Sigma 35mm F/1.4 Micro Adjust

photosample

photosample

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Kalin
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Hello people,

I am very happy with my Sigma 35mm lens, but I would like to get as much as possible form my lens.

I would like to make AF Micro Adjust, but to be honest I don't have very big experience with this and I don't have the USB dock at the moment.

Is there anyone in London or around that have sigma USB Dock and could help me to do AF Micro Adjust.

I am willing to pay the expenses, to travel, and to pay some money for using the USB dock as well., just I prefer to do it with someone more experienced.

I have tripod also, if necessary.

Thanks in advance.

Regards,
Kalin
 
twist said:
You dont need it to MA, Im assuming you have a camera capable of MA.
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Yes, the Canon 6D has this capabilities, and I can do it, but I do not feel confident, as I never did it before.

And I think that I can do micro adjust only for one focal length, If I shoot different objects on different distances ?
 
The 35mm only has 1 focal length. 35mm.

Its worth trying, even just setting up on a tripod wide open, taking a shot at -10, -5, 0, 5, 10. Then review in LR at 1:1 compare. Choose the best shot. See how you go from there.

Worth learning how to do it, even if it is this quick method as you arent only going to buy lenses that are compatible with the dock. Good luck either way.
 
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Sigma 35mm has adjustments at 0,3 - 0,4 - 0,6 - infinity.
So 4 adjustments.

I just follow and did a DOT Tune method with tripod and some high contrast lines/text/numbers.

The results is between -5 and -1, so I choose -3.

The problem is that I am not sure if it will work for all this distances.
 
photosample said:
The problem is that I am not sure if it will work for all this distances.
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It should work for most distances with only minor inaccuracies. However, I've had two copies of this lens and I've seen quite strange focus inaccuracies with it. Like perfect until 4 meters, severe backfocus at 6m, apparently somewhat erratic focussing beyond that. I have a Nikon D800, and the Dock.

For close-by adjustments, I use a slanted line of 7 or 9 dominoes. They're 7mm deep each, so I get a fairly fine adjustment. I focus on the center domino, and then check which one is actually sharp.

For infinity, I use a barb-wire fence with fairly massive concrete posts, or a 2m folding ruler, and the wall of a house :) taking pictures of the well-structured wall of the house at measured distances. The wall has a hedge on one side running at a 90° angle, so front or back focus can be seen in that hedge.

What I found out was that both copies of this lens showed the same pattern, i.e. a backfocus at 6m, and a certain softness somewhere between 12m and 14m. At first, my second lens was sharp at 6m but had approx. 3cm front focus at 1.20m. When I adjusted it to be sharp at 1.20m, it suddenly had a backfocus of about 1m at 6m. When I readjusted it to have the frontfocus at 1.20m again, the backfocus at 6m remained.

With any distances 9 meters and beyond, I feel both lenses focussed unreliably.

That said - this is from test series I've shot. Notwithstanding these testbed results, in real life situations the lens works well for me. Probably due to the nature of scenes I tend to capture with a wide angle lens, these sharpness issues don't really become obvious in my real-life shooting situations, and I've taken quite a few nice pictures with this lens, pictures which look blazingly sharp.

I have, however, also looked at some shots uploaded to the thread for this lens here in TP, and it is my impression that many of them are not as sharp as this lens can be, or don't have their max sharpness in places I'd think the photographer would have focussed on. But the photographers apparently were very happy with them.

So maybe I'm just doing something wrong.

But for shooting specific objects in the ranges above, I'll use my 50mm Nikkor ;)
 
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Thanks for all responses so far.

I will stick with MA and will try some photos to see if there is any difference.
Anyway, if I shoot with F/2.8 + I don't think there will be much difference in real life.

I attend some night club events and I shoot with NO flash, mostly at F/1.6, F/1.8 and F/2.0 and so far the focus is good.

For someone who wants some sample and to see if the focus is may be missing on some of the photos, here are examples:

http://www.flickr.com/photos/95282441@N00/sets/72157633868549348/

Regards,
Kalin
 
photosample said:
I will stick with MA
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If your MA can eliminate unsharpness (with my first copy of the lens, MA was not enough to eliminate the lenses unsharpness), then the dock is certainly not needed. As you have said, it offers 3 controls for adjustments between 0 and approx. 4ft, and then one more for everything above, so any inaccuracies in real life shooting distances with this lens can only be fixed on a global basis for the entire range. If you have focus shifts anywhere, the dock cannot do anything about it.
 
AchimT said:
If your MA can eliminate unsharpness (with my first copy of the lens, MA was not enough to eliminate the lenses unsharpness), then the dock is certainly not needed. As you have said, it offers 3 controls for adjustments between 0 and approx. 4ft, and then one more for everything above, so any inaccuracies in real life shooting distances with this lens can only be fixed on a global basis for the entire range. If you have focus shifts anywhere, the dock cannot do anything about it.
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Thanks for the asnwer.

Don't get me wrong - I am very happy with the lens so far.

Just I would like to get as much as possible, and I will play definitely with the MA in the next several days for close subjects.

Regards,
Kalin
 
AchimT said:
If your MA can eliminate unsharpness (with my first copy of the lens, MA was not enough to eliminate the lenses unsharpness), then the dock is certainly not needed. As you have said, it offers 3 controls for adjustments between 0 and approx. 4ft, and then one more for everything above, so any inaccuracies in real life shooting distances with this lens can only be fixed on a global basis for the entire range. If you have focus shifts anywhere, the dock cannot do anything about it.
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As I think I mentioned on another thread, what you describe just doesn't stack up. Assuming your test procedure is robust and your observations accurate, then I'm wondering if maybe the dock is making the lens behave very strangely. You may want to take that up with Sigma.
 
Richard - I also have no explanation for this, and I would not rule out user error on my part, but at Amazon Germany, about 25% of the buyers complain about similar focussing problems, so mine is not an isolated case. And this is the second copy of this lens which has been doing this for me - slight difference in details, but the same overall pattern. Maybe that makes it a bit more probable that it is not something I am doing wrong.

Allow me to add that I have checked my Nikon lenses as well, and they don't show this behaviour. I still don't want to rule out user error on my part entirely - I just don't know what it could be, and with all of the above together, I find it probable that it has something to do with the lens, or my camera/lens combination.

I have been told my D800 has not been incorporated in the firmware of this lens yet - maybe that could have something to do with it. OTOH, there is Keith here in this forum for whom his second copy of the lens works flawless with a D800e. But the first copy of the lens also had had issues for him.

I was also wondering whether the dock has something to do with it. But several of these reports on Amazon had been uploaded before the dock had become available, so it probably has nothing to do with the dock.

I was also wondering whether there is an interdependence between the settings of the 4 adjustable ranges, but I could not find information about this, nor could I verify anything in my tests

The second lens is actually better than the first one, especially the infinite range needing a lot less adjustment (between +5 and +8 - depending on where I want it to be sharp - as compared to +15) than the first copy. It was also much closer to perfection in the 3 lower ranges, but strangely needed the same amount of adjustment (+9) as the previous copy had needed, although this new copy had only maybe 3cm of front focus, while the first copy had had something around 10cm.

I've btw sent my first copy to Sigma service, and they did update the firmware and do some adjustments, but they didn't have the camera so they could only approximate. And then they sent the lens back, but that blurry range somewhere between 12-14m was still there.

Some of it could still be attributable to the dock - I just don't have enough time to test all and everything diligently.

Kalin - your photos look perfectly sharp to me. IMHO you have nothing to worry about - it seems you're getting the max out of this lens in terms of sharpness. I'm getting pictures as sharp as your's too (they're towards the end of the images on page two of the link in my signature) - just with those strange issues at certain distances.

The reason why I keep bringing these issues up is not that I want to bash the lens. I really like the lens, I even like its somewhat special bokeh. I'm posting this because I would really like to get it to work properly, or to find out whether it is worth for me to order a third copy to maybe get an error free one. I just cannot believe Sigma would ship 25% faulty lenses to their end customers. I still think it could be something else, something that would either be fixed with a firmware update, or maybe somehow else. And I'm hoping to find answers.

And last but not least, sorry for hijacking your thread a bit ;)
 
Achim, suggest either post your test images up here to see if there's any light can be shed that way, or take it up with Sigma.
 
HoppyUK said:
...or take it up with Sigma.
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Hi Richard, I had sent my first copy to Sigma. I received it back after 5 weeks with new firmware, modified settings, and the comment to do the detail adjustment using the USB dock. Which I did.

I was also thinking about sending them the lens and camera, but I don't want to be without my camera for 5 weeks.

This is basically why I keep asking around - I'm hoping to find some info that helps me decide whether it makes sense to order another copy of the lens, or just go ahead with the issues and work around them. After all, this second copy is better than the first one, and I'm worried I might get a worse one if I return it and re-order.

AAMOF I think I'm seeing a bit clearer meanwhile. I've done more reading in the meantime, took some new test pictures, and found some older ones which I looked at again diligently.

I think with all the information together, it seems that if the lens is set up to focus perfectly between maybe 1.20 meters and 4 meters, it has a backfocus farther away. If it is set up to be sharp from 6 meters and up, it has a front focus in the close range between 1.20 and maybe 2 or 3 meters. Others on the German Amazon report the same, I even read it happens with other Sigma lenses too - I don't know whether this is true. Add to this a certain percentage of AF failures, which added to the confusion.

Since I can still take good pictures with this lens, I think I just have to accept the fact that I won't have a perfect copy, and just work around the issues, by stopping down or using another lens at the critical distances.

I have also uploaded some test images, but unfortunately, the order seems to not be entirely correct as I had taken them, and out of habit I uploaded screen resolution, not original size, so the issue is not that easily visible, so I have to do it again, apologies for this.

If you are interested in seeing them any way, please let me know, I'll be glad to send you a link but don't want to publish it here before I've uploaded proper (large) versions of the images and made sure they are correctly numbered and arranged in the proper order.
 
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