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2500 vs 4000 dpi film scanners. Difference in final prints?

Bob Atkins , Aug 24, 2001; 02:04 p.m.

With the availability of 4000 dpi scanners for less than $1000 I was wondering how much better the results are than those from the mid-range scanners with 2400-2700 dpi resolution in the final print. On resolution tests of (photographically unrealistic) resolution targets they are obviously superior, but does the difference carry over into the print, especially when scanning real photographic images?

Since I don't have a 4000 dpi scanner I downloaded test images from the web of 4000 dpi and 2400 dpi scans of small sections of the same slide. Looking closely the magnified images it was clear that the 4000 dpi scan had better resolution and less "pixilation", as expected.

Then I printed the files on an Epson 870, having scaled them to deliver output equal to a 13.3 x 20" print from a full frame scan.

I was surprised to find that I could not see much difference between the scans done at 2400 dpi and 4000 dpi. The 4000 dpi scans were marginally better viewed from a normal (18") viewing distance), but I'm sure that some viewers not used to critically examining prints wouldn't see any difference at all. Under a loupe the difference was more noticable, but even then it wasn't huge.

Since I didn't do the scansd myself and I don't know how good the originals slides were I have no way of knowing if my results reflect what I would actually see doing my own scans of my own slides.

So my question is to anyone making reasonably large prints (8x10 to 16x20) who has used both 2500 dpi and 4000 dpi scanners. Do you see a significant difference in the final output or is the resolution difference lost somewhere in the limitations of the original slide, editing software, printer drivers and intrinsic printer limitations?

Responses


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Jim Leonard , Aug 24, 2001; 02:46 p.m.

Assuming you are using 35mm slides, if you are using the full frame to produce your printed image, the 2500 dpi scan will give you about 300 dpi at 8x10 which is considered ideal. However, if you are cropping significant amounts of the original image or printing at 16x20, you are quickly dropping down to 150 dpi of non-interpolated pixels (ie 1/4th the information density). This is where the 4000 dpi scanner becomes useful. Personally I only use digicams (where pixels have less value per pixel since each pixel only starts with 1 chroma and gets the other 2 from it neighbors) so the required numbers would be a bit different than if I were scanning film but in my (very limited) experience, I don't like printing with much less than 200 dpi of original pixels for anything with significant detail.

Dale Cotton , Aug 24, 2001; 02:51 p.m.

Perhaps a full size 4000 ppi scan will help?

Go to http://www.hively.com/canoscan/, click on "Scans from Photos", then click on "Click here to download the full size 4000dpi scan (6.4MB) in JPEG (at 70% quality compression)".

I've had a 2400 ppi scanner (HP S20) for the past year. Neither spells, incantations, Photoshop, nor Genuine Fractals has enabled me to produce anything close to the detail/resolution of Taylor Hively's FS4000 scan when it comes to printing at the 13" x 19" maximum size of my Epson 1270. And I'm a pro lens, tripod, MLU, and cable release anal type.

"Then I printed the files on an Epson 870, having scaled them to deliver output equal to a 13.3 x 20" print from a full frame scan." -I've found I often have to print at least an 8" x 10" segment to judge the cumulative effects of what seem to be marginal differences in smaller samples.

Objective data are also available at http://www.imaging-resource.com/SCANINDEX.HTM.

My father has now inherited my S20; I'll be getting an FS4000 presently.

Kevin C. O'Neil , Aug 24, 2001; 02:54 p.m.

I have seen a difference in my prints on a 2000P from the scanner I was using (Nikon 20E) and the current one (Nikon 4000). The max resolution on the 20E was 2900, versus the 4000 on the Nikon 4000. Prints which I compared were on the 11x17 semi-gloss Epson paper. Print resolution was from 240 to 400. There was more pixelization in the prints from the 20E scans, and I did consider it noticeable to the extent I re-did most of those prints with 4000 scans.

With that said, I don't think the results from my systems are really comparable. There are so many differences (software, lens, etc.) between the 20E and the 4000, including the dmax, that this direct (subjective) comparison must be taken with a grain of salt.

I wanted to respond however to let you know what I've expereinced, for whatever that may be worth.

Jim Lee , Aug 24, 2001; 03:23 p.m.

Bob - If you haven't already ran across it, you might find the information on Norman Koren's website of interest. He has a Photosmart S20 and a recently purchased Canon FS4000 and provides some comparison images.

Bob Atkins , Aug 24, 2001; 04:05 p.m.

Thanks for the link to Norman's site. I guess he basically reached a similar conclusion about prints from 4000 dpi scans "...not dramatically sharper than a 13x19 inch print from the 2400 dpi scan, which is surprisingly good, perhaps due to excellent software...", i.e. they are better, but not that much better. I hope I'm not misinterpreting his comment.

Indeed when I printed out his 2400 dpi and 4000 dpi samples, again the difference (viewed from 18") was slight, though the images were small and I agree that the difference might be more noticable in a large print.

No doubt the prints from 4000 dpi scans are somewhat better and the Canon 4000 dpi scanner is a better scanner than the HP in terms of bit depth etc. Of course only I can decide if the difference is worth $900 to me!

Dale Cotton , Aug 24, 2001; 05:29 p.m.

I suspect from your second post, Bob, that you are leaning toward the lower resolution out of cost considerations. Fair enough, and yes the difference is not *dramatic*. It is, however, just that edge it takes to make 13" x 19" prints acceptable to my eye, at least. From my S20 scans I'm quite happy printing at A3, but when I print at 13x19 most images break up on any inspection closer than about 18".

Download the Hively scan, res it down to 2500 (x 0.625). Even viewed on screen the resulting ressed down image is quite similar to an S20 scan. Now res the ressed down back up to 4000. Print an 8x10 chunk of both the original and the down-to-up image. I just did that and found the down-to-up image quite comparable to an S20 print.

What that means to me is that the $900 US buys you good 13x19 prints over merely tolerable ones. As you say, only you know whether that's critical or not.

Miles Hecker , Aug 24, 2001; 06:06 p.m.

Norman Koren visited me at the beginning of July. He compared my 13x19 inch detailed prints scanned with a Polaroid SS4000 and taken with a Contax and Zeiss lenses to earlier scans made with a Nikon LS2000.

His conclusions lead him to buy the Canon 4000 DPI scanner.

The scan is only as good as the original!! The film being scanned is very, very, very important. Provia 100F and Ektachrome 100VS were designed for scanning and max resolution. When I scan slides with these emulsions, shot on a tripod, with aperture set to f5.6 or f8 the results are remarkable.

Norman shoots mostly with negative films such as Supra 100. These films aren't as fine grained. The negative image also puts light areas such as skies into the dark part of the emulsion which are vulnerable to scanner noise.

The Nikon LS4000 and perhaps the Canon scanner aren't as noise free as the SS4000. If your shot has a lot of detail the 4000 DPI scan will be much better than 2500 DPI scans. One very overlooked detail, printer settings. The Epson 1270 type printer can print at a physical resolution of 240 dpi and 360 dpi in color. The 1440 DPI are mixed to get the actual color from a CcMmYK palette. All other settings are interpolated and prone to software errors. If you want to see the detail you've scanned make sure you've got enough pixels to set the final print to 360 DPI.

One last point, the user. Setting levels while scanning is very important. Some software does this well, some doesn't. If you are in doubt save the image as a 48 bit scan and load it into Photoshop. You now must learn to set everything yourself. Good luck!

I'm forwarding this to Norman for his response.

Jeff Drew , Aug 24, 2001; 06:11 p.m.

Okay, Bob, you have gotten me interested. I've used scanners and have been following the progress of the industry and have been waiting for the prices to decline, even further, before buying into this. Are you saying that the older, 2500dpi scanner may be the better investment for a first-time buyer? It's taken a long time for me to accept that 2 scanners (film & flatbed)are a must, but after playing with everyone elses' gear they're starting to whine about me getting my own!

Bob Atkins , Aug 24, 2001; 06:27 p.m.

I'm not sure what I'm saying, which is why I asked the question!

From what I've seen, read and experienced first hand it looks like you gain very little in the final print by going from a 2400-2700 dpi scanner to a 4000 dpi scanner unless you are printing larger than 8x12. If you are, then a 4000 dpi scanner may well be worth the extra $500-$600, particularly if you have very sharp originals. At least that's what I'm getting from the thread so far.

I currently use a 2400 dpi HP scanner which isn't the best in the world but can produce scans which are more than acceptable, in fact pretty darn good, for 8x10 prints. They do fall apart a little at larger sizes, which is why I'm thinking about a 4000 dpi scanner.

I'd also say that I agree with Norman Koren that quite soon direct digital cameras will be as good as or better than a 4000 dpi scan of a slide, so I'd look on a 4000 dpi scanner as a device to scan my existing slides plus whatever I shoot this and maybe next year, but anticipate a eventual shift to a digital EOS body.


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