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12-16-2009, 04:02 AM   #1
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Dismantling k100d viewfinder

Hi everyone,

I'm suspecting the viewfinder on my k100d is getting fungus growing on the inside of it. It appears as scratches but that shouldn't be possible as i've only ever used microfibre cloth and lenspen to clean it. I've used the camera while snowing and other times of wet weather.

When taking the eyecap off, i noticed 2 small screws on either side of the viewfinder. Has anyone had this problem and taken the first part of the viewfinder glass off to clean the inside? Do these small screws allow the outer glass to be removed?

On another similar note - the glass has colorful smudges on it which blurs the image through the viewfinder. The microfibre cloth I was using was a lens cleaning cloth. I also used it lightly on the inside mirror and now it has red smudges on it. Is it oil from the cloth or have I managed to take of some coating or something? Is that possible with rare light cleaning with microfibre?

12-16-2009, 04:24 AM   #2
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QuoteOriginally posted by fan22 Quote
I also used it lightly on the inside mirror and now it has red smudges on it. Is it oil from the cloth or have I managed to take of some coating or something?
Sorry to be of no help with your questions but I suggest to not touch the mirror. It is very delicate, much more susceptible to damage than the sensor for example. It is not your regular glass coated mirror but has reflective coatings that are easily damaged.
12-16-2009, 04:42 AM   #3
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Gosh so you think I damaged it with a microfiber lens cloth?
12-16-2009, 04:50 AM   #4
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Those two screws remove nothing on the VF. The whole top has to come off to service the VF module.

12-16-2009, 04:59 AM   #5
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QuoteOriginally posted by fan22 Quote
Hi everyone,

I'm suspecting the viewfinder on my k100d is getting fungus growing on the inside of it. It appears as scratches but that shouldn't be possible as i've only ever used microfibre cloth and lenspen to clean it. I've used the camera while snowing and other times of wet weather.

When taking the eyecap off, i noticed 2 small screws on either side of the viewfinder. Has anyone had this problem and taken the first part of the viewfinder glass off to clean the inside? Do these small screws allow the outer glass to be removed?

On another similar note - the glass has colorful smudges on it which blurs the image through the viewfinder. The microfibre cloth I was using was a lens cleaning cloth. I also used it lightly on the inside mirror and now it has red smudges on it. Is it oil from the cloth or have I managed to take of some coating or something? Is that possible with rare light cleaning with microfibre?
Firstly, there should never be the need to clean the viewfinder with a cloth! It should only be cleaned with a rocket blower and/or a soft brush. The coatings on the viewfinder are very sensitive. Also the mirror is surface-silvered, which means, any cleaning with force (microfibre cloth) may damage it permanently... The same is true for the humble viefinder screen, because these are made of plastic and can be scratched easily.

So, now to the disassembling part. What do you want to disassemble? Just remove the viewfinder screen or the whole prism assembly. If that is your goal, forget it. It needs a repair shop to do that or, to be more precise, to reassemble it and keep it within factory tolerances aligned. Otherwise your viewfinder images may be scewd or offset and your focal plane be off.

For removing the screen you should do a Search, there have been plenty of discussions on that.

Fungus in the viewfinder is very rare, except you live in a warm, humid climate. Cleaning a lens with fungus is a doable self-repait job, cleaning the camera inside is not.

Ben
12-16-2009, 05:39 AM   #6
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The screws I have marked will not remove any part of the VF. The whole top plate has to come off to reach the VF assembly. The parts can be purchased from Pentax. But you would have to be comfortable with messing about under the hood.

Last edited by wildlifephotog; 05-05-2012 at 06:44 AM.
12-16-2009, 05:50 AM   #7
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QuoteOriginally posted by fan22 Quote
Gosh so you think I damaged it with a microfiber lens cloth?
Possibly, but the streaks could also be just residual oil. I have no experience with this and cannot tell you what streak colours you should expect in either case.

Just to re-emphasise on of Ben's points: Don't try to clean the focusing screen (the one inside the camera) with anything but a blower. These things scratch very, very easily and should only be handled at their respective tabs. Some DIY people use Scotch tape to cover big FF screens for cutting them down to APS-C size and apparently manage to remove the tape without leaving residue. Having said that, I know someone who did something like this and when I look through his viewfinder it looks a mud storm had hit a windscreen. And he is a reasonable and careful person.

I hope it all turns out well for you.

Last edited by Class A; 12-16-2009 at 01:00 PM.
12-16-2009, 06:08 AM   #8
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The plastic screen inside above the mirror is not called the viewfinder screen. It is the focus screen. The viewfinder is what you look through to take a photo.

And the focus screen should never be rubbed with anything.

But the OP asked about the two screws on the back of the camera.

12-16-2009, 06:25 AM   #9
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QuoteOriginally posted by wildlifephotog Quote
The plastic screen inside above the mirror is not called the viewfinder screen. It is the focus screen. The viewfinder is what you look through to take a photo.

And the focus screen should never be rubbed with anything.

But the OP asked about the two screws on the back of the camera.
"Focusing screen", "viewfinder screen" – if you just have a quick look into the depths of the web, you will find both expressions used interchangeably (whereas "focus screen" is quite rare...). The Focal Press Encyclopedia of Photography uses different expressions throughout the publication, including "viewing screen" or the simple "ground glass screen". I don't care. as long as everybody understands what's meant - you did, obviously.

And the OP also asked not only about the two screws, but also about whether his cleaning attempts went wrong or whether his camera might show signs of fungus. The latter I cannot decide, because we should see photos of the camera to come to a conclusion.

Ben
12-16-2009, 07:31 AM   #10
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1. If you do end up having to clean the focusing screen, be warned that even with a microfiber cloth you could come out with a worse screen. The screen is plastic, easily scratched, has micro "line" (can't think of the word) that dust could get stuck on but hard to get off...

2. I think cleaning the viewfinder eyepiece (the glass piece) with the microfiber cloth is fine as I has always clean the outer surface of it with a piece of cloth and it seems fine.

3. (advertisement) If you have to order parts from Pentax, check out to see how much it will cost you in total first. I have a bricked K100d whose focusing screen, eyepiece, etc. are still good that perhaps you might want to purchase from if Pentax's parts are crazy expensive.
12-16-2009, 11:14 AM   #11
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Thanks for all the replies.

I had no idea those parts were so sensitive - I wish there was something mentioned in the user manual about cleaning do's and don'ts since this was my first dslr.

The image from the viewfinder is a bit hazy in some spots especially lights - should I just live with it instead of potentially making it worse if I assume the smudges are oil and try and get it off with a lenspen or something? Would a lenspen damage the mirror or outer viewfinder screen? I didn't press hard on the mirror because I was using the cloth to lightly brush off the dust so I'm guessing it's oil residue.

I'm getting a kx and certainly learned my lesson here. Has anyone experienced fungus on the viewfinder screen before? If not I guess it's scratches afterall.
12-16-2009, 01:57 PM   #12
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QuoteOriginally posted by fan22 Quote
Thanks for all the replies.

I had no idea those parts were so sensitive - I wish there was something mentioned in the user manual about cleaning do's and don'ts since this was my first dslr.

The image from the viewfinder is a bit hazy in some spots especially lights - should I just live with it instead of potentially making it worse if I assume the smudges are oil and try and get it off with a lenspen or something? Would a lenspen damage the mirror or outer viewfinder screen? I didn't press hard on the mirror because I was using the cloth to lightly brush off the dust so I'm guessing it's oil residue.

I'm getting a kx and certainly learned my lesson here. Has anyone experienced fungus on the viewfinder screen before? If not I guess it's scratches afterall.
A lenspen only works with pressure applied. Don't use it on the mirror at all. AND don't use it on the focusing (or viewfinder) screen at all. The "micro lines", pentaxpup refers to, are the grooves of the Fresnel lens (which is the cause, why a focusing screen can be illuminated evenly) and the lenspen will ruin those (there are tiny "balls" of cleaning agent in the lenspen, which will get stuck in these grooves).

The lenspen is only useable on lenses, that's why its sold under that name.

Question: How could you have oil residue on a microfibre cloth you use inside a camera? That should be impossible, because you would at all times only use completely new and unused material for cleaning the optical parts inside a camera - don't you?

O.k. now I give you a hint for cleaning the mirror, if it is really necessary: Use only PecPads or other completely lint free use-once pads (no cosmetic pads etc.) and apply two or three drops of pure(!) isopropylalcohol (pharmacie, highest quality they have or can order for you) onto the PecPad and then you can wipe it carefully (= very, very gently pressure only) over the mirror. Wipe only in one direction, down the mirror and avoid to rub or wipe in circles etc. The mirror is, as I wrote earlier silvered on its surface (different to household mirrors, which are mirrored on their backside, and that is the reason, why you can clean them easily) and very easily scratched.

End all you cleaning efforts with giving the mirror chamber a throrough clean with a Rocket Blower (no canned air, the pressure may be too high and damage the fragile mechanisms inside or you can end up with having even more oil residue on everything...). You would do that with the camera mount pointing down, in order to allow all dust, lost brush hairs etc, to fall out of the mirror chamber.

If I remeber rightly, the guide for cleaning a camera is right at the beginning of the manual and it does not mention cleaning mirror or viefinder or focusing screen for a reason.

Ben
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