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Johnlees45
Tinkerer
Username: Johnlees45
Post Number: 36
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 08, 2007 - 10:43 am: | 
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Another Praktica BC-1 electronic I have (not the one mentioned in other posts) is apparently scratching slide film sometimes, usually in the upper part of pictures. Stupid question this, but does that mean the problem causing the scratches is in the lower part of the camera, i.e. the picture is inverted on the negative when it is taken? The scratches are minor but annoying. They are parallel to the horizontal.
Thanks to all on this excellent forum. |
Dgillette4
Tinkerer
Username: Dgillette4
Post Number: 34
Registered: 04-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 08, 2007 - 03:41 pm: |
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Scratches on developed film can be caused by the film apeature or pressure plate or any place the film may come in contact with. usually you can see a sharp edge or point, another place this can happen is in the developing process. I've had this happen from one of the larger labs so be aware. The light trap on the cassette can get contaminated with dirt if you're in a windy sandy area. I learned to rewind slowly after shooting, especially in a cold dry atmosphere. The print looked like something out of a frankenstein movie...Don |
Ben_hutcherson
Tinkerer
Username: Ben_hutcherson
Post Number: 49
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 08, 2007 - 05:47 pm: |
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My local lab uses a roller transport machine to develop E-6. Even though I know that they keep it impeccably clean, my transparencies still get scratched every once in a while. You might check on this.
Dip and dunk tends to be scratch-free, so if you can find a local lab which uses a dip-and-dunk processor, you might give them a try and see if you still get scratches. |
Mikel
Tinkerer
Username: Mikel
Post Number: 29
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 08, 2007 - 06:35 pm: |
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If the lab returns ALL of the processed film you can easily determine the cause of the scratches.
Examine the unexposed film at the end of the roll. If it is scratched, the lab has made them. If the scratches stop at the last exposed frame, your camera is the culprit. |
M_currie
Tinkerer
Username: M_currie
Post Number: 51
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 08, 2007 - 09:10 pm: |
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In answer to the original question, yes, the picture is inverted, emulsion side toward the lens. So if the scratches are appearing on the shiny side, the first place to look is the pressure plate. The camera does not put any direct contact on the emulsion side, so of it's there, it's unlikely to be the camera, but could be the film cassette or subsequent handling. |
Johnlees45
Tinkerer
Username: Johnlees45
Post Number: 38
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, May 09, 2007 - 09:18 am: |
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Brilliant answers, gentlemen. Thank you all. Very informative. |
Arnoldharris
Tinkerer
Username: Arnoldharris
Post Number: 10
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, May 12, 2007 - 05:03 am: |
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This is an interesting topic that rarely comes to attention.
Pressure plates on cameras may well get some degree of human touch every time the film compartment is opened. If finger prints or minute bits of dirt can cause problems with shutter blades, what about the same problem with a pressure plate that transfers all that to a film strip?
Would it not be wise to clean wipe the pressure plate after the film end is loaded and before the cover is replaced in position? And if so, what sort of cleaner? Naptha or other inflammables are not the sort of substance advisable to carry around in a camera bag.
Arnold Harris
Mount Horeb WI |
Charlie
Tinkerer
Username: Charlie
Post Number: 68
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, May 12, 2007 - 05:08 am: |
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Maybe the leader will clean off the plate while advancing to the first exposure. |
