How many megapixels is enough

[Pesto]

All else being equal, is one likely to see meaningful difference between 16X20 prints created from 30-31 MP  vs a 39-40 MP file assuming that the only variable would be the pixel density of the back?

[AndreNapier]

The answer is strong NO.
Andre

[Dick Roadnight]

All else being equal, is one likely to see meaningful difference between 16X20 prints created from 30-31 MP  vs a 39-40 MP file assuming that the only variable would be the pixel density of the back?

Probably not...

Hasselblad make backs of these resolutions, so you might be trying to decide between two backs for both of which you can use phocus, and which are both Anti-Aliasing filter free.

It can depend to some extent on what printer you want to use, and what is the default pixel density of your printer.

360 pixels per inch is about the optimum for Epson printers, and if you can print at 360 original camera pixels per print inch, then you will get the highest quality that your back and your ¿Epson? printer can produce, as there is no scaling.

20 * 16 inches @ 360 ppi requires 41 Mpx (assuming that your back has the same aspect ratio), so this might indicate that, if you are using an Epsom printer, the 39/40 Mpx back might produce noticeably better prints if you printed pixel to pixel and left a border or trimmed.

If you intend to use the back on a view camera, and will be using large movements, the 39 would be a good choice, as it has no micro-lenses, which improve ISO, but do not work well with large movements.

If you have a printer that uses roll paper, you need not worry about aspect ratio.

[Nemo]

Probably not...

Hasselblad make backs of these resolutions, so you might be trying to decide between two backs for both of which you can use phocus, and which are both Anti-Aliasing filter free.

It can depend to some extent on what printer you want to use, and what is the default pixel density of your printer.

360 pixels per inch is about the optimum for Epson printers, and if you can print at 360 original camera pixels per print inch, then you will get the highest quality that your back and your ¿Epson? printer can produce, as there is no scaling.

20 * 16 inches @ 360 ppi requires 41 Mpx (assuming that your back has the same aspect ratio), so this might indicate that, if you are using an Epsom printer, the 39/40 Mpx back might produce noticeably better prints if you printed pixel to pixel and left a border or trimmed.

If you intend to use the back on a view camera, and will be using large movements, the 39 would be a good choice, as it has no micro-lenses, which improve ISO, but do not work well with large movements.

If you have a printer that uses roll paper, you need not worry about aspect ratio.

It strongly depends on the paper, the printer, the viewing distance, the eye accuracy of the observer, etc.

Two interesting (practical, simple, empirical) articles::

http://theonlinephotographer.typepad.com/t...-your-eyes.html

http://www.clarkvision.com/articles/printer-ppi/index.html

.

[David Saffir]

One might expect the differences to be negligible.  However, higher pixel densities demand more from the lenses in use. Many have discovered that lenses that seemed very sharp showed their flaws after a camera upgrade. The differences will probably be less noticeable if the chip is not "full frame", as the sweet spot of the image circle will get used.

David

[Dick Roadnight]

One might expect the differences to be negligible.  However, higher pixel densities demand more from the lenses in use. Many have discovered that lenses that seemed very sharp showed their flaws after a camera upgrade. The differences will probably be less noticeable if the chip is not "full frame", as the sweet spot of the image circle will get used.

David

I do not think they make any "full frame" (24 * 36mm) 39Mpx chips, and the only chips that are any where near "full frame" 6 * 4.5 mm are 60Mpx!

If OP is using sub-MF sensors with film lenses that will cover 6*6 cm, the increased pixel density might not result in improved IQ, even thought the sweet spot of the lenses would be used.

[Neil Folberg]

Hello, I have not done a comparison, but I make large prints as a standard, something like 60x85 cm from Leaf AFi-ii files that are 33 mp raw in Imageprint on an epson 9800 printer with good paper - they are exquisite. I do occasionally make prints that are 110 cm on the smaller side and they also look great, brilliant, crisp & deep and easily exceed what I used to do with 4x5 and scanned ektachrome . Some of this is the back and some of the quality is of course the magnificent Schneider lenses. Incidentally, in the 40mm you do see some slight chromatic aberration, but this has been easily repaired in LR.

Imageprint if I am not mistaken only needs a resolution of 180 and they have in the past claimed that 180 produces as good as a result as 360. Again, I have not done scientific testing, but myself I cannot see the difference, so i don't need further testing.

Therefore I would have to answer that a 33 mp file made with excellent lenses should easily be "good enough" for 16x20 without any problem whatsoever. It is hard for me to imagine how it could be better, though I suppose that is always possible...

Neil

 

All else being equal, is one likely to see meaningful difference between 16X20 prints created from 30-31 MP  vs a 39-40 MP file assuming that the only variable would be the pixel density of the back?

[bjanes]

All else being equal, is one likely to see meaningful difference between 16X20 prints created from 30-31 MP  vs a 39-40 MP file assuming that the only variable would be the pixel density of the back?

Linear resolution varies as the square root of the pixel count. Comparing 30 vs 40 MP, we see that the 40 MP image has only 1.15 times the resolution of the 30 MP image. One would likely see little difference. If one doubles the MP count, then the linear resolution would increase by a factor of 1.414 and this would likely be visible.

Bill

[Doug Peterson]

Well this one is easy!

Ask your preferred medium format dealer for a file from the 31 and 39 mepapixel model, make the print using your standard process (maybe asking for some advice from the dealer about the best way to handle the files) and compare them.

If you see a difference the answer (for your purposes and for you) is yes.
If you don't the answer is no!

It will cost you $30-$40 and 3-4 days of waiting, but the answer will be 100% relevant and accurate.

Doug Peterson
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[Jack Flesher]

Another POV...  15x20 is just about the native print size from a 39MP back if printed out at 360 PPI.  It also about the native file size from a 30MP back printed at 300 PPI.  What I can tell you is it's very difficult even with my nose in a print and readers on my nose to tell the difference between a modern inkjet print printed at 240 PPI through 360 PPI. (Current inkjet printers have very good dithering algorithms.)  With both prints side-by-side, I can usually find some fine detail differences in some areas, but the net difference is still relatively small.  Others with better eyesight maybe can/will see more.  However I can definitely see a difference if I view those prints with a loupe, or print down at 180 PPI.  

So I'd agree that at 16x20 output sizes, you'll probably not see much difference.  A 24x32 print is going to be a different story though...

[Bart_van_der_Wolf]

Linear resolution varies as the square root of the pixel count. Comparing 30 vs 40 MP, we see that the 40 MP image has only 1.15 times the resolution of the 30 MP image. One would likely see little difference.

I use a rule of thumb that holds for many natural phenomenae, a >10% difference is noticeable/significant.
Whether that's 'meaningful' enough for the OP (to justify a camera price difference), only he can answer that.

Cheers,
Bart

[bjanes]

I use a rule of thumb that holds for many natural phenomenae, a >10% difference is noticeable/significant.
Whether that's 'meaningful' enough for the OP (to justify a camera price difference), only he can answer that.

Cheers,
Bart

Bart,

>10% difference in linear resolution or in the pixel count. The latter would not be in the realm of a natural phenomenon.  

Bill

[Pesto]

Thank you one and all for your thoughtful responses. I am in the process of moving from DSLR ( EOS 1Ds MK III) to digital medium format and having a tough time deciding which way to go. It would be a miracle, given my history and my natural proclivities if I could convince myself that ~ 30 megapixels would comfortably do the job, but I am trying! For the record and to address some of the responses above, I use an Epson 4880 for color printing and am in the process of repairing my old 3880 to use as a dedicated black and white machine.

Thanks once again to all!!!

[Dick Roadnight]

Well this one is easy!

Ask your preferred medium format dealer for a file from the 31 and 39 mepapixel model, make the print using your standard process (maybe asking for some advice from the dealer about the best way to handle the files) and compare them.

If you see a difference the answer (for your purposes and for you) is yes.
If you don't the answer is no!

It will cost you $30-$40 and 3-4 days of waiting, but the answer will be 100% relevant and accurate.

Seems simple, Doug,,, but it depends on the type of subject, the detail in the subject etc.

To get pictures that looks sharp, you need to use enough Mpx to resolve the detail in the scene.

¿How many people can you get into a shot and still see every hair on every head?

[Jack Flesher]

¿How many people can you get into a shot and still see every hair on every head?

Depends on what color it is...

[Bart_van_der_Wolf]

>10% difference in linear resolution or in the pixel count. The latter would not be in the realm of a natural phenomenon.

Hi Bill,

Linear (1D) resolution. Square (2D) resolution doesn't make sense to me...

Cheers,
Bart

[Doug Peterson]

Seems simple, Doug,,, but it depends on the type of subject, the detail in the subject etc.

To get pictures that looks sharp, you need to use enough Mpx to resolve the detail in the scene.

¿How many people can you get into a shot and still see every hair on every head?

Hence my suggestion that he shoot his own test - because that way he is shooting the subject most common/important to him. On the internet one (informed and accurate) opinion will be based on landscape shooting, another (informed and accurate) opinion will be based on shooting time-lapses of clouds . Your point is taken however, it's not as simple as "shoot and compare" but in my head that's the closest you come to a meaningful answer.

[ced]

Hello, I have not done a comparison, but I make large prints as a standard, something like 60x85 cm from Leaf AFi-ii files that are 33 mp raw in Imageprint on an epson 9800 printer with good paper - they are exquisite. I do occasionally make prints that are 110 cm on the smaller side and they also look great, brilliant, crisp & deep and easily exceed what I used to do with 4x5 and scanned ektachrome . Some of this is the back and some of the quality is of course the magnificent Schneider lenses. Incidentally, in the 40mm you do see some slight chromatic aberration, but this has been easily repaired in LR.

Imageprint if I am not mistaken only needs a resolution of 180 and they have in the past claimed that 180 produces as good as a result as 360. Again, I have not done scientific testing, but myself I cannot see the difference, so i don't need further testing.

Therefore I would have to answer that a 33 mp file made with excellent lenses should easily be "good enough" for 16x20 without any problem whatsoever. It is hard for me to imagine how it could be better, though I suppose that is always possible...

Neil

Neil what sort of USM do you use on the big prints and are the contours noticeable without disturbing? Regards!

[Neil Folberg]

Hello, I usually use the "portrait" sharpening setting on the Leaf and then may do some further sharpening in LR, very slight (1.0 pixel); with that I print up to 60 x 85 cm without further sharpening. If I'm doing very large prints I may do a test, but in the Imageprint program I find that it handles the up-scaling so very well that it rarely requires anything further. All based on personal experience, and more-or-less the same settings work with landscape, portraits and detail work.

This produces incredibly detailed images - on a landscape with trees that has been focused and handled carefully, you're going to see every leaf and branch ...

Neil

Neil what sort of USM do you use on the big prints and are the contours noticeable without disturbing? Regards!

[ced]

Hello, I usually use the "portrait" sharpening setting on the Leaf and then may do some further sharpening in LR, very slight (1.0 pixel); with that I print up to 60 x 85 cm without further sharpening. If I'm doing very large prints I may do a test, but in the Imageprint program I find that it handles the up-scaling so very well that it rarely requires anything further. All based on personal experience, and more-or-less the same settings work with landscape, portraits and detail work.

This produces incredibly detailed images - on a landscape with trees that has been focused and handled carefully, you're going to see every leaf and branch ...

Neil

Thanks Neil!