AGeoJO wrote:
I am a proponent of AF-C. Even for stationary target, I am using AF-C and I am using the focus back button for that. I use the shutter button to only trigger the shutter and not to acquire focus, in other words. Only under certain circumstances, I use the AF-S. I believe this condition doesn't pose any problem using one of the "bad lenses" if used in the AF-C mode.
Adam,
And yet, I am getting perfectly and critically focused images using that mode and that for fast wildlife and for portraits with shallow DOF. If this postulation holds true then we could throw away the continuous Eye-AF method that a lot of people use and praise for its consistency and accuracy....Show more →
Joshua, I also only use the back button to autofocus triggering the exposure with the shutter button. I've had good results in both AF-S and AF-C on stationary subjects as well. When I was shooting with Canon I set my cameras up this way as well.
Feb 03, 2018 at 11:36 AM
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jamato8 wrote:
I used to work in the camera industry. Maybe it doesn't any longer but it used to. I put it out there as what I know about the industry.
Can you give us a bit more information then? When did you work in the industry? When you say they took lenses off the line to test them, what does that mean? How did they test them? Did they do MTF testing on an optical bench? Did they shoot test charts? Did they just take a couple snap shots and make sure it "worked" without evaluating the photos? It would be interesting to know what was and was not done in the past.
AGeoJO wrote:
Wow, that's not my quote, buddy! You may delete my original post and quoted somebody else's instead but left me as the poster. Please check the original post again.
AGeoJO wrote:
I am a proponent of AF-C. Even for stationary target, I am using AF-C and I am using the focus back button for that. I use the shutter button to only trigger the shutter and not to acquire focus, in other words. Only under certain circumstances, I use the AF-S. I believe this condition doesn't pose any problem using one of the "bad lenses" if used in the AF-C mode.
Adam,
And yet, I am getting perfectly and critically focused images using that mode and that for fast wildlife and for portraits with shallow DOF. If this postulation holds true then we could throw away the continuous Eye-AF method that a lot of people use and praise for its consistency and accuracy....Show more →
It's like any measure of AF Joshua - you'll still get lots of keepers, even the majority of which are probably so, but the precision is nevertheless measurably lower in AF-C than AF-S, both in Jim's testing and in my own observation. Here is the AF-C consistency comparison I promised you yesterday from the 24-105 landscape series I reshot in AF-C. While I was shooting I could see the consistency was lower in AF-C so I purposely shot each focal length / aperture three times, racking focus each time. I selected the best of each three for the full composite I originally posted here. These were all shot on a locked-down tripod.
Daran wrote:
Sony could correct focus-shift using a software offset table that compensates per fl and aperture. So the focus would be slightly moved whenever the aperture is changed and any focus shift in the lens design effectively compensated. If such a calibration table would somehow be out of whack, the result would rather precisely match what is reported. As in the focus is lost simply by changing the aperture.
I'm just guessing here as my own copy seems flawless (A7R2, FW4.0, lens version 01).
They could, and this has been theorized for other cameras as well, but none of the Sony lenses Jim Kasson tested are corrected for focus shift in AF-S mode, so it seems clear there is no such table implemented in Sony's firmware.
snapsy wrote:
It's like any measure of AF Joshua - you'll still get lots of keepers, even the majority of which are probably so, but the precision is nevertheless measurably lower in AF-C than AF-S, both in Jim's testing and in my own observation. Here is the AF-C consistency comparison I promised you yesterday from the 24-105 landscape series I reshot in AF-C. While I was shooting I could see the consistency was lower in AF-C so I purposely shot each focal length / aperture three times, racking focus each time. I selected the best of each three for the full composite I originally posted here. These were all shot on a locked-down tripod.
Thank you, Adam! The images are a tad small for me to evaluate much if anything. I take your words and I am not disputing your results however. But you did use the 24-105mm lens for that though and yours has the focus shift issue, right? Didn't we throw in another unknown variable into the equation that way?
AGeoJO wrote:
Thank you, Adam! The images are a tad small for my taste for me to evaluate much if anything. I take your words and I am not disputing your results however. But you did use the 24-105mm lens for that though and yours has the focus shift issue, right? Didn't we throw in another unknown variable into the equation that way?
Those are 100% crops, so they contain the level of detail necessary for focus evaluation. They were shot in AF-C, so focus shift is not an issue since the camera stops the lens down for AF-C focusing.
GMPhotography wrote:
I’m in the same boat Chuck. Keep worried mine is going to start doing it. My original thought stays the same , somehow I’m thinking a element group gets out of whack when it goes to 105mm.
I wonder if someone that has the problem could try zooming very slow to 105 than try it at a faster rate. One other question I had was this shutter/ focusing off the same release or does it do it as well with back focus.
Same here. I've had mine since mid December and it's been perfect. Absolutely love it. I've tried all ways to get it to shift focus but nothing. It's sharp right into the corners by f9 / f10 for close to infinity.
Might it be worth while to track serial numbers to see if it relates to a specific batch?
IzelPhotograph wrote:
Same here. I've had mine since mid December and it's been perfect. Absolutely love it. I've tried all ways to get it to shift focus but nothing. It's sharp right into the corners by f9 / f10 for close to infinity.
Might it be worth while to track serial numbers to see if it relates to a specific batch?
That could be interesting. Mine had a "date" of 01-2018 on the label - for Sony I don't know if that's the manufacture date, packaged date, or what it represents.. I'm happy to share SN if people want to track that.
AGeoJO wrote:
I am a proponent of AF-C. Even for stationary target, I am using AF-C and I am using the focus back button for that. I use the shutter button to only trigger the shutter and not to acquire focus, in other words. Only under certain circumstances, I use the AF-S. I believe this condition doesn't pose any problem using one of the "bad lenses" if used in the AF-C mode.
Adam,
And yet, I am getting perfectly and critically focused images using that mode and that for fast wildlife and for portraits with shallow DOF. If this postulation holds true then we could throw away the continuous Eye-AF method that a lot of people use and praise for its consistency and accuracy....Show more →
Do you continue to hold in the BBF button while you press the shutter?
thx
Parariss wrote:
Do you continue to hold in the BBF button while you press the shutter?
thx
Not for the test; as matter of fact, I used both AF-S and AF-C for the test and I got the same result. In both modes, I just pressed the back button once at wide open and stopped down the lens after that.
Steve Spencer wrote:
Interesting speculation. Anyone shown the problem with the A9? It seems if your speculation is right the faster processing of the A9 might make it less likely to happen. Perhaps the faster processing speed could keep up with the shift better.
I’ve been shooting the 24-105 on an A9 for the past week. No such issues. Incredibly accurate & sharp across all focal lengths in all focus modes. Possibly one of the best zooms I’ve owned/used.
..no issues here with my 24-105, but its going back anyway..hard to believe as my fe 24-70 is really bad at 24, but i prefer its colours, its microcontrast and its size and weight for what i do with it (prints max 120x80 cm)..i never loved it, but i like it more now..and in case i need resolution on the a7rII i still have the 55 and the batis 24..
snapsy wrote:
For those who keep wondering if it's firmware keep in mind this issue occurs with manual focusing, with the shift occurring with only a change of the aperture after manually focusing. The only way this could be firmware related then is if the camera or lens are intentionally shifting the focus element in response to the aperture change. That seems highly unlikely.
As for how this could be copy specific, this could related to the positioning of an element or the polishing/molding of one of the aspheric elements, although that's just a wild guess at his point. Hopefully Brandon will stop by and weigh in. See this thread for some graphics on focus shift. ...Show more →
But the "manual focus" isn't exactly manual focus, isn't it electronic focus-by-wire? In that case perhaps the confusing performance is tied in to the flickering viewfinder when I change apertures and it resettles focus. Seems like the offending lenses establish focus, then get the focus scrambled when stopping down, then fail to reestablish the correct focus before shutter firing. Could be coding, if so, it could be a firmware fix.
Gunzorro wrote:
But the "manual focus" isn't exactly manual focus, isn't it electronic focus-by-wire? In that case perhaps the confusing performance is tied in to the flickering viewfinder when I change apertures and it resettles focus. Seems like the offending lenses establish focus, then get the focus scrambled when stopping down, then fail to reestablish the correct focus before shutter firing. Could be coding, if so, it could be a firmware fix.
I bought mine used and fortunately without any focus shift issue. The original owner bought it from a local store in late November in Florida. The serial number is 1803903. Maybe we should start a new thread with the SN info to see whether there is any pattern; otherwise the data will be buried.
and fortunately without any focus shift issue. The original owner bought it from a local store in late November in Florida. The serial number is 1803903. Maybe we should start a new thread with the SN info to see whether there is any pattern; otherwise the data will be buried.