I have been using the Sigma 35 mm f/1.4 Art Series lens over the last year. Sometimes it produces really sharp keepers and on other occasions every image is out of focus. Recently I have undertaken AFMA calibration on a variety of lenses using Focal in order to investigate this. I was not surprised to get these results for my Sigma 35 Art.
Distance to target AFMA required Focal result confidence
1 metre -3 Excellent
2 metre +4 Good
3 metre +2 Good
4 metre 0 Good
In contrast all but one of my Canon lenses when tested with my EOS 6D require a very consistent AFMA setting at different subject distances.
Having researched the Sigma USB dock, I thought that it allowed AFMA calibration of the lens at up to 4 different distances. I thought that this could solve the problem. BUT on trying my lens in the dock it appears that it is not possible for the user to select what these distances are ?!
In the case of my 35 mm lens this will make the dock calibration process of little benefit. If for example I use optimization pro to set AFMA at infinity and at 0.75 M then the calibration will be correct at these distances and off in between 1 and 4 metres. I am struggling to understand the logic of optimization pro since with a 35 mm lens if you are using it for photographing people then you are going to need to work within this distance range. Why have three of the four AFMA distances for this lens at less than 1 metre when any close up/macro type work is likely to use MF anyway ?
At present when shooting wide open I have AFMA = 0 and use the 35 mm exclusively around 1.5 metres distance to subject. At other distances then I have to change either the AFMA setting or use MF or stop down significantly. Hardly an ideal arrangement!
I would appreciate any help as regards:
1) Is there a way of adjusting the lens AFMA calibration distances in the Optimization Pro software?
2) Has anyone had a similarly performing lens and had any success with sending it back to Sigma for calibration – did this improve the AFMA consistency with distance ?
Distance to target AFMA required Focal result confidence
1 metre -3 Excellent
2 metre +4 Good
3 metre +2 Good
4 metre 0 Good
In contrast all but one of my Canon lenses when tested with my EOS 6D require a very consistent AFMA setting at different subject distances.
Having researched the Sigma USB dock, I thought that it allowed AFMA calibration of the lens at up to 4 different distances. I thought that this could solve the problem. BUT on trying my lens in the dock it appears that it is not possible for the user to select what these distances are ?!
In the case of my 35 mm lens this will make the dock calibration process of little benefit. If for example I use optimization pro to set AFMA at infinity and at 0.75 M then the calibration will be correct at these distances and off in between 1 and 4 metres. I am struggling to understand the logic of optimization pro since with a 35 mm lens if you are using it for photographing people then you are going to need to work within this distance range. Why have three of the four AFMA distances for this lens at less than 1 metre when any close up/macro type work is likely to use MF anyway ?
At present when shooting wide open I have AFMA = 0 and use the 35 mm exclusively around 1.5 metres distance to subject. At other distances then I have to change either the AFMA setting or use MF or stop down significantly. Hardly an ideal arrangement!
I would appreciate any help as regards:
1) Is there a way of adjusting the lens AFMA calibration distances in the Optimization Pro software?
2) Has anyone had a similarly performing lens and had any success with sending it back to Sigma for calibration – did this improve the AFMA consistency with distance ?
