Top-end digital concerns

[bglick]

> If the sensor acts as a shutter, then theoretically, each pixel could act as a shutter; you could have an HDR image quite easily.


Yes, this is theorecticaly true, although I am not sure its being worked on.... but it would be a joy if the pixels all accepted light for x period of time, eliminating the need for a shutter.


I never used the s5... I never heard of it classified as HDR... maybe a stop more of light? The design is excellent for color fidelity as you mention, its shortcoming is resolution. A major tradeoff...the market seems to prefer more resolution.



> Do you see any value in comparing the two by ever shooting cy/mm targets and comparing results ?

yes I have, this is what I am basing my comments on.... of course, the scanner variable is a big one....




> SOoo... You have proved this because the Signal to Noise Ratio of both confirms this ?


I don't think S/N ratio is an accurate description...but yes, it has been proven over and over....and falls under the same Nyquist principles I mentioned in your other thread. Its called over-sampling.... which creates inefficiency. There is a slew of other variables that also determines how inefficient the scan file will be vs. the first generation image.

[rvhalejr]

> IMO, the MP wars are hitting brick walls.

Amen. We still have Color Fidelity, Dynamic Range and how to decouple diffusion from resolution, etc.

By the way, your MP values for c41 seem rather high given the amount grain (noise)
I seem to get when its quantified on the computer in PS. Hmmm .,.

Bye the Bye you all familiar with how to quantify grain/noise as opposed to signal (image detail) ? No math involved and only takes a few minutes, be happy to detail the procedure if you do not recall.

[rvhalejr]

> I never used the s5... I never heard of it classified as HDR... maybe a stop more of light?

If I recall the S3 was said to have a really big photo-site to resolve shadows and a little photo-site to resolve highlights, combining both into one pixel. Simple design but very effective, two taking on the workload of one

[rvhalejr]

Posted by bglick
> .. The pure pixel count of a scanned file, converted to MP's is vooodo math...
Reply#1 by rvhalejr
>> SOoo... You have proved this because the Signal to Noise Ratio of both confirms this
Reply#2 by bglick
>>> I don't think S/N ratio is an accurate description..

Digital Electronic fundamentals are far from being vooodo math...

There cannot be any meaningful objective digital comparisons unless S/N is taken into account.

[bglick]

>>> I don't think S/N ratio is an accurate description..

Digital Electronic fundamentals are far from being vooodo math...

There cannot be any meaningful objective digital comparisons unless S/N is taken into account.


Rich, you are mis-applying my comment. S/N ratio is a component of scanning film. However, the reason the scanned file is so much larger than its digital capture cousin, is due to many other MORE significant factors. Such as optics, lighting, mechanical movement, object sizes on film, as well as the Nyquist principle of over-sampling. If you re-read what i wrote, I suggested that converting a scanned file MB's into MP's is voodoo math....there is NO sensible relationship between the MB's of a scanned file and MP's of a digital captured file. Many people mistakenly promote this fallacy.

Instead of creating a NASA level project from these comparisons, its easier to view through a microscope what your film can resolve...that's the true resolution, and represents the MP's of IQ the film contains. (very general statement, as resolution can vary across film)....

the IQ MP's / MP's converted from scanned MB's , represents the scanner efficiency. It will range from 25% - 90%. I can't fathom why anyone in the photography world would need to dissect each component of the over-all scanner efficiency value..?

Got it?

[Lenny Eiger]

>
f22 - 329 MP
f32 - 204 MP
f45 - 125 MP
f64 - 72 MP

OK, so I reviewed this - and I understand some of the logic you use, but I have to admit it makes no sense to me in real life. I recently did a test of the same image shot from f 22 to f 64. The only difference I can see is in depth of field. The sharp areas are very sharp in each one. If I read the above correctly, the f22 ought to be really superb as far as detail (at least where it is sharp) and the f64 ought to be about 1/4 the resolution - and 1/4 the file the other is. They are both very good.

This is where I have trouble - the numbers don't match my experience. This might be true in a tabletop situation, I couldn't say, haven't tested it. But outside in the daylight the f64 version is not 1/4 the file that the f22 is.. There is lots of data everywhere. I have scoured these negs and the resulting scans.

I am using a Nikon 300 on my Canham, developing the Efke 25 in D-23, stock.

I'm not trying to be argumentative. I just don't see it.

Lenny

[dh003i]

OK, so I reviewed this - and I understand some of the logic you use, but I have to admit it makes no sense to me in real life. I recently did a test of the same image shot from f 22 to f 64. The only difference I can see is in depth of field. The sharp areas are very sharp in each one. If I read the above correctly, the f22 ought to be really superb as far as detail (at least where it is sharp) and the f64 ought to be about 1/4 the resolution - and 1/4 the file the other is. They are both very good.

This is where I have trouble - the numbers don't match my experience. This might be true in a tabletop situation, I couldn't say, haven't tested it. But outside in the daylight the f64 version is not 1/4 the file that the f22 is.. There is lots of data everywhere. I have scoured these negs and the resulting scans.

I am using a Nikon 300 on my Canham, developing the Efke 25 in D-23, stock.

I'm not trying to be argumentative. I just don't see it.

Lenny

It could be that the f/22 images are not focused properly, as f/22 is less forgiving than f/64. Hence, they look to be of equivalent sharpness in the sharpest areas, but that's because your focusing is slightly off and f/22 thus doesn't seem any different than f/64 in the sharpest areas?

[Bruce Watson]

OK, so I reviewed this - and I understand some of the logic you use, but I have to admit it makes no sense to me in real life. I recently did a test of the same image shot from f 22 to f 64. The only difference I can see is in depth of field. The sharp areas are very sharp in each one.

You likely won't see it unless the scene itself is providing you with high enough frequency information. For example, distant pine needles on a Douglas-fir tree. A single sharp edge isn't enough -- all your f/stops will show it sharp as you have seen. It needs to be multiple edges and they have to be close enough together -- IOW, high enough visual frequency. That's why people see this in complex landscape work but not in, say, a table top study of a single flower blossom.

[Lenny Eiger]

It could be that the f/22 images are not focused properly, as f/22 is less forgiving than f/64. Hence, they look to be of equivalent sharpness in the sharpest areas, but that's because your focusing is slightly off and f/22 thus doesn't seem any different than f/64 in the sharpest areas?

I focused on a car tire. I can see the little parallel ribs on the sidewall and the text. There are some minor differences - some places where one is sharper than the other, so the focus may be slightly off, but there are areas fully focussed in both of them and they both look good, and both look good overall, plenty of detail, plenty of fully rendered pixels, etc. The real deal for me is that one image is not great and the other crap, or if not crap, just poor.... or 1/4 as good.

This leads me to the conclusion that, as with many numbers, they are theoretical. Imacon is famous for claiming that they have a DMAx of 4.8, which is beyond the maximum density of film. What did they use to test? Aluminum foil? When I complained about this, and referenced independent tests that show it has a DMax around 3.0-3.1, another person on the Scan list pointed out how they came to that number. It was a theoretical extrapolation of what the scanner "could" do.

I understand resolution, lines per mm and a lot of things around this issue. However, i have a 8x10 image, scanned at 2000 ppi I am looking at that is just over 300 mgpxels (16000 x 20000), about 500 megs of B&W and I don't see how it relates to being only 1/3 usable pixels. It isn't that shredded, not by a long shot. The f22 vs f64 does not display a huge difference, one to the other, in terms of quality. It's minor.

Lenny

[Ron Marshall]

I agree with what is stated below (although I haven't checked the numbers), diffraction does degrade image quality (just look at a pinhole image for an extreme example).

But don't forget, the image produced by a lens in front of a digital is also degraded by diffraction.

I offer the following....using 1/R, If we consider diffraction limited lenses, at 100 lp/mm MTF for high resolving B&W film, at these f stops, the max. resolution of 8x10 film is...

f32 - 204 MP
f45 - 125 MP
f64 - 72 MP

And in the rare situation, where you can infinity focus at f22 - 468 MP


Of course, with 8x10 color film the numbers are significantly less...using 60 lp/mm MTF of the film...

f32 - 139 MP
f45 - 92 MP
f64 - 54 MP

f22 - 204 MP

For those interested..... 4x5 color film at 60 lp/mm

f16 - 58 MP
f22 - 44 MP
f32 - 30 MP
f45 - 20 MP