How does Better Light calculate MP count?

[sanking]

There was some discussion in another thread today about Better Light scanning backs. Never having used one of these I looked at the product line and came away confused about how total MP count is determined.

For example, here is the description of the Model 6000E-HS.

"Model 6000E-HS — The economical solution for pro photographers, museums and art repro companies who are easing into digital capture. Native maximum resolution at 100% = 6000 x 8000 pixels. Maximum file size at 100% = 137 MB in 24-bit RGB (274 MB 48-bit). Price: $9,495 with 2-year warranty."

Now, if you download the .pdf for product information the Model 6000E-HS is said to give a file size of 144 MP. The Model 6K-HS, which is also listed as 6000X8000 pixels, is said to give a file size of 216 MP.

Question, how do you get 144 MP and 216 MP from a scan of 6000X8000 pixels? I would have calculated this as 48 MP for both backs. Are the higher figures interpolated resolution?

Sandy King

[Jim collum]

There was some discussion in another thread today about Better Light scanning backs. Never having used one of these I looked at the product line and came away confused about how total MP count is determined.

For example, here is the description of the Model 6000E-HS.

"Model 6000E-HS — The economical solution for pro photographers, museums and art repro companies who are easing into digital capture. Native maximum resolution at 100% = 6000 x 8000 pixels. Maximum file size at 100% = 137 MB in 24-bit RGB (274 MB 48-bit). Price: $9,495 with 2-year warranty."

Now, if you download the .pdf for product information the Model 6000E-HS is said to give a file size of 144 MP. The Model 6K-HS, which is also listed as 6000X8000 pixels, is said to give a file size of 216 MP.

Question, how do you get 144 MP and 216 MP from a scan of 6000X8000 pixels? I would have calculated this as 48 MP for both backs. Are the higher figures interpolated resolution?

Sandy King

i'm not entirely sure.. but i suspect they're compensating for the fact that each pixel is non-interpolated (there's no Bayer mosaic going on). You get more real detail at the pixel level compared to the rest of the digital cameras

[erie patsellis]

Sandy, from what I remember (always a scary concept) there is a JEDEC or other trade group standard for calculating MP ratings. On a scan back, they are (claimed) to be equivalent to 3x the raw resolution. Apparently this figure compensates for Bayer pattern "irregularities" in photosites vs. actual resolution.

[JeffKohn]

They're pulling the same marketing BS as Sigma did with their Foveon sensors, and tripling the effective MP count since each photosite location samples R, G, and B. But you're not going to get 3x the resolution from one of these backs as you would from a Bayer sensor with the same number of photosite locations. The real world gain is in the 25-50% range.

[sanking]

They're pulling the same marketing BS as Sigma did with their Foveon sensors, and tripling the effective MP count since each photosite location samples R, G, and B. But you're not going to get 3x the resolution from one of these backs as you would from a Bayer sensor with the same number of photosite locations. The real world gain is in the 25-50% range.

That makes sense.

In the BL literature it is noted that at a print size of 20" X 26.7" the resolution would be 300 spi. Since the sensor size is 72mm X 96mm (2.8" X 3.78") a print that size represents about a 7X magnification, which suggests effective resolution of around 2000 ppi, which would only be about 40 lp/mm. That sounds low to me.

Sandy King

[Ben Syverson]

40 lp/mm. That sounds low to me.

Seriously... A flatbed scan of a negative could get near that at a substantially lower cost, and you could use an instantaneous exposure! Step up to a drum scan and there's no comparison. Especially at 8x10.

[jkuska]

Seriously... A flatbed scan of a negative could get near that at a substantially lower cost, and you could use an instantaneous exposure! Step up to a drum scan and there's no comparison. Especially at 8x10.

BL backs are effectively flatbed scanners that have been redesigned to fit into a form factor similar to the Polaroid 545 back so that they may be used in basically any 4x5 view camera ;-)

[Ben Syverson]

BL backs are effectively flatbed scanners that have been redesigned to fit into a form factor similar to the Polaroid 545 back so that they may be used in basically any 4x5 view camera ;-)

Right, but if they're only getting 40 lp/mm, then there's no image quality advantage to using them, and many many workflow disadvantages.

You know what else can be used in basically any 4x5 view camera? Sheet film.

[jkuska]

Right, but if they're only getting 40 lp/mm, then there's no image quality advantage to using them, and many many workflow disadvantages.

You know what else can be used in basically any 4x5 view camera? Sheet film.

Sheet film, while having a Dmax of 4.0 implying a 12 stop range, only has about a 5 or 6 stop range of printable detail, BL has an 11+ stop dynamic range with printable detail basically through out. And when you are focusing which one of the many multiple layers of emulsion in the film are you focusing on and is the film ever held flat in the film holder? The tri-linear array is perfectly flat flying across a flat plane.
Can you do this with film?
http://www.betterlight.com/zoomify/zoom_bigMoney.html
Or this?
http://www.artisan-digital-services....capture-7.html
Or this?
http://www2.iath.virginia.edu/panorama/watson_uva.html
This last shot by Tom Watson was shot a 2/3 rds rez with a 6K, zoom in on the central quad and look at all of the folks sitting about and the blades of grass in the lawn.

[D. Bryant]

Or this?
http://www2.iath.virginia.edu/panorama/watson_uva.html
This last shot by Tom Watson was shot a 2/3 rds rez with a 6K, zoom in on the central quad and look at all of the folks sitting about and the blades of grass in the lawn.

I must admit that example is pretty incredible, but there is one woman walking that looks very strange.

Don Bryant