| Author |
Message |
    
Aphototaker
Tinkerer
Username: Aphototaker
Post Number: 231
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 10, 2010 - 10:48 am: | 
|
While I was examining my AE-1 last night as to why it is off by one stop (as shown in the viewfinder Av display), I noticed this strange buildup or white crusty substance on the SPC. I wonder if this is the cause of the one stop difference in the meter I am noticing (the camera wants to overexpose by 1 stop). Perhaps the substance is blocking some light from falling on the photo cell.
Is this stuff usual? If not, how do I remove it?
Photo1:
Photo2:
Thanks. |
Brcamera
Tinkerer
Username: Brcamera
Post Number: 6
Registered: 08-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 10, 2010 - 11:16 am: |
|
The white stuff on the photocell looks like residue from water/moisture damage. I would check the rest of the camera for small clues of moisture damage such as the white residue on the photo cell, small signs of rust on the top of screw heads. A very lightly moist Q-Tip should clean it off and hopefully it is not an indicator of a larger problem! |
Aphototaker
Tinkerer
Username: Aphototaker
Post Number: 232
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 10, 2010 - 11:52 am: |
|
No, no relevant damage anywhere that I can see. Nothing in the light seal near it, nothing on the screws near it, the lens in front of the SPC and before the prism is also clean. The prism also doesn't have any tell tale signs of such elemental exposure. |
Glenn
Tinkerer
Username: Glenn
Post Number: 822
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, August 11, 2010 - 02:09 am: |
|
It has nothing to do with moisture/water damage. A very cursory examination by XRF / electron microscopy on the old firms equipment seems to indicate some form of chemical reaction between a plastciser and the substrate. Therefore as other people have found, a gentle clean or scrape with a wooden lollypop stick sharpened to a chisel edge soon solves the problem. There is more information in the Archive. |
Aphototaker
Tinkerer
Username: Aphototaker
Post Number: 239
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, August 11, 2010 - 07:16 am: |
|
Glenn, looks like you are correct. I found the information in the archives last night in which, IIRC, you mentioned that you would be interested in examining it under an electron microscope of somebody could offer a camera body for examination. There was no conclusion in that post, however. In fact, you cited a few examples of your own in which you saw no exposure error even with this substance on the sensors. The post is this one:
https://kyp.hauslendale.com/classics/forum/messages/6900/5420.html
In any case, I still went ahead and gently scrapped it off. It felt like a powdery substance and wasn't hard or brittle. It just came off upon gentle scratching.
The good news is that the exposure error is gone!
I suppose it depends on the extent of the buildup as to if there any affect on the exposure. The photos I have attached at least show in a qualitative manner what to expect with this amount substance.
On a related note, has anybody ever actually removed that little square glass covering (on which the substance forms) from the photocell to clean the glass? Is it hard to remove or are there any gotchas?
Thanks.
Regards. |
Glenn
Tinkerer
Username: Glenn
Post Number: 824
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, August 11, 2010 - 01:20 pm: |
|
I have never considered removing the glass covering and as I do not have a scrap one handy, I cannot state how it is fixed to the photocell - So cannot help you there. As cleaning in situ has always brought the meter back on examples that showed an error, I have never even considered removal. Just keep a lolly stick in the repair box. |
Tylerwebb
Tinkerer
Username: Tylerwebb
Post Number: 21
Registered: 07-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, August 11, 2010 - 01:38 pm: |
|
Thats great that yours is working now too! Good job |
Aphototaker
Tinkerer
Username: Aphototaker
Post Number: 242
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, August 11, 2010 - 06:03 pm: |
|
Glenn: Thanks for the feedback.
Thanks, Tyler.
Man, it was fun! :-) |
