How does Better Light calculate MP count?

[tgtaylor]

I think that there is two definitions of grain. One defines grain as the space between the silver halide particles, and the other as the silver particles themselves. The LF thread referred to in my post above was using the latter definition and comparing a pixel to a silver particle. In other words, a grain of silver is comparable to a pixel.

In Jerry's post earlier today he sates:

"Since the narrow dimension of the high end Canon is 3744 lines AND the narrow dimension of a BL back is either 6000 or 8000 lines BL is certainly are capturing a finer record of the scene in the larger format at equivalent coverage, enlargement or magnification .

"6000 & 8000 lines divided by 72mm divided by 2 = 42 & 55 lp/mm (with 12 and 9 micron sensors) at the imaging plane. Canon doesn't clearly post lp/mm used for their MTF charts but 3744 lines divided by 25.4mm divided by 2 = 78 lp/mm (6 micron sensors) but it's not clear if their lenses can actually deliver this level of detail either. Regardless, the larger image of the BL back has more total lines AND the larger sensor used in BL becomes diffraction limited much less quickly (at 81 and 144 µm² they have a diffraction limit around f16 and 11 for a far greater depth of field) than the smaller sensors in smaller cameras. Large sensors generally also have a greater "well depth" also which provides a superior dynamic range."

He appears to be saying that for digital systems larger pixels (81 and 144 um) coupled with large sensor platform is better than smaller pixels in a smaller platform. But what about film which has a much larger platform and a variable "pixel" (i.e., silver particle) size that varies from less than a micron to many microns depending on the energy (i.e., light) encountered?

Thanks for the Casanave link! Much appreciated.

[rdenney]

I think a nice post of a Martha Casanave pinhole image ( http://marthacasanave.com/coastal.htm ) should bring back a reminder of what's really important....

Given the choice between a $30,000 digital capture setup, or her eye.... i know which i'd choose

Heh. You gotta love that infinite depth of field, and her amazing use of it.

Rick "sharpness is a state of mind" Denney

[tgtaylor]

Upon waking this morning I remembered that I took that image of San Francisco from Twin Peaks with a 300mm lens and not a 150mm as stated above. Specifically, a 300mm Nikkor-M.

Also, I took a peak in the data sheets for the resolving power and "diffuse RMS granularity value" for two of the film that I use. For Fuji Acros:

1.6:1 = 60lp/mm
1000:1 = 200 lp/mm
Diffuse Granularity = 7 um

For Kodak's TMax 100:

1.6:1 = 63 lp/mm
1000:1 = 200lp/mm
Diffuse Granularity = 8 um

A brief explanation from Wikipedia:

Film grain or granularity is the random optical texture of processed photographic film due to the presence of small grains of a metallic silver developed from silver halide that have received enough photons.

Contents [hide]
1 RMS granularity
2 Selwyn granularity
3 Grain effect with film and digital
4 See also
5 References


[edit] RMS granularity
Granularity, or RMS granularity, is a numerical quantification of film-grain noise, equal to the root-mean-square (rms) fluctuations in optical density,[1] measured with a microdensitometer with a 0.048 mm (48-micrometre) diameter circular aperture, on a film area that has been exposed and normally developed to a mean density of 1.0 (that is, it transmits 10% of light incident on it).[2]

Granularity is sometimes quoted as "diffuse RMS granularity times 1000",[3] so that a film with granularity 10 means an rms density fluctuation of 0.010 in the standard aperture area.

When the grains are small, the standard aperture area measures an average of many grains, so the granularity is small. When the grains are large, fewer are averaged in the standard area, so there is a larger random fluctuation, and a higher granularity number.

The standard 0.048 mm aperture size derives from a drill bit used by an employee of Kodak.[citation needed]

[Gordon Moat]

All true, but to claim that the 160 megapixels on the Seitz produces an equivelent resolution to a betterlight's would be to claim that NO useful information can be gained from interpolating the three seperate channels into one single file. Is that your contention?

I don't think there is much use in asking, though his claims that Bayer pattern interpolation vastly destroys data shows a lack of understanding. However, he works for Better Light, so I doubt he would ever concede that anything could be equal, or better. My opinion is that there is no point in getting him to honestly compare the Seitz to the Better Light, because all he does is type out the same tired responses over and over.

[jkuska]

The fact that you prefer a print from a betterlight is not a technical specification or industry standard. That was the "third" point he was refering to.

What do you mean by "enlarged to equal degrees?" If you mean it as it sounds, I think you're being deliberately mis-leading.

"Enlarged to equal degrees" means an equal degree of enlargment. A 300 dpi print of a 6000 x 8000 betterlight file (48mp) would be a 20 x 27 inch print.

A 300 dpi print of a 7500 x 21250(160 mp) Seitz file would be a 25x70 inch print.

This is an equal degree of enlargment from each file, but the final print sizes are vastly different.

I'm sure the Non-interpolated Betterlight looks better inch for inch, but thats hardly a useful comparison. I'll make a a 1x1 inch print from the original Canon Digital Rebel, and it will look FANTASTIC inch for inch.

Print the Betterlight at a comperable size, not a comperable degree of enlargement. Then you can compare.

I'm not sure pointing people to a Seitz file of one subject and asking them to compare to a file of several stiched betterlight exposures of a different subject is any less mis-leading.

That is NOT a stitched Better Light file, that is a single, continuous panorama exposure, just as the Seitz shot is. It ONLY measures 3750 x 65000 (732mp) while the Seitz file likely measures 7500 x 21250 (160mp) - their standard 6 x 17 format. Both subjects have architectural details, grass, tree leaves and fine branches to examine. To my eyes the Seitz file falls apart at full zoom and the BL file holds together with clean crisp detail in comparison. Note that the pixel height of the BL file is HALF that of the Seitz file.

[jkuska]

I suspect it's the real thing. Most of the Super 8K backs are sold into the art reproduction market, where you can control the environment, depth of field, and choose a specific high resolution lens for copy work. I suspect that back is an 8K. My comments were mainly used for my work.. I usually don't choose a lens for it's resolution as much as it's 'character'. If anyone would like to try a comparison with their own lens/camera, and are in the Santa Cruz, Ca. area.. let me know.. I'd be happy to supply the back for it.

Jerry will need to confirm the back type used in that example.

You can clearly see the "Handle" of Richards system as he is inserting it into his Sinar, it's Blue in color which means it's a Super 8K-HS, the Super 6 is Maroon and the Super 10 is Green, non-super models are Black, be they 4's or 6's.

[Gordon Moat]

That is NOT a stitched Better Light file, that is a single, continuous panorama exposure, just as the Seitz shot is. It ONLY measures 3750 x 65000 (732mp) while the Seitz file likely measures 7500 x 21250 (160mp) - their standard 6 x 17 format. Both subjects have architectural details, grass, tree leaves and fine branches to examine. To my eyes the Seitz file falls apart at full zoom and the BL file holds together with clean crisp detail in comparison. Note that the pixel height of the BL file is HALF that of the Seitz file.

On your computer monitor? That's how you are comparing?