Sigma 35mm 1.4 Art lens

[Cornfield]

I have borrowed a Sigma 35 Art for a few days.  First test shots on my d800 were not in focus.  I then tried it on a d610 and results were spot on and image quality was first rate.

Next I set up Lens Align for autofocus fine tune session.  On the d610 the lens did not require any adjustment, zero was spot on.  On the d800 an adjustment value of +20 (maximum value) did not generate a sharp image.  Is this margin of difference between cameras unusual? Should I have the d800 focus system checked?

[Paul2660]

How do all your other Nikon lenses seem with AF on the D800?  If they are OK, I would not send in the camera to Nikon for any adjustments.  Sigma lenses can be very different between two cameras, just like Samyang etc.  At least from my use of the 20mm and 35mm 1.4 Arts on the D810 and D750.

Paul C

[E.J. Peiker]

While it isn't terribly unusual for a lens/body combination to produce a result that is outside the user adjustable calibration range, the Sigma 35 f/1.4 has not been a lens prone to this in my business.  I just checked my database and I have calibrated 31 of these lenses on various Nikon bodies.  On the D800/800E, the maximum adjustment from the center point of zero has been a -7. That said, there are a number of Sigma lenses that require a very large adjustment, the Sigma 150mm f/2.8 OS Macro needing the most on average.

Also realize that that lens in particular has a significant amount of focus shift between wide open and stopped down a bit.  Unless you are regularly using that lens at f/1.4 or f/2, I would recommend calibrating it at f/2.8 for better focus results in most shooting situations.  In my experience there can be as much a 5 point calibration difference between f/1.4 and f/2.8.

[Cornfield]

All my other lenses are with a reasonable range of +7 to -4.  I have just borrowed this lens but I'm interested in some of the other Sigma Art series as the rendering of the 35mm is excellent. 

Interesting to hear about the focus shift at different apertures.  The Sigma USB dock is probably essential to ensure best results.

[E.J. Peiker]

Yes the Sigma dock will allow you to have different offsets in the lens based on subject distance (and focal length on zoom lenses) but it does not allow you different offsets based on aperture.

[rwong2k10]

thanks for the info, I realize when I was calibrating my 35a I notied the focus shift in between f1.4 f2.8 thanks for confirming my suspicion

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