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.
Mine got progressively worse towards 105mm but it wasn't a sudden change. I didn't try back focus, but as others have mentioned, using AF-C mode it was fine (presumably because it stopped down to focus rather than focusing at f/4 and then stopping down after). When manually focusing or using AF-S at f/4 at 105mm I could get very sharp images. In manual focus, I progressively decreased the aperture the focal plane moved towards the camera and the original point of focus became very blurry. Leaving the focus untouched, if I shift the aperture back to f/4, the image was sharp again. I don't know enough about lens design to know what variation in assembly could cause a focus shift like this, but it seems like people either have it bad enough that it's noticed immediately, or they don't.. I'll be curious to see what comes of all of this.
I honestly don’t think it’s focus shift as F8 would normally cover up that at least to a certain degree, this problem seems wildly out of that. It’s just too much out of focus shift and really we are talking only two stops. It sounds more like the lens is tilting out of place. But not sure why that would happen when it’s only being stopped down. How about F11 f16 does it actually get worse or stays the same level of out of focus. If it stays the same level than I would think it’s a tilt that got engaged somehow at F8
GMPhotography wrote:
I honestly don’t think it’s focus shift as F8 would normally cover up that at least to a certain degree, this problem seems wildly out of that. It’s just too much out of focus shift and really we are talking only two stops. It sounds more like the lens is tilting out of place. But not sure why that would happen when it’s only being stopped down. How about F11 f16 does it actually get worse or stays the same level of out of focus. If it stays the same level than I would think it’s a tilt that got engaged somehow at F8...Show more →
My first copy I sent back got worse as it was stopped down further.
Steve Spencer wrote:
What makes you think X number of lenses are checked in a line? I don't think that happens with anything but very expensive lenses like the Cine lenses at Zeiss and Leica M lenses. I think none of the typical DSLR and mirrorless lenses are checked in production.
At least in the past, QC checks would be that every 50th or 100th lens would be checked for tolerances. Not torn down but checked. The number isn't important, it is that they pulled lenses and did a QC check. That was how they verified that the line was doing its job.
GMPhotography wrote:
I honestly don’t think it’s focus shift as F8 would normally cover up that at least to a certain degree, this problem seems wildly out of that. It’s just too much out of focus shift and really we are talking only two stops. It sounds more like the lens is tilting out of place. But not sure why that would happen when it’s only being stopped down. How about F11 f16 does it actually get worse or stays the same level of out of focus. If it stays the same level than I would think it’s a tilt that got engaged somehow at F8...Show more →
In SA focus shift, it's the wide-open aperture that actually has the shift, i.e. the wrong aggregate plane of focus. Stopping the aperture down actually "corrects" the shift by moving the converged focus to the correct plane. This might seem counterintuitive since we see the shift as we stop down, which implies it is "going wrong" when we stop down, but the opposite is true.
Feb 03, 2018 at 10:17 AM
Steve Spencer Offline • • • • • • • Upload & Sell: On
jamato8 wrote:
At least in the past, QC checks would be that every 50th or 100th lens would be checked for tolerances. Not torn down but checked. The number isn't important, it is that they pulled lenses and did a QC check. That was how they verified that the line was doing its job.
Again what makes you think this actually happened? From Roger's postings at lens rentals blogs (and maybe he can comment more here), it seems to me he doesn't believe this happens with any manufacturer. Personally, I think it is an internet myth. How would they check it? Do they have a lens testing set up at the factory? I highly doubt that. Maybe, but I doubt even that they make sure that it turns on, and I there is now or ever has been any testing beyond perhaps simply checking that the lens turns on except with the very expensive lenses such as Zeiss Cine lenses and Leica M lenses.
An observation from yesterday when I checked this issue again - each time I turned the dial to close down the aperture, I noticed that the viewfinder blinked ever so slightly. I had the camera on my tripod and maybe this made it more noticeable.
It seems to me that the focus shift does take place each time you stop down the aperture but the camera/lens refocuses each time and as such, it does maintain the focus on the target. Maybe the focus shift is a part of the design and the difference in the copies circulating out there is the ability of the lens to keep up with that shift. And in the so called "bad" ones, the command to do so is not processed properly. Again, this is pretty much just a speculation based on an observation at this point. Who knows what the real issue is.
Feb 03, 2018 at 10:25 AM
Steve Spencer Offline • • • • • • • Upload & Sell: On
AGeoJO wrote:
An observation from yesterday when I checked this issue again - each time I turned the dial to close down the aperture, I noticed that the viewfinder blinked ever so slightly. I had the camera on my tripod and maybe this made it more noticeable.
It seems to me that the focus shift does take place each time you stop down the aperture but the camera/lens refocuses each time and as such, it does maintain the focus on the target. Maybe the focus shift is a part of the design and the difference in the copies circulating out there is the ability of the lens to keep up with that shift. And in the so called "bad" ones, the command to do so is not processed properly. Again, this is pretty much just a speculation based on an observation at this point. Who knows what the real issue is. ...Show more →
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.
AGeoJO wrote:
An observation from yesterday when I checked this issue again - each time I turned the dial to close down the aperture, I noticed that the viewfinder blinked ever so slightly. I had the camera on my tripod and maybe this made it more noticeable.
It seems to me that the focus shift does take place each time you stop down the aperture but the camera/lens refocuses each time and as such, it does maintain the focus on the target. Maybe the focus shift is a part of the design and the difference in the copies circulating out there is the ability of the lens to keep up with that shift. And in the so called "bad" ones, the command to do so is not processed properly. Again, this is pretty much just a speculation based on an observation at this point. Who knows what the real issue is. ...Show more →
My A7rII also blinks when I change aperture. It appears related to the Live View Setting "ON" processing, because I don't see the blinking when I turn it off.
Can I ask a newby question since I am thinking about ordering another one on the hopes its problem free. Since 90 percent of the time I use AF-C and on my last one that had the issue I used AF-C all the time with 99 percent of my shots being in focus and looking great. Does AF-C take anything away that you get with AF-S? In other words if I buy another 24-105mm and the AF-S problem is there what would I be missing not using AF-S and just using AF-C? Thanks
snapsy wrote:
My A7rII also blinks when I change aperture. It appears related to the Live View Setting "ON" processing, because I don't see the blinking when I turn it off.
Adam,
So, the slight blink indicates the screen is adjusting to the dimmer conditions then. Yes, I could see that. So, the question still remains though. Is there enough effect of the focus shift that is noticeable in the "bad" copies and that the lens/camera combo cannot address or there is no focus shift or just very minimal in the "good" ones?
scalanc2 wrote:
Don’t you think strange no official comment from Sony (or Sony Artisan) on this subject till now?
From my life in product management -
It is very common, in fact nearly universal, that big companies don't comment on bugs/product problems until they have a solution to offer. Otherwise they risk being accused of/sued for knowingly continuing to sell a 'defective' product. Even if they might want to make some statement of acknowledgement, their lawyers will (generally) slap them down.
Alex W wrote:
Can I ask a newby question since I am thinking about ordering another one on the hopes its problem free. Since 90 percent of the time I use AF-C and on my last one that had the issue I used AF-C all the time with 99 percent of my shots being in focus and looking great. Does AF-C take anything away that you get with AF-S? In other words if I buy another 24-105mm and the AF-S problem is there what would I be missing not using AF-S and just using AF-C? Thanks
AF-C has reduced focus precision (consistency) vs AF-S on Sony cameras.
AGeoJO wrote:
Adam,
So, the slight blink indicates the screen is adjusting to the dimmer conditions then. Yes, I could see that. So, the question still remains though. Is there enough effect of the focus shift that is noticeable in the "bad" copies and that the lens/camera combo cannot address or there is no focus shift or just very minimal in the "good" ones?
For lenses which are focused wide open in AF-S mode, Sony does not correct for focus shift. The PDAF cycle which acquires the fast initial focus is followed by a CDAF confirmation cycle, both of which occur with the lens wide open. For the camera to correct for the shift in AF-S it would need to change the CDAF cycle to occur with the lens stopped to its shooting aperture...or always focus the lens stopped down like it does other lenses like the 24-70GM. If I'm understanding your question correctly
Alex W wrote:
Can I ask a newby question since I am thinking about ordering another one on the hopes its problem free. Since 90 percent of the time I use AF-C and on my last one that had the issue I used AF-C all the time with 99 percent of my shots being in focus and looking great. Does AF-C take anything away that you get with AF-S? In other words if I buy another 24-105mm and the AF-S problem is there what would I be missing not using AF-S and just using AF-C? Thanks
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.
snapsy wrote:
AF-C has reduced focus precision (consistency) vs AF-S on Sony cameras.
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.
Snapsy wrote:
For lenses which are focused wide open in AF-S mode, Sony does not correct for focus shift. The PDAF cycle which acquires the fast initial focus is followed by a CDAF confirmation cycle, both of which occur with the lens wide open. For the camera to correct for the shift in AF-S it would need to change the CDAF cycle to occur with the lens stopped to its shooting aperture...or always focus the lens stopped down like it does other lenses like the 24-70GM. If I'm understanding your question correctly
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).
I don't seem to have focus shift with my copy....but I have better luck in general with good focus using AFC...this is wide open or stopped down.The eye af is esp. great in afc, even in dicey light.
in the 105mm/ƒ8 shot, it looks like quite a lot of shift. About how far forward would the box have to move to be in focus?
Mike - while not shown above, I've tested at infinity and at MFD and get a similar result. I really didn't study it any further since out of focus is out of focus and defective. I have the lens boxed and getting ready to send back to B&H.
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).
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.
Steve Spencer wrote:
Again what makes you think this actually happened? From Roger's postings at lens rentals blogs (and maybe he can comment more here), it seems to me he doesn't believe this happens with any manufacturer. Personally, I think it is an internet myth. How would they check it? Do they have a lens testing set up at the factory? I highly doubt that. Maybe, but I doubt even that they make sure that it turns on, and I there is now or ever has been any testing beyond perhaps simply checking that the lens turns on except with the very expensive lenses such as Zeiss Cine lenses and Leica M lenses....Show more →
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.
