Focusing an FM3a

wintoid · Joined: 31 Aug 2008 Posts: 138 Location: West Wickham, UK

Hi all,

Like most people here, I have several lenses and several bodies. Usually I shoot with a rangefinder, but sometimes an SLR is just more convenient.

I have 2 SLRs. A Contax Aria and a Nikon FM3a. I find that the Aria is way way more consistent in focusing than the FM3a.

The FM3a has a K3 screen, which I am considering changing out for a B3 or E3. Has anyone tried this? Am I alone in finding the FM3a hard to focus?

I was so disappointed to find that so many shots are out of focus, sometimes way out.

Esox lucius · Expire: 2011-11-18

I think these product numbers apply to your FM3 focusing screens as well, though this is how I am using (and swapping) focusing screens for my FM2n

K2 (K3 for FM3a) focusing screen - split image and microprism focusing aids. I find it the best for general photography that requires critical focus (narrow depth of field).

B2 (B3 for FM3a) focusing screen - for close-up and duplication work. I don't use much, my macro is all digital.

E2 (E3 for FM3a) focusing screen - with horizontal and vertical grid lines. I find it most useful for architecture as well as landscape, especially with wide-angle lenses.

The B and E screens do not have focusing aids. The K has the split image which is the best for critical MF work, just as long as you learn to read and use it correctly. In a pinch (fast focusing required) I rather look for how the center border (the prism area) "de-blurs" rather than aim the split line at a point and release the shutter. The E2 screen is my most used one, I find it especially valuable for compositions that involve horizon or architecture, wide or normal lenses.

Another reason you might be missing focus is the viewfinder diopter. It is replaceable and many times should be replaced, it can be scratched, fogged or dusty (needs a clean). If you need eyeglasses then you should be aware that taking the diopter to an optician and asking him to replace the glass with one corrected for your eyesight will reward you plentiful.

I have fairly good vision, but I am a bit "cross-eyed" or "misaligned" on my right eye (I don't know if it is the right word in English). My right eye I use for camera work so this is why I have replaced all my SLR camera's viewfinder diopters with custom made lens put in by my optician. Results immediately improved vastly - I nowadays find manual focus even in difficult circumstances I can pull through with very high success ratio.

Hope this was of assistance to you.

wintoid · Joined: 31 Aug 2008 Posts: 138 Location: West Wickham, UK

Hi Vilhelm,

Thanks for your response and your time.

I don't wear glasses, and I've usually been able to focus SLRs just fine. This is my second FM3a, actually, and I had the same problem with the first one. Such a nice camera, so I really want to solve this problem.

I don't think there is a diopter on the viewfinder, just the usual rubber ring. If it had a diopter, the ring should be marked, right?

I seem to find the split image really hard to use. I am usually trying to look "around" the split part, but it's a very distracting way to focus. If I have lots of time, and a stationary subject, I can use the split image, and I think it's accurate, but I have kids, and they move fast...

I'm sure it doesn't help that Nikons focus "backwards" too.

With a B2/E2 do you find you can focus even an f1.4 lens fairly accurately? I usually live at f/2.0 in the evenings.

peterqd · Expire: 2014-01-04

Hi wintoid, I know nothing about Nikon cams so I don't know if this will be applicable to you! Smile

Focussing screens sometimes become inaccurately positioned or adjusted. When this happens the image on the film is not in focus when it is on the screen. You can check this using the tape measure test - focus on a set dimension from the camera along a tape measure, and take a shot. The film image should of course be focussed on the same dimension as in the viewfinder, but if there is any misadjustment, the film image will be focussed in front or behind your dimension. BTW, you don't need to use actual film - you can see the image by sticking 3M Magic tape (the translucent kind) over the picture frame between the film rails. You'll need a magnifier to check it properly.

I had a similar situation to you with my Canon 400D and discovered that the focussing screen wasn't seated properly in its recess, so you might like to check that first. If all is well, there might be some adjustment screws inside the camera to adjust the screen or the mirror. Alternatively you can adjust the position of the screen using shims or spacers cut from aluminium foil or Magic tape again. Ask on the Classic Camera Repair forum about your particular camera.

Vilhelm, I agree with you about using dioptric lenses in the viewfinder. It helps a lot. I never thought of asking my optician, though, good idea! I made some dioptric lenses for my Spotmatics from a pair of old reading glasses: Smile

http://forum.mflenses.com/correction-lenses-t13568.html

hexi · Expire: 2011-11-18

wintoid · Joined: 31 Aug 2008 Posts: 138 Location: West Wickham, UK

Thanks for all the responses.

I found a B3 for £15 so I'm going to try that and see if it helps. I'll report back once I know what I think. I was surprised the focus screens were so cheap, actually. Much cheaper than Katz Eye.

Esox lucius · Expire: 2011-11-18

wintoid · Joined: 31 Aug 2008 Posts: 138 Location: West Wickham, UK

I *think* I'm doing better with the B3 screen than I was before. Early days yet, but looks like I'm keeping the FM3a now Very Happy

Scoo · Joined: 16 Jun 2009 Posts: 62 Location: Finland

Did you check what's being projected at the film plane? That will tell you what's really in focus (without having to possibly waste film for test shots, not an issue of course if you develop b&w yourself or such). A slightly easier way than tape may be to cut a piece of acrylic (say CD case) and grind one side with a fine sandpaper (size P180/P220+). That might be easier to put in the film gate.