Just picked up a Sigma 35mm 1.4 for my 5Dc. What are your testing recommendations ?
I'm hoping to mine your collective consciousness for your tried and tested methods of testing third party lenses.
As its a Sigma there's always the possibility of the reverse engineered algorithm not getting it quite right all the time. So, whilst I'm still in the return period, I wanted to ask what your recommended ways of testing a lens for front/back/distance focus.
There's the method of putting it on a tripod, aiming it at an autofocus test chart like the one here : http://regex.info/blog/photo-tech/focus-chart but I was wondering if there's anything else e.g accepted ways of seeing how a 35mm lens performs for subjects at a distance and what is considered anomalous.
Also, given that there's a Sigma dock out for finetuning focus where could I read up about the methodology behind the fine tuning ? Is it just a case of playing around with settings at each distance scale setting or is there a nice summary somewhere that can explain the theory behind it ?
Many thanks in advance ! Looking forward to hearing your tips.
I'm not sure about methods, but mine is the sharpest lens I ever had even at f1.4. I need no micro adjusts, focusing is spot on, etc.
After you check for accuracy of focus, you could shoot some test charts at various f/numbers and check the resolution at the centre and edges.
I printed A4 size and set up a board with 5 charts; see my gallery.
Multiply best resolved number x300 to get LPPH. Compare with data from the following site.