.amazon.com/dp/B0H32D2PKL?th=1
Of course, I just noticed I forgot to remove the numerical labels
.
Thanks for sharing. I hadn't even thought to search for it yet as I thought it would be awhile. Was hoping I could get the dark shadow camo I have on my 300GM but doesn't look like they have that one (yet?). I'll probably just order the Jungle or Reed.
Was the fitment for the rear most piece good? Their 400GM one was poor and stuck off the end a bit making it risky that the lens and TCs locked properly. Although my 600GM, 200-600 and 300GM ones were good fitment.
I wish I could only order some of those pieces and save some $$
. I won't be covering any of the black parts of the lens.
For those of you who are thinking about a cover for this lens, I have always liked the RolanPro covers. This was a straightforward install, I will adjust a little once I use it for a month or so. Ordered off of Amazon from China, fast shipment, 4 days via FedEx.
The hood was the most difficult, more or less. Just had to realign the release 5x or so. Everything else is velcro.
https://www.amazon.com/dp/B0H32D2PKL?th=1
Of course, I just noticed I forgot to remove the numerical labels
.Thanks for sharing. I hadn't even thought to search for it yet as I thought it would be awhile. Was hoping I could get the dark shadow camo I have on my 300GM but doesn't look like they have that one (yet?). I'll probably just order the Jungle or Reed.
Was the fitment for the rear most piece good? Their 400GM one was poor and stuck off the end a bit making it risky that the lens and TCs locked properly. Although my 600GM, 200-600 and 300GM ones were good fitment.
I wish I could only order some of those pieces and save some $$
. I won't be covering any of the black parts of the lens.Jun 17, 2026 at 12:57 PM
p.6 #3Sony 100-400 f/4.5
I used a Chasing Birds cover on the 300 f2.8 and I liked the fit but there are times when I'd like to take a section off easily. Other than the hood are the RolanPro's sections easily removable? It appears they attach via a velcro wrap?
Jun 17, 2026 at 01:07 PM
p.6 #4Sony 100-400 f/4.5
Seems to be OK, I kind of remember this piece being an issue on the 400 as well. Just put this cover on today so time will tell how much they loosen. Having said that, I used the heck out of my 400 f/2.8 and they stayed in place pretty well.
Jun 17, 2026 at 01:13 PM
p.6 #6Sony 100-400 f/4.5
hyken wrote:
Seems to be OK, I kind of remember this piece being an issue on the 400 as well. Just put this cover on today so time will tell how much they loosen. Having said that, I used the heck out of my 400 f/2.8 and they stayed in place pretty well.
Thanks. That looks good. Mine have all held up well. My 600GM is the oldest from ~2021 or so.
Seems to be OK, I kind of remember this piece being an issue on the 400 as well. Just put this cover on today so time will tell how much they loosen. Having said that, I used the heck out of my 400 f/2.8 and they stayed in place pretty well.
Thanks. That looks good. Mine have all held up well. My 600GM is the oldest from ~2021 or so.
Jun 17, 2026 at 01:18 PM
p.6 #7Sony 100-400 f/4.5
Lethimcook wrote:
This might be a silly thought but don't built in TCs on zooms just make the lens a variable aperture zoom?
I for one agree with the approach of the 300GM without TCs. It's lightweight, and anyone that wants a TC can buy the appropriate one, and then shift said TCs onto the lens they want to use at the moment. It's modular. Rather than pay for a built-in TC 3-4 times you just pay once, and deal with the quirks of putting them on or off lenses.
A prime (with or without TC) works well if you have subjects easily framed at the proper distance. Mostly you end up cropping and losing much of the IQ or too tight and completely missing the shot. I feel like that was enough in the 20th century and I'd rather have better zooms at any cost.
EBH
This might be a silly thought but don't built in TCs on zooms just make the lens a variable aperture zoom?
I for one agree with the approach of the 300GM without TCs. It's lightweight, and anyone that wants a TC can buy the appropriate one, and then shift said TCs onto the lens they want to use at the moment. It's modular. Rather than pay for a built-in TC 3-4 times you just pay once, and deal with the quirks of putting them on or off lenses.
A prime (with or without TC) works well if you have subjects easily framed at the proper distance. Mostly you end up cropping and losing much of the IQ or too tight and completely missing the shot. I feel like that was enough in the 20th century and I'd rather have better zooms at any cost.
EBH
Jun 17, 2026 at 01:22 PM
p.6 #8Sony 100-400 f/4.5
Steve Spencer wrote:
I for one agree with the approach of the 300GM without TCs. It's lightweight, and anyone that wants a TC can buy the appropriate one, and then shift said TCs onto the lens they want to use at the moment. It's modular. Rather than pay for a built-in TC 3-4 times you just pay once, and deal with the quirks of putting them on or off lenses.Part of the value of built-in TCs is that they are tuned to the lens and therefore lead to better performance. Sometimes that is quite noticeable. Canon builds TC into the 400 f/2.8 and 600 f/4 RF lenses and the built-in TCs produce better results than the ir regular modular TC. I think that is the primary reason to build in a TC. Modularity is good, but so is better performance and if you are going to spend over ten thousand for a lens, spending a couple thousand more for optimal TC performance seems like something a lot of people willing to spend that kind of money would want.
With regard to just making a zoom lens a variable aperture lens instead, I don't think it is that easy. I think adding a TC and making a variable aperture lens are very different designs and no variable aperture zoom that I know of has performance at 1.4X less than the max aperture at 1.4X less than the max focal length. So, for example, if the 100-400 f/4.5 was a 140-560 lens, I have never seen a variable aperture zoom that would be f/4.5 at 400, so you would be sacrificing versatility at 400, and at least some of the focal length range below that, to make it a variable aperture zoom instead of a fixed aperture zoom that also takes a TC.That certainly seems logical, but I don't think it's always true. I seem to recall Nikon users saying the 180-400 with built in converter wasn't as sharp as it was using an external 1.4x.If that were true, then that would be a fail from Nikon for that lens. They ought to be able with a dedicated tuned TC get better performance than a generic TC that has to work with many different lenses and if they can't, then they should just introduce the lens without a buit-in TC, IMO. Maybe there was a construction issue with that lens and they had trouble making it to specifications and when the TC was engaged in at least some copies it didn't operate as it was designed.
I've seen people report that not just with the 180-400 but with the 400/600 primes. Usually it is very close but sometimes an external ends up being slightly better than the internal.
Same with Canon. My 200-400TC was slightly better with my external 1.4 vs the internal. But I'm sure there were others that had the opposite experience.
People always claim the internal ones should be so much better but user experience has proven that to be false for both Canon and Nikon.
scott f wrote
Steve Spencer wrote
Lethimcook wrote
This might be a silly thought but don't built in TCs on zooms just make the lens a variable aperture zoom?I for one agree with the approach of the 300GM without TCs. It's lightweight, and anyone that wants a TC can buy the appropriate one, and then shift said TCs onto the lens they want to use at the moment. It's modular. Rather than pay for a built-in TC 3-4 times you just pay once, and deal with the quirks of putting them on or off lenses.
With regard to just making a zoom lens a variable aperture lens instead, I don't think it is that easy. I think adding a TC and making a variable aperture lens are very different designs and no variable aperture zoom that I know of has performance at 1.4X less than the max aperture at 1.4X less than the max focal length. So, for example, if the 100-400 f/4.5 was a 140-560 lens, I have never seen a variable aperture zoom that would be f/4.5 at 400, so you would be sacrificing versatility at 400, and at least some of the focal length range below that, to make it a variable aperture zoom instead of a fixed aperture zoom that also takes a TC.
I've seen people report that not just with the 180-400 but with the 400/600 primes. Usually it is very close but sometimes an external ends up being slightly better than the internal.
Same with Canon. My 200-400TC was slightly better with my external 1.4 vs the internal. But I'm sure there were others that had the opposite experience.
People always claim the internal ones should be so much better but user experience has proven that to be false for both Canon and Nikon.
Jun 17, 2026 at 01:51 PM
p.6 #9Sony 100-400 f/4.5
arbitrage wrote:
I for one agree with the approach of the 300GM without TCs. It's lightweight, and anyone that wants a TC can buy the appropriate one, and then shift said TCs onto the lens they want to use at the moment. It's modular. Rather than pay for a built-in TC 3-4 times you just pay once, and deal with the quirks of putting them on or off lenses.Part of the value of built-in TCs is that they are tuned to the lens and therefore lead to better performance. Sometimes that is quite noticeable. Canon builds TC into the 400 f/2.8 and 600 f/4 RF lenses and the built-in TCs produce better results than the ir regular modular TC. I think that is the primary reason to build in a TC. Modularity is good, but so is better performance and if you are going to spend over ten thousand for a lens, spending a couple thousand more for optimal TC performance seems like something a lot of people willing to spend that kind of money would want.
With regard to just making a zoom lens a variable aperture lens instead, I don't think it is that easy. I think adding a TC and making a variable aperture lens are very different designs and no variable aperture zoom that I know of has performance at 1.4X less than the max aperture at 1.4X less than the max focal length. So, for example, if the 100-400 f/4.5 was a 140-560 lens, I have never seen a variable aperture zoom that would be f/4.5 at 400, so you would be sacrificing versatility at 400, and at least some of the focal length range below that, to make it a variable aperture zoom instead of a fixed aperture zoom that also takes a TC.That certainly seems logical, but I don't think it's always true. I seem to recall Nikon users saying the 180-400 with built in converter wasn't as sharp as it was using an external 1.4x.If that were true, then that would be a fail from Nikon for that lens. They ought to be able with a dedicated tuned TC get better performance than a generic TC that has to work with many different lenses and if they can't, then they should just introduce the lens without a buit-in TC, IMO. Maybe there was a construction issue with that lens and they had trouble making it to specifications and when the TC was engaged in at least some copies it didn't operate as it was designed.I've seen people report that not just with the 180-400 but with the 400/600 primes. Usually it is very close but sometimes an external ends up being slightly better than the internal.
Same with Canon. My 200-400TC was slightly better with my external 1.4 vs the internal. But I'm sure there were others that had the opposite experience.
People always claim the internal ones should be so much better but user experience has proven that to be false for both Canon and Nikon.
The 1.4x III was a little better than the internal TC of the 200-400/4. I no longer have access to optical engineers to explain if it is a true limitation or depends on the particular combination. Maybe a lens designer here can chime in.
EBH
Steve Spencer wrote
scott f wrote
Steve Spencer wrote
Lethimcook wrote
This might be a silly thought but don't built in TCs on zooms just make the lens a variable aperture zoom?I for one agree with the approach of the 300GM without TCs. It's lightweight, and anyone that wants a TC can buy the appropriate one, and then shift said TCs onto the lens they want to use at the moment. It's modular. Rather than pay for a built-in TC 3-4 times you just pay once, and deal with the quirks of putting them on or off lenses.
With regard to just making a zoom lens a variable aperture lens instead, I don't think it is that easy. I think adding a TC and making a variable aperture lens are very different designs and no variable aperture zoom that I know of has performance at 1.4X less than the max aperture at 1.4X less than the max focal length. So, for example, if the 100-400 f/4.5 was a 140-560 lens, I have never seen a variable aperture zoom that would be f/4.5 at 400, so you would be sacrificing versatility at 400, and at least some of the focal length range below that, to make it a variable aperture zoom instead of a fixed aperture zoom that also takes a TC.
Same with Canon. My 200-400TC was slightly better with my external 1.4 vs the internal. But I'm sure there were others that had the opposite experience.
People always claim the internal ones should be so much better but user experience has proven that to be false for both Canon and Nikon.
The 1.4x III was a little better than the internal TC of the 200-400/4. I no longer have access to optical engineers to explain if it is a true limitation or depends on the particular combination. Maybe a lens designer here can chime in.
EBH
Jun 17, 2026 at 02:14 PM
p.6 #10Sony 100-400 f/4.5
Great shots. Can't wait to get mine. These people here have nothing better to do than whine and pixel peep at 400% are not photographers, they are gear people that have nothing better too do and complain about everything (sell the lens and/or cancel your preorder.. Just ignore them and enjoy the lens as you say. Bunch of whiners.
Jun 17, 2026 at 03:09 PM
|
p.6 #11Sony 100-400 f/4.5
arbitrage wrote:
I for one agree with the approach of the 300GM without TCs. It's lightweight, and anyone that wants a TC can buy the appropriate one, and then shift said TCs onto the lens they want to use at the moment. It's modular. Rather than pay for a built-in TC 3-4 times you just pay once, and deal with the quirks of putting them on or off lenses.Part of the value of built-in TCs is that they are tuned to the lens and therefore lead to better performance. Sometimes that is quite noticeable. Canon builds TC into the 400 f/2.8 and 600 f/4 RF lenses and the built-in TCs produce better results than the ir regular modular TC. I think that is the primary reason to build in a TC. Modularity is good, but so is better performance and if you are going to spend over ten thousand for a lens, spending a couple thousand more for optimal TC performance seems like something a lot of people willing to spend that kind of money would want.
With regard to just making a zoom lens a variable aperture lens instead, I don't think it is that easy. I think adding a TC and making a variable aperture lens are very different designs and no variable aperture zoom that I know of has performance at 1.4X less than the max aperture at 1.4X less than the max focal length. So, for example, if the 100-400 f/4.5 was a 140-560 lens, I have never seen a variable aperture zoom that would be f/4.5 at 400, so you would be sacrificing versatility at 400, and at least some of the focal length range below that, to make it a variable aperture zoom instead of a fixed aperture zoom that also takes a TC.That certainly seems logical, but I don't think it's always true. I seem to recall Nikon users saying the 180-400 with built in converter wasn't as sharp as it was using an external 1.4x.If that were true, then that would be a fail from Nikon for that lens. They ought to be able with a dedicated tuned TC get better performance than a generic TC that has to work with many different lenses and if they can't, then they should just introduce the lens without a buit-in TC, IMO. Maybe there was a construction issue with that lens and they had trouble making it to specifications and when the TC was engaged in at least some copies it didn't operate as it was designed.I've seen people report that not just with the 180-400 but with the 400/600 primes. Usually it is very close but sometimes an external ends up being slightly better than the internal.
Same with Canon. My 200-400TC was slightly better with my external 1.4 vs the internal. But I'm sure there were others that had the opposite experience.
People always claim the internal ones should be so much better but user experience has proven that to be false for both Canon and Nikon.
With Canon I was thinking of the RF 400 f/2.8 vs the RF 800 f/5.6 and the RF 600 f/4 vs the RF 1200 f/8. The longer lenses in each pair are the shorter lens with a custon 2X TC permanently built in and there seems to be pretty good consensus that the RF 800 f/5.6 is better than the RF 400 f/2.8 with the external 2X TC and the RF 1200 f/8 is better than the RF 600 f/4 with the external 2X TC.
I expect whether the built-in TC is better than the external TC may well depend on both the quality of the built-in TC and how well it is built and the qualty of the external TC and how well it is built. Copy variation could also play a role of course. For some lenses the internal TC might not provide any performance advantage, but for others it might.
Steve Spencer wrote
scott f wrote
Steve Spencer wrote
Lethimcook wrote
This might be a silly thought but don't built in TCs on zooms just make the lens a variable aperture zoom?I for one agree with the approach of the 300GM without TCs. It's lightweight, and anyone that wants a TC can buy the appropriate one, and then shift said TCs onto the lens they want to use at the moment. It's modular. Rather than pay for a built-in TC 3-4 times you just pay once, and deal with the quirks of putting them on or off lenses.
With regard to just making a zoom lens a variable aperture lens instead, I don't think it is that easy. I think adding a TC and making a variable aperture lens are very different designs and no variable aperture zoom that I know of has performance at 1.4X less than the max aperture at 1.4X less than the max focal length. So, for example, if the 100-400 f/4.5 was a 140-560 lens, I have never seen a variable aperture zoom that would be f/4.5 at 400, so you would be sacrificing versatility at 400, and at least some of the focal length range below that, to make it a variable aperture zoom instead of a fixed aperture zoom that also takes a TC.
Same with Canon. My 200-400TC was slightly better with my external 1.4 vs the internal. But I'm sure there were others that had the opposite experience.
People always claim the internal ones should be so much better but user experience has proven that to be false for both Canon and Nikon.
With Canon I was thinking of the RF 400 f/2.8 vs the RF 800 f/5.6 and the RF 600 f/4 vs the RF 1200 f/8. The longer lenses in each pair are the shorter lens with a custon 2X TC permanently built in and there seems to be pretty good consensus that the RF 800 f/5.6 is better than the RF 400 f/2.8 with the external 2X TC and the RF 1200 f/8 is better than the RF 600 f/4 with the external 2X TC.
I expect whether the built-in TC is better than the external TC may well depend on both the quality of the built-in TC and how well it is built and the qualty of the external TC and how well it is built. Copy variation could also play a role of course. For some lenses the internal TC might not provide any performance advantage, but for others it might.
Jun 17, 2026 at 03:50 PM
p.6 #12Sony 100-400 f/4.5
arbitrage wrote:
Did a very quick IQ comparison. It is close but the 100-400/2x was resolving some finer details on the $5 bill I shot when zoomed in to 200%. It had just slightly better contrast. But very close.
The 100-400 is a much nicer lens to use, handhold and AF for BIF is way more consistent. 100-400 balances much better in the hand.
That sounds perfect. The 200-600mm + TC 1.4x is already a decent to good combo, so expecting a TX 2x to drastically beat it is not that realistic, especially since at f9 we are into diffraction territory.
The idea of having a 100-400mm f4.5 for lowish light, a 140-560mm f6.3, and 200-800mm f9 all in one, that is overall lighter than the 200-600mm while overall having better IQ, better AF, and better handling (drop in filters, etc) sounds very appealing.
DWOfPaul wrote
Has anyone compared the 100-400mm f4.5 + TC 2x vs the 200-600mm f6.3 + TC 1.4x?The 100-400 is a much nicer lens to use, handhold and AF for BIF is way more consistent. 100-400 balances much better in the hand.
That sounds perfect. The 200-600mm + TC 1.4x is already a decent to good combo, so expecting a TX 2x to drastically beat it is not that realistic, especially since at f9 we are into diffraction territory.
The idea of having a 100-400mm f4.5 for lowish light, a 140-560mm f6.3, and 200-800mm f9 all in one, that is overall lighter than the 200-600mm while overall having better IQ, better AF, and better handling (drop in filters, etc) sounds very appealing.
Jun 17, 2026 at 05:07 PM
p.6 #13Sony 100-400 f/4.5
Steve Spencer wrote:
I for one agree with the approach of the 300GM without TCs. It's lightweight, and anyone that wants a TC can buy the appropriate one, and then shift said TCs onto the lens they want to use at the moment. It's modular. Rather than pay for a built-in TC 3-4 times you just pay once, and deal with the quirks of putting them on or off lenses.Part of the value of built-in TCs is that they are tuned to the lens and therefore lead to better performance. Sometimes that is quite noticeable. Canon builds TC into the 400 f/2.8 and 600 f/4 RF lenses and the built-in TCs produce better results than the ir regular modular TC. I think that is the primary reason to build in a TC. Modularity is good, but so is better performance and if you are going to spend over ten thousand for a lens, spending a couple thousand more for optimal TC performance seems like something a lot of people willing to spend that kind of money would want.
With regard to just making a zoom lens a variable aperture lens instead, I don't think it is that easy. I think adding a TC and making a variable aperture lens are very different designs and no variable aperture zoom that I know of has performance at 1.4X less than the max aperture at 1.4X less than the max focal length. So, for example, if the 100-400 f/4.5 was a 140-560 lens, I have never seen a variable aperture zoom that would be f/4.5 at 400, so you would be sacrificing versatility at 400, and at least some of the focal length range below that, to make it a variable aperture zoom instead of a fixed aperture zoom that also takes a TC.That certainly seems logical, but I don't think it's always true. I seem to recall Nikon users saying the 180-400 with built in converter wasn't as sharp as it was using an external 1.4x.If that were true, then that would be a fail from Nikon for that lens. They ought to be able with a dedicated tuned TC get better performance than a generic TC that has to work with many different lenses and if they can't, then they should just introduce the lens without a buit-in TC, IMO. Maybe there was a construction issue with that lens and they had trouble making it to specifications and when the TC was engaged in at least some copies it didn't operate as it was designed.I've seen people report that not just with the 180-400 but with the 400/600 primes. Usually it is very close but sometimes an external ends up being slightly better than the internal.
Same with Canon. My 200-400TC was slightly better with my external 1.4 vs the internal. But I'm sure there were others that had the opposite experience.
People always claim the internal ones should be so much better but user experience has proven that to be false for both Canon and Nikon.With Canon I was thinking of the RF 400 f/2.8 vs the RF 800 f/5.6 and the RF 600 f/4 vs the RF 1200 f/8. The longer lenses in each pair are the shorter lens with a custon 2X TC permanently built in and there seems to be pretty good consensus that the RF 800 f/5.6 is better than the RF 400 f/2.8 with the external 2X TC and the RF 1200 f/8 is better than the RF 600 f/4 with the external 2X TC.
I expect whether the built-in TC is better than the external TC may well...Show more →
Ah yes these two lenses are $27K and $31K in Australia. So they better be the best damned lenses in the history of lenses anywhere in the universe for that insane pricing. $11K for a custom in-built 2x is literally taking the p i s s. I assume they only think Hollywood or cashed up astrophotographers would buy it so price is of no concern.
arbitrage wrote
Steve Spencer wrote
scott f wrote
Steve Spencer wrote
Lethimcook wrote
This might be a silly thought but don't built in TCs on zooms just make the lens a variable aperture zoom?I for one agree with the approach of the 300GM without TCs. It's lightweight, and anyone that wants a TC can buy the appropriate one, and then shift said TCs onto the lens they want to use at the moment. It's modular. Rather than pay for a built-in TC 3-4 times you just pay once, and deal with the quirks of putting them on or off lenses.
With regard to just making a zoom lens a variable aperture lens instead, I don't think it is that easy. I think adding a TC and making a variable aperture lens are very different designs and no variable aperture zoom that I know of has performance at 1.4X less than the max aperture at 1.4X less than the max focal length. So, for example, if the 100-400 f/4.5 was a 140-560 lens, I have never seen a variable aperture zoom that would be f/4.5 at 400, so you would be sacrificing versatility at 400, and at least some of the focal length range below that, to make it a variable aperture zoom instead of a fixed aperture zoom that also takes a TC.
Same with Canon. My 200-400TC was slightly better with my external 1.4 vs the internal. But I'm sure there were others that had the opposite experience.
People always claim the internal ones should be so much better but user experience has proven that to be false for both Canon and Nikon.
I expect whether the built-in TC is better than the external TC may well...Show more →
Ah yes these two lenses are $27K and $31K in Australia. So they better be the best damned lenses in the history of lenses anywhere in the universe for that insane pricing. $11K for a custom in-built 2x is literally taking the p i s s. I assume they only think Hollywood or cashed up astrophotographers would buy it so price is of no concern.
Jun 17, 2026 at 11:56 PM
p.6 #14Sony 100-400 f/4.5
Steve Spencer wrote:
I for one agree with the approach of the 300GM without TCs. It's lightweight, and anyone that wants a TC can buy the appropriate one, and then shift said TCs onto the lens they want to use at the moment. It's modular. Rather than pay for a built-in TC 3-4 times you just pay once, and deal with the quirks of putting them on or off lenses.Part of the value of built-in TCs is that they are tuned to the lens and therefore lead to better performance. Sometimes that is quite noticeable. Canon builds TC into the 400 f/2.8 and 600 f/4 RF lenses and the built-in TCs produce better results than the ir regular modular TC. I think that is the primary reason to build in a TC. Modularity is good, but so is better performance and if you are going to spend over ten thousand for a lens, spending a couple thousand more for optimal TC performance seems like something a lot of people willing to spend that kind of money would want.
With regard to just making a zoom lens a variable aperture lens instead, I don't think it is that easy. I think adding a TC and making a variable aperture lens are very different designs and no variable aperture zoom that I know of has performance at 1.4X less than the max aperture at 1.4X less than the max focal length. So, for example, if the 100-400 f/4.5 was a 140-560 lens, I have never seen a variable aperture zoom that would be f/4.5 at 400, so you would be sacrificing versatility at 400, and at least some of the focal length range below that, to make it a variable aperture zoom instead of a fixed aperture zoom that also takes a TC.That certainly seems logical, but I don't think it's always true. I seem to recall Nikon users saying the 180-400 with built in converter wasn't as sharp as it was using an external 1.4x.If that were true, then that would be a fail from Nikon for that lens. They ought to be able with a dedicated tuned TC get better performance than a generic TC that has to work with many different lenses and if they can't, then they should just introduce the lens without a buit-in TC, IMO. Maybe there was a construction issue with that lens and they had trouble making it to specifications and when the TC was engaged in at least some copies it didn't operate as it was designed.
That's not necessarily a design or manufacturing failure, but it could simply be a result of the restrictions based on the built-in TC setup by the fact that the TC elements go into the existing empty space within the lens, whereas in an external TC setup, the primary lens is moved further from the sensor and the TC fills in that space between the rear element and sensor. It may simply be that the latter is a better place for the TC elements to be, from an optical design point of view, and by restricting the design into one where the insertion of the TC into the optical path causes no change in the positions of the primary lens' elements relative to the sensor is so severe that the design with external TC ends up being optically slightly superior in some reported cases.
The reason lenses with built-in TCs are made is because they free the user from the hassle of
1. Removing the cap from the front of the TC, laying it into a place where rain or dust does not hit the front element of the TC
2. Taking the camera off the lens, and laying it on a place where rain or dust does not hit the exposed camera internals
3. Inserting the TC into the back of the lens
4. Removing the TC rear cap
5. Mounting the camera on the lens
6. Rebalancing the fluid or gimbal head so that it stays in balance at different angles
7. Placing the caps into a safe place where they can be easily found and are not soiled or forgotten in the dirt.
This process (and its reverse) now becomes just flicking a switch on the side of the lens while continuing to shoot in the snow, rain, wind, dust, sand, salt water etc. in the air. That's why lenses with built-in TCs are made, purchased, and used. The optical design is what it is, I am sure the manufacturers are doing their best in that area given the extortionate price they are charging for the lenses with built-in TCs.
scott f wrote
Steve Spencer wrote
Lethimcook wrote
This might be a silly thought but don't built in TCs on zooms just make the lens a variable aperture zoom?I for one agree with the approach of the 300GM without TCs. It's lightweight, and anyone that wants a TC can buy the appropriate one, and then shift said TCs onto the lens they want to use at the moment. It's modular. Rather than pay for a built-in TC 3-4 times you just pay once, and deal with the quirks of putting them on or off lenses.
With regard to just making a zoom lens a variable aperture lens instead, I don't think it is that easy. I think adding a TC and making a variable aperture lens are very different designs and no variable aperture zoom that I know of has performance at 1.4X less than the max aperture at 1.4X less than the max focal length. So, for example, if the 100-400 f/4.5 was a 140-560 lens, I have never seen a variable aperture zoom that would be f/4.5 at 400, so you would be sacrificing versatility at 400, and at least some of the focal length range below that, to make it a variable aperture zoom instead of a fixed aperture zoom that also takes a TC.
That's not necessarily a design or manufacturing failure, but it could simply be a result of the restrictions based on the built-in TC setup by the fact that the TC elements go into the existing empty space within the lens, whereas in an external TC setup, the primary lens is moved further from the sensor and the TC fills in that space between the rear element and sensor. It may simply be that the latter is a better place for the TC elements to be, from an optical design point of view, and by restricting the design into one where the insertion of the TC into the optical path causes no change in the positions of the primary lens' elements relative to the sensor is so severe that the design with external TC ends up being optically slightly superior in some reported cases.
The reason lenses with built-in TCs are made is because they free the user from the hassle of
1. Removing the cap from the front of the TC, laying it into a place where rain or dust does not hit the front element of the TC
2. Taking the camera off the lens, and laying it on a place where rain or dust does not hit the exposed camera internals
3. Inserting the TC into the back of the lens
4. Removing the TC rear cap
5. Mounting the camera on the lens
6. Rebalancing the fluid or gimbal head so that it stays in balance at different angles
7. Placing the caps into a safe place where they can be easily found and are not soiled or forgotten in the dirt.
This process (and its reverse) now becomes just flicking a switch on the side of the lens while continuing to shoot in the snow, rain, wind, dust, sand, salt water etc. in the air. That's why lenses with built-in TCs are made, purchased, and used. The optical design is what it is, I am sure the manufacturers are doing their best in that area given the extortionate price they are charging for the lenses with built-in TCs.
Jun 18, 2026 at 04:49 AM
p.6 #15Sony 100-400 f/4.5
There's a big difference between a built in TC and a built in switchable TC.
With the two Canons, not only is the lens not required to work without the TC, the TC is also in a different part of the optical design. While the 'welded on TC' description appears to be close to the truth, it's more a case of split the optical formula and 'weld in' the TC.
Having never seen a teardown of and lens with switchable TC, surely there must be at least 1 lens element that needs to be inserted into the optical path when the TC is not switched in. Just as big primes come with a 'dummy' drop in filter holder, which has (I believe) just a flat piece of glass which is removed when an actual drop in filter is fitted.
Steve Spencer wrote:
With Canon I was thinking of the RF 400 f/2.8 vs the RF 800 f/5.6 and the RF 600 f/4 vs the RF 1200 f/8. The longer lenses in each pair are the shorter lens with a custon 2X TC permanently built in and there seems to be pretty good consensus that the RF 800 f/5.6 is better than the RF 400 f/2.8 with the external 2X TC and the RF 1200 f/8 is better than the RF 600 f/4 with the external 2X TC.
I expect whether the built-in TC is better than the external TC may well...Show more →
With the two Canons, not only is the lens not required to work without the TC, the TC is also in a different part of the optical design. While the 'welded on TC' description appears to be close to the truth, it's more a case of split the optical formula and 'weld in' the TC.
Having never seen a teardown of and lens with switchable TC, surely there must be at least 1 lens element that needs to be inserted into the optical path when the TC is not switched in. Just as big primes come with a 'dummy' drop in filter holder, which has (I believe) just a flat piece of glass which is removed when an actual drop in filter is fitted.
Steve Spencer wrote:
With Canon I was thinking of the RF 400 f/2.8 vs the RF 800 f/5.6 and the RF 600 f/4 vs the RF 1200 f/8. The longer lenses in each pair are the shorter lens with a custon 2X TC permanently built in and there seems to be pretty good consensus that the RF 800 f/5.6 is better than the RF 400 f/2.8 with the external 2X TC and the RF 1200 f/8 is better than the RF 600 f/4 with the external 2X TC.
I expect whether the built-in TC is better than the external TC may well...Show more →
Jun 18, 2026 at 05:38 AM
p.6 #16Sony 100-400 f/4.5
Choderboy wrote:
There's a big difference between a built in TC and a built in switchable TC.
With the two Canons, not only is the lens not required to work without the TC, the TC is also in a different part of the optical design. While the 'welded on TC' description appears to be close to the truth, it's more a case of split the optical formula and 'weld in' the TC.
Having never seen a teardown of and lens with switchable TC, surely there must be at least 1 lens element that needs to be inserted into the optical path when the TC...Show more →
I expect whether the built-in TC is better than the external TC may well depend on both the quality of the built-in TC and how well it is built and the qualty of the external TC and how well it is built. Copy variation could also play a role of course. For some lenses the internal TC might not provide any performance advantage, but for others it might.
I'd agree with that. A switchable TC is not the same as what Canon did with their rushed job of making the 800 and 1200.
As far as I know, there is no element that drops in when the built-in TC lenses switch their TCs out. Because the TC is not at the end of the optical path in these lenses it seems they are designed to work as a bare lens when the TC is out. Unlike a rear mounted switchable TC that would need extra glass for the "1x" setting to not act as an extension tube when switched out.
There's a big difference between a built in TC and a built in switchable TC.
With the two Canons, not only is the lens not required to work without the TC, the TC is also in a different part of the optical design. While the 'welded on TC' description appears to be close to the truth, it's more a case of split the optical formula and 'weld in' the TC.
Having never seen a teardown of and lens with switchable TC, surely there must be at least 1 lens element that needs to be inserted into the optical path when the TC...Show more →
Steve Spencer wrote
With Canon I was thinking of the RF 400 f/2.8 vs the RF 800 f/5.6 and the RF 600 f/4 vs the RF 1200 f/8. The longer lenses in each pair are the shorter lens with a custon 2X TC permanently built in and there seems to be pretty good consensus that the RF 800 f/5.6 is better than the RF 400 f/2.8 with the external 2X TC and the RF 1200 f/8 is better than the RF 600 f/4 with the external 2X TC.I expect whether the built-in TC is better than the external TC may well depend on both the quality of the built-in TC and how well it is built and the qualty of the external TC and how well it is built. Copy variation could also play a role of course. For some lenses the internal TC might not provide any performance advantage, but for others it might.
I'd agree with that. A switchable TC is not the same as what Canon did with their rushed job of making the 800 and 1200.
As far as I know, there is no element that drops in when the built-in TC lenses switch their TCs out. Because the TC is not at the end of the optical path in these lenses it seems they are designed to work as a bare lens when the TC is out. Unlike a rear mounted switchable TC that would need extra glass for the "1x" setting to not act as an extension tube when switched out.
Jun 18, 2026 at 05:53 AM
p.6 #17Sony 100-400 f/4.5
Choderboy wrote:
There's a big difference between a built in TC and a built in switchable TC.
With the two Canons, not only is the lens not required to work without the TC, the TC is also in a different part of the optical design. While the 'welded on TC' description appears to be close to the truth, it's more a case of split the optical formula and 'weld in' the TC.
Having never seen a teardown of and lens with switchable TC, surely there must be at least 1 lens element that needs to be inserted into the optical path when the TC...Show more →
I expect whether the built-in TC is better than the external TC may well depend on both the quality of the built-in TC and how well it is built and the qualty of the external TC and how well it is built. Copy variation could also play a role of course. For some lenses the internal TC might not provide any performance advantage, but for others it might.
Nobody said that a built-in TC that is not switchable is the same as a built-in TC that switches in and out. I certainly didn't say that. I raised the example of the Canon RF 800 f/5.6 and 1200 f/8 to make the point that a TC, switchable or not, that is custom designed for the lens has the potential to produce better IQ than using a TC that is designed to work with several different lenses. I think that point stands.
It is certainly true that switchable TCs have to be designed and built differently that TCs that are added to the lens as a fixed part of the design (i.e., welded onto the lens), but that doesn't change the potential for a custom built TC to improve IQ over a more general design that has to work with several different lenses.
There's a big difference between a built in TC and a built in switchable TC.
With the two Canons, not only is the lens not required to work without the TC, the TC is also in a different part of the optical design. While the 'welded on TC' description appears to be close to the truth, it's more a case of split the optical formula and 'weld in' the TC.
Having never seen a teardown of and lens with switchable TC, surely there must be at least 1 lens element that needs to be inserted into the optical path when the TC...Show more →
Steve Spencer wrote
With Canon I was thinking of the RF 400 f/2.8 vs the RF 800 f/5.6 and the RF 600 f/4 vs the RF 1200 f/8. The longer lenses in each pair are the shorter lens with a custon 2X TC permanently built in and there seems to be pretty good consensus that the RF 800 f/5.6 is better than the RF 400 f/2.8 with the external 2X TC and the RF 1200 f/8 is better than the RF 600 f/4 with the external 2X TC.I expect whether the built-in TC is better than the external TC may well depend on both the quality of the built-in TC and how well it is built and the qualty of the external TC and how well it is built. Copy variation could also play a role of course. For some lenses the internal TC might not provide any performance advantage, but for others it might.
Nobody said that a built-in TC that is not switchable is the same as a built-in TC that switches in and out. I certainly didn't say that. I raised the example of the Canon RF 800 f/5.6 and 1200 f/8 to make the point that a TC, switchable or not, that is custom designed for the lens has the potential to produce better IQ than using a TC that is designed to work with several different lenses. I think that point stands.
It is certainly true that switchable TCs have to be designed and built differently that TCs that are added to the lens as a fixed part of the design (i.e., welded onto the lens), but that doesn't change the potential for a custom built TC to improve IQ over a more general design that has to work with several different lenses.
Jun 18, 2026 at 06:16 AM
p.6 #18Sony 100-400 f/4.5
I can see why a 'substitue element' may not be needed.
I'm not surprised a switchable TC will not always beat a rear mounted TC.
From the old DSLR days, when a lot more discussion happened, it was fairly common knowledge that even after MFA was introduced, bodies and lenses would be sent to Canon for 'calibration'.
I believe there were 3 thicknesses of bayonets and these were sometimes changed to arrive at a workable combination to allow for tolerances in both lenses and body.
So the tolerances are very tight.
Therefore I think meeting tolerance requirements with a TC that needs to swing in and out of position would be an engineering challenge.
I'm not surprised a switchable TC will not always beat a rear mounted TC.
From the old DSLR days, when a lot more discussion happened, it was fairly common knowledge that even after MFA was introduced, bodies and lenses would be sent to Canon for 'calibration'.
I believe there were 3 thicknesses of bayonets and these were sometimes changed to arrive at a workable combination to allow for tolerances in both lenses and body.
So the tolerances are very tight.
Therefore I think meeting tolerance requirements with a TC that needs to swing in and out of position would be an engineering challenge.
Jun 18, 2026 at 06:26 AM
p.6 #19Sony 100-400 f/4.5
I think it is logical to expect a TC, custom made for a lens, should have potential to be superior to a more general design.
It does not seem to be the result we can expect though, with existing lenses.
This applies to both switchable TC designs and the Canon 800 and 1200s.
Steve Spencer wrote:
Nobody said that a built-in TC that is not switchable is the same as a built-in TC that switches in and out. I certainly didn't say that. I raised the example of the Canon RF 800 f/5.6 and 1200 f/8 to make the point that a TC, switchable or not, that is custom designed for the lens has the potential to produce better IQ than using a TC that is designed to work with several different lenses. I think that point stands.
It is certainly true that switchable TCs have to be designed and built differently that TCs that...Show more →
It does not seem to be the result we can expect though, with existing lenses.
This applies to both switchable TC designs and the Canon 800 and 1200s.
Steve Spencer wrote:
Nobody said that a built-in TC that is not switchable is the same as a built-in TC that switches in and out. I certainly didn't say that. I raised the example of the Canon RF 800 f/5.6 and 1200 f/8 to make the point that a TC, switchable or not, that is custom designed for the lens has the potential to produce better IQ than using a TC that is designed to work with several different lenses. I think that point stands.
It is certainly true that switchable TCs have to be designed and built differently that TCs that...Show more →
Jun 18, 2026 at 06:32 AM
p.6 #20Sony 100-400 f/4.5
Choderboy wrote:
I think it is logical to expect a TC, custom made for a lens, should have potential to be superior to a more general design.
It does not seem to be the result we can expect though, with existing lenses.
This applies to both switchable TC designs and the Canon 800 and 1200s.
It is certainly true that switchable TCs have to be designed and built differently that TCs that are added to the lens as a fixed part of the design (i.e., welded onto the lens), but that doesn't change the potential for a custom built TC to improve IQ over a more general design that has to work with several different lenses.
I think the potential is there and that potential is even realized with the Canon RF 800 and 1200. It remains to be seen if it will be realized in future lenses.
I think it is logical to expect a TC, custom made for a lens, should have potential to be superior to a more general design.
It does not seem to be the result we can expect though, with existing lenses.
This applies to both switchable TC designs and the Canon 800 and 1200s.
Steve Spencer wrote
Nobody said that a built-in TC that is not switchable is the same as a built-in TC that switches in and out. I certainly didn't say that. I raised the example of the Canon RF 800 f/5.6 and 1200 f/8 to make the point that a TC, switchable or not, that is custom designed for the lens has the potential to produce better IQ than using a TC that is designed to work with several different lenses. I think that point stands.It is certainly true that switchable TCs have to be designed and built differently that TCs that are added to the lens as a fixed part of the design (i.e., welded onto the lens), but that doesn't change the potential for a custom built TC to improve IQ over a more general design that has to work with several different lenses.
I think the potential is there and that potential is even realized with the Canon RF 800 and 1200. It remains to be seen if it will be realized in future lenses.
Jun 18, 2026 at 06:59 AM