What is this mark on my viewfinder?

Prince Harbinger · 07-10-2018, 08:26 PM

I brought this camera for $15.00 Mainly wanted it for the Super Takumar it came with. I have decided that I would like to clean it up and possibily use it one day. I have taken it apart to see if I can get to the viewfinder element. However I need to purchase a tool to remove the dial with the two pin holes. Does anyone know what this mark is? I hope I can remove it.

Here are some photos.

Dropbox - 20180710_230900.jpg

Dropbox - 20180710_230510.jpg

Dropbox - 20180710_230424.jpg

Dropbox - 20180710_230437.jpg

**kiwi_jono** · 07-10-2018, 08:40 PM - **1 Like**

I'm assuming the mirror looks ok (its bit hard to see the whole mirror but it looks ok from what I can see)?

Possibly a cracked focus screen (should be visible by looking up at it inside the mirror box.

**pentaxus** · 07-10-2018, 08:56 PM - **3 Likes**

That is desilvering at the fromt of the prism. The adhesive on the foam that was put on the front of the prism damaged the silvering. The desilvering is normally on the top of the prism caused by tape put there, but the result is the same, ugly dark areas. The only solution is to replace the prism. It does not affect the pictures, but may affect the light meter a bit.

Prince Harbinger · 07-10-2018, 09:07 PM

Originally posted by pentaxus

That is desilvering at the fromt of the prism. The adhesive on the foam that was put on the front of the prism damaged the silvering. The desilvering is normally on the top of the prism caused by tape put there, but the result is the same, ugly dark areas. The only solution is to replace the prism. It does not affect the pictures, but may affect the light meter a bit.

I think you hit the nail on the head. unfortunately I didn't find any replacement prisms on Ebay. I guess I could buy a broken one for cheap and harvest the prism I need for it.

**pentaxus** · 07-10-2018, 10:01 PM - **1 Like**

Be careful. People sometimes think the desilvered top of the prism issue is a dustball in the viewfinder.

**Alex645** · 07-11-2018, 12:03 PM - **1 Like**

Originally posted by Prince Harbinger

I think you hit the nail on the head. unfortunately I didn't find any replacement prisms on Ebay. I guess I could buy a broken one for cheap and harvest the prism I need for it.

I had a K1000 with the same desilvered pentaprism and bought a cheap "as is" camera for parts. Just make sure the 'donor' camera has a clean prism! Swapping out the pentaprisms isn't too difficult with jeweler tools and a well lit clean table area. There are some good YouTube videos on how-to.

07-10-2018, 08:26 PM	#1
Prince Harbinger Veteran Member Join Date: Jul 2018 Location: New Jersey Posts: 429	What is this mark on my viewfinder? I brought this camera for $15.00 Mainly wanted it for the Super Takumar it came with. I have decided that I would like to clean it up and possibily use it one day. I have taken it apart to see if I can get to the viewfinder element. However I need to purchase a tool to remove the dial with the two pin holes. Does anyone know what this mark is? I hope I can remove it. Here are some photos. Dropbox - 20180710_230900.jpg Dropbox - 20180710_230510.jpg Dropbox - 20180710_230424.jpg Dropbox - 20180710_230437.jpg

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07-10-2018, 08:40 PM - 1 Like	#2
kiwi_jono Loyal Site Supporter Join Date: Dec 2009 Location: Christchurch, New Zealand Photos: Gallery \| Albums Posts: 2,437	I'm assuming the mirror looks ok (its bit hard to see the whole mirror but it looks ok from what I can see)? Possibly a cracked focus screen (should be visible by looking up at it inside the mirror box.

07-10-2018, 08:56 PM - 3 Likes	#3
pentaxus Site Supporter Join Date: Jun 2010 Location: Central Coast, CA Posts: 1,313	That is desilvering at the fromt of the prism. The adhesive on the foam that was put on the front of the prism damaged the silvering. The desilvering is normally on the top of the prism caused by tape put there, but the result is the same, ugly dark areas. The only solution is to replace the prism. It does not affect the pictures, but may affect the light meter a bit.

07-10-2018, 09:07 PM	#4
Prince Harbinger Veteran Member Join Date: Jul 2018 Location: New Jersey Posts: 429 Original Poster	Originally posted by pentaxus That is desilvering at the fromt of the prism. The adhesive on the foam that was put on the front of the prism damaged the silvering. The desilvering is normally on the top of the prism caused by tape put there, but the result is the same, ugly dark areas. The only solution is to replace the prism. It does not affect the pictures, but may affect the light meter a bit. I think you hit the nail on the head. unfortunately I didn't find any replacement prisms on Ebay. I guess I could buy a broken one for cheap and harvest the prism I need for it.

07-10-2018, 10:01 PM - 1 Like	#5
pentaxus Site Supporter Join Date: Jun 2010 Location: Central Coast, CA Posts: 1,313	Be careful. People sometimes think the desilvered top of the prism issue is a dustball in the viewfinder.

07-11-2018, 12:03 PM - 1 Like	#6
Alex645 Site Supporter Join Date: May 2015 Location: Kaneohe, HI Photos: Albums Posts: 3,526	Originally posted by Prince Harbinger I think you hit the nail on the head. unfortunately I didn't find any replacement prisms on Ebay. I guess I could buy a broken one for cheap and harvest the prism I need for it. I had a K1000 with the same desilvered pentaprism and bought a cheap "as is" camera for parts. Just make sure the 'donor' camera has a clean prism! Swapping out the pentaprisms isn't too difficult with jeweler tools and a well lit clean table area. There are some good YouTube videos on how-to.