Beware rant!
Found a cheap cheap Sigma 105mm macro boxed complete and in perfect condition for 120 euros.....screw-drive version.....I had the same in the Pentax mount...
Very well centered and really sharp wide open.....a little LOCAs but other than that an excellent optical performance!
AF........well here we go again with Sigma.......on the D750 (Nikon lenses have around normally 0 +- 1-5 AFFT) this Sigma requires more than +20 to reduce front focus to just a little!.....
.............on the D500 which also hardly needs AFFT gererally; it needs only +5 to nail the spot!
...my AF50mm F1.8D has an adjustment of +3 on the D750, on my friends D600 it needs more than -20 and still isn't enough.....His camera needs to be calibrated by Nikon, so we called Nikon France, they want 90 euros to calibrate the AF post included both ways, less than the fixed charge of 130 euros from Canon, but nontheless, for Nikon it's good earner...no wonder they stick with DSLRs.
If you have just one body then once calibrated your fine, but throw three bodies into the mix and all hell breaks loose!
So ML fans will pleased to hear "me say" that if starting again especially in portraiture,
I would never ever pick another DSLR
..for anything other than birding!
.... ..........between my two bodies and my friends recently found, it has been a constant round of AF problems....and the whole thing isn't over yet!
Two Sigma macros (105mm +150mm EX macros) and both can't focus accurately for portraiture and only the 105mm works in LV, so I suppose I'll put a trilby hat on and shoot like Jason Lanier in LV!...
Thank god for my AF85mm F1.8D..... , like most of the Nikors at least it focuses fine.
I mean really !
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Stop whining around, man. 
You wanted a cheapo lens, you got one. +5 AFMA on the D500 - are you joking to complain about that peanut? I had lenses which needed around +15, one was +25. So what? Do it and get sharp pics afterwards. Why are you trying so desperately to ignore the fact there are tolerances - and there are as well, at least in your D500, inbuilt routines to compensate them?
You can try to send the lens to Sigma to adjust it. Matter of fact, I don't know which Nikon serves as reference to their own calibration, but it can't be a good one - I always have to adjust the lens, no matter if Nikon or Sigma (or Tamron). The 100-400 was a pure exception in my eyes.
I don't mind adjusting lenses JoJu, you know that! But when they fall outside adjustment parameters, your stuffed!
Actually the D750 needs very little AFFT on most lenses, between -4:+5, so a small spread around 0.
The fact that it is excellent on the D500 is something for sure, but I bought it for portraiture on the D750...and there even with the max +20 it's still front focused! so that's what..so not so good!
Sigma will only calibrate the lens with the camera, not on it's own, I spoke to the guy, they estimate three weeks! I can't be without it at the moment.
Still LV works pretty well and is spot on.
One gets these disparaging moments JoJu, the de-centered Nikor 50mm F1.4G for example and a couple of others that didn't materialize.....
...life can only get better! :wacko:
And I can see why so many here went ML because of these issues!
You went through a phase yourself if I remember........n'est pas? 
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Well, it's good to know both flaws (DSLR and mirrorless ones) from the inside. I think, if I had such a problem with a Sigma lens, the dealer/importer would fix it in less than a week - Sigma CH is really quick. I know, that's not helping you.
is there some kind of analogy between D500 and D750? Like "if one is +5, the other will be -3"? I found that always strange, of course D850 and D810 have different AFMA on the same lens, but on another lens the difference between both AFMA values is not the same.
Now, knowing your DIY skills, the next thing will be you become Mr. Sigma and get the lens back on track? Is there something mechanical one could do? I really don't know, but I guess, not all is firmware based, some things could also be adjusted by hardware?
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01-23-2018, 06:44 PM
(This post was last modified: 01-23-2018, 06:45 PM by thxbb12.)
Dave, have you considered keeping all of your birding gear just for that : birding, and use a ML system for all other uses?
I think you might like it
Usually models don't fly around so much... And chances are that you will love the face recognition mode : your keeper rate in terms of AF will sky rocket.
A few portrait suggestions from the ML world:
- Fuji X-E3/X-T20 + Fujinon 56 f1.2 or 90 f2
- Oly E-M10 II/Pany GX85 + Oly 45 f1.8 or Oly 75 f1.8 (when distance is not an issue)
- Sony A7II + Sony 85 f1.8
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thxbb12, I guess, dave needs some serious earthquakes in his gear landscape to only consider going ML :lol:
And he's a big fan of grey imports or second hand, it's just: good ML lenses 2nd hand are not so easy to find.
I have considered it sure, if I was considerably richer......the Sony A7III would be very nice indeed now that the battery life has improved and all the other features like fast shooting etc.
But right now, is not the moment, I'm helping a guy with his studio and money just isn't there.......at all.
Hence the cheap lenses......not that the price was a factor here, it's great on the D500 after all......it's just the overall fickleness of PDAF which is frustrating me especially with my Sigma lenses.
Quote:Well, it's good to know both flaws (DSLR and mirrorless ones) from the inside. I think, if I had such a problem with a Sigma lens, the dealer/importer would fix it in less than a week - Sigma CH is really quick. I know, that's not helping you.
is there some kind of analogy between D500 and D750? Like "if one is +5, the other will be -3"? I found that always strange, of course D850 and D810 have different AFMA on the same lens, but on another lens the difference between both AFMA values is not the same.
Now, knowing your DIY skills, the next thing will be you become Mr. Sigma and get the lens back on track? Is there something mechanical one could do? I really don't know, but I guess, not all is firmware based, some things could also be adjusted by hardware?
Funny you should mention that JoJu, I took out the spacer shims behind the bayonet.......thoughts being that the lens would be closer bla bla bla....to no avail...... what happens is the AF just compensates for it....the point didn't move a millimetre! so, it's all down to where the AF algorithms decide it should stop the lens in relation to what it is seeing from the AF range-finders!
The analogy is difficult to spot, my guess on the D750 it "needs"" +25 (max +5) and "gets" +5 on the D500.... knowing that both cameras are well set up it must be more to do with a non compatibility.......that's incomprehensible to all but the chosen few!
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I have typed it a few times before: the idea that the flange distance needs to be exact for AF to be on point is just plain wrong. So shims or no shims, it does not matter. What does matter? The lens making the final step less precise than the camera and user would want.
Or: some colour focussing at a different plane than others, a colour that the camera's AF sensor is sensitive to. This makes the camera see things in focus, when the user does not in the final image.
Dave, I feel reluctant to ask you a question since you rarely answer on point when I do. But I will make myself ask it anyway: Do you perhaps use different light sources for the close up situations and the further away situations?
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Quote:Stop whining around, man.
You wanted a cheapo lens, you got one. +5 AFMA on the D500 - are you joking to complain about that peanut? I had lenses which needed around +15, one was +25. So what? Do it and get sharp pics afterwards. Why are you trying so desperately to ignore the fact there are tolerances - and there are as well, at least in your D500, inbuilt routines to compensate them?
You can try to send the lens to Sigma to adjust it. Matter of fact, I don't know which Nikon serves as reference to their own calibration, but it can't be a good one - I always have to adjust the lens, no matter if Nikon or Sigma (or Tamron). The 100-400 was a pure exception in my eyes.
I've had a Sigma 105/2.8 macro for too many years. AF isn't fast, but never had any focus issues with it.
When Canon 'upgraded' their firmware and the sigma didn't work right I sent it to Sigma for an update. They're customer service was great. The update was free and it only took about 10 days from the day I shipped it to the day I got it back. The paper that came back said they checked the optics too. It may be worth sending it in.
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