snapsy wrote:
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 truth
Yeah, it's a bummer. I sold my 24-70/2.8 too. Nonetheless, this lens will go back to B&H. Good thing I still have my Contax 35-70/3.4. I was looking forward to taking the 24-105mm on the road next week.
rji2goleez wrote:
Yeah, it's a bummer. I sold my 24-70/2.8 too. Nonetheless, this lens will go back to B&H. Good thing I still have my Contax 35-70/3.4. I was looking forward to taking the 24-105mm on the road next week.
You can still take it with you but will need to focus using AF-C, and also take a few photos each time to make up for the lower consistency of AF-C focusing. Then you can return it and hopefully get a good copy.
snapsy wrote:
You can still take it with you but will need to focus using AF-C, and also take a few photos each time to make up for the lower consistency of AF-C focusing. Then you can return it and hopefully get a good copy.
True . . . and of course, MF works just fine and this lens doesn't seem to hard to use that way.
I'm trying (not sure it's going to be successful, we'll see) to get some clarification about focus shift in this lens on the optical bench. There's a lot of variables, and copy-to-copy difference, but my impressions for now:
1) Field tilt is fairly common in this lens so AF anywhere other than the center may have a side-to-side or top-to-bottom or whatever else you want difference. I don't think this is a major factor.
2) The degree of focus shift is different at different focal lengths. I need to look at a lot more samples but the tendency I'm seeing is it's more significant at the wider end. I've seen one copy that went from positive shift at the wide end to negative at the long.
3) Shift did continue from f5.6 to f/8 so it's not just a one-stop effect.
4) I've only looked at a few, but so far I haven't found any with a huge amount of shift, in fact if it wasn't for the discussion I wouldn't be too impressed. I'll do some more copies next week and see if I find a big shifter.
I'm still not certain some of this might not be an electronic camera AND lens issue that makes things worse in reality than it appears on the bench. Right now I'm seeing the effect, but my armchair thoughts are the amount of shift I'm seeing in just the lens isn't nearly enough to account for what I see in a number of carefully taken images. Might be when I look at more copies I see some with a more pronounced shift. Might be that electronics are involved and I won't see anything. But that would mean and electrical adjustment could correct it.
To clarify the above, this is a typical field I'm seeing for this lens. Focused dead (horizontal black line) in the center a test chart shows a 2-D even amount of sharpness from edge to edge. Focused to the right or left, and depending on focusing direction, you might stop at either arrow in which case edge-to-edge sharpness would suck.
This doesn't account for the focus shift issues being reported, but I point it out because it will affect some photographs too.
RCicala wrote:
I'm trying (not sure it's going to be successful, we'll see) to get some clarification about focus shift in this lens on the optical bench. There's a lot of variables, and copy-to-copy difference, but my impressions for now:
1) Field tilt is fairly common in this lens so AF anywhere other than the center may have a side-to-side or top-to-bottom or whatever else you want difference. I don't think this is a major factor.
2) The degree of focus shift is different at different focal lengths. I need to look at a lot more samples but the tendency I'm seeing is it's more significant at the wider end. I've seen one copy that went from positive shift at the wide end to negative at the long.
3) Shift did continue from f5.6 to f/8 so it's not just a one-stop effect.
4) I've only looked at a few, but so far I haven't found any with a huge amount of shift, in fact if it wasn't for the discussion I wouldn't be too impressed. I'll do some more copies next week and see if I find a big shifter.
I'm still not certain some of this might not be an electronic camera AND lens issue that makes things worse in reality than it appears on the bench. Right now I'm seeing the effect, but my armchair thoughts are the amount of shift I'm seeing in just the lens isn't nearly enough to account for what I see in a number of carefully taken images. Might be when I look at more copies I see some with a more pronounced shift. Might be that electronics are involved and I won't see anything. But that would mean and electrical adjustment could correct it. ...Show more →
Thanks Roger. The only way I can see that electronics could be involved in the amount of shift observed when mounted on the camera (vs your optical bench) is if changing the aperture is somehow triggering the lens to alter the position of the focus element on the lens, even when the lens is in MF mode, where you wouldn't expect the camera/lens to be ever adjusting the focus element on its own.
Here's something very interesting though. While considering the possibility above I decided to check if I can see/hear the focus element move when changing the aperture. I couldn't...but what I can hear is a constant hum coming from the lens while it is powered on. This hum occurs even with IS disabled. I don't hear this hum on my 24-70GM - on that lens I only hear some settling for about a second after focusing. On the 24-105 the hum is continuous. Either this hum is from the IS mechanism locking the element down even when IS is disabled, or it indicates there is something "active" going on inside the lens which may actually relate to the issue we're chasing.
Sorry Bob (and others) who are negatively impacted by this focus anomaly.
I'm still looking for more sunny weather to get out and do some more testing. I can say that I was very unhappy attempting to use AF-C on the a7R2, starting out hoping to avoid focus problems. I'm used to the smallest square to get precise focus using center AF point. Very awkward if there are intervening twigs and branches crossing near center!
So far, I'm not alarmed, but wary nonetheless. If it turns out I have a problem, I'll be sending to Precision Camera, due to my 30 day return to B&H will probably be out of date.
I am happy that I bought a nice Canon 24-70/2.8L II before purchase of the Sony, so I'm covered with a sharp lens that I can rely on, regardless of what I find on the Sony. Not at win, but not a disaster either!
More testing to come! I'll try it on my second a7R2 body and see what results. I don't have my a7R with me (almost brought it!), and curious how the lens works there -- anyone test the a7R yet??
The 24-105 is my first native mount so I have no practice whatsoever with how AS settings impact usage. However, poking around in the menus, I set the following using AF-S:
Disp Cont AF area = ON
Phase Detect. Area = ON
Pre-AF = ON
and
e-front curtain shut = OFF
(OSS was on)
Sequential shots taken at f/4, f/5.6 & f/8 all had the correct focus.
Now what...
kdrk888 wrote:
OK, I am a noob with this stuff. If I don't change the aperture, it's a non issue, correct?
Wrong if you're shooting on AF-S
Here's my crude handheld test but it shows how bad it can be. In each shot, I set the aperture, focused away from target and re-focused on the E-mount. There are two sets here. The first at 24mm showing the full shot then 1:1 crops at f/4 and f/8. The second set is at 105mm. This is pretty bad. Using AF-C (not shown), I get good AF at 24mm and 105mm at f/4 and f/8
rji2goleez wrote:
Wrong if you're shooting on AF-S
Here's my crude handheld test but it shows how bad it can be. In each shot, I set the aperture, focused away from target and re-focused on the E-mount. There are two sets here. The first at 24mm showing the full shot then 1:1 crops at f/4 and f/8. The second set is at 105mm. This is pretty bad. Using AF-C (not shown), I get good AF at 24mm and 105mm at f/4 and f/8
That's exactly how mine look from the lens I received yesterday when shooting in AF-S mode..
———————— [this is supposed to be a quote from snapsy and Bob, I messed up the formatting]
You can still take it with you but will need to focus using AF-C, and also take a few photos each time to make up for the lower consistency of AF-C focusing. Then you can return it and hopefully get a good copy.
True . . . and of course, MF works just fine and this lens doesn't seem to hard to use that way.
—————————
On A7R3... my testing... hopefully this is helpful...
MF: with live view setting on, you are focusing at working aperture. I had no focus shift. With live view setting off, you are working at f/4 so you will get focus shift unless you half press shutter before focusing (it stops down to determine exposure)
AF-C: stops down to working aperture regardless of live preview setting. No focus shift.
AF-S: acquires focus wide open regardless of live preview setting. Focus shift below f4
Note that in AF-C it doesn’t stop down to working apertures below f8 (presumably so AF can work). It acquires focus at f8 then stops down at full shutter press. So perhaps you could still get focus shift at smaller apertures in AF-C.
I got focus shift at all focal lengths and apertures below f4 per above.
Easiest most reliable way I found to determine if your lens is faulty is to MF with live view setting on, on tripod, 2s delay, focus at f4 and then stop down and take exposures at 5.6,8,etc.
The focus errors I got were obvious, just like Bob’s example above.
X number of lenses are normally checked in a line but in this case, I am surprised that Sony isn't giving far more attention to QC. This has to be one of the worse rollouts of a product I have seen. Come on Sony.
BTW, my samples were shot with a 7R2 with the latest firmware. I set my camera to manual focus and played around with different focal lengths and apertures. From a quick and dirty check, using the back of the camera, 24mm - 50mm focus shift seems relatively minor. On my copy the issue seems to become noticeable from 50mm - 105mm. As shown in my samples the focus shift is significant even one stop down at f/5.6.
Given that some copies of this lens have focus shift and others reportedly do not, I am completely perplexed! It would seem that the inherent design of the lens (and stop-down software programming) would either cause it to have the problem... or not. What manufacturing tolerance deviation would allow for such a major focus shift in some lenses and not others? Since camera firmware updates have included changes in stop-down behavior, is the problem a difference in camera firmware versions?
I was planning on ordering this lens, but now I am not so sure. I have found that AF-C is just not as consistently precise as AF-S, so that is not a solution, for myself.
I have been dealing with Sony lens copy variations for five years and it becoming a bit fatiguing. On one of the last lenses I dealt with, the GM 70-200mm f2.8, the first copy was pathetically soft and the second copy was amazingly sharp.
I am retired from running manufacturing companies, and with all the widely adopted programs such as six-sigma, how does a company the size of Sony produce products, in this day and age, with such enormous tolerance variations?? As an engineer, I just don't get it.
