There's a famous quote from actress Tallulah Bankhead: "They used to photograph Shirley Temple through gauze. They shouldQuote:
Originally Posted by andrewch59
photograph me through linoleum."
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There's a famous quote from actress Tallulah Bankhead: "They used to photograph Shirley Temple through gauze. They shouldQuote:
Originally Posted by andrewch59
photograph me through linoleum."
;););)
Thank you. You have been very clear and I agree completely.Quote:
Originally Posted by StoneNYC
Actually I am trying to define a standard procedure to get a large negative from the sources available to me , which are b/w 24x36 and 6x6 negatives, 24x36 slides, 24x36 colour negatives, and finally digital images.
Considering for the moment the 24x36 b/w negatives I intend to use x ray film for duplicating/reversing a b/w 24x36 film, stripping the opposite emulsion and enlarging on a normal xray film, to get a negative to be used for gum or carbon printing.
For the 24x36 slides I see the only possibility in enlarging them on an orthocromatic film, unless I don't care about red blindness of xray film.
I have no plan for the 24x36 color negative, so I keep them apart for the moment, even if I have a lot of them.
I hope to use the digital images by projecting them on a 18x24 cm xray film by means of a rudimental camera/optical bench I made.
Outdoor Test: Olympia WA
Shen-Hao 5 x 7 with Fuji 210 WS. Fuji film RX-N Blue developed in Pyrocat-HD. Cropped and toned.
Attachment 131307
Hi, can someone tell me the difference between green and blue sensitive?
Has anyone tried Fuji HR-U? (not hr-u30)
if I'm not mistaken, is orthochromatic, I could use with red light?
many thanks
There's no difference, I've had a further talk with my X-Ray tech friend, he explained that the green and blue have to do with the "screens" they use, in X-Ray world, the screen has a phosphorous layer facing the film that is sensitive to X-Ray waves and luminesces when it is bombarded with X-Rays, the screen labeled blue or green and is placed in a holder with blue or green film, now I guess you can mix and match the screens (use a blue screen with a green film) and that will for example HALF the speed of the film, but all films for X-Ray with the screens are considered 400 speed films. It's the screens that are used that change the speed.Quote:
Originally Posted by principiante
That said he and I do not know if the green and blue are actually more sensitive to green or blue light, or if the phosphorous in the blue screens luminesces more blue and the green screens luminesces more green, not sure.
So I have to apologize for my statement that green films are 400 speed, because that's all dependent on the screen used.
Which in normal photography we don't use a screen at all.
He works at Yale and hasn't used film in probably ten years since they obviously have very modern digital equipment, so he couldn't experiment for me or anything.
We did have a laugh when I mentioned the film being "Ortho" film as to him, that meant orthopedic, haha, but again he only studied with film in school but as soon as he started working it was all digital.
I find it all fascinating.
Suffice to say he did say that he was able to read the details and recommend certain films to me that might be inherently more contrasty or inherently less contrasty depending on certain factors and we'll sit down at some point to go over all that in person.
Also, as far as I know all X-Ray film is Orthochromatic, so yes you can use a red/amber light, some of it is more or less sensitive but just test it out, I can say that AGFA CURIX UV-G and Kodak EKTASCAN are both just fine under an amber Thomas' Deluxe safelight.
Wrong. Having the sensitization centered on a certain spectrum of color can make a big difference on the resultant image. Yes, they are both "ortho" and not sensitive to red light, but being blue or green sensitive is still important - for instance, blue will be much more sensitive to the sky and shadow colors, hence why many people adjust their ISO depending on the time of day when using this film. Also it is why foliage shows up so bright when I use green sensitive film.
Here's a spectral sensitivity chart I found for some green film. You can see how it drops off after hitting a peak in the green area, not the blue.
This explains why the blue/green screens give half/full speed. But you really shouldn't tell a newbie they are the "same."
Attachment 131532
I would also suggest not using an amber safelight w/o testing. Red is safe in my experience but I initially had a lot of fogged film that seemed to trace to an amber safelight. And, I really question the idea of the X-ray film being 400 speed in the usual film sense. Lots of people using film meters find it rates around 64-80 speed in mid-day daylight and speed reduces a lot as the day is earlier or later due to the change in the color of the light out doors. Indoors color temperature matters for exposure too: incandescent or "warm" lights (lower color temperature) is a lot slower (?a couple stops?) than your meter will indicate when compared to daylight (higher color temp bulbs).
"Ortho" is a Greek derived prefix relating to position as used in Organic chemistry. Generally it means "right" as in correct, straight etc. hence for Orthopedic straight bones. Not sure how it was applied to film originally. But it seems to mean now B/W film that is sensitive to more of the visible spectrum than daguerreotype or typical wet plate or most home made dry plates which are sensitive to UV and Blue. Certain dyes extend the spectral sensitivity of the emulsion. Initially to the green region (orthochromatic film) and eventually to red (panchromatic or all sensitive, the Greek "pan" = all in English)
Based on examples seen here, to my eyes, blue x-ray looks more like daguerreotype or tintypes whereas green or Ortho film prints look different and pan films (artista edu, Tmax, tri-x, ilford etc) look different again.
Ymmv
My Navy fleet hospital (500 beds in a tent with expandable ISO containers) was initially supplied with green-flashing intensifying screens and blue sensitive film. The two are entirely incompatible, and half-speed doesn't begin to describe the huge increase of radiation needed to produce even a grossly under exposed radiogram. The various films are mated to their proper screens for optimal performance. A mismatch results in a terrible failure radiographically.
Pictorially, the films respond differently to objects of different colors in different ways, like wet plate and panchrome b/w films do. Film speed has been addressed in this thread several times already.
R
Good post, Fr. Mark. I use only a red safelight, actually a LED safelight, and I even gave that lite the CD prism test. All orthochromatic films are blind to red light. I use blue sensitve X-ray film when I want that pre 1900 look, and Ektascan when I want the true ortho look. Green X-ray film is a milder orthochromatic film than Ektascan, maybe, but Ektascan is backed with an anti-halation layer which comes off during development. Don't be surprised by this variation of various films to light. Pan film also is. There used to be 3 different Pan films in their recording of light. Pan-A, B, C. Now there is only one Type A pan film - Fuji Acros. Everything else is Type C which is really over-corrected for red light.Quote:
Originally Posted by Fr. Mark