How Many Megapixels do I Need?


I have 700 very precious slides of the work of a top Canadian visual artist. Ive been given permission to digitize these. Im happy to take this on. I do not have an unlimited budget. I will need to purchase a camera?

Was thinking of a 20-24 megapixel DSLR or mirrorless camera, likely Nikon, with ES-2 digitizing attachment.

My budget would be strained to get a top-of-line 45 megapixel camera like the D850 or Z7…but maybe it could be possible.

Would 20-24 megapixels “extract” most/all of the information on the slides?

(Later I have personal 35mm negs to digitize, mostly black and white)

Would 45 megapixels be hugely better?

How large could I print in each case?
How large a 4k TV screen could I fill in each case with a HD image?

If 20-25 megapixels would give great results, thats great.
If Im going to do all this work, and 45 megapixels would be HUGELY better, maybe Id better, somehow, get the cash for a better camera.

Would really appreciate your feedback.

Let’s look a at 24 mpixels. They usually come as 4’000 x 6’000 pixels.

  • If you print at 300 pixels/inch, 24 Mpixels will enable a 20 in wide print - iff you fill the frame.
  • 4k has up to 4096 pixels horizontally, which means that a 24 Mpixel shot overfills a 4k screen.

24 Mpixels should be enough for any but the highest resolution films. And you can always stitch a few shots for better resolution (for better visibility of grain)

Higher pixel count allows for less tight shooting without compromising quality.
If you buy a lens, check the specifications. Many macro lenses cannot do 1:1 without additional equipment like bellows or extension rings.

Search the forum for a whole lot more information on technical details.

I’ve used a Nikon D7100 (24 mp), D800 (36) and a D850 (46) for digitizing a variety of film sizes from 35mm to 5x7 in. Some points:

  1. The tests I’ve done with Kodachrome, Provia and Velvia 35mm slides show virtually no increase in real detail going from 24 to 36 mp. I think that 24 (4000x6000 pixels) more than covers the available resolution from 35mm slides. This roughly matches the resolution of Nikon slide scanners.
  2. On medium-format film, there definitely is an increase in detail going to 36 mp from 24. Using the D850 over the D800 on medium format gives a very small, almost negligible, advantage. I expected more, given the higher resolution and no low-pass filter.
  3. If you’re using a full-frame camera with a 1:1 macro lens, a small amount of the slide mount will show. This can be cropped out later, or just left to show that nothing was cropped out of the original (other than what’s hidden behind the slide mount). Using an APS-C sensor with a 1:1 macro lens, you can crop in tighter to avoid the slide mount showing, if desired.
  4. Use a good macro lens, such as the Nikkor 60 f2.8, which I presume you’re planning to use since you’re using the ES-2.
  5. Clean the slides well. If they have been previously scanned at service bureaus, or stored in less than optimal conditions, they will have likely have a lot of very small dirt specs. I remove these by pressing on 3M magic tape with my finger, then pulling it off. Don’t rub the tape across the surface of the slide or it will leave a residue. Compressed air will not generally remove these small, persistent dirt specs. You should get permission from the photographer before doing this.
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