scanning film to print a1- scan resolution?

[jlamarca]

Hi, just want to check my math and ask if my scenario is realistic, since I know nothing about scanning.  Let's say I want to scan 35mm color negative and print A1 at 300dpi.  I'm not doing a large number of scans so I would be going to the lab to get the negatives scanned.  

The way I figure, at 300dpi, the long edge of an A1 print is 9933 pixels long (33.11 inches x 300).  So to get 9933 pixels out of a 35mm film negative, I would need to scan at 7200ppi (9933 / 1.38 inches).

Is this feasable?  This would give me a 67mp file- seems a bit unrealistic.  Do labs have film scanners that go up to 7200ppi?  What are the limitations of scanning film negatives to make prints?  Am I missing something or asking the wrong questions?

Thanks!

[KeithR]

Hi, just want to check my math and ask if my scenario is realistic, since I know nothing about scanning.  Let's say I want to scan 35mm color negative and print A1 at 300dpi.  I'm not doing a large number of scans so I would be going to the lab to get the negatives scanned. 

The way I figure, at 300dpi, the long edge of an A1 print is 9933 pixels long (33.11 inches x 300).  So to get 9933 pixels out of a 35mm film negative, I would need to scan at 7200ppi (9933 / 1.38 inches).

Is this feasable?  This would give me a 67mp file- seems a bit unrealistic.  Do labs have film scanners that go up to 7200ppi?  What are the limitations of scanning film negatives to make prints?  Am I missing something or asking the wrong questions?

Thanks!
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DPI and PPI are not the same thing, so don't confuse the two. Think ppi as input and dpi as output. It is a conversion and in most if not all cases it (dpi & ppi) is not one to one. In most instances it takes a few pixels to create a single dot! High quality sacns will produce large files, so expect it. Your lab should be able to tell you the file size the scan is going to be, and at what resolution. And you want a high bit depth(16) and not a low, 8 bit. You also should be aware that scans need to be sharpened. I would recommend at least reading up on a multi stage sharpening workflow. like which could found at pixelgenius.com

[pfigen]

For all intents and purposes, especially here, ppi and dpi are interchangeable. The math is right. Scanning a 35mm is no problem. Howtek, Aztek or ICG all have scanner models that will give you a true optical 8000 ppi on the scan. It's a 240 (roughly) mb scan in 8 bit RGB and double that in 16 bit. The higher the resolution of the scan, the less sharpening you need, especially from a drum. You will very likely NOT want to sharpen this type of scan at all. It'll just emphasize the grain more than you want.

BTW, when you get your scan, these scanner will only scan at either 4000 or 8000, and not anywhere in between, no matter what the lab may tell you. Get the larger scan and size it down yourself.

[tived]

most newer Imacon/Hasselblad scanners will 8000dpi and I would assume a good pro lab would have atleast one of those babies but you usually pay by the mb!

regards

Henrik

[:Ollivr]

What works well for my sharpening of scans is a three-stage process:

-At first I sharpen the edges with a fairly high radius (2)
-Then I try to get it as close to desired sharpness as possible without getting artifacts in hi-contrast areas.
-Then I selectively sharpen certain areas of the image which can have more - either by masking or with the brush.

Regards
O.

[Neil Hunt]

I think it depends what you are trying to achieve and what it will be printed on. If you are hoping for something which looks good as a straight print, I doubt there is any point aiming for 300 dpi in an A1 print from a 35mm colour neg. At A1 the viewing distance will hopefully be quite long, you'll find anything over 200 DPI will be fine. Go for 250 if you want insurance. It won't be very sharp no matter what you do, and although smart sharpening can help it won't disguise it completely so getting the other attributes right is the main thing.

Finally bear in mind that drum scanning can cost 50 times more than a normal CCD scan. From a 35mm neg all you need is a decent quality well balanced, noise free scan from a desktop unit and don't worry if it needs to be interpolated upwards by up to 50%.

 

Hi, just want to check my math and ask if my scenario is realistic, since I know nothing about scanning.  Let's say I want to scan 35mm color negative and print A1 at 300dpi.  I'm not doing a large number of scans so I would be going to the lab to get the negatives scanned. 

The way I figure, at 300dpi, the long edge of an A1 print is 9933 pixels long (33.11 inches x 300).  So to get 9933 pixels out of a 35mm film negative, I would need to scan at 7200ppi (9933 / 1.38 inches).

Is this feasable?  This would give me a 67mp file- seems a bit unrealistic.  Do labs have film scanners that go up to 7200ppi?  What are the limitations of scanning film negatives to make prints?  Am I missing something or asking the wrong questions?

Thanks!
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[pfigen]

"most newer Imacon/Hasselblad scanners will 8000dpi and I would assume a good pro lab would have atleast one of those babies but you usually pay by the mb!"

The Imacon will claim to scan at 8000 ppi from 35mm, but it's not nearly as sharp as the same 8000 ppi from a Howtek or ICG. Do a comparison and you'll see.If you've got a really sharp piece of film, and especiallly if you have any old Kodachromes, there will be a very visible difference, plus, it's very difficult to actually scan the rebate edges on an Imacon.

[neil snape]

Yet to scan a 35mm negative film , I see no real point in scanning higher than around 2700ppi optical. That's what I do , and I do have an ICG still. Uprez in Photoshop or use a plug-in if that is your thing.
I cannot agree with the poster that thinks a desktop scanner will do a large high quality scan. A Scitex or Fuji may, but not an Epson flat bed which I also have.
The Imacon is pretty good for a CCD scanner, and in the case of negatives going to be almost as good as the drum.
These days the price of drum scans is around the same as any high quality scan. Nancy Scans, WestCoast imaging, are two good places, many more are out there.

[pfigen]

Neil,

Having made many comparison scans, I can say that on ISO 100 color transparency, TMAX 100 and even on Tri-X, I can see visibly finer detail scanning at 8000 vs. scanning at 4000 - when I've got really sharp images. Now exactly where the threshold is difficult to say because there is a single jump in resolution, at least on the Howtek. I've seen improvements on sharp 2-1/4 images on Provia as well. We're not talking huge differences, but they are there, and it's only on the largest prints where you would see it. I do agree with you that (it's 2666 on the Howtek) approx. 2700 is sufficient for many purposes.

[neil snape]

Hi Peter,
Yes on certain technical films even perfectly developed chrome the higher resolution settings can be better.

The OP said 35mm color negative film. Other than an old long gone 25 ISO Ektar I don't think there are any color neg films that need more than 2700-3000 ppi, mind you those numbers only apply to drum scanners at true optical whereas many assume a CCD scanners optical ability to be what the manufacturer says.

[pfigen]

Oh, I forgot about the color neg aspect. I would go one step further. The smallest effective scanning aperture I've used on Portra 160 is 12.7 microns, which is equal to 2000 dpi, and most are better scanned at 16 microns, which is 1600 dpi, or even 19 microns, which I can't do the math in my head. 1600 dpi and then rezzing from there is fine, and then maybe some Noise Ninja.