Dirty ground glass - replace, clean or ignore?

thecornflake

thecornflake

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Simon
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I've been examining the worse of my two current 35mm slrs as out of the two it has more shutter speed options and I prefer the viewfinder (it's a Fujica st705w, the other being a AZ-1). It's in worse condition than the AZ-1, because the AZ-1 was passed on to me by someone who had looked after it well and the st was found in an old collapsed chest of drawers inside a damp shed.

Mechanically it seems fine, and after replacing batteries the meter works fine and matches my separate Sekonic meter. However inside isn't so good. The mirror buffer foam has pretty much disappeared, the mirror isn't very clean and the ground glass is marked.

Now I'm happy replacing the foam, and I can probably live with seeing a couple of marks in the viewfinder if they're nowhere near the split screen and I know they won't be on the actual photos, so I'm wondering whether I should just leave it alone? Other options are replacing - not sure how possible this is and is probably beyond me, or cleaning which is full of potential to mess it up even more. The camera isn't really worth paying someone to professionally sort it, so these are my 3 options. Picture below showing the marks. Also you can see some sort of grey flap above the mirror which seems to be not fully attached, I assume this is some sort of light seal.

View attachment 6668
 
do you mean the focus screen?

If it can be easilly removed like the nikons it is easy to clean with great care.
 
i would remove all the foam in one go first and then with a cotton bud and water see if you can gently clean the mirror up.

you can use alcahol on the foam residue with care as well and cotton buds but steer clear of plastics.
 
To clarify its the frosted glass with the split circle in it that has the main issue. Wasnt sure if denatured alcohol etc would mess up the frosting.
 
oh yes alcahol will make a mess of that sucker.

I do my nikon ones, very carefully remove it with latex gloves if possible and do not touch the services AT ALL, just handle by the very edge.

Nikon ones are easy to get out they have a screw or a clip which lowers the screen holder and then you can slip it out.

Then still with the gloves on rince under slow luke warm water for a minute both side.

then I use hand soap just drip a few drops on one side at a time and super gently with finger tips only massage the glass, no rubbing action just excite the soap.

repeat on the other side. note which side is up and which is down in the camera, one side will be flat polished glass and one side will have the fresnal screen (i think in nikons its fresnal up polished down)

rince thoughly and lay on toilet paper to get the excess water off, no rubbing.

then use a hairdryer holding the screen at the edges and that will remove the streaks don't over cook.
 
I cant see any screw or clip. If I gently push the glass it moves slightly upwards and feels like theres a spring somewhere pushing back. Under that grey flap there are 2 screws, I was going to glue it back down as its stuck down inside the az-1 (very similar inside).
 
some screens are not removable as far as i can see, i had a practica TL5 i think and i could not see a way to remove it.
 
is the underside of the screenthe polishedside?
if it is you might be able to clean gently with a cotton bud, don't touch it if it is the fresnal side.
 
Er... it's got a slight texture to it. This increasingly sounds like I'm stuck with how it is.
 
Isopropyl Alcohol will not affect the ground glass, but be careful when rubbing the glass as dirt may scratch or streak it
 
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