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06-10-2011, 10:59 PM   #1
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Cleaning really dirty focusing screen

OK I have made a bit of a mess of my lovely K-5's foucsing screen

I was trying to clean the sensor using the Pentax kit. Although that went OK (unfortunately it didn't seem to get what I was hoping it would clean), I seem to have gotten hairs, dust, and a small spot on the focusing screen There looks to be some kind of streak across the top as well (a squished hair/fiber?).

I've tried cleaning it with cosmetic brushes, 3M microfibre cloth, a foot pump and a giottos blower but nothing seems to shift it. I also tried cleaning the mirror with the above gear. The more I try, the worse it seems to look.

I know it doesn't affect the image quality, but is there any other ways I can clean the focusing screen so it looks a bit more respectable? I guess the only other option is taking it out and cleaning it somehow, or getting it done professionally?

Lesson learnt I guess

Thanks in advance for your help.


Last edited by nandystam; 06-10-2011 at 11:34 PM.
06-11-2011, 12:03 AM   #2
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i know how troubling it is to we OCD'ers to see little dust specks on the screen.

I have definitely removed and cleaned the screens a few times with excellent results.

First, set up in a bathroom with no carpet or some other place where you can control dust. I carefully wiped down the room to reduce any airborne contaminants and ran the shower to humidify the air. if your workspace is super clean, you'll obviously have better results. I laid out a sheet of saran wrap on a plastic tray and opened the camera. the screen pops out easily via a little metal catch (search YouTube to see it done a few times first).
VERY carefully, handle the screen by the edges to prevent scratching it. i hold it under a stream of water to clean it but any tough specks or sticky residue may require a few drops of dish soap or glass cleaner. Note most manufacturers say to not put anything on the screen so be warned. regardless, i have gotten them beautifully clean this way with no damage or residue. i then air dry using a rocket blower or canned air (NO towels obviously), and do not set it down at this point. when dry, install it carefully and you're all set.
If you skip the room prep ritual and or work on the couch where your dog sleeps, you will certainly introduce MORE dust than you had.

beware microfibre cloths, most shed a tremendous amount of lint...sometimes the screen becomes statically charged and the lint sticks like a magnet.
06-11-2011, 03:22 AM   #3
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Thanks for the reply.

Its more than a few spots. There are hairs, dust and some kind of spot. I might find out how costly a pro clean is as although it seems easy to do, I'm not confident about the cleanliness of where I'd be working on it.

I guess the nature of the glass means the hairs and other junk is caught in the "grooves" of the focussing screen?
06-11-2011, 06:28 AM   #4
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I've attached a shot of the focusing screen and mirror taken with an old P&S so you can see what I'm up against.

It doesn't look good to me..

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06-11-2011, 10:59 AM   #5
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As mike said, take out the focus screen and wash it with soap and water. If you have a shaving soap brush, use it to 'gently scrub' the surface of the screen while it's lathered with soap. Rinse under running water and dry with hair dryer with no heat. Reinstall the screen in the camera without setting it down anywhere before.

To remove and re-install focus screens, follow the installation procedure found at KatzEye website. I put down couple of sheets of lens tissues folded on top of the mirror, before I pop the focus screen retainer clip down. Use a long precision screwdriver to clip and unclip the focus screen retainer. I do not use those cheap plastic tweezers to remove and install screens because they are too stubby and my hamlike fingers end up being too close to the mirror box, hampering my view. Instead, I use a small (5 or 6 inch) hemostat or a locking forceps to remove and re-install the focus screens. Look for ones that have slim and long clamping jaws, they are more springier and require less force to lock the clamp. Generally the curved jaw hemostats are slimmer than the straight ones and the curve places your clamping hand away from the line of sight of the mirror box, giving you a better view of the work at hand. But it does take some getting used to working with the curved jaw, so practice picking up small things and putting it back down in the same spot a few times before attempting the focus screen removal.

Hope this helps,
06-11-2011, 05:14 PM   #6
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QuoteOriginally posted by excanonfd Quote
... so practice picking up small things and putting it back down in the same spot a few times before attempting the focus screen removal.

yes, dig out the "OPERATION" boardgame for a little practice before the main event, lol.
06-11-2011, 05:16 PM   #7
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from the pics, the little hairs will be a piece of cake to clean off with water, but i also see what look like scratches, parallel as if from wiping...if those are scratches, you'll need to learn to love 'em i suppose. good luck!
06-11-2011, 06:51 PM   #8
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What is the approximate cost for replacement?

And is the mirror damaged as well?

It also looks like a hair may have dropped onto the sensor, would that be possible? I can't seem to get it off with the pentax cleaning kit, but I don't think I will keep trying anymore.

I feel like such an idiot


Last edited by nandystam; 06-11-2011 at 08:02 PM.
06-11-2011, 10:11 PM   #9
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A focusing screen will set you back about 50-60 dollars, if you intend to use any MF lenses, now might be a good time to invest in a split prism screen. If the mirror is damaged, that would have to be dealt with by Pentax service which won't be cheap. You might try using canned air as a last resort (before servicing) to blow out the mirror box with sustained, strong blasts of air. Pentax do not recommend using canned air but as long as you follow the directions on how to use the can properly, there shouldn't be any danger of liquid propellant shooting out the nozzle. I use it all the time with my K20D to clean the mirror box and the sensor. I started using canned air because the act of squeezing the rocket blower affects the nozzle, making it difficult to direct the flow of air to where it would do most good. I now use the blower out in the field to dust off lenses. If you think your sensor is dirty, go into sensor cleaning mode with the lens off, raise the mirror and blast the sensor with air. If it's just hair it should blow off quite easily.

Thanks,
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