Enlarging 4x5 Polaroid prints. How big?

[Bill_1856]

A 4x5 B&W Polaroid print can be a beautiful thing. How big can it be enlarged by flat-bed scanning, Photoshopping, and digitally printing, while still maintaining the look of sharpness associated with good LF photographs?

[Antonio Corcuera]

As a general rule, scanned prints must be output at 100% actual size at the most. Downsizing or downsampling works the best. I once tried 2x enlargments from Polaroid sheet packs (type 87 and 88) and they looked awful.

[David A. Goldfarb]

If you shoot type 55 and scan or enlarge the neg, I think you'll get a much better result. It's usually sharper and cleaner than the print.

[Donald Qualls]

I've had pretty decent results scanning Type 667 (same stuff as Type 57) on my (8 year old, but originally high-end) flatbed; I was able to view a 600 ppi, 16 bits per pixel scan on screen without noting loss of definition or sharpness, and that would correspond to printing as 8x10 if originally scanned from 4x5. I did find it helped a lot, with my scanner (which has a transparency lid that leaves a bit of space between top and bottom glass), to put something behind the print that would compress under the lid and hold the emulsion flat on the scanner glass.

I'd agree that the ideal would be Type 55, exposed for the negative and scanned or printed from the negative -- but 55 is awfully slow, and if (for instance) you're shooting with a Polaroid back in a Speed Graphic or similar and want immediate results, with the option to later make prints, faster film than EI 25-40 would be very welcome. Even the ISO 3000 Type 667/57 has grain that's only just visible (with a loupe) in the print, combined with excellent sharpness and good gradation, plus enough speed to hand hold at f/22 in a well lit interior (or, with my Model 350, at f/8.8 in pretty dim light). There are also 100, 400, and 800 B&W options in 4x5 -- all of which make nice prints that I'd expect to scan well.

http://i11.photobucket.com/albums/a183/dqualls/Polaroid%20350/56587969.jpg

Type 667, Polaroid Model 350 w/ 473 Close-Up Kit, ceiling bounce from M-3B in #268 flash. In the original 600 ppi scan, I could count the hairs around the cat's eyes, as well as seeing every stitch in the comforter she was resting on.

[Antonio Corcuera]

hmm, that's very interesting Donald, your shot looks nice on screen. Did you actually try a print at the size you mention (8x10, ie 2x)? Do you think that would be the enlargment limit, or further?

[Bill_1856]

Thanks Donald. That's what I was looking for. Bill.

[Donald Qualls]

No, Antonio, I don't have the ability to print acceptable B&W in house, so to print an 8x10 I'd have to burn this on a CD and take it to Costco. Not impossible, but I haven't done it (and since this is a 3x4 original, I'd get more like a 6x8 than 8x10 with a 2x magnification). For reference, I've gotten some nice 5x7 inch Noritsu (I think) prints from Minolta 16 negative scans, 10x14 mm at 2400 ppi, which comes to about 200 ppi in the print (though I wouldn't want to go any lower resolution than that). The limitation with scanning a print is, first, the grain in the print (if it's an enlargment) and second the sharpness limit of the print. Since the Polaroid is effectively a contact print, it's closer to scanning a negative than scanning an enlargement; the grain is that of the negative (as translated through Polaroid's diffusion transfer process) and the sharpness is just barely less than what would go on a Type 55 or Type 665 negative (there's a tiny loss from the diffusion that moves the silver from negative to print).

I could probably scan this same print at 1200 ppi and print it at 4x and still be ahead of a 12x16 from 35 mm (which would be around 12x in that print size). I haven't done so because I was scanning for web display, not for reprint purposes.

[Michael S. Briggs]

Of course it depends on your expectations, but since you want sharpness of LF photographs, you are probably better off working from a Type 55 negative than one of the prints. Polaroid prints looks very slightly soft compared to conventional silver prints, do doubt due to spreading of the silver in the diffusion process. You would be enlarging this -- but you could regain some sharpness digitally. The datasheet for Type 55 (available in PDF form on Polaroid's website) gives the high contrast resolution (1000:1) as 20 to 25 lp/mm for the print and 160 to 180 lp/mm for the negative. The MTF curve shows the response falling to about 55% at 4 cycles per mm (this must be for the print since it is similar for the Type 52 MTF curve). People usually say that sharp prints need signal at 5 lp/mm, so this doesn't leave much room for enlargement without the print starting to look soft.

[Bill_1856]

Just thought that I'd resurrect this old thread, to see if anyone had any new information. Thanks.

[lungovw]

I experimented once, not with a polaroid, but with a normal print, that was difficult to scann, to wet the emulsion and then apply it against a thin glass and then scan it while wet. All the "noise" caused by the paper texture in a dry scan, that was really disturbing in that case, disapeared. Maybe it can help with the polaroid too.

Wagner Lungov