Nikon D750 and Sigma 35 1.2 ART Micro Adjustment

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gpc1

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Hi All

I am finding that my shiny new D750 and Sigma 35 1.4 Art seem to need about a +18 Micro Adjustment

somewhere between +15 and +20

its a fairly unscientific test. I have a focal chart stuck to a wall and im shooting at a 45 degree angle, with the focus point over the centre.

Im actually thinking of returning it back to panamoz. +18 is quite a bit of back focus
 
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Doesn't the 35 art use the USB dock for adjustment?
I find many people mess up the AF worse by attempting AFMA incorrectly. It needs to be "a scientific test"... and if you are shooting at 45* to a focus/resolution chart you are doing it wrong.

Personally, if it is w/in the AFMA tolerances I would consider it a good combination.
 
yeah, i should do it properly really. I just set it a 45 degrees to some wording and focusses on a particular word, and then adjusted until that word was sharp.

just done it again and it more like +15.

will try again when i can concentrate properly. I tried the dot tune method but it was a nightmare

even withthe dock you still have to get the adj numbers. the dock just allows you to input the test result and then it calibrates the lens rather than the lens camer combo
 
Your target should be square to the lens/focal plane. You can set a ruler at 45 next to it to see the offset, but focus on the test chart (with a tripod and higher SS).
 
gpc1 said:
its a fairly unscientific test... Im actually thinking of returning it back to panamoz. +18 is quite a bit of back focus
Click to expand...
You're wasting your time. Do the test properly or don't bother. And don't return a lens for a non-existent "fault".
 
I've the same body and lens. One plus of the newer sigmas is the ability to AF adjust via the dock. That allows different offsets at four distances. But again, you need to do the rest properly in order to input the correct offsets.
 
going to get the reikan focal tool, and do all my lenses / bodies from now on....

Will be interesting to see what it says

I tried the dot tune method but the results were all over the place. I think the reikan uses the dot tune in the background but either way I think its time for some cal software lol
 
gpc1 said:
Hi All

I am finding that my shiny new D750 and Sigma 35 1.4 Art seem to need about a +18 Micro Adjustment

somewhere between +15 and +20

its a fairly unscientific test. I have a focal chart stuck to a wall and im shooting at a 45 degree angle, with the focus point over the centre.

Im actually thinking of returning it back to panamoz. +18 is quite a bit of back focus
Click to expand...

If it is +18 out and that solves it - then that's a result

do you notice any difference in your shots at 0 and +18 …….. or is it that the chart "says so"

post the ruler images at 0 and +18
(I spent hours testing my lens with these charts - not much fun with 300mm and 600mm primes and at the end of the day I'm back to 0 - I've got Focal - but it's a b****r to play around with - maybe better if you are a Canon user)
 
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sk66 said:
Focal seems to be pretty useless for FL's beyond ~200mm...
Click to expand...

I have just got 3 new pairs of glasses - one especially for the computer - everything now seems sharper!!!
 
BTW, the 35mm art backfocus at longer distances is a known tendency... It will be *much* better to adjust the backfocus only at the relevant distance(s) using the dock as opposed to an in camera AFMA setting.

And "focus" is very much a lens/body combination thing... particularly with PDAF. I have lenses that require different settings on different bodies, but there is nothing "wrong" with the lens.
 
BillN_33 said:
If it is +18 out and that solves it - then that's a result

do you notice any difference in your shots at 0 and +18 …….. or is it that the chart "says so"

post the ruler images at 0 and +18
(I spent hours testing my lens with these charts - not much fun with 300mm and 600mm primes and at the end of the day I'm back to 0 - I've got Focal - but it's a b****r to play around with - maybe better if you are a Canon user)
Click to expand...

will try and do a more scientific test, There was a noticeable difference.
I also put the TV remote on a worktop on its side and at a 45deg angle to the lens. I focussed on the number 8 but the 0 (which was the button directly below the 8) was what was in focus and the 8 was blurred.

This may be a daft question, but do lenses 'settle down'

When I get the Reikan Focal I will adjust it properly
 
gpc1 said:
This may be a daft question, but do lenses 'settle down'
Click to expand...

Depends on what you mean... if using a tripod that is marginal for the task, then yes. The camera/lens may need to "settle down" after the mirror moves.
If you mean "do they become more accurate/consistent" over time, then not likely. One thing that I've found is that the PDAF "in focus point" can vary a bit depending on if the lens is focusing out, or focusing in. Either way, do not expect PDAF to become entirely consistent; it won't. PDAF gives up a little accuracy in favor of speed.
 
phone has gone a bit bonkers and posting old posts
 
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gpc1 said:
Like I said, it was quick and unscientific so will do it again with some proper testing kit.

Anyone tried the dot tune method? The range I got was huge.
Click to expand...

some days my lens are "dead sharpe" other days they are as soft as they come
 
been speaking to someone who has one on canon. Has a +15 adj, so its just seems that that's how it goes!

Ordered focal so will test and MF properly

rgds
 
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