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I'm using it sometimes for carbon transfer and kallitype printing. Seems like quite a setup to develop your x-ray film... I have never gotten scratches when I use flat-bottomed trays, in film sizes up to 14x17. Have you developed with your set up yet? It looks like you'll need quite a bit of developer, to cover the film completely, as it's quite elevated.
Probably you have more experience than me in treating delicate films.Quote:
Originally Posted by Andrew O'Neill
I did not make yet a real film development test, but I simulated it with a pure water bath.
The present set up requires confortably from 800 to 1000 ml of solution.
The distance between the clamp and the plexy sheet is about 1 cm in the present set up, to avoid contact in the middle of the film, due to arching which brings the film to about 4 mm from the sheet.
In a more refined future device, giving some lateral stretch to the film, with a more planar film holding, the clamp to sheet distance can drop to a few millimeters, reducing the quantity of developing solution probably to about 400-600 ml.
In the search of a mount to keep the solution at a minimum, I am considering also the use of a vertical tank, with a width of 5 mm, on which drop the film kept precisely in vertical position.
No agitation will be possible, but I remember that long time ago I used to develop Xray film for crystallographic purposes some vertical vessels without any agitation. For reasonably long development times the simpkle diffusion is probably sufficient.
Given the needed size, say 19 x 25 x 0.5 cm for a 18x24 film the solution volume could reach 237 ml, which I believe is the real minimum.
A lot of trouble to go to as Andrew has said. I use new plastic trays with the grooves on the bottom and the moulding nipples that tend to scratch the negs, I negated the problem by simply using blank cleaned film on the bottom. Haven't had any problems except for unclipped fingernails occasionally. Oh and I moved up a size in trays, if you use the appropriate size the developer laps the sides a bit quick and causes uneven development.
Hey David,Quote:
Originally Posted by davidrcarls
is there some site or page where I can check all your typology shots made so far? I am shooting very similar project for last 3-4 years called "Close Ones - Up Close". I am also planning something very similar with people living in the city where I live now (Shanghai, China) where I would try to do similar project on the street with my Cambo MaxiPortrait 4x5.
I have a very stupid question, but I couldn't find anything about in the web:
Why the substrate of X-ray films is green or blue and not simply clear?
There are technical reasons or commercial?
Thanks.
X-ray film base is blue because it is a transparency, looked at on an illuminated light box along with hundreds more over the course of a long day. The blue tint enhances contrast and soothes eye strain for the radiologist. Blue vs green refers to the sensitivity of the film to light, because it was exposed by blue or green fluorescent screens that converted a relatively few x-ray photons to lot of light photons, thereby reducing the patient's x-ray dose.
R
Thank you for the explanation, but if the goal is to relieve strain, why not simply dim the lamps in the light box?Quote:
Originally Posted by Ralph Weimer
And why not tinting in green the substrate, a wavelength where human eye is more sensitive?
Finally, why blue or green should enhance contrast?
Visibility would suffer too much beyond a certain point, resulting in more strain instead of less.Quote:
Originally Posted by salvatore
My guess is that since blue-sensitive film is less sensitive to green light, the double sided nature of that film would complement less with a green substrate (the 'dark' side would receive less exposure, necessitating higher xray doses for patients to achieve the same contrast). Hence blue seems like a logical color to standardize on. I can also imagine that the availability, stability and cost of dyes plays a role, but you'd have to ask an industrial expert. Another factor that could play a role is the emission spectrum of the CFL light used in light boxes.Quote:
And why not tinting in green the substrate, a wavelength where human eye is more sensitive?
I don't know, honestly.Quote:
Finally, why blue or green should enhance contrast?
Have you tried contacting an industry expert with your questions? They sound a bit specific for a photography community - I'd love to hear the outcome if you found someone capable of asking your questions. Even though they don't seem to be of very high relevance to photographic applications, but like you, I'm curious ;)
As I've continued my testing of Ektascan I'm finding shadow areas to be sorely lacking in detail vs what I'd expect to get with regular panchro-type film; to wit, Zone III areas are very near or total black with Zone IV areas showing very little detail. I've been exposing the film at EI80 and developing in Pyrocat-HD. I'm really curious what other's experience is with this film and shadow detail? Should I expect good detail in Zone IV or should shadow areas where I want good detail be closer to Zone V? In any typical outdoor sunshine scene is the significant amount of blue light in the shadows--especially those open to blue sky--a factor? Or, is this just a very limited dynamic range film? Which, come to think of it, given its usual application a lot of dynamic range probably isn't necessary; I'm no x-ray technician, though. Thoughts?
Thank you for any insight provided.
Are you shooting with a Petzval formula lens?Quote:
Originally Posted by gdi