j4nu wrote:
Well, if I ever decide to drop 3300e on a lens, then I'd probably be fine with paying extra to be 100% sure I get a good copy ...
The question is: how much? Would you for example be willing to pay 6000€ instead of 3000€ to get a lens that's centered at all focal lengths? Maybe I would, maybe not.
It's not primarily a question of (cheap) testing but more a question of what to do with lenses, that are outside of a certain tolerance in the test. There are the following options:
1. Throw away all lenses, that are outside of the tolerance. Depending on the percentage, this would likely double price for the remaining lenses (6000€ instead of 3000€).
2. Sell two categories of the same lens: For example 2000€ for lenses outside of the tolerance and 5000€ for within the tolerance. Would this work, probably not. It would likely not be accepted by the customer.
3. Adjust any lens (likely manually) if outside of the tolerance. Zeiss does this with their Cine lenses. I've visited their factory. Impressive. It works, but their lenses costs minimum 20000€. Maybe this could be achieved for a bit less in other countries or with a higher automation level. But a 12-24 GM would likely cost then minimum 10000€.
4. Design a lens to be more robust against (unavoidable) production tolerances. Definitely the most cost effective way. But this often leads to much larger lenses and with certain key requirements is just not possible. I'm not sure if you really could design a relatively small 12-24 f/2.8 zoom lens to be robust against production tolerances.
5. Just accept that a certain percentage of all lenses have a weaker (corner) performance, even with GM lenses costing above 3000€. The assumption is, that most customers will likely not test their lenses and won't see the problems. This is also a cost effective way (for Sony) and this is what's happening right now. I don't like this solution, but I understand it from a business perspective. And I think there is no easy way around it, unless a lot of people are willing to pay much higher prices for 100% tested lenses and stricter tolerances and/or accept much larger lenses.
Bobu wrote:
The question is: how much? Would you for example be willing to pay 6000€ instead of 3000€ to get a lens that's centered at all focal lengths? Maybe I would, maybe not.
It's not primarily a question of (cheap) testing but more a question of what to do with lenses, that are outside of a certain tolerance in the test. There are the following options:
1. Throw away all lenses, that are outside of the tolerance. Depending on the percentage, this would likely double price for the remaining lenses (6000€ instead of 3000€).
2. Sell two categories of the same lens: For example 2000€ for lenses outside of the tolerance and 5000€ for within the tolerance. Would this work, probably not. It would likely not be accepted by the customer.
3. Adjust any lens (likely manually) if outside of the tolerance. Zeiss does this with their Cine lenses. I've visited their factory. Impressive. It works, but their lenses costs minimum 20000€. Maybe this could be achieved for a bit less in other countries or with a higher automation level. But a 12-24 GM would likely cost then minimum 10000€.
4. Design a lens to be more robust against (unavoidable) production tolerances. Definitely the most cost effective way. But this often leads to much larger lenses and with certain key requirements is just not possible. I'm not sure if you really could design a relatively small 12-24 f/2.8 zoom lens to be robust against production tolerances.
5. Just accept that a certain percentage of all lenses have a weaker (corner) performance, even with GM lenses costing above 3000€. The assumption is, that most customers will likely not test their lenses and won't see the problems. This is also a cost effective way (for Sony) and this is what's happening right now. I don't like this solution, but I understand it from a business perspective. And I think there is no easy way around it, unless a lot of people are willing to pay much higher prices for 100% tested lenses and stricter tolerances and/or accept much larger lenses....Show more →
Yes, all valid points... I think if it wasn't for production in volume, such lenses would cost several times more... so we need to take this production process with all its pros and cons.
Of course, it also boils down to the pricing matching the intended customer base, as in your example with Zeiss Cine lenses, but even for "plain" photographers there are brands that charge a lot more for their products than Sony .
Still, as a receiver of a bad copy, it's a tough pill to swallow if you know that for the same money you could be getting a "perfect" one... but I don't expect this to change due to reasons you outlined above.
Bobu wrote:
The question is: how much? Would you for example be willing to pay 6000€ instead of 3000€ to get a lens that's centered at all focal lengths? Maybe I would, maybe not.
It's not primarily a question of (cheap) testing but more a question of what to do with lenses, that are outside of a certain tolerance in the test. There are the following options:
1. Throw away all lenses, that are outside of the tolerance. Depending on the percentage, this would likely double price for the remaining lenses (6000€ instead of 3000€).
2. Sell two categories of the same lens: For example 2000€ for lenses outside of the tolerance and 5000€ for within the tolerance. Would this work, probably not. It would likely not be accepted by the customer.
3. Adjust any lens (likely manually) if outside of the tolerance. Zeiss does this with their Cine lenses. I've visited their factory. Impressive. It works, but their lenses costs minimum 20000€. Maybe this could be achieved for a bit less in other countries or with a higher automation level. But a 12-24 GM would likely cost then minimum 10000€.
4. Design a lens to be more robust against (unavoidable) production tolerances. Definitely the most cost effective way. But this often leads to much larger lenses and with certain key requirements is just not possible. I'm not sure if you really could design a relatively small 12-24 f/2.8 zoom lens to be robust against production tolerances.
5. Just accept that a certain percentage of all lenses have a weaker (corner) performance, even with GM lenses costing above 3000€. The assumption is, that most customers will likely not test their lenses and won't see the problems. This is also a cost effective way (for Sony) and this is what's happening right now. I don't like this solution, but I understand it from a business perspective. And I think there is no easy way around it, unless a lot of people are willing to pay much higher prices for 100% tested lenses and stricter tolerances and/or accept much larger lenses....Show more →
I have the 12 24 g f.4 and it is perfect at all focal lengths and costs the goal .. on this they controlled better?
Stefano 1967 wrote:
I have the 12 24 g f.4 and it is perfect at all focal lengths and costs the goal .. on this they controlled better?
Congratulations!
And no, it's probably even worse. I tried 5 samples of this lens and all were decenterend at different corners/sides (and gave up with this lens). I think Fred had to test 10 samples of this lens to find a good one.
In my experience Zeiss and Leica lenses have the best percentage of good (enough) lenses (about 80% are keepers).
Sigma is next with about 60-70% keepers (but only with their current generation, in the past they were much worse).
And Sony zoom lenses are the worst with only 30-40% keepers.
But this is just my personal experience based on maybe 30 lens purchases. The number is far too low for any statistical evidence.
And no, it's probably even worse. I tried 5 samples of this lens and all were decenterend at different corners/sides (and gave up with this lens). I think Fred had to test 10 samples of this lens to find a good one.
In my experience Zeiss and Leica lenses have the best percentage of good (enough) lenses (about 80% are keepers).
Sigma is next with about 60-70% keepers (but only with their current generation, in the past they were much worse).
And Sony zoom lenses are the worst with only 30-40% keepers.
But this is just my personal experience based on maybe 30 lens purchases. The number is far too low for any statistical evidence.
...Show more →
probably i was lucky with all my Sony optics until the 24 105 is perfect i also have the batis 18 single af optic then the loxia 21mm over 24 gm 135 gm 400 600 gm 70 200 gm and 100 400 gm all perfect maybe my shopkeeper give good stuff ... I have a doubt because that pecentuali that you say I do not reply in Italy
I don't believe that there is "good stuff" and "bad stuff" and certain shops get all the good stuff. The 24 GM, 135 GM, 400 GM and 600 GM seems to have a rather low sample variation, from what I've read (no personal experience with theses lenses). But with the 24-105, 70-200 and 100-400 you were probably just lucky.
Bobu wrote:
I don't believe that there is "good stuff" and "bad stuff" and certain shops get all the good stuff. The 24 GM, 135 GM, 400 GM and 600 GM seems to have a rather low sample variation, from what I've read (no personal experience with theses lenses). But with the 24-105, 70-200 and 100-400 you were probably just lucky.
we will see when i get my 12 24 gm tuesday if i get lucky. however the trusted seller is trying it for me before sending it to me
Fortunately for Sony, and unfortunately for a some of us, it appears that most all buyers of lenses are not as discerning as some of us on these forums, so Sony (and others) can get by with selling lenses with such flaws.
With nearly every manufacturer, including Sony, now adopting Six-Sigma programs in their manufacturing, this tells me that they are not even performing QA inspections on de-centering. If they are, their acceptable tolerance band is obviously huge. In the end, I'm sure that this is all based upon buyer acceptance levels, which is obviously very accommodating to some optical flaws.
When Sony first released the FE 35mm f1.4, I received it just hours before a trip, so I did not test it before I left. On return from the trip (outside the 30 day vendor return window), with a lot of soft images, I technically tested the lens. It was horribly de-centered and not particularly sharp - even in the center. I sold the lens, expecting that I would be taking a return and refunding the buyer, thus creating an expensive paper-weight. A couple weeks later, I received a PM from the buyer who 'waxed poetic' about how stunning the lens was.
Over the years, I have sold many dozens of lenses that I considered to be optically challenged. In every case, the buyer(s) were very happy with the lenses. Every case!
It is not just Sony. Several years ago, I went through four copies of the Canon 16-35mm f2.8 III to obtain one that was not terribly de-centered. I went through a lot of Nikon lenses, when I shot Nikon. I'm surprised that vendors did not cut me off, with all my exchanges!
I now shoot a lot of Sigma ART lenses. The positive hit-rate for optical integrity has been amazingly good, for me, with the ART series. With Sony, my best experience was with the GM 135 (or 100-400), which was almost optical perfection.
My GM 12-24mm f2.8 arrives Tuesday. I'm begging the lens-gods to make this a good one!
In the end, I am just an amateur photographer hack that reinvigorated the hobby in my retirement; but, if I am going to spend some time on it, I would like the results to be of high quality.
I agree that for many (most?) users corner asymmetry may not even be noticed, so suboptimal lenses can be just fine for them. When I buy a used lens outside this forum it's very rare that the seller even knows how their lens performs in that regard. And even if you are more discerning, DOF will often impact your corners anyway unless you focus stack.
I suspect the number of us who really need very sharp corners is pretty small, and therefore it may not be a high priority for manufacturers. They can make claims for sharpness based on theoretical or selective samples of the lens, and that will keep most users satisfied that they have a good lens without actually testing it.
They would all do their sums. The rate of return may be quite inelastic relative to the cost of designing, testing and resourcing better lens design QA protocols (it starts there, some designs are more tolerant like slow lenses and low element count lenses), then better fabrication control and assembly, finishing and testing control.
Many character lens buyers rank tech perfection below what they are looking for the lens to deliver, a case of very different criteria. Many want the full image to deliver these criteria of theirs, and don't go 'looking for problems' at high magnifications.
I believe the makers are doing a good job, all of them, given the complexity of modern lenses and the imperative to market them at their designated price points. But yeah. It's one reason I love using high tech manual focus lenses, much less going on inside and makers know their audiences 'have standards' and expect their lenses to last.
Fred Miranda wrote:
Do you see any asymmetry at other focal lengths? If it happens consistently throughout the range (only changing in severity), you could try this: https://www.fredmiranda.com/forum/topic/1662397
Basically it's a method to correct focus plane tilt. It should work well with primes but it's always worth investigating.
My 3rd copy of the GM 12-24 arrived today, and there was good news and bad news.
The bad news was that again corner symmetry was below what I consider acceptable. But the good news was that it went away once stopped down to about 5.6, and was similar in pattern across the whole zoom range, which to me implied a shim inside the lens mount might indeed improve things in this case.
I paused momentarily before opening up a brand new US$3000 lens, but then looked at my self-adhesive copper foil that I still had from my adapter shimming days, and decided trying this might be a lot less painful than cycling through who-knows how many more copies to get a good one.
Luckily it turned out not too hard if you have some experience doing this sort of thing, and a few hours later I had a copy I now consider acceptable, albeit clearly not perfect. This is with a single layer of foil in just one corner inside the lens' mount plate. I tried two layers as well but that was too much, so for now this will have to do. Unfortunately I don't remember the thickness of the foil, but I'm pretty sure it wouldn't be more than 10um.
****** PLEASE NOTE *******
I'm not suggesting anyone else should try this on such an expensive lens, and will not be held responsible if you do and something goes wrong
********************************
Below are F2.8 extreme corner comparisons before and after shimming, at 12 and 24mm, 100% crops from 61MP (minimal sharpening).
I realized tonight I've been doing this the hard way. Putting the adhesive shims temporarily on the outside of the lens' mount plate (or on the camera's mount) should work just as well for exploratory purposes, and avoids removing the plate on each iteration. I will try some more variations tomorrow, and post if I get any further imrovements.
The way the Sony 12-24/2.8 GM rear filter slot works, glass filters won't fit since the filter must blend in order to go in. (only flexible gel/film filters work)
rvh23 wrote:
I realized tonight I've been doing this the hard way. Putting the adhesive shims temporarily on the outside of the lens' mount plate (or on the camera's mount) should work just as well for exploratory purposes, and avoids removing the plate on each iteration. I will try some more variations tomorrow, and post if I get any further imrovements.
Is the lens decentered or focal plane tilted? The best way to find out is to focus at the very corners individually and compare them. If they corners look equal, the lens is not decentered and there is hope of fixing the asymmetry. The trick with zooms is that as we change focal length, the focal plane usually gets swung or tilted and therefore shims may not work for all FLs.
Fred Miranda wrote:
Is the lens decentered or focal plane tilted? The best way to find out is to focus at the very corners individually and compare them. If they corners look equal, the lens is not decentered and there is hope of fixing the asymmetry. The trick with zooms is that as we change focal length, the focal plane usually gets swung or tilted and therefore shims may not work for all FLs.
There is definately a consistent tilt/swing that has improved across the whole range with the shim I installed. But in addition to that, the lower left corner does seem slightly weaker (perhaps a little more astigmatism) even when each corner is focused on in turn. I'm really on the fence with this copy. I know it could be better but it could be a whole lot worse too, and stopped down a bit it's fine.
I’m perplexed as to how anyone could efficiently utilize these rear-mount filters.
First, I find that removing lenses outdoors is a sure-fire recipe for sensor dust - a real problem when shooting stopped-down.
If I am shooting ND filters, I always take shots of the scene without the filter, in case vegetation moved, skies are blown out (no variable filter), portions of the water too softened, etc. I can then selectively paint layers in PS for correction.
I realize that some static scenes, would work, but it sure seems like a ton of flexibility is lost, compared with front filters.
I bit the bullet and ordered my Nisi holder for this lens, yesterday, since I have little use for the gels.
InFocus2014 wrote:
I’m perplexed as to how anyone could efficiently utilize these rear-mount filters.
First, I find that removing lenses outdoors is a sure-fire recipe for sensor dust - a real problem when shooting stopped-down.
I've used the same Haida rear filters (without the new adapter) on my last trip to Scandinavia with my Sigma 14-24. I must say that I'm really happy with the usuability/handling. They are very easy to change. Just matter of seconds. Even under difficult conditions. And they are so small and light. I vastly prefer them over any 150mm front filter solution. I would never buy an UW lens anymore that doesn't accept rear filters.
rvh23 wrote:
There is definately a consistent tilt/swing that has improved across the whole range with the shim I installed. But in addition to that, the lower left corner does seem slightly weaker (perhaps a little more astigmatism) even when each corner is focused on in turn. I'm really on the fence with this copy. I know it could be better but it could be a whole lot worse too, and stopped down a bit it's fine.
Does that softer corner improve when focusing on it? If not, the lens could have a decentered element as well.
Shimming can fix focal plane tilt/swing but it won't be useful if the lens is decentered.
A fellow FM member just emailed me his centering test and his lens looked excellent at 12mm and 24mm.
...
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I had a copy I now consider acceptable, albeit clearly not perfect. This is with a single layer of foil in just one corner inside the lens' mount plate. I tried two layers as well but that was too much, so for now this will have to do. Unfortunately I don't remember the thickness of the foil, but I'm pretty sure it wouldn't be more than 10um.
