scanning film with sd quattro

Artemka wrote:

rf-design wrote:

Artemka wrote:

Being new to this forum, i would like to say greetings first. I've shot several sigma cameras during the past years, including sigma dp1m, dp3m, dp2x, mostly in monochrome and have always been astounded by the advantage they give over conventional Bayer pattern cameras.

However.

For the past several months i got hooked on film and now i rarely touch my digitals...

My usual workflow is as follows - BW film -> Fuji X-E1 w/ macro -> dcraw linear 16 bit TIFF -> inverted in Silverfast Negafix or manually inverted and tweaked in PS. I usually make one shot scans for online use and 4 shots stitch for a 6x4.5 negative which I intend to print. By stitching 4 shots I think I can go as far as the grain structure of the film. That is, with Bayer quality. Intended printing size is up to 24" at 300dpi.

My question towards the technically minded people here:

1. How big would be the advantage of replacing the Fuji X-E1 with Sigma SD (H) Quattro?

A multilayer sensor do not give in principle higher resolution. If you scan B/W you must get rid of the Demosaic. This should give you the same resolution as all RGB pixels are avaible w/O interpolation. In stead you must adjust the 2x2 color channels for minimum derivation. This depend on the light source while making a scan/picture with the Bayer cam. It should be best a flash light because of vibration and spectral distribution.

I think RT have the capability to adjust color channels w/o Demosaic

I've tried processing with RPP (Raw Photo Processor), which claims it can take the Luminosity without Demosaic-ing it. The results are somehow inferior to using normally processed files in dcraw. When enlarged to 400% the RPP file shows jagged lines and blotches and is very inconsistent in quality. As I mentioned, I can sort of overcome it by stitching and ending up with higher res, but man, every time I see the micro detail of Foveon...

The issue in the flow w/o Demosaic ist that the luminace response form the RGB is different. This gives the noise. If the three, assuming 2 equal green sensitivities, channels are equalized the noise vanish.

I use an LED light panel as in your setup below. Masking the negative with a black frame to prevent flare and using a tripod/cable release gives me sharp images.

A further trcik for stitching is to use an school technical drawing table. There can fix the movement into two directions and make markings for the stitch.

2. How big is the importance of a quality macro optic. Sigma SA is surprisingly hard to find over here (in Europe), so I've narrowed my choices to Sigma 105/2.8 APO or something like Nikkor 55mm/2.8 AIS with adapters (Nikon F->M42, M42->SA).

I am in the process to optimze the scanning of 6x7 negative from Neopan and Velvia. My UMAX Powerlook III is not up to the capabilities of the Neopan. So I decide to scan and stitch with a macro setup. This is also the plan for 8x10 which is useable with the Powerlook III. The setup is an old enlarger with a M42 bellow and a white LED A4-size light table. The best objective I found up to now for 1:2 are a lens from a microfiche reader. Sometimes you can found them cheap from a replacement stock. Alternative are the microphoto objectives with 25mm to 35mm from Canon or Minolta. Up to 1:1 the Sigma 2.8/50mm works perfect. I am not using a Foveon, instead a Sony NEX3N because it has live view and flip monitor, perfect on the enlarger stand and the resolution difference is compensated by the much higher speed processing nonSigma RAWs.

3. Inverting negatives requires a linear raw file which can be inverted before gamma is applied. Is there any way to get a raw linear file from a Sigma? No option in SPP as far as I know. Since I am interested in Luminocity only, there might be third party converters that can do a decent job?

Kalpanika seems the only option.

Thank you for your attention and replies.

Artem.