HELP - Pentax KX gunk in viewfinder

goldendeerboi13 · 10-16-2020, 02:11 AM

Hello everyone! I'm new here. I just bought a Pentax KX from an online shop and while looking through the viewfinder I saw this dark yellowish gunk on my view.

I checked if it's from the lens but it doesn't seem to be the case.

Anyone have an idea what it is and how to clean it? Will it affect my photos?

D1N0 · 10-16-2020, 04:21 AM

It won't affect your photo's. Your viewfinder has a different optical path to the lens. It is probably a dirty focussing screen. Is it a analog KX or a digital K-x?

**Viking42** · 10-16-2020, 05:44 AM

If you take the lens off and look inside the body with a flashlight, you will see the mirror and the bottom of the focusing screen directly above it. It's possible there is something on either of those. Post back here with what you find, and we can advise how to clean.

SharkyCA · 10-16-2020, 07:29 AM

Possible dirt or contaminated diopter lens, remove it and check it first before going internal on camera.Pentax O-ME53 Magnifying Eyecup 30150 B&H Photo Video

Last edited by SharkyCA; 10-16-2020 at 07:07 PM. Reason: Repair Link

beachboy2 · 10-16-2020, 09:19 PM

A common problem with these cameras is de-silvering of the prism. Gives a blury strip or two where the silver is deteriorating. Search for threads on this. I have the problem on one of two KXs.

goldendeerboi13 · 10-17-2020, 12:00 AM

Originally posted by D1N0

It won't affect your photo's. Your viewfinder has a different optical path to the lens. It is probably a dirty focussing screen. Is it a analog KX or a digital K-x?

It's the analog KX

goldendeerboi13 · 10-17-2020, 12:08 AM

Originally posted by Viking42

If you take the lens off and look inside the body with a flashlight, you will see the mirror and the bottom of the focusing screen directly above it. It's possible there is something on either of those. Post back here with what you find, and we can advise how to clean.

Hello, here are the photos I took of the camera's internals. What do you think?

Attached Images

goldendeerboi13 · 10-17-2020, 12:12 AM

Originally posted by beachboy2

A common problem with these cameras is de-silvering of the prism. Gives a blury strip or two where the silver is deteriorating. Search for threads on this. I have the problem on one of two KXs.

I was suspecting this could be the case too. Saw one of the threads you commented on last 2017 (!!) were you able to fix it? Will having the camera CLA'd help?

SharkyCA · 10-17-2020, 04:21 AM

Originally posted by beachboy2

A common problem with these cameras is de-silvering of the prism. Gives a blury strip or two where the silver is deteriorating. Search for threads on this. I have the problem on one of two KXs.

Just a quick note, the prism does not have silvering, however the "mirrors" used for reflecting the image into the "prism" are quite different than a regular mirror, to achieve image quality instead of the silvering being under the glass it is on top and therefore CAN BE SCRATCHED QUITE EASILY also desilvering also occurs to them.

Reflex mirror: what is it and how does it work? - What Digital Camera

**Viking42** · 10-18-2020, 09:02 AM

Originally posted by goldendeerboi13

Hello, here are the photos I took of the camera's internals. What do you think?

It's a bit hard to see clearly in there from the pictures, but I can't discern any yellow gunk. You should be able to tell better for yourself by looking in there with a flashlight. Try shining the flashlight through the viewfinder and then looking at the focusing screen from inside the body (backlighting the screen). That might show up any dirt on the top of the screen. If it's clean, have you tried Sharky's suggestion of cleaning the diopter lens? If none of these, then it's likely a desilvered prism mirror. In any case, none of these things will affect your pictures, and it's just an annoyance (which hopefully isn't so bad that it prevents you from using this camera).

Hope you get it sorted. The KX is a nice camera!

SharkyCA · 10-18-2020, 11:35 AM

Originally posted by goldendeerboi13

Hello everyone! I'm new here. I just bought a Pentax KX from an online shop and while looking through the viewfinder I saw this dark yellowish gunk on my view.

I checked if it's from the lens but it doesn't seem to be the case.

Anyone have an idea what it is and how to clean it? Will it affect my photos?

Originally posted by beachboy2

A common problem with these cameras is de-silvering of the prism. Gives a blury strip or two where the silver is deteriorating. Search for threads on this. I have the problem on one of two KXs.

Originally posted by Viking42

It's a bit hard to see clearly in there from the pictures, but I can't discern any yellow gunk. You should be able to tell better for yourself by looking in there with a flashlight. Try shining the flashlight through the viewfinder and then looking at the focusing screen from inside the body (backlighting the screen). That might show up any dirt on the top of the screen. If it's clean, have you tried Sharky's suggestion of cleaning the diopter lens? If none of these, then it's likely a desilvered prism mirror. In any case, none of these things will affect your pictures, and it's just an annoyance (which hopefully isn't so bad that it prevents you from using this camera).

Hope you get it sorted. The KX is a nice camera!

Just a little more info on pentaprism vs pentamirrors, with pentamirrors being hollow and prisms being solid the chances of the prism being desilvered are less likely than the "mirror variety" Video of both types being removed from cameras with comparison of weight.

Youtu.be

D1N0 · 10-18-2020, 02:54 PM - **1 Like**

Afaik a prism does not need a silver coating. The KX has a Pentaprism, not a Pentamirror (the Digital K-x does have a Pentamirror). Above the focussing screen there is a condenser lens then there is the pentaprism. So maybe something got between the screen and the lens or the lens and the prism, or maybe the condenser lens is cemented to either prism or screen and what you are seeing is separation.

10-16-2020, 02:11 AM	#1
goldendeerboi13 New Member Join Date: Oct 2020 Posts: 4	HELP - Pentax KX gunk in viewfinder Hello everyone! I'm new here. I just bought a Pentax KX from an online shop and while looking through the viewfinder I saw this dark yellowish gunk on my view. I checked if it's from the lens but it doesn't seem to be the case. Anyone have an idea what it is and how to clean it? Will it affect my photos?

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10-16-2020, 04:21 AM	#2
D1N0 Pentaxian Join Date: May 2012 Location: --- Photos: Gallery Posts: 6,802	It won't affect your photo's. Your viewfinder has a different optical path to the lens. It is probably a dirty focussing screen. Is it a analog KX or a digital K-x?

10-16-2020, 05:44 AM	#3
Viking42 Site Supporter Join Date: Aug 2020 Location: Caledon, Ontario, Canada Photos: Albums Posts: 504	If you take the lens off and look inside the body with a flashlight, you will see the mirror and the bottom of the focusing screen directly above it. It's possible there is something on either of those. Post back here with what you find, and we can advise how to clean.

10-16-2020, 07:29 AM	#4
SharkyCA Pentaxian Join Date: Sep 2017 Location: Carleton Place, Ontario, Canada Photos: Gallery Posts: 806	Possible dirt or contaminated diopter lens, remove it and check it first before going internal on camera.Pentax O-ME53 Magnifying Eyecup 30150 B&H Photo Video Last edited by SharkyCA; 10-16-2020 at 07:07 PM. Reason: Repair Link

10-16-2020, 09:19 PM	#5
beachboy2 Senior Member Join Date: Dec 2012 Location: Perth Western Australia Photos: Gallery Posts: 222	A common problem with these cameras is de-silvering of the prism. Gives a blury strip or two where the silver is deteriorating. Search for threads on this. I have the problem on one of two KXs.

10-17-2020, 12:00 AM	#6
goldendeerboi13 New Member Join Date: Oct 2020 Posts: 4 Original Poster	Originally posted by D1N0 It won't affect your photo's. Your viewfinder has a different optical path to the lens. It is probably a dirty focussing screen. Is it a analog KX or a digital K-x? It's the analog KX

10-17-2020, 12:08 AM	#7
goldendeerboi13 New Member Join Date: Oct 2020 Posts: 4 Original Poster	Originally posted by Viking42 If you take the lens off and look inside the body with a flashlight, you will see the mirror and the bottom of the focusing screen directly above it. It's possible there is something on either of those. Post back here with what you find, and we can advise how to clean. Hello, here are the photos I took of the camera's internals. What do you think? Attached Images

10-17-2020, 12:12 AM	#8
goldendeerboi13 New Member Join Date: Oct 2020 Posts: 4 Original Poster	Originally posted by beachboy2 A common problem with these cameras is de-silvering of the prism. Gives a blury strip or two where the silver is deteriorating. Search for threads on this. I have the problem on one of two KXs. I was suspecting this could be the case too. Saw one of the threads you commented on last 2017 (!!) were you able to fix it? Will having the camera CLA'd help?

10-17-2020, 04:21 AM	#9
SharkyCA Pentaxian Join Date: Sep 2017 Location: Carleton Place, Ontario, Canada Photos: Gallery Posts: 806	Originally posted by beachboy2 A common problem with these cameras is de-silvering of the prism. Gives a blury strip or two where the silver is deteriorating. Search for threads on this. I have the problem on one of two KXs. Just a quick note, the prism does not have silvering, however the "mirrors" used for reflecting the image into the "prism" are quite different than a regular mirror, to achieve image quality instead of the silvering being under the glass it is on top and therefore CAN BE SCRATCHED QUITE EASILY also desilvering also occurs to them. Reflex mirror: what is it and how does it work? - What Digital Camera

10-18-2020, 09:02 AM	#10
Viking42 Site Supporter Join Date: Aug 2020 Location: Caledon, Ontario, Canada Photos: Albums Posts: 504	Originally posted by goldendeerboi13 Hello, here are the photos I took of the camera's internals. What do you think? It's a bit hard to see clearly in there from the pictures, but I can't discern any yellow gunk. You should be able to tell better for yourself by looking in there with a flashlight. Try shining the flashlight through the viewfinder and then looking at the focusing screen from inside the body (backlighting the screen). That might show up any dirt on the top of the screen. If it's clean, have you tried Sharky's suggestion of cleaning the diopter lens? If none of these, then it's likely a desilvered prism mirror. In any case, none of these things will affect your pictures, and it's just an annoyance (which hopefully isn't so bad that it prevents you from using this camera). Hope you get it sorted. The KX is a nice camera!

10-18-2020, 02:54 PM - 1 Like	#12
D1N0 Pentaxian Join Date: May 2012 Location: --- Photos: Gallery Posts: 6,802	Afaik a prism does not need a silver coating. The KX has a Pentaprism, not a Pentamirror (the Digital K-x does have a Pentamirror). Above the focussing screen there is a condenser lens then there is the pentaprism. So maybe something got between the screen and the lens or the lens and the prism, or maybe the condenser lens is cemented to either prism or screen and what you are seeing is separation.