DIY focusing screen for my Sigma SD10

[ludoo]

To tide me over until I decide to get an SD15 or a Fuji S5 pro (or both), last week I managed to acquire a Sigma SD10 from ebay uk in lovely condition, at an attractive price. I knew in advance, having briefly owned an SD9, that its focsing screen is completely useless for manual focusing, so as soon as I had the time I set down to make me a nicer one.

To make it short, I bought a Canon EE-S from amazon (29€ with free shipping), sanded it down to size like shown in this thread on dpreview, cut the framelines with an x-acto knife, and swapped it for the original screen. As soon as I shot a couple of test frames, I discovered that it had quite severe front focusing, and as its thickness is the same as the original screen, this means the camera left the factory with a calibrated autofocus, but hugely imprecise manual focus. Not that it matters with the stock screen, as you can't see any difference at close focus even if you shift focus by 5cm.

This is what I had, focusing on the "15" mark on the right


Luckily, some time ago I had stumbled on a thread describing how to calibrate focus by adjusting the camera mirror, and since a thinner screen is impossible to use even for the manufacturer, this seemed like the obvious solution to my problem. After about ten iterations (remove the hot filter, adjust the mirror, put the hot filter back on, shoot, check) I managed to get this, still focused on the "15" mark



Much better. Now my SD10 is usable with manual lenses.

I might invest some more time in the future, as the framelines on the screen could be better (I cut them on the wrong side and they are not as crisp as they might be), and after a few test shots I discovered I have the tendency to front focus by a few millimetres, so I might add a slight backfocus, but for now I'm pretty happy, and focus seems pretty spot on.

This is a test shot from a few minutes ago with the SMC Takumar 55/1.8, of a moving subject (harder to focus)



100% crop

[rbelyell]

wow! amazing! congrats to you! i loved this cam but had to sell it because it was impossible to focus manually (and iso 400+ sucked), but it sounds like you really knew what you were doing and can now get those fabulous foveon images! good luck!

[ludoo]

[LucisPictor]

The camera does not offer great usability or great high ISO performance, but it does offer a Foveon.

[ludoo]