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Dust Pentaprism & viewfinder of SLR camera body

Dust accumulated in pentaprism of slr camera body how do I remove or do I have to replace prism?

Posted by Anonymous on

  • kakima May 11, 2010

    Some cameras have an interchangeable prism, which makes cleaning a snap. Others don't, making cleaning harder. In some cases you'll have to have a professional do it. What make and model camera do you have?

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Having received no response in over a month, I assume this is no longer a problem.

Posted on Jun 14, 2010

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2 Answers

Why can't I see through the viewfinder?


sounds like the shutter could be stuck, give it a sharp knock(not too hard) on a counter top, as you work the on off button/switch
all I could find on this , is the manual
press the helpful button
ricoh kr 10 XR 1000X users manual

Feb 03, 2016 | Ricoh KR-10 SE 35mm SLR CAMERA w 50mm f/2...

1 Answer

Nikon f100 metering selector is not working


Hi David,
Are you talking about the dial on the right side of the pentaprism? If so I believe that entire top can be removed then replaced with a new/used. Check with Nikon for the part number then have your fingers do the walking.

Cordially,

Apr 03, 2013 | Nikon F100 35mm SLR Camera

1 Answer

I have 2 canon AT-1s. I was setting the exposure on one of them, and the circle indicator on the light meter came away. I am ok with using a light meter, but would prefer the camera was in factory working...


Set camera at bulb/3200 ASA to remove top cover. Remove cover on front first to get to two hidden screws. Carefully remove the shutter speed/asa dial. It connects to a round plastic piece with a cutout. This piece is connected to a tungsten wire that goes over a series of pulleys around the eyepiece to the rewind side of the top, then through another series of pulleys down the side of the mirror box. Even if you are an experienced tech if the wire comes loose from the side of the mirror box, it is a royal pain to put back.

Now, if you can see the lollypop (what the circle is called) and it is still attached but not moving, then this wire may have broken, or if the camera was shocked, it may have come off of one of the pulleys and jammed. If it is floating free around inside the viewfinders, then the circle has come unglued.

You will have to unsolder the flexible circuit on top below the top cover and then remove the prism to get to the lollypop. If the tungsten wire has come loose from one of the pulleys you may be able to put it back in place. I usually carefully remove the plastic piece and wire from the eyepiece pulleys keeping slight tension on it and then tape it to the film door so it stays in place.

Mar 05, 2011 | Canon AT-1 35mm Film Camera

1 Answer

When I looking through camera you see almost a prism affect. Ideas?


If you're looking at it through the front then you will as there is a pentaprism inside feeding the lens view through to the viewfinder so that it displays the right way up and right way around. Almost all SLR's have them which is why they have a hump on top.

As long as the image in the viewfinder is correct then there's no problem. If the prism effect is visible, then the prism has become dislodged and on an N65/F65 it's not really worth repairing. The camera is very definitely a consumer grade model which was never intended to be dismantled for major repair and as there are millions of perfectly good free ones available (late, consumer grade, 35mm AF bodies from most manufacturers are seen as worthless liabilities) there's really little point in attempting a repair except to gain knowledge of how your camera comes apart. If you manage to dismantle, repair and reassemble without breaking anything or finding other broken and unobtainable parts inside then it's a bonus.

If you want to find a free SLR then check out FreeCycle: you may need to check often and be patient but they do come up. Be flexible: you may have to accept any make or model but if they come with lenses then it's no problem. Most of the freebies are Nikon or Canon anyway so if you need to stay with Nikon then it's not a major problem. I recently got a boxed and barely used F75 kit with a 28-100 lens and all it needed was new batteries and film.

Aug 30, 2010 | Nikon N65 35mm SLR Camera

1 Answer

Cant see through veiwfinder


If it's fuzzy and grey then all you need to do is replace the batteries.

If it's completely dark then remove the lens and look into the lens mounting. If the mirror is stuck in either the fully up or partially up position, then the most likely cause is also a flat battery.

If the mirror is fully down and you still have a completely dark viewfinder then you have either left the lens cap on or you have a dislodged pentaprism (usually the result of a dropped camera). The second problem will put the camera totally beyond any economic repair unless you open it up and try to resecure the pentaprism yourself; it's not really a DIY job and if you find that there are broken parts inside then the camera is destined for the trash can, but you'll have nothing to lose by trying.

Jan 29, 2010 | Nikon N75 35mm SLR Camera

1 Answer

Camera with a sticky substance on the back


It's a very common problem with older cameras and is an irreversible breakdown of the foam which was used to provide light-proof seals on the camera back and also to cover the pentaprism and provide a mirror buffer. (The pentaprism and mirror buffer are part of the viewfinder system).

The first problem is that when the foam turns to goo it allows light to leak into the camera and spoil the film, but that's the least of it. Where it gets serious is that the goo spreads inside and can gum up delicate moving parts; worst of all the goo is somewhat corrosive and can damage the coatings on the pentaprism leaving permanent residual ghosting images in the viewfinder.

The good news is that it's a well understood problem and every professional camera repairer can remove the goo and restore the camera as part of the regular service that all SLR's should periodically undergo. The foam will be replaced by modern materials which do not degrade. Some repairers also replace the mirror buffer, others will just remove the old foam and omit the buffer, but I always insist on a new buffer. At the same time, the repairer will give the camera a thorough CLA service (Clean, Lubricate, Adjust) which for a camera in non-professional use will often see it through a few more years, but I'd recommend getting a CLA done annually if you're well off and every couple of years if funds are tighter. The CLA will also ensure that the light metering is correct and on cameras using the older mercury oxide batteries can include a meter recalibration to allow use of modern silver oxide equivalents which have a higher voltage as the mercury cells are no longer available. (Some folks use manganese dioxide batteries, but they start off at a voltage slightly higher than the camera was designed for and constantly drift down with use to way below the nominal voltage, so metering is neither consistent nor accurate). A regular CLA with foam removal costs a bit more than a regular CLA but is a once only expenditure. Some repairers charge for recalibrating the meter for silver oxide batteries, but most won't if you politely explain that you can always take the camera elsewhere.

DIY kits are also available and some are very good indeed, but they can be fiddly and messy to fit and none of them address the more serious issue of the pentaprism. In practice, repairers will remove the old foam from the pentaprism but almost never fit a replacement. It's not strictly necessary and the reluctance to fit a replacement stems from the risk of further damage to the pentaprism by the adhesive. The outside of the pentaprism is normally painted black from new, but foam goo usually attacks the paint and partially removes it. it also attacks and removes any optical multicoatings on the prism. When this has occurred there is no fix: the problem will not worsen once the foam has been removed but there will be residual damage visible in the viewfinder as ghostly dull patches, but this is something which can be tolerated and will not affect image quality.

If you want a cheap quick fix, then use a q-tip (UK= cotton bud), a wooden cocktail stick/toothpick and some alcohol to remove all visible traces of gooey foam. Omit the mirror buffer altogether and take your chances with the prism foam. To replace the rear light seal just use a length of woollen yarn: you'll find that if you twist it slightly it will reduce in diameter and allow you to press it into the slot where the foam was using a toothpick. Usually you can get away without gluing it, but if any glue must be used then use a few very sparing dots of something easily removed such as Copydex or the rubber cement sold for repairing bicycle inner tubes. At the hinge end of the camera back will be a thicker, wider bit of foam. Just use a few dabs of glue or to secure a good thick double or even triple width of yarn. The fix isn't a professional one, but it's good enough and was how the seals were made before rubber foam was invented. It also buys you the time to decide whether you like using your Nikon enough to invest in a professional CLA with the additional options.

I hope that my reply has given you a few options and will enable you to get your camera into working condition again. All I ask is that you return the favour by taking a moment to rate my answer.

Jan 09, 2010 | Nikon Photography

1 Answer

Canon AV-1: Seal on the


Very much so!

It's a very common problem with older cameras and is an irreversible breakdown of the foam which was used to provide light-proof seals on the camera back and also to cover the pentaprism and provide a mirror buffer. (The pentaprism and mirror buffer are part of the viewfinder system).

The first problem is that when the foam turns to goo it allows light to leak into the camera and spoil the film, but that's the least of it. Where it gets serious is that the goo spreads inside and can gum up delicate moving parts; worst of all the goo is somewhat corrosive and can damage the coatings on the pentaprism leaving permanent residual ghosting images in the viewfinder.

The good news is that it's a well understood problem and every professional camera repairer can remove the goo and restore the camera as part of the regular service that all SLR's should periodically undergo. The foam will be replaced by modern materials which do not degrade. Some repairers also replace the mirror buffer, others will just remove the old foam and omit the buffer, but I always insist on a new buffer. At the same time, the repairer will give the camera a thorough CLA service (Clean, Lubricate, Adjust) which for a camera in non-professional use will often see it through a few more years, but I'd recommend getting a CLA done annually if you're well off and every couple of years if funds are tighter. The CLA will also ensure that the light metering is correct and on cameras using the older 5.4v mercury oxide (PX28) batteries can include a meter recalibration to allow use of modern 6.2v silver oxide (4SR44) equivalents as the mercury cells are no longer available. (Some folks use 6v manganese dioxide [PX28A] batteries, but they start off at a voltage slightly higher than 6v and constantly drift down with use to below 5v, so metering is nneither consistent nor accurate). A regular CLA with foam removal costs a bit more than a regular CLA but is a once only expenditure. Some repairers charge for recalibrating the meter for 6.2v, but most won't if you politely explain that you can always take the camera elsewhere.

DIY kits are also available and some are very good indeed, but they can be fiddly and messy to fit and none of them address the more serious issue of the pentaprism. In practice, repairers will remove the old foam from the pentaprism but almost never fit a replacement. It's not strictly necessary and the reluctance to fit a replacement stems from the risk of further damage to the pentaprism by the adhesive. The outside of the pentaprism is normally painted black from new, but foam goo usually attacks the paint and partially removes it. it also attacks and removes any optical multicoatings on the prism. When this has occurred there is no fix: the problem will not worsen once the foam has been removed but there will be residual damage visible in the viewfinder as ghostly dull patches, but this is something which can be tolerated and will not affect image quality.

If you want a cheap quick fix, then use a q-tip (UK= cotton bud), a wooden cocktail stick/toothpick and some alcohol to remove all visible traces of gooey foam. Omit the mirror buffer altogether and take your chances with the prism foam. To replace the rear light seal just use a length of woollen yarn: you'll find that if you twist it slightly it will reduce in diameter and allow you to press it into the slot where the foam was using a toothpick. Usually you can get away without gluing it, but if any glue must be used then use a few very sparing dots of something easily removed such as Copydex or the rubber cement sold for repairing bicycle inner tubes. At the hinge end of the camera back will be a thicker, wider bit of foam. Just use a few dabs of glue or to secure a good thick double or even triple width of yarn. The fix isn't a professional one, but it's good enough and was how the seals were made before rubber foam was invented. It also buys you the time to decide whether you like using the AV-1 enough to invest in a professional CLA with the additional options.

I hope that my reply has given you a few options and will enable you to get your camera into working condition again. All I ask is that you return the favour by taking a moment to rate my answer.

Jan 05, 2010 | Canon AV1 35mm SLR CAMERA SPARES OR REPAIR...

1 Answer

Minolta X-370 Spot driving me nuts!


If its inside the viewfinder, then you'll really need to take it in for a repair, but bear in mind, that will require disassembly and that will likely run you $75-$100, which is more than a used X370 goes for on eBay.

One thing I would check is the underside of the focussing screen as maybe it is on there. Remove the lens and then look thru the viewfinder. If you still see the spot, then its in the body and not in the lens.

Look inside at the underside of the prism - thats where the focussing screen is. Do not touch the screen with any cleaning fluid or your finger. instead, grab something fairly stiff but pliable, like the straw on the edge of a dust blower. and gently rub the general area on the screen where the spot might be. Then blow the area with air to clean it all up. Look thru the viewfinder again and see if that got it.

Its pretty rare for dust to get inside the viewfinders unless they had previously been open for a repair, so theres a good chance its stuck to the focussing screen. Don't touch it with solution or your finger though as the screen can be damaged easily.

Dec 29, 2008 | Minolta X-370S 35mm SLR Camera

2 Answers

Viewfinder Obstruction


If the dust/dirt is visible in the finder, it is in one of three locations: - if very sharp, it is on the "grind" side of the viewing screen, which, unfortunately for cleaning ease [unless the screen is user-removeable], is often the upper side of the screen in newer cameras. - if fairly sharp, it is on the non-"grind" side of the screen, and it may be possible to remove it with a VERY soft (very clean!) small brush or a VERY gentle blowing with a hand syringe-type blower (blowing hard into a VF area just about guarantees that dust will be blown in). - if very soft-looking, it is on the underside surface of the pentaprism (being able to clean the VF area without a repair is an excellent arguement for having the interchangeable-screen feature...). Prevention is the best way - never leave the body cavity uncovered (except briefly, when changing lenses); never change lenses in a windy area; keep the rear area of the lens clean; get in the habit of facing the open camera downward while changing lenses; NEVER blow into the body cavity (unless you know what you are doing, the mirror is up, or the screen is removeable). Hope This Helps

Oct 27, 2005 | Nikon Coolpix 3200 Digital Camera

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