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PaulG
18th March 2010, 06:43 PM
One for the large formateers, I'm afraid...

Having taken delivery of a very nice handmade oak 8x10 pinhole, I've been having a bash at making some exposures and contact prints. I've only exposed 5 sheets of film so far, but I seem to be having a recurring problem with dark streaks on the negatives.

I thought this might have been down to poor agitation during development, so with my most recent attempt I took great care to vary the direction of agitation, but I still seem to have ended up with the same result. In this case, it was a modified Paterson orbital, but I seem to get the same result in open trays as well. I don't see the problem with 5x4 sheet film.

The film is Ilford Delta 100, developed in Ilfosol 3 at 1+9 and 20 degrees, continuous agitation. Developer volume was 120 ml.

A contact print of my most recent sorry effort is attached. The problems are all too aparent. I'm hoping someone can help me out before I end up broke. At nearly £4 a sheet, this is a problem I'd like to resolve sooner rather than later. :eek:

Dave miller
18th March 2010, 06:58 PM
Light leak/reflection? Are the marking similar on each negative? You could try experimenting with 10x8 r/c paper, as it's cheaper than film, until you find the cause.

Trevor Crone
18th March 2010, 07:23 PM
I would tend to agree with Dave, it looks like light fogging the film or an extreme case of film creasing.

What are your film holders and are they new? Are you loading them in absolute darkness - darkroom or changing bag.

When removing the darkslide protect the slot with it or your hand if working in directional light. I've had the odd streak caused by light entering the opening when working in strong sunlight, particularly with the larger 8x10 DDS.

As Dave says try paper negatives until you resolve the problem.

Good luck,
Trevor.

kev curry
18th March 2010, 07:35 PM
Judging from the streaks it looks like it could possibly be light leaks coming from the bottom of the camera back? Wrapping the camera in a dark cloth during exposure could establish either or...

Peter Hogan
18th March 2010, 08:49 PM
It's fogging; you've got a light leak somewhere in your camera...:(

PaulG
18th March 2010, 08:58 PM
Thanks all. The camera has a simple back-plate with a wedge to hold it in place and I wonder whether this is not adequate to secure the holder and prevent light ingress as the darkslide is removed. :slap:

The holders I have are on loan, but they look to be in pretty good nick, so I'm hoping that's not where the problem lies.

With regard to paper negs, any thoughts on exposure times? (Pinhole is f/250). Also, there seem to be lots of suggestions of pre-flashing paper before loading it. Would this be to the same extent that I would flash paper for printing purposes?

(Sorry for all the questions)

Dave miller
18th March 2010, 09:54 PM
Thanks all. The camera has a simple back-plate with a wedge to hold it in place and I wonder whether this is not adequate to secure the holder and prevent light ingress as the darkslide is removed. :slap:

The holders I have are on loan, but they look to be in pretty good nick, so I'm hoping that's not where the problem lies.

With regard to paper negs, any thoughts on exposure times? (Pinhole is f/250). Also, there seem to be lots of suggestions of pre-flashing paper before loading it. Would this be to the same extent that I would flash paper for printing purposes?

(Sorry for all the questions)

I think the pre-flashing is to lower the contrast. I recommended the use of using a paper negative as a cheaper way of helping you in tracing, and fixing the light leaks. If that is the intent then the niceties of accurate exposure are not so important. I suggest you start at ISO 1 and use a dilute paper developer to lower contrast.

You might need an alarm clock as an exposure timer, but just think of the money that you will save. ;)

PaulG
19th March 2010, 08:56 AM
I think the pre-flashing is to lower the contrast. I recommended the use of using a paper negative as a cheaper way of helping you in tracing, and fixing the light leaks. If that is the intent then the niceties of accurate exposure are not so important. I suggest you start at ISO 1 and use a dilute paper developer to lower contrast.

You might need an alarm clock as an exposure timer, but just think of the money that you will save. ;)

Thanks Dave, I appreciate the main reason for trying paper negs is to pin down the source of the problem I've been having. My problem is a naive optimism that it will all work, so I may as well be prepared for the best result I can get! One step at a time... :)

Phil
19th March 2010, 09:04 AM
I'd agree on lightleaks too - are the streaks consistent on each frame? Using paper negs you'll be able to see this; it's a very simple, effective and cheaper way of ascertaining problems.
Phil

Trevor Crone
19th March 2010, 11:08 AM
Paul, try the set up with and without the dark cloth wrapped around the back of the camera. If there are no leaks with the dark clothed wrapped around you know its a problem with either the DDS or the seating of the DDS and camera back.

However it sound as if its the camera back not holding the DDS firm enough. What is this wedge contraption you mention? I take it the camera does not have the standard international sprung back?

PaulG
19th March 2010, 12:31 PM
However it sound as if its the camera back not holding the DDS firm enough. What is this wedge contraption you mention? I take it the camera does not have the standard international sprung back?

I'll try to post a picture later, but the back is literally a piece of wooden board that sits behind the film holder, with a cross piece that allows a wedge to be inserted to provide the pressure to hold everything in place. I thought this might be a bit suspect with a film holder inserted, so have added some strips of closed cell foam that, when compressed, help to hold everything in place. Maybe even that isn't enough. Time for some experiments methinks.

Thanks again to everyone for their help and suggestions. The collected wisdom, and the generosity with which it's given, is one of the things that makes FADU such a great group.

Phil
19th March 2010, 03:00 PM
The collected wisdom, and the generosity with which it's given, is one of the things that makes FADU such a great group.


You've put into words something I've thought ever since I signed up!
Phil

PaulG
19th March 2010, 06:15 PM
I'll try to post a picture later, but the back is literally a piece of wooden board that sits behind the film holder, with a cross piece that allows a wedge to be inserted to provide the pressure to hold everything in place. I thought this might be a bit suspect with a film holder inserted, so have added some strips of closed cell foam that, when compressed, help to hold everything in place.

Here are some piccies. You can see how 'high' the wedge sits once a film holder is inserted...

Trevor Crone
19th March 2010, 07:13 PM
Paul, I can now see where the possible cause of the problem is. Perhaps make a couple of similar wedges to hold each side firmly in place (I don't know if the foam insert will be firm enough). Also is there the grove in the camera body that helps form a light tight seal with the film holder?

Trevor Crone
19th March 2010, 07:21 PM
Another thought has just occurred to me and that is to have two oak battens, top and bottom with accompanying wedges. The problem may be the back not seating properly either at the top or the bottom. However from the pictures it looks nicely made.

PaulG
19th March 2010, 09:45 PM
Another thought has just occurred to me and that is to have two oak battens, top and bottom with accompanying wedges. The problem may be the back not seating properly either at the top or the bottom. However from the pictures it looks nicely made.

Thanks Trevor. As wooden boxes go, it's lovely! :) There are some nice brass inlays as well for composing the image. I think you're right about the need for extra battens - will attempt some 'modifications' to see if I can hold the back and film holder more securely.

8x10 negatives are amazing things. so I'd really like to get this pinhole working properly.

Trevor Crone
20th March 2010, 07:32 AM
Paul, could you post some more pictures of this camera, eg., front, interior, etc.? You mention brass inlays for composing, is there no GG screen?

I do agree with you about the attraction 8x10 negatives and their contact prints. I fell in love with them when I first saw the photographs of Edward Weston and Paul Strand :)

Dave miller
20th March 2010, 07:59 AM
Paul, could you post some more pictures of this camera, eg., front, interior, etc.? You mention brass inlays for composing, is there no GG screen?

I do agree with you about the attraction 8x10 negatives and their contact prints. I fell in love with them when I first saw the photographs of Edward Weston and Paul Strand :)

There isn't normally a glass screen with this type of camera, at f295 it would be a little dim. ;) Composition is done by eye-balling across the sights, in this case the brass inlays.

Trevor Crone
20th March 2010, 08:28 AM
There isn't normally a glass screen with this type of camera, at f295 it would be a little dim. ;) Composition is done by eye-balling across the sights, in this case the brass inlays.

Yes, that makes sense. A true point and shoot camera :)

Paul, what is the suggested focal length of this camera? Only I must confess to being quite fond of WA pinhole photographs.

PaulG
20th March 2010, 09:57 AM
As Dave says, there is no ground glass, just the inlays on the top and side to sight down for composition. The focal length is 125mm, pinhole size is 0.5mm (laser drilled) and the "aperture" is f/250.

The camera is oak, with the insides painted matt black and a strip of flocking around the back where the rear plate and film holder sit.

PaulG
20th March 2010, 10:01 AM
Paul, could you post some more pictures of this camera, eg., front, interior, etc.? You mention brass inlays for composing, is there no GG screen?

A bit of a cop out Trevor, but this (http://farm5.static.flickr.com/4039/4352868365_0ffbc58c56_o.jpg) is a link to a photo of it and its baby brother (5x4) where you can at least see the front and the inlays.

Trevor Crone
20th March 2010, 10:35 AM
A bit of a cop out Trevor, but this (http://farm5.static.flickr.com/4039/4352868365_0ffbc58c56_o.jpg) is a link to a photo of it and its baby brother (5x4) where you can at least see the front and the inlays.

Thanks Paul, looks a fine piece of kit ;)