Steve Spencer wrote:
Is the Sigma 85 f/1.4 DG DN worse than the FE 85 f/1.8 at the same apertures? One would expect worse AF performance especially for fast erratically moving subjects with a wider aperture (i.e., narrower depth of field). If the Sigma really is doing worse, then I wonder whether Sony really has fully open mount protocols, or if they are holding back and only providing third parties with some, but not all, the AF mount protocols for E mount. If Sony truly has an open mount, then they should have no inherent AF advantage for their lenses.
Absolutely.
The FE 85/1.8 hardly ever misses on my A9, regardless of the aperture or speed of the subject. The same goes for other fast focusing Sony lenses like the 135GM and 100-400 GM.
I just can't say the same thing about my 85 DG DN (and 45) even though I feel their AF motors are plenty fast as well.
All Sigma DG DN lenses I own or tried so far (45, 85, 100-400) have the tendency to backfocus during tracking. A subject doesn't even have to be super fast to cause this.
The first shot of a sequence is spot on most of the time, the following ones often are not. Press the AF button again during tracking and the first shot again is perfectly fine... etc etc. This shows me that the AF motor is fast enough for the subject itself, but that the lens software can't keep up with the actual tracking.
It's not a deal breaker, but it would've been so nice if the AF-C performance matched their great optical quality and price.
I guess you can't have it all.
Jochenb wrote:
The FE 85/1.8 hardly ever misses on my A9, regardless of the aperture or speed of the subject. The same goes for other fast focusing Sony lenses like the 135GM and 100-400 GM.
I just can't say the same thing about my 85 DG DN (and 45) even though I feel their AF motors are plenty fast as well.
All Sigma DG DN lenses I own or tried so far (45, 85, 100-400) have the tendency to backfocus during tracking. A subject doesn't even have to be super fast to cause this.
The first shot of a sequence is spot on most of the time, the following ones often are not. Press the AF button again during tracking and the first shot again is perfectly fine... etc etc. This shows me that the AF motor is fast enough for the subject itself, but that the lens software can't keep up with the actual tracking.
It's not a deal breaker, but it would've been so nice if the AF-C performance matched their great optical quality and price.
I guess you can't have it all. ...Show more →
This may be conflating AF motor speed with something else.
I believe Sony significantly increased the lens communication rate with the A9 and their more recent lenses. This is only documented by them with the list of lenses that are compatible with 20 FPS burst tracking on the A9. So far third-party lenses haven't supported that. Recent lower end bodies without 20 FPS capability seem to benefit with these newer lenses too. The greatly improved focusing performance of the FE 50mm F1.8 on the third generation and newer bodies is an example. It is one of the lenses on the 20 FPS list.
I received my 2nd copy earlier today. While there are small traces of dust, they are no where near the size of the FOD in the first copy I sent back. I updated the lens firmware to v02 and will be taking the lens out downtown tomorrow morning to break it in.
Jochenb wrote:
That's not a fair comparison at all, because of the super slow AF motor in the GM.
The one in the 85 DG DN is very fast (that's why the first shots in an AF-C burst are spot on most of the time), but in tracking it's just not reliable.
For slowly predictable moving subjects it's all fine, anything faster/erratic not.
The FE 85/1.8 is MUCH better at this (on my A9) than the Sigma 85 DG DN. The exact same goes for the 100-400 DG DN compared to the Sony 100-400.
All this "it's not designed for that" talk is just too easy. Sigma's AF algorithm just isn't at the same level as Sony's own native lenses. That's my clear conclusion on both my A9 and A7RIII.
Other than that the Sigma DG DN line are lovely lenses for a great price.
I don't think it's only about the motor in the GM, as about the much heavier lens elements that have to be moved in an F1.4 lens, powered by the camera battery. The extra mass means that there is more momentum, so changes are much harder to execute smoothly. So it's no surprise that f1.8 class lenses track better (compare the 1.8/55 and 1.4/50 Sony lenses tracking, and they both have lighter elements than the comparable speed 85s).
So I think erratic movement tracking is likely to be a bit poor in 1.4 class short teles. This doesn't mean there won't be cases where lenses vary for other reasons, and perhaps sometimes it's down to firmware, but there are so many variables. Some very long lenses, though, if they aren't too fast, can be focused with very light focussing groups. But it depends on design trade-offs. Interestingly, it often takes a rather larger design to get focussing to work well with very small focussing group elements.
Jochenb wrote:
All this "it's not designed for that" talk is just too easy. Sigma's AF algorithm just isn't at the same level as Sony's own native lenses. That's my clear conclusion on both my A9 and A7RIII.
Thanks for your conclusion, but in my opinion it's not just "too easy", I think this is "laziness" if Sigma doesn't keep finding ways to improve their AF-C performance.
Unless Sigma has made a strategic calculation and this is "intentional laziness" because they know "potential buyers of this lens will buy this lens no matter what, and besides those who are aware of AF-C performance issue, will make excuses for our complacency, even citing SA as the reason for poor AF-C performance."
We shouldn't give Sigma an excuse to not improve their AF-C performance on Sony bodies. GM85 has SA at 1.4 too which I like the look of. but I don't see that lens missing focus in AF-C.
Jochenb wrote:
All Sigma DG DN lenses I own or tried so far (45, 85, 100-400) have the tendency to backfocus during tracking. A subject doesn't even have to be super fast to cause this.
First, thanks for providing this user experience, I only have the Sigma 45 DG DN so I didn't know their other DG DN lenses suffer from AF-C performance too. This confirms my concern that buying the 35mm DG DN lens and hoping its AF-C works like a native Sony is unrealistic.
Jochenb wrote:
It's not a deal breaker, but it would've been so nice if the AF-C performance matched their great optical quality and price. I guess you can't have it all.
I agree with you 100%. I am in love with the optical design of 45 DG DN -- SA wide open and sharpness picks up when stopping down. Why can't they work a bit harder to deliver better AF-C performance to supporters like us?
j4nu wrote:
Comparing 45mm AF-C performance to other DG DN lenses is ridiculous...
I don't know if you are insulting me as a ridiculous person or the idea itself is ridiculous, but in either case, could you elaborate please why I am ridiculous or the idea itself is ridiculous so I can be "educated?"
I didn't mean to insult you, so please accept my apologies if it came off this way.
The reason I said this so directly is because there is a huge difference between those lenses.
45mm AF-C is not reliable even on static targets. You can take a couple photos with the same focus point and see the focus changes (more or less) between nearly every shot.
On the other hand, remaining DG DN lenses in AF-C are weaker than Sony's offerings in tracking moving targets, but in general use it's hard to tell them apart...
Wonderful photos that almost have me sold on the Sigma 45mm f/2.8. However, I already have a Voigtlander Nokton 50mm f/1.2. Would I just be duplicating rendering and relative FL with a Sigma 45 purchase? Thanks for any insight anyone can provide.
j4nu wrote:
I didn't mean to insult you, so please accept my apologies if it came off this way.
The reason I said this so directly is because there is a huge difference between those lenses.
45mm AF-C is not reliable even on static targets. You can take a couple photos with the same focus point and see the focus changes (more or less) between nearly every shot.
On the other hand, remaining DG DN lenses in AF-C are weaker than Sony's offerings in tracking moving targets, but in general use it's hard to tell them apart...
Thanks for your clarification and no need for apologies, just looking for clarifications, but I appreciate it though.
Thanks also for giving a couple of examples, these really show that we must use lenses carefully and mindfully based on their characteristics, especially for this 45mm DG DN.
I got mine here on the B&S forum for half the price of a few Batis 40s I was chasing. Supposed to be delivered Thursday and hoping it's a good copy and will replace zony 35/2.8 filling the gap between Batis 25 and 85.
'45mm AF-C is not reliable even on static targets.'
Sigma's 45mm is schizophrenic and is going through an identity crisis. It needs professional help. When it sees the images its users so readily produce, well it thinks it's a manual focus lens and slows down the autofocus to try to make the transition.
Wonderful photos that almost have me sold on the Sigma 45mm f/2.8. However, I already have a Voigtlander Nokton 50mm f/1.2. Would I just be duplicating rendering and relative FL with a Sigma 45 purchase? Thanks for any insight anyone can provide.
What I wouldn’t give for a CV 50/1.2 with autofocus. I can always dream.
Dec 08, 2020 at 01:12 AM
Steve Spencer Offline • • • • • • • Upload & Sell: On
FJR1 wrote:
Wonderful photos that almost have me sold on the Sigma 45mm f/2.8. However, I already have a Voigtlander Nokton 50mm f/1.2. Would I just be duplicating rendering and relative FL with a Sigma 45 purchase? Thanks for any insight anyone can provide.
I have both lenses and like both a lot, but I don't think the rendering is the same. The Sigma 45 has the fairly unique combination at f/2.8 of having very low CA (including axial CA) and relatively high SA. The CV 50 f/1.2 at f/2.8 has both a bit more axial CA and bit less SA (at wider apertures the CV 50 f/1.2 has quite a bit more SA, especially at closer focus distances, but also quite a bit more axial CA), so although I like the rendering of both lenses I don't think they are all the similar. I should admit, however, that the reason we have the Sigma 45 is my wife prefers AF lenses and she has the Sigma 45 in her bag almost all the time, whereas I prefer MF lenses and I have the CV 50 f/1.2 in my bag almost all the time.
Steve Spencer wrote:
I have both lenses and like both a lot, but I don't think the rendering is the same. The Sigma 45 has the fairly unique combination at f/2.8 of having very low CA (including axial CA) and relatively high SA. The CV 50 f/1.2 at f/2.8 has both a bit more axial CA and bit less SA (at wider apertures the CV 50 f/1.2 has quite a bit more SA, especially at closer focus distances, but also quite a bit more axial CA), so although I like the rendering of both lenses I don't think they are all the similar. I should admit, however, that the reason we have the Sigma 45 is my wife prefers AF lenses and she has the Sigma 45 in her bag almost all the time, whereas I prefer MF lenses and I have the CV 50 f/1.2 in my bag almost all the time....Show more →
Thanks for the thorough and thoughtful reply. I greatly appreciate the explanation of the rendering differences and decided to sell the CV 50 1.2 based on my preference for AF at this focal length.
My original plan on taking the lens out last week was a bust. However, I was able to escape the house this morning and spend some time downtown with it. I must say, the lens felt "just right" in hand. It's definitely not big and heavy and surely doesn't feel like there's nothing attached to the camera. It's presence felt firm and unobtrusive. A true Goldilocks lens!
I set my camera to AF-S as AF-C felt too slow, even at medium to far off distances.
Mystik wrote:
Just got mine after sitting on the fence for months. Glad I did...renders beautifully and the form factor is awesome.
Just got the lens too. Need more time to test it, but already have a question. Some reviewers say the focusing is almost silent, but I'd say it's a bit louder than my FE 28/2 (but much quieter than the FE 50/1.8). Am I being too picky? What do you think of it? Thanks!
trepet wrote:
Just got the lens too. Need more time to test it, but already have a question. Some reviewers say the focusing is almost silent, but I'd say it's a bit louder than my FE 28/2 (but much quieter than the FE 50/1.8). Am I being too picky? What do you think of it? Thanks!
If my memory serves me right, I recall the AF-C autofocus making more noise than AF-S...which is understandable since this lens struggles with AF-C which causes the motor to work more and thus make more noise. I decided to only use AF-S with this lens because of its continuous focusing struggle. The noise the lens makes when focusing in AF-S mode was quiet for me...partly because it was quick. I don’t shoot video so autofocus noise isn’t a concern to me...autofocus speed does, however.
I only have two other AF e-mount lenses (Tammy 28-75/2.8 & Sony 85/1.8) which I rarely use and couldn’t even tell you (from memory) if they were louder our not. The 85/1.8 though, has awesome autofocus speed in both AF-C and AF-S modes though.
