ssmc
Well-known
The other day I was playing with my Minolta X-700 and I noticed a few annoying specks of dust in the VF that would not be dislodged with a rocket blower or even a camel's hair brush. Turned out it was on top of the focusing screen 
. So I carefully removed the screen and the dust, but while I was doing it I noticed a sort of uneven haze on the bottom of the prism. I thought "oh, well, I better give that a bit of a clean too". Whatever was on there was very difficult to remove and I ended up using Eclipse fluid (which I originally bought to clean the sensor of my old D70), lots of Pec Pads and many, many cotton swabs :bang:. But eventually I got it all off (let's just say it got a lot worse before it got better). Replacing the focusing screen was a good deal less nerve-wracking than removing it. Then I put the lens back on and...
Drum roll, please...
When I looked through the viewfinder I was blown away by how clear and bright it was. It's just... unbelievable for a 23-y.o. camera. I don't ever remember it being like that even when it was new (it's a one-owner) and wonder if that grunge has been there all along.
Anyway, while I cannot universally recommend this procedure (steady hands and a lot of patience are required), if you have an old camera with a removable screen it might be worth taking it out and shining a bright light on the base of the prism to see what it looks like - whether you decide to take it further is up to you, but I'm stoked that I did! (FWIW, Nikon screens are a lot easier to remove than Minolta ones, if you have the right tool)
Hope this info is useful to someone!
Scott
. So I carefully removed the screen and the dust, but while I was doing it I noticed a sort of uneven haze on the bottom of the prism. I thought "oh, well, I better give that a bit of a clean too". Whatever was on there was very difficult to remove and I ended up using Eclipse fluid (which I originally bought to clean the sensor of my old D70), lots of Pec Pads and many, many cotton swabs :bang:. But eventually I got it all off (let's just say it got a lot worse before it got better). Replacing the focusing screen was a good deal less nerve-wracking than removing it. Then I put the lens back on and...Drum roll, please...
When I looked through the viewfinder I was blown away by how clear and bright it was. It's just... unbelievable for a 23-y.o. camera
. I don't ever remember it being like that even when it was new (it's a one-owner) and wonder if that grunge has been there all along. Anyway, while I cannot universally recommend this procedure (steady hands and a lot of patience are required), if you have an old camera with a removable screen it might be worth taking it out and shining a bright light on the base of the prism to see what it looks like - whether you decide to take it further is up to you, but I'm stoked that I did! (FWIW, Nikon screens are a lot easier to remove than Minolta ones, if you have the right tool)
Hope this info is useful to someone!
Scott
charjohncarter
Veteran
Good, mini essay. I'm not good enough to try this, but I sure wish I could do something similar on my Diacord G.
pachuco
El ****
I have a Pentax I should try this on, it is quite dirty inside.
nikku
Well-known
My OM-2n needs a vf/prism cleaning. It has some sort of haze. My OM-1n that I had overhauled by John H. is way brighter.
Laurencet
Newbie
Just a wee note of caution: Go easy on the focussing screen - I spoiled an OM one recently - keep the cleaning fluids away from it.
Paul Luscher
Well-known
Being a mechanical klutz and a coward, I will let John Hermanson do this kind of thing to my OMs...
Fawley
Well-known
I have also read that you have to be very carefull with focusing screens. Many of them are plastic.
Thomas Tomosy, in "Camera Repair and Maintenance" says "If the dust particles you see in the finder are in sharp focus, they are between the screen and the pentaprism and not on the mirror. If they show up as soft blurry spots they are on the under surface of the focusing screen. Anything on the mirror, the lens, the eye piece or between the eyepiece and the prism forms no discernible image."
hans voralberg
Veteran
I've clean a lot of screen and prism from Nikons, Pentaxes and Olys. One tip I find useful for cleaning the screen is to submerge it in pure water mix with photoflow/dish cleaning liquid. Photoflo I use a 1:400 solution, then blast with hair dryer