Repairing discoloured pentamirrors

[yuvipuvi05]

Hello and happy new year!

I am the proud owner of a Minolta Dynax/Maxxum 5. Unfortunately, the pentamirror is discoloured due to old glue being old glue. This has created a mix of violet and blue hues spread around the edges of my viewfinder. Now, it doesn't quite bother me usually because it simply means I need to be a bit extra aware when composing since I often tend to oversee what's going on in the corners.

Since it's such a cheap camera, I don't mind experimenting with it. How would one go about clearing the glue or otherwise completely switching out the pentamirror? I have a friend who is an optician who might be willing to help. I would be grateful for any advice possible. Of course, I know it would be cheaper to get a new camera, but I am simply in love with the Dynax 5, and I've invested in a couple of lenses at this point.

 

[koraks]

Welcome to Photrio and best wishes!

Sorry, no advice to share on clearing or exchanging the mirror. I suspect the latter will be easier than the former, as it'll likely boil down to the same process minus the cleaning. I'm copying in @Andreas Thaler because he's been posting lots of very nicely illustrated repair processes lately. While I don't think he's done anything with a Dynax 5 yet, maybe he has some thoughts to share.

 

[yuvipuvi05]

Welcome to Photrio and best wishes!

Sorry, no advice to share on clearing or exchanging the mirror. I suspect the latter will be easier than the former, as it'll likely boil down to the same process minus the cleaning. I'm copying in @Andreas Thaler because he's been posting lots of very nicely illustrated repair processes lately. While I don't think he's done anything with a Dynax 5 yet, maybe he has some thoughts to share.

Thank you! Do you reckon I could exchange the pentamirror for a prism? Or would that possibly mess with the light meter?

 

[Andreas Thaler]

If the camera can be sacrificed, you could make a teaching project out of it. It will be a matter of opening the camera and getting to the prism.

Without knowing the Dynax in more detail, there will be some electronics on flexible conductor tracks above the prism that need to be removed. The prism itself will be adjusted and installed on the mirror box. Even if the damage can be repaired, everything has to be reassembled precisely.

But perhaps it is easier with the Dynax than with the previous Minoltas, as the electronics are already more highly integrated and it is more about modules than cables and individual components.

Definitely an interesting project, also to see how the case is assembled. So still traditionally with screws or with plastic catches.

 

[Andreas Thaler]

This can help:

Minolta Maxxum 5 Service Manual

Factory service manual

learncamerarepair.com

Of course I'm interested, I'll take a look at it straight away.

 

[Andreas Thaler]

Here from the service manual for an overview of how the prism is installed:

 

[Andreas Thaler]

The layout of the flexible circuit board that lies over the prism and is expected to need to be removed in whole or in part:

 

[Andreas Thaler]

I would start by dismantling the top cover (screws) and then see how the board is connected.

It's not easy, but that's the case with all electronic SLRs

 

[Andreas Thaler]

But then it's still unclear what you do with the prism itself to remove the color cast.

 

[Andreas Thaler]

But when it comes to taking photos with the camera, I would test whether the exposure metering is influenced by the artifacts. If not, I would look at it like dust and dirt in the viewfinder. Annoying, but harmless within certain limits.

Every attempt at repair is risky and apart from the fact that something is broken or can no longer be put back together, the factory settings can also be influenced. Then the camera is misaligned.

 

[Andreas Thaler]

Pentamirror versus pentaprism:

Pentamirror - Wikipedia

en.wikipedia.org

I have equated the terms here, which is not entirely correct. But it's about the same component.

 

[neilt3]

Swapping the pentamirror out of a donor camera might be easy enough , but as all this late series of cameras seem prone to this discoloration at some point , I doubt it'll be a permanent solution.
Likewise, I doubt you'll be able to substitute the mirror for a prism and still retain metering .
I also think the prisms are higher than the mirror type , so space might be an issue .
I've several of these late series and last series Dynax cameras , the 5 I use is also stained , though it was more recent it appeared.
When I got it around 2006 new , it was fine .
I just use it as normal and ignore the discolouration.

 

[Andreas Thaler]

Thank you! Do you reckon I could exchange the pentamirror for a prism? Or would that possibly mess with the light meter?

That would definitely affect the optical system. These optical components are tailor-made for the respective camera and are integrated into the electronics.

 

[xkaes]

Of course, I know it would be cheaper to get a new camera, but I am simply in love with the Dynax 5, and I've invested in a couple of lenses at this point.

On EBAY, you can get a Maxxum/Dynax 5 with one (and sometimes two) zoom lens for under $25. USe the one you have as a backup.

 

[yuvipuvi05]

Swapping the pentamirror out of a donor camera might be easy enough , but as all this late series of cameras seem prone to this discoloration at some point , I doubt it'll be a permanent solution.
Likewise, I doubt you'll be able to substitute the mirror for a prism and still retain metering .
I also think the prisms are higher than the mirror type , so space might be an issue .
I've several of these late series and last series Dynax cameras , the 5 I use is also stained , though it was more recent it appeared.
When I got it around 2006 new , it was fine .
I just use it as normal and ignore the discolouration.

I suppose I'll switch to a different camera for night time photography. The discolourations make composing in the dark really hard, especially given that pentamirrors are much less bright than prisms.

That would definitely affect the optical system. These optical components are tailor-made for the respective camera and are integrated into the electronics.

Thank you so much for your help, you're brilliant. I'll shelf the idea for now, whilst I'll read more about pentaprisms.

 

[Andreas Thaler]

Just to ask: the focusing screen is ok?

 

[yuvipuvi05]

Just to ask: the focusing screen is ok?

Oh absolutely, and the mirror too!

Edit: as a matter of fact, the mirror is half-translucent. Perhaps for the metering?