DSLR Scanner: Scans and Comparisons

[Peter De Smidt]

So here are some comparisons.

First, we have a scan from the dslr scanner. The layers are from different lenses.

https://dl.dropboxusercontent.com/u/...ergger_200.tif

This is a full-sized 8-bit Gamma 2.2 layered file. The sample area was the center of a 4x5" of Bergger 200 film developed in PMK. It was taped to the glass. With one lens, the exposure was 1/100th of a second, and with the other one it was 1/60th. I used the light source to roughly equalize the channels.

The files were brought into Lightroom 5, where I inverted them. I then used the curve feature to stretch each channel until it almost clipped, which should be pretty representative of actual use. Default Lightroom sharpening was applied to both. (Each could stand quite a bit more sharpening.)

After bringing the files into Photoshop, I converted to Grayscale 2.2 using the green channels, which showed a little more detail.

Second, we have a scan of the same area on my Cezanne:

https://dl.dropboxusercontent.com/u/..._test-0109.tif

I scanned this version at 8000 spi and then down-sampled to roughly the size of the dslr scan in Photoshop using Bicubric sharper. No other sharpening was applied.

[Ken Lee]

I'm late to this thread and no expert with real scanners but the two are not dramatically different to my amateur eyes.

I can't tell if we're seeing grain or digital noise in some of the darkest areas, but both scans seem to getting right down to the practical limit. Some parts look better in one file than the other, much like the example you already posted: it's hard to tell whether what we're seeing is due to sharpening or actual resolution.

I'd call it a draw myself. Is the DSLR version much cheaper and easier to make ?

Would it be more revealing to scan something with finer grain, like TMX ?

[Peter De Smidt]

I appreciate your opinion, Ken.

With the dslr scans, digital noise would appear first in the brightest tones, as those are the densest areas of the negative. There was a very small amount of sharpening applied to the raw conversion in Light room, using it's standard default setting.

Easier to make? That's a hard one to quantify. If you're scanning 35mm, then the dslr scanner is much faster than the old pro flatbed.

My dslr scanner takes up about 1/4th the space of my Cezanne. Over time, the big flatbeds are going to get even harder to find and more expensive to keep running. Minus the dslr, my DIY scanner costs less than new bulbs for my Cezanne.

I used the Bergger film, the grainiest I've used in large format, for a couple of reasons. It lays flat, it makes a very good optical print, and I wanted to see how the systems handle grain. I don't want to get rid of grain. For my small format work, I often like grain, but I prefer it to appear equally sharp and close to what it does on the negative. Many scannessr exacerbate the grain dramatically, which was my experience with a Coolscan film scanner and grainy film. With larger format, I generally don't want to see grain in a print, but if the grain is well imaged in the scan, I expect that the overall quality of details in the negative should look good. I'll do some scans of finer-grained film down the road.

[Ken Lee]

Perhaps the scanners which exaggerate grain (like the Nikon Coolscan) use a collimated beam of light, like a condensor enlarger. They give an impression of greater sharpness but introduce the Callier Effect: dense areas rendered disproportionately dense, often to the point where the tones are lost.

I don't have a DSLR, but if I did (or some other camera with a good sensor and a good macro lens) I'd try your approach. It would be nice indeed to get all the data that the film has to offer !

[Kirk Gittings]

Damn dude I think you've done it!

[Peter De Smidt]

Perhaps the scanners which exaggerate the grain (like the Nikon Coolscan) use a collimated beam of light, like a condensor enlarger. They give an impression of greater sharpness but introduce the Callier Effect: dense areas rendered disproportionately dense, often to the point where the tones are lost.

I think you're right. Grain aliasing might also be involved.

Damn dude I think you've done it!

Thank you, Kirk! Richard Iles, our Arduino programer, and Daniel Moore were at least as responsible for where we are now as I was, and a number of other people here contributed greatly to the endeavor. I still have some refinements to make, but once that's done, I'd be happy to scan a negative for each of you so that you can compare. Daniel will probably get even better results with his D800e.

[SURF]

Nice done, Peter!

It would be interesting to scan resolution target with both scanners. Geometrically the images are good. I think you should never use bicubic sharper cause it is for those who do not want to bother with fine tuning the sharpening. It applies rather big radius.

What is the calculated resolution of the DSLR setup?

Lens R looks better for the first sight.

Still wonder what is the real resolution of the Cezanne scanning different sizes. Never played with it. I will state that the resolution race is finished with DSLR setup when real 6000 dpi will be reached. Of cause it is for 35 mm only. OK, 5000 dpi will be good too.

To my eyes the DSLR scan looks better.

[Peter De Smidt]

The Cezanne should be getting at least a true 6000 spi. I've seen that confirmed by a couple of sources. I'd love to scan a good resolution target, but I don't have one, and they're pretty pricey. My conclusion is that the dslr scans are very close in quality to one of the best bw negative scanners. And that's at 1:1. I did scan a 35mm Technical Pan negative yesterday, and the dslr resolved the grain just fine. I had a slight alignment issue with my extension tube,though, and so I'll have to redo it. It's an open question as to whether higher magnification would be useful. It might be that the depth of field gets too small, and I'd have to use focus stacking. That might be ok for 35mm negatives, but I doubt it'd be useful for LF ones.

[Peter De Smidt]

50mm Componon-s Reversed 2x F5.6 4x5 Bergger 200 PMK:

https://dl.dropboxusercontent.com/u/...sed_upload.tif

[Peter De Smidt]

To give some perspective, here's the complete image: