p.2 #1 · What's the deal with aperture stopping down during AF?
Joshua, I agree for the Batis 25mm at f/16 there would be no focus shift to speak off. In fact there should be no reason to stop down a 25mm lens except for f/2 to f/4... maybe for close to medium distances.
p.2 #3 · What's the deal with aperture stopping down during AF?
Since we are referring to the case of the Batis 25, here is the link from another thread of the image: https://www.fredmiranda.com/forum/topic/1451678/11#13968261 that I finally captured. You guys can also see the lighting conditions. It wasn't very bright but still the sun was still out there although it was deliberately "hidden" behind some tree branches. Again, I focused on the center area at f/8 and then I stopped down. The image I took when the AF failed was blurry.
p.2 #4 · What's the deal with aperture stopping down during AF?
Joshua I wonder being a busy scene like that if the AF got confused. If you where in AFC mode no question it could happen. AFS less likely for sure unless it tried to refocus during capture
p.2 #6 · What's the deal with aperture stopping down during AF?
nandadevieast wrote:
So which lenses don't do this?
85/1.8
55/1.8
Loxia 21 ?
FE 16-35 ?
I warranty the Loxia wont shift during AF
Mar 21, 2017 at 06:31 AM
Steve Spencer Offline • • • • • • • Upload & Sell: On
p.2 #7 · What's the deal with aperture stopping down during AF?
What does the camera do in manual focus? Does it let you focus wide open? It seems that a good solution for some images (and I think it would have worked well for the shot that Joshua took, which is quite beautiful by the way) would be to switch to manual focus. That is only going to work, however, it the camera let's you focus wide open and then stops down for the shot.
p.2 #8 · What's the deal with aperture stopping down during AF?
I'm wondering if this is happening also with the GM 24-70 as I ran into a focus issue on my last shoot. It was awards and I missed a group and had them come back at the end. First time ever I missed something like this. Glad I did they just emailed me for another gig in San Diego
p.2 #9 · What's the deal with aperture stopping down during AF?
GMPhotography wrote:
Joshua I wonder being a busy scene like that if the AF got confused. If you where in AFC mode no question it could happen. AFS less likely for sure unless it tried to refocus during capture
Guy, the AF mode was AFS and I am using the AF back button. So, the AF is not trying to refocus when I press the shutter button.
Steve Spencer wrote:
What does the camera do in manual focus? Does it let you focus wide open? It seems that a good solution for some images (and I think it would have worked well for the shot that Joshua took, which is quite beautiful by the way) would be to switch to manual focus. That is only going to work, however, it the camera let's you focus wide open and then stops down for the shot.
That's a good point, Steve! Since I am aware of the aperture stopping down during the AF acquisition process and I recognized it as such, what came to my mind first was to open up the aperture some more to get the AF. I didn't think of switching to MF. I will try that later on. Thank you!
GMPhotography wrote:
I'm wondering if this is happening also with the GM 24-70 as I ran into a focus issue on my last shoot. It was awards and I missed a group and had them come back at the end. First time ever I missed something like this. Glad I did they just emailed me for another gig in San Diego
Guy, yes, the GM 24-70 does that to, as well the other two GM lenses, the 85mm and 70-200mm. I know it happened to me previously with all 3 before.
p.2 #10 · What's the deal with aperture stopping down during AF?
Joshua thanks your last comment on the GMs is what I feared. Damn I may have to sell the GM 24-70. I need low light ability with these AF lenses. So this is not happening with most likely the Metabones or Sigma adapters. I might have to switch gears here. Now I'm wondering if the FE 35 1.4 does this as well. I don't think it does. I could possibly go with three AF primes to replace the GM 24-70. Before anyone panics here , this is about special needs that I run into. These lenses are awesome and may never run into this stuff.
p.2 #11 · What's the deal with aperture stopping down during AF?
Guy, I don't think it is a major issue or actually any at all, with the GM lenses, at least. I consider this as a part of the lens design now. I am not selling any of my GM lenses, that's for sure. The few times I encountered this is mostly in the studio, especially the GM 85mm at f/8 or so and that's when the lighting was dim since only the modeling light was used. But this is not a studio lens, I reckon. The 24-70 shows the least of the 3, IMHO.
It just struck me as odd the other day when the Batis 25mm, an ultra wide angle lens, gave me fit with the AF at f/16. I don't know at what aperture it would do that and I don't used f/16 that often either and as you notice the lighting conditions were not that great. The ISO setting was 2000 to get f/16 and 1/125 sec.
p.2 #12 · What's the deal with aperture stopping down during AF?
Agree why I sold the GM 85 . On the 24-70 it's not nearly as bad. I can deal with it just have to pay more attention to it. I'm mostly in ballrooms and such at events with the 24-70. When I rent the 70-200 I have plenty of stage light so this did not show up. The 24-70 is the heart of these PR gigs.
p.2 #13 · What's the deal with aperture stopping down during AF?
Plus, with the new A9 or whatever Sony would call it with its superior AF capabilities , this may not be any issue whatsoever. So, don't jump too fast or you may regret your decision having to rebuy those lenses again .
p.2 #14 · What's the deal with aperture stopping down during AF?
Exactly. I'm hoping things will change. I'll hold on to the GM 24-70 but I did sell the GM 85 for the new Sony 85 1.8 . That's okay though. I will be buying a 135 for portraits and more bokeh stuff anyway. The 85 will be more studio,stage type stuff. Landscape I have my ZM 85 which is a awesome lens and I don't use AF on landscape anyway.
AGeoJO wrote:
Plus, with the new A9 or whatever Sony would call it with its superior AF capabilities , this may not be any issue whatsoever. So, don't jump too fast or you may regret your decision having to rebuy those lenses again .
p.2 #15 · What's the deal with aperture stopping down during AF?
AGeoJO wrote:
Guy, I don't think it is a major issue or actually any at all, with the GM lenses, at least. I consider this as a part of the lens design now. I am not selling any of my GM lenses, that's for sure. The few times I encountered this is mostly in the studio, especially the GM 85mm at f/8 or so and that's when the lighting was dim since only the modeling light was used. But this is not a studio lens, I reckon. The 24-70 shows the least of the 3, IMHO.
It just struck me as odd the other day when the Batis 25mm, an ultra wide angle lens, gave me fit with the AF at f/16. I don't know at what aperture it would do that and I don't used f/16 that often either and as you notice the lighting conditions were not that great. The ISO setting was 2000 to get f/16 and 1/125 sec....Show more →
Seems that at that focal length and f-stop EVERYTHING looks like it's in focus. I know that when I put my 15/4.5 Voigt to f/8 on my A7RII and then use 100% magnification to find best focus it's really really difficult because it takes a lot of focus ring turning to see a difference. At f/16 diffraction has taken a firm hold knocking off the sharpness that the AF system needs to find the best focus.
If found similar things with the 18-35G on my D800 - stop it down even in bright daylight and the AF system has trouble getting accurate focus.
The main problem is that when you need to stop down a lens in order to focus accurately you consequently have less light available in order to focus rapidly.
Sony seems to favor accurate focusing, which makes sense - it doesn't matter how fast focusing is if the result is out of focus. So, lenses which exhibit focus shift necessarily have stop down focusing. I haven't seen a master list of which lenses stop down, or whether all Sony lenses do (but I'd like to).
Additionally, you can't have live view without stopping down, by definition. Perhaps there are situations/lenses where you can gain a better user focusing experience by turning off live view. ...Show more →
I tested lenses that show this behavior like the FE 50/1.4ZA, 85/1.4GM and 24-70/2.8GM and didn't detect any noticeable focus shift! . Focusing these lenses in low light at stop-down apertures is a huge problem and there is really no excuse for it. Sony is been very stubborn to correct this and it makes no sense to me.
p.2 #18 · What's the deal with aperture stopping down during AF?
GMPhotography wrote:
As usual I agree with Fred.
The 85/1.4GM was designed for professional portrait photographers which often shoot under studio lighting at f/5.6 or even f/8 apertures.
It makes zero sense the lens will attempt to achieve focus at f/8!! It's to a point where the AF system will be forced to switch to contrast detect points.
Luckily for me, I mainly use this lens from f/1.4 to f/2 but I can see how irritating that would be for studio shooters.
This should be a quick firmware upgrade for Sony...
p.2 #19 · What's the deal with aperture stopping down during AF?
For me shooting that clothing catalog which i consider in the photo business a very common scenario shooting at F8. This makes very little sense to have this stop down setup. These lenses do not have focus shift. Bottom line i don't need Sony to protect me from focus shift thats the end users worry.
p.2 #20 · What's the deal with aperture stopping down during AF?
For stopped-down shooting I imagine the Canon 24-70 w/adapter focuses faster than the native 24-70GM since the A7rII focuses wide-open on the adapted lens. That would get Sony's attention
, this may not be any issue whatsoever. So, don't jump too fast or you may regret your decision having to rebuy those lenses again 
.
It's to a point where the AF system will be forced to switch to contrast detect points.