Mamiyaflex C - Focus screen cleaning?

[andre_reinders]

I have never done any camera repairs - and minimal cleaning. I am

soon to replace the light seals on my Nikkormat FT-2 but that is

another story (and 'circa' 1975 doesn't cut it here :-P ) Anyway, I

have something on the focus screen - oil? It is on the bottom, and

it is starting to bug me - but it really doesn't interfere. I was

going to remove the circled screws and try to clean it. You can see

the 'patch' in the attached photo.

 

I need any tips or suggestions you can offer, please. I understand

that one needs to be careful with focus screens.

 

Thanks!<div></div>

[mike_elek]

As I've recently learned, not all screens are alike. This week, I encountered a screen that actually was composed of three screens.

 

It's possible that you have two screens with some type of liquid between the two. It's also possible that it's simply some haze.

 

In general, yes, you would need to remove those screws to remove the shroud. I'm not sure if you need to remove all of those screws.

 

Make note of which side faces the mirror (generally but not always the matte side). Also make note of the orientation of the screen. It wouldn't hurt to use a black marker to tag one of the corners. The mark will never show because it's under the shroud.

 

You can wash the screen under some running water with a drop of dishwashing soap. Just clean with your fingers, dry, blow it off with some compressed air and reassemble. While you have it open, dry clean the mirror. If you need a little moisture breathe on it. Also clean the back of the viewing lens.

[skygzr]

The C220 and C330 screens were one piece, and could only be inserted in the camera one way. I don't know that the Mamiyaflex was built the same way but I wouldn't be surprised.

 

I think the screws on the top are the ones you want. There's some screws UNDER the screen (once you remove it) that you should not touch. They should be lacquered in place. They adjust the registration distance of the screen.

[leonard_robertson]

Andre - I dug out my "parts" Mamiyaflex C (which, except for a missing wind knob, is actually in better shape than my "good" C) and removed the top frame. You need to unscrew the top five screws you have circled in your picture. On my camera (and maybe yours), the rear two screws seem to be slightly longer than the front three, so note the lengths when you remove them. Under the front of the top frame are a couple of fiber spacer strips which the front three screws pass through. The rear two screws get rather tricky - under the frame on each side are three thin flat washers. That is, each of the two rear screws passes through the frame, then through three flat washers (and the number may be different for your camera). I suspect the front fiber shims and rear washer stack are adjustments for the ground glass registration. When the frame is removed and turned over, there are four screws holding the ground glass to the top frame. I didn't take this apart, although it appears to be a two piece screen. You may have to take the two pieces apart to get to where you need to clean. Finally, the camera I'm working on is an original Mamiyaflex C like yours. I can see in your picture the "hook" at the top rear of the body that holds the finder on. The C2 and later used a knurled knob which tightened to trap the rear of the finder. Please do let us know how your cleaning job goes.

[glenn_thoreson]

Anyone need an original lens cap for their C? I have one around here somewhere. Let me know and I'll look for it and get back to you.

[andre_reinders]

Just completed - looks much better. It was a 2 piece screen. I undid the 5 screws and took off the unit and flipped it over onto the table. There were 2 spring/tension type clips - 2 screws each which held the 2 piece screen in place. I just loosened the screws and slid the screen out one side. I took the screens out and dunked (and swished) them in a container filled with cool water and a very small amount of dish soap. I then wiped them, while wet, with my fingers, and then rinsed them in cool running water. I laid them on a paper towel to dry a bit, but then used a lens tissue and compressed air to finish the drying job. I put it all back together and it looks much better. The only think I am unsure of is if they went back with the correct side facing the proper way. When the camera is sitting upright, the top piece is smooth on top, and has the matte type finish on the bottom (I am pretty sure this is correct). The bottom piece has the smooth part on the bottom, and the 'rough' side with the clear center (like circular grooves - like a record) on the top. This results in the smooth finish on the outside of the 'sandwich' and the 'marked' sides toward the center. Looks OK anyway. I also noticed that the mirror was pretty scratched - like someone used fine sandpaper to clean it. Oh well. :( It works.

 

Leonard: I didn't find any adjusting washers....

 

Glenn: I have a metal lens cap for my 80mm, but the felt liner which keeps it snug has deteriorated...this is my next job, to replace the lining so the cap won't fall off whenever someone blinks.

 

Thanks for the suggestions everyone.

[david dutchison]

When you work on any camera, place it in a large (preferably light coloured) tray so that if any of the tiny screws or shims fall, they'll be safely contained.

 

As noted above, pay really close attention for any spacing shims that may be found under the frame. These will need to be returned to their original locations - in the same numbers, or the else the camera may not focus accurately. I've found the easiest way to reassemble a sack of shims is apply a thin film of Vaseline to each one and stick them together.

 

If you're thinking of cleaning the mirror,a word of caution first. Be aware that these are not like normal mirrors. They are usually just a coating of silver or aluminum, several molecules thick, with no protective glass covering at all (google "front surface mirrors" for more details).

 

These are extremely delicate, far more so than the screen, and especially so in the case of your camera which is approaching 50 years old. If compressed air will not clean it enough, get good solid advice on how to safely clean an old front surface mirror before touching it with anything. Start with small area on the edge, and inspect carefully for damage before proceeding.

 

I think you'll do fine with the screen, I'd leave the mirror alone on a camera of this vintage though.

[david dutchison]

Wow, you finished it in the time it took me to type my post ;-) , good work!

[jorn ake]

Andre:

 

Sounds like you got the "sandwich" right. Fresnels (the lower part with the rough side) typically are positioned below the ground glass with the fresnel (rough) side against the ground glass. Not sure if this is the way with Mamiyaflexes, but it is the way with most fresnel setups.

 

You might check the focus while you are there. Set the camera on a tripod, remove the back, focus on infinity, stick a piece of ground glass (or anything translucent and flat like ground glass) on the film plane and see if the focus of the viewfinder screen matches that on the piece of ground glass. Compare other distances too. If no match, you can decide whether you want to add a few shims of your own making beneath the viewfinder screen.

[david_richert]

Welcome to the world of tinkering with cameras.... Soon you will be asking about shutters and fixing bellows :^)

[andre_reinders]

Just an update: Last night I put new felt(?) on the lens cover for the 80mm lens, so it had a more snug fit. Not major repairs, but I am feeling proud. I also replaced the seals in the Nikkormat FT-2 and just got the test roll back - no light leaks. (Mind you I didn't have light leaks before when most of the seal was gone...)

 

Now I am looking for something else to fix....I have a Ricoh AF-5D Which has an awful sounding winder - forward or back, otherwise it works. Gave it to my mother-in-law 2 years ago, got it back when I convinced her to buy a Olympus Stylus Zoom 80 last week.