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CJ
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, June 10, 2005 - 11:57 pm: | 
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Just a confession:
I recently acquired a Fujica ST605 for $40 with a f/2.2 lens.
...So I decided to take the lens off tonight, because the finder was making things look yellow, and I figured I could clean the mirror and ground glass, and remove the nasty light seal goop which has begun to shed...
To make a long story short, I've realized that ground glass is not always....glass. It appears to be plastic, in this case, and I've added a bunch of nasty cleaning marks by taking a Q-Tip (cotton bud) to it. The finder is now a marked-up mess, and is still yellow. Grrrrrr.
I'm an idiot.
Was I correct in guessing that the 'ground glass' is plastic, and I've screwed it up beyond repair?
Do any of you have SLRs with nasty-looking finders, and do you find you're able to make use of them, in spite of this?
/going to bed...done enough damage for tonight.
-CJ |
Gary
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 11, 2005 - 12:40 am: |
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CJ, Are you sure you actually scratched the plastic screen (fresnel)? Maybe you just smeared it with contaminants that were already on the screen? Maybe I'm off base here but I think if you gently used only small amounts of denatured alcohol or glass cleaner on several cotton swabs, that in and by itself would not ruin the screen. What did you use for a cleaning agent? When one cleans the underside of the screen they certainly need to be careful. Some solvents can attack plastic and using too much fluid can allow seepage between the lamination of fresnel and condenser or groundglass (depending on the design). Any gooey or dried out foam seals in and around the screen including mirror bumper should be first removed carefully with alcohol and later renewed with the proper foam. Note: Jim Goodman's foam kits have step-by-step instructions. Always avoid getting that crud on the screen as it just creates more work. I'm sure there are some real good 'how to's' in the archives of this and other sites that will give you good advice on cleaning a screen. Some of that yellow look (smoke-like haze?) might also be inside the viewing glass, on prism surfaces, and on the top surface of the screen. Yes, one can live with it as it has no impact on a photo. Just another distraction I suppose. Perfectionists for sure will detest it. |
WernerJB
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 11, 2005 - 09:23 am: |
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Hi CJ, you are not alone, I have just damaged a 35 electro by trying to separate the lens barrel from the lens board, it is beyond repair and can now only be used as a spare part donor. I could kick myself, as everything on that camera was working properly, but I intended to make it even more perfect.
Maybe this is consolatory in a way: shxt just happens ! |
paul ron
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 11, 2005 - 10:19 am: |
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Gee you guys are bitching about the cost of an education. If you didn't make that mistake, you'd learn nothing. So $40 to learn to leave well enough alone is not a bad price. You'll not make that mistake again.
Over the years I've destroyed more expensive cameras than that. A few would have been worth a small fortune as collectors items today. Back then they were just junk pile finds.
Can you get another screen for that camera?... maybe a retro fit? Perhaps it would look nicer with a clear, clean screen? You're up to your elbows in learning so why stop? |
WernerJB
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 11, 2005 - 11:59 am: |
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Making mistakes when learning by doing is mandatory, no question about that, but if one feels sorry for screwing up a camera one was working on for two days has absolutely nothing to do with the financial loss of that camera's price.
No matter what you consider an adequate reaction, I didn't think of giving up, not for the split of a second, but I will definitely stop being entertaining, subject closed. |
rick
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 11, 2005 - 12:31 pm: |
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If you get to the point of removing the focusing screen from the camera, email me with its exact dimensions. I have some leftovers of unknown heritage, maybe we'll get lucky and one will fit.
: ) = |
paul ron
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 11, 2005 - 04:48 pm: |
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Oh no not making fun of ya dude. We've all screwed up perfectly good working cameras, and cars, it part of the DIY course. Although the camera you've been working on is still functional, it's not a total loss but it's a lesson learned for the next one, just pass it on.
BTW What you did, doesn't effect the image at all just viewing. Is it too dificult to fit a new screen in that camera? Be careful, some cameras have a spring loaded string linking the speed dial to the metering system. Once you remove the cover it pops off the pullies and imposable to put back. I made the mistake of opening a Canon with a similar string system, it's a box of parts today. |
CJ
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 11, 2005 - 05:09 pm: |
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Thank you, Rick. When I'm knowledgeable & brave enough to open the camera again, I'll measure the screen and let you know the dimensions. Months ago I passed-up a focusing screen while sifting through a parts bin. D'oh!!
paul ron and WernerJB: Well said.
Gary: I'm hoping the fresnel isn't plastic, and since I don't know much about ground glass screens like this, I'm compelled to ask you all:
Which side faces the mirror/outside of the pentaprism? The 'ground' side (which I'd guess could very easily catch light seal mush, etc.) or perhaps a polished side?
FYI: I polished the mirror and fresnel with lens cleaning liquid, Q-Tips, and Kodak lens cleaning paper. |
Mike
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 11, 2005 - 06:03 pm: |
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CJ, I'm sorry to say that almost all 35mm camera fresnel screens are plastic, and very soft plastic at that. Only a few of the very first 35mm SLR's used glass for focusing and they are matte, not fresnel.
I have certainly ruined a few of them myself, one by cleaning with alcohol. I learned over the years to clean them only with windex (or ronsonol when contaminated with mirror bumper goo). |
rick
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 11, 2005 - 10:13 pm: |
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ALL Fresnel lenses are plastic, at least on this kind of size scale. They can make them in glass for railroad signal lenses and lighthouses, but anything requiring fine detail can only be done in plastic. They are soft and sensitive to chemicals, and should not be touched unless absolutely necessary.
Generally speaking, the Fresnel side goes down (toward the mirror) and the matte side goes up (toward the prism). This way the lines of the Fresnel are blurred by the matte surface and you have a good clean focusing surface.
There were a few cameras with real glass screens, mostly German: the Exakta and Praktina (and the Pentacon Six) had them (though some Exaktas had plastic ones). In this case it was not a Fresnel but a condenser with the flat side frosted and the other side a steep convex curve. These always went flat-side-down. Any screen that's thin and flat, or any screen that has a microprism pattern anywhere on it, is going to be plastic........
: ) = |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 12, 2005 - 07:59 am: |
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Having used ronsonol to remove any goo I clean my Canon screens in an ultrasonic cleaning bath.I just use water with a drop or two of washing-up liquid.Rinse in distilled water and air dry.No matter how you clean Fresnel screens always wipe with the Fresnel pattern and never at right angles to the pattern lines.This way you reduce the chance of damaging the sharp peaks of the pattern.It is these marks that show up as scratches. |
Stuart Willis
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, June 13, 2005 - 08:08 am: |
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I think the subject has been pretty much done to death but in general you can say that if an acrylic fresnel screen (and very soft acrylic is what they are) gets dirty or contaminated and will not clean up with a blower brush - then nothing but nothing will restore it whilst in situ.
You have one option. To remove the fresnel and gently finger-wash it in dishwashing liquid, rinse thoroughly and then blow dry.
This is the best you going to get. Lens-cleaning fluid, spirit, alcohol or anything else will wreck it. With respect to an earlier well-meaning contribution here - you never touch 'em and you never wipe 'em. And there are some SLR's which virtually have to be reduced to the sum of their parts to replace a fresnel screen. Canon AE1 for instance.
Stuart Willis (I learned the hard way!).
per a blo |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, June 13, 2005 - 07:48 pm: |
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You can never say never in the restoration business.Sometimes the only way of removing contamination from a screen is to wipe using a suitable inert cleaning agent and applicator.Using a wiping action that is least likely to cause more damage or scratches is a must in this instance.
Over the years I have collected a full set of Canon A and F Series screens.Most were purchased or acquired as removals from scrap bodies and all required serious cleaning.The only failures have been in 2 or 3 cases, where contact adhesive was used in bad mirror buffer replacement.
Most of these screens have seen considerable professional use whilst in my possession. So all I will say is that personally I am quite happy to clean by whatever means, if it saves me having to search for a replacement. |
Gary
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, June 20, 2005 - 04:13 pm: |
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Another member of this forum just made reference to a good website that covers cleaning a plastic fresnel. Isopropyl alcohol was mentioned as a appropriate cleaner whereas denatured alcohol might well damage some plastic screens. Thus far I have been lucky using denatured alcohol but I'll be much more careful in the future! Here's that website: http://www.in-fotech.com/cleaning_optics.htm It's a very good read. |
Leo Gottfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, June 23, 2005 - 08:24 pm: |
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I do not believe you actually ruined the camera (I am telling you from my experience) - you just smeared the goo all over the place.
I had my cameras (2 pentaxes and a chinon) focusing screens cleaned with Goof Off2 - Warter Based - this is water based - not your regular harsh stuff. I got it from LOWES.
Use a Sponge swab - not a cotton- You do not want the cotton fiberd stuck there.
Let me know if it worked for you. See http://www.onewipe.com/goofoff/PRODUCTS/goofoff.html |
suzanne
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 11, 2006 - 05:28 am: |
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Hi
what should I use to clean the (removable) focus screen of my Nikon F, it has some old gooey foam from the mirror bumper stuck on it. Is dishwashing liquid and water enough? |
