Cleaning Spotmatic's Viewfinder

[mszargar]

This is definitely not a rangefinder question, but then I don't know any better place to ask this kind of question. I just bought a Spotmatic SP1000 for almost nothing. The camera works perfectly (surprisingly, even the light meter and slow shutter), but the foam pads have gone all bad and there is some dust visible in the viewfinder.

I will get a pre-cut kit to replace the foams, but I wonder if the fresnel/viewing screen can be cleaned as well. Since the mirror slap dampening foam has been falling off for a while, there are tiny bits of foam everywhere in the mirror box.

I have cleaned the mirror and the viewing screen as much as possible using compressed air and some accessories from my lens cleaning kit. Yet, there are still specks of dust visible the viewfinder. I wonder where these specks can be: On the mirror, on the fresnel, between fresnel and the pentaprism, or between the pentaprism and the viewfinder glass? I upload the image here so you can see how the dust specks look in the viewfinder.

Now, if I understand correctly, some of these specks are definitely between the fresnel and the pentaprism. But how easy is it to take out the fresnel on the Spotmatic 1000s? Can one try to do that at home? Have you seen any guide anywhere on the net?

 

[peterm1]

This might help.

http://rick_oleson.tripod.com/index-113.html

http://rick_oleson.tripod.com/index-27.html


It looks like a bit of a "to do" to get the top plate off and get at the inner workings of the prism and screen for cleaning. But by following the image and instructions it should be do-able with a little patience and care. Although it should be said that getting these things back together is always harder than getting them apart. BUt there again patience and care work.

The Spotmatics are great old cameras with an excellent range of lenses. The only better Pentaxes (IMHO) are the earlier pre Spotmatic cameras which do not have any metering. They are smaller and more elegant and take exactly the same lenses as the Spotty.BUt the Spotmatic is a fine old camera.

BTW to check if they are on the mirror or on the fresnel, try this. If the spots appear sharp when the image being viewed is in focus they will tend to be on the fresnel. If they are blurry then its more likely to be on the mirror. I think that is how it works. Someone else might comment but I recall this being told to me by a camera tech many years ago. The only question is - is my remembrance correct? If you need to clean the mirror just remember that the silvering is on the front face of the mirror (not the back face as in a bathroom mirror). So its awfully easy to damage. A blower followed by a sensor cleaning pod might work without damaging it.

 

[Ranchu]

The sharp ones are inside the screen the out of focus ones are on the outside facing the mirror. You have to take the entire optical system out from the top, clean everything, remove and replace all the foam in it, and put it back together. Don't touch the three little screws visible in the mirror box. The foam adheres to the black paint of the prism, so that can come off with the foam. This doesn't look bad enough for me to do it again, if it were me. You might try a brand new (natural, soft) make up brush to dislodge the specks on the outside, and blow it off some more.

 

[mszargar]

Great links... I also found this one: http://www.pentaxforums.com/forums/...-f-focusing-screen-dust-dirt.html#post2140467 , which is as comprehensive as it can get.

Given the price I have paid for this camera, I consider it kind of a "project camera", and I don't mind tussling with it a little bit. And apparently what I miss is a spanner wrench. But these cameras are so well-designed I wonder why their viewing screen has not been designed to be user-accessible... Mystery.

 

[peterm1]

Great links... I also found this one: http://www.pentaxforums.com/forums/...-f-focusing-screen-dust-dirt.html#post2140467 , which is as comprehensive as it can get.

Given the price I have paid for this camera, I consider it kind of a "project camera", and I don't mind tussling with it a little bit. And apparently what I miss is a spanner wrench. But these cameras are so well-designed I wonder why their viewing screen has not been designed to be user-accessible... Mystery.

Great link. Very useful. As to a spanner wrench I found that there are alternatives. If you have a hardware / tool store nearby you may find a pair of engineers dividers - these are like a draftsman's compass but with sharp metal points on both ends to scribe a circle on metal etc. which with minor modification will work well.

Or you might find a pair of circlip pliers. These are pliers with a pointy nose designed to open those springy circlips that are sometimes used to hold parts together in various engineering applications.

You can also modify small round nosed pliers.

Each of these tools have pointy ends that can be called into service in place of a spanner wrench. I have used each and each work for smaller applications - lenses are a bit more problematic due to the need to span a larger distance and none of these tools are really designed to do that.

Some pictures.........

Circlip Pliers

http://www.chinatraderonline.com/DIY-Tools/Pliers/Internal-or-External-Circlip-Pliers-221928469.htm

Engineers dividers

http://tooltray.com/Engineering-Tools/Dividers---Spring.htm

Round Nose Pliers

http://www.tronextools.com/tronex-pliers/round-nose-pliers/

 

[mszargar]

Of course it does not mention how to clean the screen. I just had a look at the screen under strong light. I can definitely see the shadow of the specks on the other side. So, and tell me if I am wrong, I assume that I can clean the other side of the screen in the same way as this side. But I am pretty sure there is at least one magnifying lens on top of the viewing screen, and this document doesn't cover how to remove that. I couldn't find anything in Pentax's repair manual either. If you have any other resource on this, please let me know... Maybe I can remove it with a vacuum cup?

The wrench is needed in several steps, and it can't be replaced with a rubber pad... But if I find circlip pliers with sharp-enough tips, I will definitely go for that... They may come in handy in so many other circumstances...

 

[Ranchu]

Here is a service manual, many thanks to Kim Coxon. Once you have it out, you can clean a screen in a film container filled with distilled water and a half a drop of dishsoap. Shake it, rinse it off with distilled water and blow off the water with a rocket blower. Don't use alcohol or any solvent. Don't wipe, let it evaporate. I wouldn't recommend this now, it's not hard to ignore these dusts, and a it's useful skill to have.

http://pentax-manuals.com/manuals/service/servicemanuals.htm