19 September 2010
More Manual Focus
I got a response from Nikon service reasonably quickly, however the response itself was fairly useless. They couldn’t give me a price for doing any work without seeing the camera and said that if the focus screen wasn’t a Nikon one (as far as I know Nikon don’t make split prism screens for their DSLRs) they may replace it during the service.
So, next stop was to try and find a local camera repair shop and see what they could do. I phoned RCCR as they’re pretty close by and had a very helpful conversation with Ray. Whilst he couldn’t actually help me he was very happy to explain in detail what might be going wrong.
Conveniently I’ve also currently got a trial version of Lightroom 3 installed. I’d read that this allows you to do tethered shooting, and sure enough after changing the USB setting on my camera, tethered shooting worked without a hitch. This allowed me to check the focus of my photos at 1:1 on my laptop as I took them, which is a lot more useful than looking at them on the back of the camera.
Ray was worried that the mirror adjustment might noticably mess with the autofocus (contrary to what I’d read previously). It seems that he was right, thanks to the tethered shooting I saw a noticable change in sharpness as I moved the mirror adjustment this time.
According to Ray I should have seen a difference in focus performance after taking the existing shims out. The first time I took them out and put them in a few times and didn’t really notice anything changing. This time I thought that instead of using the autofocus and seeing how far misaligned the split prism was I would try focusing with the split prism and see if I could tell the difference in the pictures. This turned out to be a much better idea and showed that focusing with some thick paper shims I made was clearly worse than no shims.
Unfortunately because in both cases the focus was off in the same direction I have to conclude that either my camera just can’t do accurate manual focus, or that I’ve got a duff focus screen - if it’s thicker than the existing screen plus the shims then it’s probably going to be impossible to use.
So for now I’ve re-installed the original screen and gone back to my mostly reliable autofocus. Drat.