Im looking to make larger negs for silver contact prints under Gum bichromate or straight gum prints.
The spectrum response part of the questions was wondering if the tungsten enlarger lamp is too red for the film to see it (the projected image). But you say it can see tungsten so that's very good.
Any xray film that has a blue tint seems like it would surly raise contrast problems if using a multigrade silver paper, right?
Thank you both for the help, I really appreciate it
Robert
While I did not end up making any headway with enlarging a negative for alt process, I (and many others) have printed x-ray negatives just fine. My cold-light head emits a bluish light anyway. I couldn't tell you if contrast filters have different or more/less effect on x-ray film, not having made any kind of extensive tests, but they certainly seem to work. I haven't shot x-ray film in a while otherwise I might could check more specifically.
It works. I tried it, under an enlarger with a regular halogen bulb. There's more than enough blue and green light there to make enlargements onto x-ray film. Getting exposure and contrast right will require quite a bit of experimentation though.Originally Posted by rknewcomb
Not really. It may have an influence, but I have contact printed xray negatives onto VC paper and it worked just fine.Any xray film that has a blue tint seems like it would surly raise contrast problems if using a multigrade silver paper, right?
Most xray films don't have anti-halation back layer.
This is the reason for the softness mentioned by Corran.
Edge sharpness is diminished by highlights bleeding into adjacent lower values.
Which is ok-ish for in-camera negatives that are contact printed, but if you enlarge (inter-positive/inter-negative, in your case) the effect will be even more pronounced.
The films I know of, which have anti-halation layer are the Agfa HDR mammography film and the Kodak ektascan b/ra film. (possibly the Fuji AD-M mammography film, but I have not tried that one yet.)
Like Corran and koraks, I too have had no problems printing with mutligrade filters/papers despite the inherent blue tint of xray films.
Do you think this softness issue is still the same if I'm enlarging from a regular (non xray film) negative?
I have been using a 4x5 enlarger to blow up magic lantern slides onto 8x10 x-ray film, you don't get great density to make an alt process print, although they work. I then scan my 8x10 negs, which can then be adjusted and sharpened, and print them onto transparency film using an Epson p800 printer. The difference is worth the trouble, these are then used for kallitypes.
It will always be a bit of an issue, but in my experience halation is especially an issue with very bright highlights as you'd get from the sun or strobes. It will therefore be less problematic under an enlarger.
Another contributor to softness, however, is the double-sided nature of most x-ray films. Under an enlarger you can (sort of) overcome this by stopping down quite a bit - which you will likely need to do anyway as x-ray film is a whole lot faster than paper.
In the 'real world', I find the softer backside a bit annoying and it can practically only be overcome by stripping the backside of the film after developing the negative. Which I find messy and prone to damage to the image side. Or use a single-sided x-ray film, of course, although in my area, the costs of that are pretty close to Foma 100 8x10 (in addition to the logistic issue, and the Foma product is of course panchromatic as a 'bonus'), so I personally just forget about that option, but it can be worthwhile if you're in the US.
Is xray duplicating film single side emulsion and about the same speed as photo paper? I have made many enlarged negative on photo paper. If duplicating film would act about like paper but without all the paper fibers then that might work for me.
In your case, the problem is not the enlarging part (since you'll use a regular negative) but the accumulation of the effect that the lack of anti-halation has, because the edge softness in the inter-positive will be added to the edge softness in the inter-negative.
At the moment I have a broken leg that refuses to heal, so I can't go to the darkroom and bring some negatives to scan and illustrate the effect, but I can tell you this:
The problem with the lack of anti-halation layer, becomes obvious in a side by side comparison of a film that has it and a film that doesn't.
If you contact print a Stouffer step wedge on both, the edge bleed that I described becomes blindingly obvious.
The double-sided nature of most x-ray films, that koraks mentioned, is indeed another thing that will work against you, twofold (see first sentence.)
The films with anti-halation layer I mentioned earlier are also single sided, providing a solution to both these problems, albeit at a price.
Thank you for sharing your knowledge with me. I checked on the film you mention that has the anti-halation backing. I found a seller and can buy some, although its sold in a case of 5 boxes so kind of expensive.
Robert
Posting Permissions
Reply With Quote
Bookmarks