How big is a 4x5 B&W from flatbed scanner

[Bill_1856]

I know so little about this, that I hope my question makes sense.
How big is the file of a 4x5 B&W negative scanned on a mid-priced flatbed scanner (such as Epson 4990)?

[venchka]

At 2100 dpi, 16 bit grayscale, 4x5 negatives on an Epson 4990, my TIFF files are 130mb, give or take.

[Ole Tjugen]

Just do the calculation: DPI squared times area times bytes/pixel: (2100x2100)x(4x5)x(16/8) gives about 176Mb for an uncompressed TIF file. A little less since the image area is a little less than 4x5".

[Bill_1856]

Thanks, Guys -- I had no idea. I'm afraid that my old PC would choke to death trying to handle that size file.

[Brian Ellis]

There's no rule that says you have to always scan at the maximum ppi the scanner is capable of resolving (about 2100 ppi for the 4990). Depending on the desired dpi in the print (assuming you're scanning to make a print as opposed to just posting on the web) and the desired size of the print, you may be able to scan at considerably less than the scanner's maximum. Or you could always scan at a lesser ppi and resample to get the desired dpi in the print. See the thread below titled "what bit depth to at" for more information.

[nathanm]

What are the specs on your "old PC"? Sure it's a nice idea to scan at max res and 16-bit, but this extra data will just drag you down once you start adding adjustment layers with masks. I have done a few scans at 16-bit and generated drive-grinding, 1GB files, but I don't think it was really that necessary. Decide what size print you want and stick with that. If the slowness is going to cripple your creative work on the file then what's the point?

Someone suggested scanning a huge hero shot, saving it off and working on a reduced-size working copy which is a great idea, although could cause a some regret depending on how much work you put into the reduced copy. It could likely being a case of that old raw monster just sitting around unused for a long time.

[venchka]

I should add that I use an ancient Gateway Pentium 4 machine, Windows XP Home, 512mb ram and Adobe Lightroom. Lightroom has a silly 10k pixel on the long side file limit. The files do require a bit of loading time, but it's not terrible. For 6x7 negatives, I use 2400dpi on the same Epson 4990. Those files are 60something mb. My other machine is a Dell dual Xeon with 4gb of ram. Things work a little better on that machine. I don't print very big. I'm not hyper-critical. Working with MF and 4x5 negatives provide all the quality I need.

[Brian Ellis]

"what bit to at?" My proofing wasn't very good. Should be "what bit to scan at" in case anyone cares.

[nathanm]

"what bit to at?" My proofing wasn't very good. Should be "what bit to scan at" in case anyone cares.
I care! It's good of you to correct your mistake. :)

[sanking]

People generally determine scanning resolution based on either final print size, or on archive size. Print size is what you want it to be, archiving is usually at the highest practical resolution that one can scan and save the file.

If what you want is to determine file size based on final print size this can be done in Photoshop easily. Go to the File>New and a box will pop up that will allow you to enter size, resolution, and mode. When you do, the box will tell you the file size. The attached screen shoot shows file size for a final size of 16X20", 16 bit grayscale. Change the final print size, resolution or mode and the file size will change.

Sandy King

[Harold_4074]

The limit of visibility for pixelation is often taken to be around 300 dpi; this would imply that a 2100 dpi scan could be printed 7 times the original negative size with no degradation (in practice it isn't quite this simple...) so you would be talking about a 28x35 inch print to be viewed close up. This is probably not realistic, implying that you should start with the intended print size and resolution, then work back to the necessary scan resolution and see if the file size is workable. Having a bit more in the scan than is needed in the print is always preferable, of course.

[AFSmithphoto]

You can apply adjustment layer changes made on a small file to a much larger one using this method:

http://www.youtube.com/watch?v=GqWrh7OG5yQ
http://www.youtube.com/watch?v=-UNXJdTQKuw

You can't however, apply dodging, burning, or dust spoting on the small file and expect it to work for the larger while. Good luck.

[nathanm]

I've tried that method in the past, but always felt guilty about it. It makes 100% sense if there are just adjustment layers with no mask, but it gets into subjective territory when you're thinking about interpolated masks. It's one of those things where even though you know for a fact the quality has been compromised you may be hard pressed to actually tell. The softer your masks are the more sense it makes, but if you had a detailed, hard-edged mask of some object it might not scale well. But again, it might just be technical guilt and not a real issue.

Dust-spotting is the inescapable part. That's like doing homework. No way around it. At what stage do you guys do dust spotting? Get it out of the way first and then do the fun stuff, or do the fun stuff first and only spot when you've decided you have a winner image?

[aphexafx]

"Dust-spotting is the inescapable part. That's like doing homework. No way around it."

Sorry to just pop in on a conversation that I have nothing to do with previously...

I do spotting work first after scanning and preliminary adjustments. I generally don't scan an image unless I know I am going to do something with it, or at least knowing that I'm going to give it a shot. In other words, any frame or plate or whathaveyou that I feel is worth scanning I also feel is worth spot removal.

Because: while doing spot work you are looking over the entire image at 100% and in doing so you will come across most of the things (beyond dust) that you are going to want to fix or attend to, so not only is spot work important on its own right, it provides a very intimate sit-down with the imagery with which you are about to spend hours of your life working.

Besides, I find spot work relaxing. Perfectionists love it. Great time to enjoy a cup of tea, right!?

[Keith S. Walklet]

It is possible to work with larger scans on an underpowered machine by using the Layer Transfer Method, which permits one to apply all adjustments to the image in a smaller, discreet version of the scan, which is then upsized to the desired output measurement, flattened and sharpened before printing.

For a more detailed explanation, see this thread: http://www.largeformatphotography.info/forum/showthread.php?t=12528