Focus screens

[Javelin]

Well my A700 is actually on the bench at Sony now being repaired. I asked the tech about installing a focus screen in it while he has it apart and he's gone to see what they have on hand. Now my dilemma, I expected him to say no but I think I piqued his curiosity because he hasn't done one yet. Anyhow I know split screens are better for tele and matte screens are better for dark/ wide angle (or do I have it backwards?). seems to me on my film cameras the split screens wewre tough to see in the dark .. but anyway. I have a hard time ensuring sharp focus on tele shots. which would be a better focus screen for that ?

[David Kilpatrick]

For fast teles, the dimmer type M matte screen is more accurate, but you need to be working with f2.8 lenses ideally. The ML screen with grid lines is my favourite. There is no official split image screen from Sony, they do work well with teles (including f5.6 models, but not f6.3) and they are quite difficult with wides, where microprisms work best. The only screens of this type made are third party.

David

[Javelin]

Thanks David. I haven't heard back from them yet so I donlt even know what they have on hand. My Z700 had a split screen but it also had little prisms in a circle in the middle. what are the grid lines all about ? and how do you know about where it's sharp? is it like matching the 1/2's of the image on the lines like the split screen does. also the A700 VF is pretty bright .. how dim wll screens like the ML make it with say an F4 lens on it. ? hate to not be able to use my beercan anymore

[David Kilpatrick]

An f4 will be nice. You have to judge sharpness by eye with the matt screen, no focus aids, but it is about twice as accurate as the standard screen and also shows you the depth of field preview more accurately. The grid lines are there to help you keep your horizons level, line up architectural shots etc, but they also provide a reference for focusing your eyes (set the dioptre control until the grid looks dead sharp). On the DSLRs, the focus area marks are NOT reliable focus references. They actually live on another screen, which is a thou or two out of position from the focus screen. Many people make the mistake of adjusting the dioptre until the focus rectangles are crisp. If you do this, and then use the standard screen for manual focus, your eyes will compensate and you will probably backfocus slightly every time.

With the standard screen, you should set the dioptre so the metering marks (circle) are sharpest, not the focus marks. These marks are actually on the focus screen itself, and give your eyes an exact lock-on. The same goes for the grid screen grid.

David

[Javelin]

Ok well thats what I will try for then. it's gotta be better than the standard screen. the slowest lens I have is my big beercan and thas only used in bright situations. I have no 5.6 other than that. I was considering the 500mm mirror but I have trouble holding the 300mm so I think it would be a waste for me. and being F8 it would be strictly in blazing sun too .

[Javelin]

No Focus screens in Canada :/ Just heard from the shop. they have the instructions and there are part numbers on their system but no stock. They also don't have a mechanizm to let me know when something like that would become available so I would have to call periodically to find out if they have them. The part numbers seem like part numbers from everything else on the camera and the ML meant nothing to him which I suspect is a model number?

They have a room dedicated to adjustment on the DLSR cameras and I suspect the broadcast cameras (they are repaired there as well) which is where my camera is now aparently because the repairs are complete. I expect they will call to pick it up tomorrow. which will make it 1 week in the shop including last weekend.