Optimal resolution for digitizing slides

<p>I'm going to be having my father's slides digitized, and am unsure what the optimal resolution should be. I had assumed that the highest available resolution would be best, but the manager of the place where I'm having it done claims that ultra-high resolution scans would exceed the resolution of slide film and expose and exaggerate imperfections, thereby yielding inferior results compared to scans done at more modest resolutions. (The cost per slide will be the same regardless of the output resolution.) </p>

<p>Almost all of my dad's slides are Kodachrome. They were shot between the late 1960's and late 70's with his Minolta SRT-101 and Rokkor lenses, and are well exposed and in remarkably good condition, having been stored in cool, dry, dark conditions.</p>

<p>I will be sharing most of the photos online and on computer via DVD or flash drive, but would like the option of being able to make fairly large prints of some of them. But, even more importantly, since my main motivation for the project is to archive part of my family history, I don't want to later regret that I chose a sub-optimal resolution.</p>

<p>So, in a nutshell, which output resolution(s) would be optimal for my purposes?</p>

<p> </p>

<p>I can't see where "too much" resolution is a problem. It would only more sharply define the existing film grain structure (and Kodachrome doesn't have much)<br>

I scanned some B&W 35mm at 4000 lines, here's the result.. http://goo.gl/1oyWrL</p>

Minimum of 2000 dpi would get you 2000x3000 or about 6mp equivalent. That would give you very nice prints at 12"x18"

and even acceptable prints at 16x20

 

But higher resolution is better.

<p>In my experience, 4000dpi is about the ideal resolution. Any higher and you're just magnifying the grain. </p>

At the maximum optical resolution for the scanner being used, and recorded in the TIFF format using the Pro Photo RGB

color space. At 4000 pip, the files will be approximately 110mb per slide.

<p>Thanks for the quick responses, guys. It seems that the consensus is 4000 dpi. What would be the approximate megapixel equivalent to that resolution? Would higher be even better, or overkill?</p>

<p>Anthony, those are stunningly good concert portraits of some of my idols! (I'm a jazz lover.) I greatly admire your ability, and even more greatly envy the fact that you were able to witness (and photograph) those legendary musical artists live.</p>

<p> </p>

<p>Thank you, Mark. You can see why I took pains to get the scans right. Those were done on a Howtek, under liquid. I didn't own the machine, nor do I want to buy one now.. but I'm in the market for a scanner, as I have thousands more frames to digitize, 35mm and 6x7cm.</p>

<p>Check out this site. They use a Heidleberg Tango scanner the best.<br>

http://www.westcoastimaging.com/#intro</p>

<p>You didn't say what the lab's scanner is and what are the practical limitations of their scanner. Asking them to provide 4000 when their scanner's effective range is only 2400 will not provide more resolution and may increase the noise around grain. Find out what they provide and if it's not high enough resolution, then you may need a better scanner from another lab. Note that better scanners cost more money to scan. So you'll have to take that into consideration. Also, you can select the photos you may want to blow up and scan those at higher and more costly resolutions. Leave the rest for smaller prints and archiving all at a lower cost.</p>

<p>Kodachrome is wonderful film. Here some scans I did from 45 year old slides. It was my own flatbed type scanner - Epson V600. I used 2400dpi which was reduced for the web. I didn't print these so I can't comment on how big I could make them. Good luck.<br /> https://www.flickr.com/photos/alanklein2000/sets/72157626911395064</p>

<p> </p>

<p>Note that Kodachrome scans will need a fair bit of post processing to look good. And unfortunately it's no matter of finding out the right setting for a certain type of film or for a certain batch, you'll need to adjust every scan individually.</p>

<blockquote>

<p>What would be the approximate megapixel equivalent to that resolution? Would higher be even better, or overkill?</p>

 

</blockquote>

<p>Technically the megapixel equivalent of a 35mm slide at 4000dpi will be around 21.5 megapixels. However, that does not mean the resulting scans will match the image quality of a 21 megapixel DSLR. They will be nowhere near as detailed but at least you can be confident that you have captured just about all the detail possible. Scanning at a higher resolution will just be overkill. You'll just be enlarging the grain and filling up disk space.</p>

<p>Make sure the scans are being done on a proper dedicated film scanner and not a flatbed scanner. Flatbed scans are only good for 2800dpi at best.</p>

 

<blockquote>

<p>OTOH, a 21.5MP DSLR actually shows much less than advertised.</p>

 

</blockquote>

<p>But more than a frame of 35mm film, which was my point.</p>

Discussing the theoretical maximum resolution of a frame of 35mm film compared to a digital camera is of little use to us

now, when we are considering scanner technology which hasn't progressed in more than ten years. Alas, scanner

technology is not likely to advance at all from that historic point.

 

We are left with what we have. And of that, what is available for a reasonable cost and quality (based on the skill and

care of the service provider)

 

Now, it may even be best to simply photograph a slide show projected on a high quality screen with a state of the art

digital camera.

 

Back in the olden times, it was considered that the maximum size print one should attempt with a 35mm frame was 8" by

10". Given that standard, a 2000x3000 scan provides much more resolution than is necessary.

 

One should consider how many of those thousands of frames would be printed at larger than 8x12 and take that into

consideration for their scanning strategy.

 

Of course with careful cataloging and preservation of the originals, an occasional candidate could easily be retrieved and

sent out for an advanced scan.

Oh, by the way, Digital ICE supposedly doesn't work on Kodachrome.

 

The film is more like black and white in that regard. So they will probably have to turn ICE off and you will have to clean

up the dust and dirt in photoshop.

<p>Find out on what exact scanner they scan. A serious lab will tell you that.<br />Also tell them, that part of the films are Kodachrome. This practically excludes ICE.</p>

<p>The last Nikon Coolscan scanners (like the V) had ICE that would sometimes work with Kodachrome. When you need it and it works, it's great.</p>

<p>Look at the prices for scancafe.com, who do 3000 dpi scans from slides for $0.22 each. That's plenty of resolution, and they have a fine reputation.<br>

<strong>KEEP THE ORIGINAL SLIDES AFTER SCANNING. KODACHROME IS VERY STABLE, DOESN'T HAVE HEAD CRASHES.</strong></p>

<blockquote>

<p>Is this unqualified statement based on your own personal experience/results or are you referencing third party info? Can you share your data supporting this?</p>

 

</blockquote>

<p>Not falling into that trap Les :-)</p>

<p>It seems like doing some test scans at different resolutions would be a good idea. </p>

<blockquote>

<p><em>Not falling into that trap Les :-)</em></p>

</blockquote>

<p>Too late. I would argue that, by making a broad brush statement, without being prepared to back it up, you are already IN. That's OK, by the way, people will draw their own conclusions. Cheers.</p>

<p>Whoa! I ask an innocuous question about slide scanning, and end up fueling the flames of the film vs. digital debate. Just to set the record straight, I appreciate the respective virtues of both film and digital photography, and would never argue for one over the other. <br>

<br>

When I asked the question about the megapixel-equivalent resolution of Kodachrome, I just wanted to get a rough idea what "digital resolution" would best fit the film's resolution. (Since I use my DSLR's a lot more than my film cameras, I tend to think in terms of digital resolution.) I know that it's comparing apples to oranges, since their are many other variables at play, but I was looking for a crude approximation.<br>

<br>

And it seems that Google is my friend (thanks, JDM!), since a cursory search revealed that the approximate digital resolution equivalent of 35mm Kodachrome slide film is 20MP. That "fact" suits me fine, since my full frame DSLR happens to be 21MP. Now that that "academic" issue has been settled for me, I can get on to the practical task of getting my Dad's slides scanned - at 4000 dpi.<br>

<br>

Upon further inspection, I have discovered that not all of his slides are Kodachrome, anyway. Many are Ektachrome, and some have no film-identifying markings at all, since they were presumably not developed at official Kodak labs. The good news is that most of them have survived well. Even the Ektachrome slides have retained their colour and not faded to an orange hue (as cheaper slide film tend to do over time). Some slides have lost some of their emulsion around the edges, or look a bit splotchy in the background, but in all cases the subjects of the photographs are clear and identifiable.<br>

<br>

I want to thank everyone who has contributed to this tread, especially those who provided examples of their own slide scans and those who recommended a 4000 dpi minimum scan resolution. And I would appreciate any further commentary.<br>

<br>

Cheers,<br>

<br>

Mark<br>

</p>

<p>ICE works on Ektachrome but not Kodachrome. Good luck with your project.</p>

<p>Here are my Ektachromes. Like my Kodachromes, these were scanned at 2400dpi and 16 bit color. I used the auto correction built into the scanner (Epson V600) which on retrospect caused many shots to clip. But I was into my learning curve at the time. I don't know if outside labs have similar problems with their auto adjusts.</p>

<p>https://www.flickr.com/photos/alanklein2000/tags/ektachrome/</p>

<p>This is an interesting discussion for me, as I am in the market for a quality scanner. I would prefer multi-format, as I have 35mm and 6x7cm frames to scan, but I am looking for some wisdom and experience before I take the plunge. The Nikon 9000 looks good to me; any relevant advice would be appreciated.</p>

<p>I gotta chime in here because I went down this road.</p>

<p>I scanned a TMX negative that was developed in TMAX at 7200dpi on a Plustek. I got a HUGE file - that I since deleted because it was pointless. [EDIT] Got rid of the scanner too and now I'm 100% analog for film.</p>

<p>Wanting to see how big I could make the image, I zoomed in /enlarged to the maximum size and I saw sliver grains.</p>

<p>There's a point where scanning at a high dpi becomes counter productive because there is only so much information a negative holds <em>about the image and subject. </em>Capturing the individual silver grains is just irrelevant information for a digital file - unless you are saving the file so that your great great great great grandchildren can replicate the negative at the silver level in their replicators on their star ship.</p>

<p>I would even argue that if you want a huge print to scan at a <em>lower</em> dpi so that the silver grains are blurred. It would look better at a distance and up close - and add a bit of silver print character.</p>

<p>This whole scanning at obscene DPIs is just another form of pixel peeping.</p>

<p><strong>4,000 dpi is more than enough for any negative.</strong><br /> <strong><br /></strong>And to add, I took a 5MP image on a Kodak point a shoot and printed it at 11x14 at Wolf and that thing is sharp and clear. Meaning, that thing captured a small fraction of the information you can get from a 35mm negative and it looks AWESOME!</p>

<p>Don't get me started on these new 50+ MP SLRs on the market ...OY!</p>

<blockquote>

<p>Do you have supporting data for this or is this statement just based on a casual observation from your own personal results or third party reference?</p>

 

</blockquote>

<p>Here he goes again... my advice to R David would be not to respond. That is unless he wants to see lots of pics of coloured pencils and 100% crop scans of human hair.</p>