mapgraphs wrote:
Is manual focus-by-wire and aperture control done via software?
There's an electronic linkage and probably some software non-linear dampening but that still has no impact on this issue - it only changes how much you had to turn the focus ring to arrive at the correct focus. Switching the aperture to f/8 then shits the plane of focus without any change to the focus element.
mapgraphs wrote:
I tried another series of shots, 105mm at f/4 with AF-S - without changing the aperture. First shot acquires focus, subsequent shots (same aperture and framing) loose focus. It's fairly (but not completely) consistent. There is no need to stop down to see the change (or loss) of focus at 105mm. Stopping down only makes it worse. Challenging lighting doesn't help either. This feels more like a software issue, not an optical issue.
My first copy of this lens had this issue but second don't.
While I am not downplaying the focus shift issue but this is not how we go about taking pictures in real life, right? Normally in AF-S, we choose the aperture that we need, then we focus on the target and press the shutter button. If we are in the AF-C button, then this is a non-issue, isn't it? Am I missing something?
AGeoJO wrote:
While I am not downplaying the focus shift issue but this is not how we go about taking pictures in real life, right? Normally in AF-S, we choose the aperture that we need, then we focus on the target and press the shutter button. If we are in the AF-C button, then this is a non-issue, isn't it? Am I missing something?
AF-C is a workaround for the shift issue, but on Sony cameras AF-C is also noticeably less precise than AF-S. For example:
AGeoJO wrote:
While I am not downplaying the focus shift issue but this is not how we go about taking pictures in real life, right? Normally in AF-S, we choose the aperture that we need, then we focus on the target and press the shutter button. If we are in the AF-C button, then this is a non-issue, isn't it? Am I missing something?
When not shooting MF, I shoot AF-S probably 95% of the time, 5% AFC.
The problem with AF-S is that the A7RIII body acquires focus wide open then stops back down to take the exposure, which results in focus shift and OOF shots. Even with live preview on, when you press the shutter button, it opens up momentarily, acquires focus, then closes down to working aperture again. You can observe the behavior by looking at the aperture.
So on my first copy, all shots at > f4 in AF-S resulted in OOF shots, rendering the lens useless for most of my AF shooting. My 2nd copy appears to have no such problems, however.
I’ve never returned a Sony lens for defect... until now. I’ve never had a problem that bothered me until this lens. I tend to just shoot a bunch for a few days and if I don’t see any obvious problems on the LCD or computer screen, I keep. I’ll often do a few quick test shot sequences so I get a general understanding of the lens behavior, but I’m not methodical about testing.
This lens was pretty obviously defective. My typical aperture series of my backyard tree just to see how a lens improves stopping down so I know what optimal apertures are revealed the focus shift right away.
Thank you, Adam. The lens evaluated there is a GM 100-400mm and I am not sure how much of a role it plays since the lens in question here is the 24-105mm. Yet, I do have that GM 100-400mm lens and I have been using it mostly in the AF-C mode for wildlife and I didn't detect any AF issues in that mode.So, maybe I am blissfully unaware of any shortcomings for real life photography and I am less concerned about tests here and tests there.
AGeoJO wrote:
Thank you, Adam. The lens evaluated there is a GM 100-400mm and I am not sure how much of a role it plays since the lens in question here is the 24-105mm. Yet, I do have that GM 100-400mm lens and I have been using it mostly in the AF-C mode for wildlife and I didn't detect any AF issues in that mode.So, maybe I am blissfully unaware of any shortcomings for real life photography and I am less concerned about tests here and tests there.
I don't agree with the less precise statement....in my tests , the afs setting consistently focused slightly in front of the target.
AGeoJO wrote:
Thank you, Adam. The lens evaluated there is a GM 100-400mm and I am not sure how much of a role it plays since the lens in question here is the 24-105mm. Yet, I do have that GM 100-400mm lens and I have been using it mostly in the AF-C mode for wildlife and I didn't detect any AF issues in that mode.So, maybe I am blissfully unaware of any shortcomings for real life photography and I am less concerned about tests here and tests there.
Joshua, every lens Jim tested on the A7rIIi showed the same precision variance in AF-C vs AF-S. He doesn't have a 24-105 yet but I noticed the same AF-C variance on my copy when I reshot my landscape series in AF-C. I was surprised by my experience - I never shoot AF-C myself since nearly everything I photograph doesn't move I'll post AF-C samples here next time I'm at my computer. As for your AF-C experience, if you're saying you get the same near-perfect precision as I get in AF-S then you'll definitely have to teach me a few things next time we meet up
snapsy wrote:
Joshua, every lens Jim tested on the A7rIIi showed the same precision variance in AF-C vs AF-S. He doesn't have a 24-105 yet but I noticed the same AF-C variance on my copy when I reshot my landscape series in AF-C. I was surprised by my experience - I never shoot AF-C myself since nearly everything I photograph doesn't move I'll post AF-C samples here next time I'm at my computer. As for your AF-C experience, if you're saying you get the same near-perfect precision as I get in AF-S then you'll definitely have to teach me a few things next time we meet up ...Show more →
Check out my tests on page 34....the focus point is parallel with #23 on the ruler....the afs shots...the focus depth winds up more in front of the precise point , where the afc shots wind up slightly behind the spot, which is as it should be.
darrellc wrote:
When not shooting MF, I shoot AF-S probably 95% of the time, 5% AFC.
The problem with AF-S is that the A7RIII body acquires focus wide open then stops back down to take the exposure, which results in focus shift and OOF shots. Even with live preview on, when you press the shutter button, it opens up momentarily, acquires focus, then closes down to working aperture again. You can observe the behavior by looking at the aperture.
So on my first copy, all shots at > f4 in AF-S resulted in OOF shots, rendering the lens useless for most of my AF shooting. My 2nd copy appears to have no such problems, however.
I’ve never returned a Sony lens for defect... until now. I’ve never had a problem that bothered me until this lens. I tend to just shoot a bunch for a few days and if I don’t see any obvious problems on the LCD or computer screen, I keep. I’ll often do a few quick test shot sequences so I get a general understanding of the lens behavior, but I’m not methodical about testing.
This lens was pretty obviously defective. My typical aperture series of my backyard tree just to see how a lens improves stopping down so I know what optimal apertures are revealed the focus shift right away. ...Show more →
I see and I understand your point. Yours definitely has a quite severe focus shift issue. Although we can figure out a work around but that doesn't address the issue. And indeed, it would be best if you return the lens and it seems like you did that already. A work around would be by using the back button to focus in AF-C but you trigger the camera using the shutter button. Believe it or not, this is pretty much my AF work flow most of the time although I realize that some folks may find that method odd.
BTW, I am almost sure that the focus shift issue is pretty much present throughout the entire FL range but it is masked in the shorter FL range but more magnified at 105mm.
One thing I noticed at my grandchildrens back to school is the focus seems to get more precise after a few shots, as if the system needs to warm up. I was using afc mostly eye af indoors.
snapsy wrote:
Joshua, every lens Jim tested on the A7rIIi showed the same precision variance in AF-C vs AF-S. He doesn't have a 24-105 yet but I noticed the same AF-C variance on my copy when I reshot my landscape series in AF-C. I was surprised by my experience - I never shoot AF-C myself since nearly everything I photograph doesn't move I'll post AF-C samples here next time I'm at my computer. As for your AF-C experience, if you're saying you get the same near-perfect precision as I get in AF-S then you'll definitely have to teach me a few things next time we meet up ...Show more →
Hi Adam, like I mentioned though, circumstances that I am not aware of, do not bother me. And I am not looking for potential issues and I am not saying that some folks here do but I am not a lens tester. What I can do is to show you what I do next time we meet up. I hope before my CR trip but if, then it would shortly after in March. Thanks!
echelonphoto wrote:
I don't agree with the less precise statement....in my tests , the afs setting consistently focused slightly in front of the target.
I know that you quoted my post but is that by mistake?
Got home, opened the box and mounted the lens. It doesn't look good. AF on AF-S is no problem at any aperture at 24mm. At 105mm, it achieves critical focus at f/4. At f/8 it appears to try to get to critical focus but 'settles' at a point that is out of focus. I can see the AF very briefly 'flash' at the critical focus point but then falls back to yield an out of focus result. I don't even need to take the image as I can see all of this in the viewfinder.
It doesn't matter if I start at f/4, focus and then stop down. I can turn on the camera, dial in f/8 and half press the shutter to see this effect. It seems to be worse at infinity but I'm not too please with MFD either. I guess mine is going back . . .
rji2goleez wrote:
Got home, opened the box and mounted the lens. It doesn't look good. AF on AF-S is no problem at any aperture at 24mm. At 105mm, it achieves critical focus at f/4. At f/8 it appears to try to get to critical focus but 'settles' at a point that is out of focus. I can see the AF very briefly 'flash' at the critical focus point but then falls back to yield an out of focus result. I don't even need to take the image as I can see all of this in the viewfinder.
The brief moment you see it in focus is while the lens is still at f/4 during the AF cycle. Once the aperture is returned back to f/8 for the "Live View Settings ON" preview you get the sad, "shifted" truth
! 