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Green responds to a much wider spectrum of light. Blue responds to blue and UV (there is a toe that does respond somewhat to lower wavelengths). Green starts at orange through yellow, blue and UV, and is reasonably close to old-timey orthochromatic films and plates.Quote:
Originally Posted by aaronnate
I started using Ektascan (1-sided, green sensitive) but switched to half-speed double-sided blue. I got into x-ray film because I wanted something with the spectral sensitivity of collodion w/o the chemical & explosive hazards. Blue is the closest.
I expect most folks favor green because the speed is more consistent throughout the day & it is closer to orthochromatic.
My 8x10 setup uses a 100-year old Rapid Rectilinear lens, and I contact print on albumen to get prints that look like they could be a hundred years old. Green comes closest to the film available at the time.
Can you explain about the speed consistency?Quote:
Originally Posted by seezee
I haven't tested it, but as it is sensitive to a much broader range of light frequencies, it stands to reason that it would not lose speed as much in the early hours of morning or later in the afternoon, since those colors are more present in natural light then.Quote:
Originally Posted by aaronnate
It's well-documented (in this thread) that x-ray film loses speed in natural light when the colors it is sensitive to are not present (duh). Most of us rate it slower in before 10 AM and after 2 PM and faster between those hours when shooting in natural light. Cloud and shade have similar effect so you may need to apply some mental reciprocity failure calculations when shooting in those conditions.
If you dig into this thread deeply enough you will run across examples like "ISO 80 at noon, but ISO 25 at 9:30 AM."
Is this for green or blue sensitivity?Quote:
Originally Posted by seezee
This thread got so long and disjointed when they merged the two that it is cumbersome to read. I'm picking my way through though, and have not seen any references to this.
I wish I could remember. I've only used x-ray film (blue or green) in the studio. If I get a chance I'll do some exposure tests with half-speed blue & let you know what I find out.Quote:
Originally Posted by aaronnate
Scan of a darkroom print on Ilford MGWT RC paper.
This is a composite picture, with two negatives printed simultaneously on the same paper.
The picture of the Moon is on a 9x12cm sheet of film, which is projected on the baseboard of a 4x5" enlarger (at a 4.5 magnification), and onto an 18x24cm sheet of film containing the clouds (which is contact printed).
With the same exposure (and some minimal dodging and burning) the two negatives are combined into one print.
Both negatives are Fuji AD-M xray film.
They were both shot with the same camera, a Kodak Master 8x10" view camera, but on different dates.
The Moon was shot with a Symmar 360mm lens on May 29, 2018.
The clouds were shot with a Fujinon W 180mm lens on June 14, 2018.
Both negatives were developed in Rodinal (RO9) at 1+100 dilution (1lt solution in a 10x12" tray), at 24C, with intermittent agitation.
The Moon for 10'min.
The clouds for 12'min.
https://farm2.staticflickr.com/1980/...9b6ac07c_b.jpg
Thodoris, that is phenomenal. Absolutely perfect, well done. A joy to look at.
I went ahead and bought a 100 sheet box of green sensitive double sided 8x10 from zzmedical, mainly because it was the least costly option they offer. I cut some into 4x5 and shot it and developed it in Rodinal and liked it. I also enlarged some 35mm negatives on to it to create B&W positive transparencies, which came out way better than I expected. Strangely the second batch I processed came out great with the exception of having a noticeable blue tint. What is causing the blue tint, and does it mean I didn't rinse it well enough? Thanks.