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09-19-2014, 10:57 AM   #1
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Build up residue on focusing screen?

The focusing screen has been dusty since I got my used K200D. Finally today I decided to open the frame, take the screen out and clean it. The dust was old and stubborn, so I used microfiber cloth to remove all dirt. Then I placed the screen back, attached the lens and omg! clear view, not a bit "foggy" like before, but super clean.

Like on mirrors, it seems that with time some foggy residue builds up. However, I've never seen the recommendation to clean focusing screen.
Obviously it worked for me today. The minor dust traveled from the area between screen and viewfinder I did not reach, but it's not so critical like before, and it does not affect images.
So, is it recommended to clean focusing screen and how often?

09-19-2014, 11:05 AM   #2
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You were lucky. Most times those who clean the focusing screen inevitably scratch it and there is no fix for a scratched focusing screen other than install a new one.
09-19-2014, 11:09 AM   #3
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LOL, I scratched it very, very little because first I tried the same watchmakers sharp ends tweezers that some youtube guy used in his video, but quickly realized it's safer to take wider ones instead.
Oh, those youtube experts... I better be more careful following them.
09-19-2014, 11:12 AM   #4
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Since focusing screen scratches don't show up on photos, I'd leave mine be rather than risk scratching it more.

09-19-2014, 11:16 AM   #5
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Nope, it does not affect either image or my view. As I told it's very tiny mark on top.
But my question is: is it recommended to clean focusing screen to restore the clarity? If so, how often?
09-19-2014, 11:16 AM   #6
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I've cleaned focusing screens in an ultrasonic cleaner - lukewarm water with a drop of detergent in it. Then a good rinse with distilled water. Pat dry on a lint free cloth or tissue (microfiber cloth or something like kimwipes) or air dry using your rocket type blower. Avoid rubbing. Rubber exam gloves are a must to keep skin oils off the screen.

If your focus screen, pentaprism and mirror are clouding up either something is out gassing in the camera - lubricants, light seals or electronic components are the most likely suspects. Another source can be the materials used in camera bags or a polluted or smoky environment.

How often depends on how often the surfaces cloud up. The best solution would be to eliminate the source of out gassing or pollution.
09-19-2014, 11:35 AM   #7
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QuoteOriginally posted by Not a Number Quote
I've cleaned focusing screens in an ultrasonic cleaner - lukewarm water with a drop of detergent in it.
Thanks for tutorials. I thought about cleaning with water, but when microfiber did good job, I decided to leave it that way.

QuoteQuote:
If your focus screen, pentaprism and mirror are clouding up either something is out gassing in the camera - lubricants, light seals or electronic components are the most likely suspects.Another source can be the materials used in camera bags or a polluted or smoky environment.
The background is unknown. However, I know that in couple of years any glass, and any mirror will build up some cloudy residue if exposed to the open air or being inside unsealed box.
It must be the same with screens, plus, they are too close to human contact (sweat, oils). The camera is 6years old, and I doubt that screen has been ever cleaned.

The difference in clarity is amazing. If I knew, I would clean the screen long time ago.
09-19-2014, 11:37 AM   #8
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QuoteOriginally posted by micromacro Quote
But my question is: is it recommended to clean focusing screen to restore the clarity? If so, how often?
How often? Almost never. I have cameras that were manufactured in the late 1960s whose screens have never been cleaned.

As to how to accomplish? I think the instructions that KatzEye provides are probably the best I have seen. And no, they don't include scrubbing with a microfiber cloth.

On the subject of using a lens cloth:
KatzEye Optics: Cleaning with a lens cloth
On dust removal:
KatzEye Optics: How to remove dust
On how to clean if badly soiled:
KatzEye Optics: Cleaning a badly soiled screen

Steve

09-19-2014, 11:47 AM   #9
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QuoteOriginally posted by stevebrot Quote
How often? Almost never. I have cameras that were manufactured in the late 1960s whose screens have never been cleaned.

As to how to accomplish? I think the instructions that KatzEye provides are probably the best I have seen. And no, they don't include scrubbing with a microfiber cloth.
Are you an original owner of those old cameras?
In my defense , I have not use lens microfiber, but auto soft and fluffy microfiber, after cleaning the dust away with the brush. I did not get an impression that focusing screen such a fragile piece, soft plastic- yes. Softer than glass obviously, but all that cleaning with water and air drying? Hm... I don't know.
09-19-2014, 12:09 PM   #10
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QuoteOriginally posted by micromacro Quote
Are you an original owner of those old cameras?
Yes, I am the original owner or know the original owner and history of the cameras. I have about a dozen SLR bodies dating from the mid-1980s back to the early 1960s.

As for rubbing the screen, the issue is the Fresnel lens on the bottom surface. There is increased risk of scratches due to the texture and also the possibility of flattening or bending over the ridges of the Fresnel. That would result in a dimmer screen and/or a blotchy appearance in the viewfinder.

I am surprised that you had significant build up of contaminant on your K200D. Up until a few months ago I used a K10D that I purchased new and the screen (a KatzEye that I install six years ago) was essentially in the same condition when I sold the camera as when the screen was installed. I guess there are benefits to the clean air, low dust, and moderate temperatures we enjoy here in the Pacific Northwest!


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09-19-2014, 12:21 PM   #11
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Best cleaning methods I have used...
- lighter fluid OR
- isopropyl alcohol.

DO NOT RUB... just bathe / poor over it the solution and let it air dry.

And build up dust and residues could, in time, affect how camera reads the light. It all depends through what the camera went trough and how rough the environment is... also how religious you are with keeping the camera clean.

Last edited by mrNewt; 09-19-2014 at 12:27 PM.
09-19-2014, 12:32 PM   #12
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I don't know, Steve, why the screen was so "foggy". Maybe, polluted city, who knows.
I need to google Fresnel lens, it's always something new here
Plastic itself can not be softer than amber, and I do polish amber, so I have an idea.

---------- Post added 09-19-14 at 12:34 PM ----------

QuoteOriginally posted by mrNewt Quote
Best cleaning methods I have used...
- lighter fluid OR
- isopropyl alcohol.
The last thing for me would be using rubbing alcohol on ANY plastic without testing. You never know what to expect.
09-19-2014, 12:37 PM   #13
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I see you have many answers now so I'll bow out of this thread. But one more thing to say, I use isoproply alcohol on plastic fans inside computers all the time and it never hurts them. Though the alcohol I use is either denatured or at least 90%. And though I do that on those fans, I don't know if I'd do that on a Fresnel lens.

Last edited by photolady95; 09-19-2014 at 12:43 PM.
09-19-2014, 12:40 PM   #14
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QuoteOriginally posted by micromacro Quote
Plastic itself can not be softer than amber, and I do polish amber, so I have an idea.
Look up Fresnel lens and you will understand why you should not polish a focus screen


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09-19-2014, 01:09 PM   #15
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QuoteOriginally posted by stevebrot Quote
Look up Fresnel lens and you will understand why you should not polish a focus screen Steve
Got it, thanks. But I did not polish the screen. I cleaned it, that's the difference. It survived!

---------- Post added 09-19-14 at 01:16 PM ----------

QuoteOriginally posted by photolady95 Quote
I use isoproply alcohol on plastic fans inside computers all the time and it never hurts them. Though the alcohol I use is either denatured or at least 90%. And though I do that on those fans, I don't know if I'd do that on a Fresnel lens.
I use 70% alcohol. Never cleaned computer fans, but have cleaned different plastic parts on other devices. Sometimes plastic gets dull, losing the shine, sometimes the surface suffers badly. I've learned my lessons: test it on your own before using. I also keep plastic cleaner in the kitchen, it's good to have.
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