I was going to have some digital files recorded onto FP4 to see what the quality would be like when enlarged in the darkroom. What I can't understand, though, is how the recorder's resolution works.
The files would be recorded at 4K. I think the actual resolution is 2732 x 4096. How do you work out what size of enlargement is possible from this resolution? What is the limiting factor? It's also possible to have digital files recorded onto 120 FP4 at 3072 x 4096 resolution. Again, I'm flummoxed. Does the medium format advantage still apply when it comes to enlargements or, since max resolution seems to be the same, is there no longer any benefit from the larger film size? Hopefully this will be straightforward to someone because it's complete bollocks to me!
If anyone's tried this route before at similar resolutions, I'd be very interested in your opinions of the output quality.
Bruce
I have not used this class of film recorders. The one you are looking at probably uses a CRT image focused onto the film with lenses. The CRT is like a computer monitor (but small and much higher res), and can only display a fixed number of pixels. These are then focused onto the film. So there is an upper limit imposed by the CRT on resolution. The advantage of the larger film in this case would be lower grain. And you may see a bit more usable resolution.
Also, the CRTs have some issues with blooming in the highlights, from what I hear. You may want to have the image written out several times as a test. For one version try decreasing the max brightness from 255 down to maybe 240. That should in theory cut down on the blooming, and just require a bit more development to bring it all back.
A good rule of thumb for resolution is you want at least a certain level of pixels per inch (ppi) for the image to appear reasonably sharp. This number varies by output technology and individual preference. 200ppi seems to be a general level many people consider the minimum, but with you testing it yourself I can't say for sure what you will like with this output path.
The math is simple though. If you image out at 4096 on the long side simply take that film and make ever increasing enlargements. At 10 inches on the long side you will be at about 410ppi (4096pixels/10inches). So a 20" enlargement will be at 205ppi. I imaging some where between these will be your limit, so maybe 11x14. But that's just a guess and you will need to test to be sure.
The other option in film recorders is to use one that doesn't have a fixed image size, but rather writes out to the film at a certain resolution using lasers (or maybe an other tech for the LVTs - i'm not sure). The two big names you will hear are LVT and Lightjet. I am only familiar with the lightjet, so that is waht I will explain. These can image on sheet film from 5x7 upto 11x14. They have resolutions that are usually referred to as res 80, or res 40. That is, 80pp/mm with equates to 2032ppi. So if you write out a 4x5 image (onto larger film) it could address an image that is 8128 x 10160 pixels, or 82 megapixels. They can also go larger.
If your images come from a 6 or 8MP camera, you may not see much resolution difference between the two technologies. However if you are scanning large or medium format film you will get much more of your scan onto the output film. The LVT or Lightjets do give higher quality than the CRTs from everything I have read.