digital vs film for sharpness


Rataegeoff

Link Posted 28/10/2011 - 23:48
Hi all, Please could someone explain why its seems that digital photos are not as sharp as their film body equivalents? Seems to me that digital only has one lens to worry about whereas film also need an enlarger's lens to give large pics.

Am I missing something?

Thanks
K10D,KX, DA 18-55, DA 17-70 AL(IF) SDM, DA*50-135, Sigma 70-300, DAL 50-300mm, Kenko 1.5x, loads of SD cards and even more optimism

johnriley

Link Posted 28/10/2011 - 23:53
If anything, it's the other way round. Digital when oversharpened can look ludicrously sharp, like razor wire.

It's a different process and it depends on the type of image as well - architectural shots with straight lines will look ultra sharp on digital, for example.

Also, digital images need post-processing and definitely need the application of Unsharp Mask to produce a good, sharp final result.
Best regards, John

Rataegeoff

Link Posted 29/10/2011 - 00:06
Thanks John. I know we can sharpen or soften in post process -indeed on jpeg the camera has sharpening levels which we can also vary.

My quandry is why would we need to. If the sensor is like a film and the image is focused perfectly on its surface then the result without digital manipulation must be as sharp as the lens quality will allow.

Kind regards
Geoff
K10D,KX, DA 18-55, DA 17-70 AL(IF) SDM, DA*50-135, Sigma 70-300, DAL 50-300mm, Kenko 1.5x, loads of SD cards and even more optimism

johnriley

Link Posted 29/10/2011 - 00:09
It's a fair question and the answer lies in how a digital image is produced. The image is slightly softened to prevent moire effects and therefore needs to be sharpened after capture.

There's no right or wrong about it and not really any sort of purist approach, it's just how the system works. Basically the sensor isn't like a film and therefore is handled differently.
Best regards, John

pentaxian450

Link Posted 29/10/2011 - 10:15
Unlike a film, which has a random silver halide cristal surface, the digital sensor has a very precise grid of light collectors. That grid will interact with some other man made objects which form a regular pattern, creating a moire pattern. To avoid the moire pattern, there is a softening filter in front of the sensor, therefore the need to sharpen the image in post.

Some digital cameras designed for landscape have no softening filters since landscape don't generally have regular pattern inducing moire. Those cameras, like the Pentax 645D, don't need as much sharpening.
Yves (another one of those crazy Canucks)

Dangermouse

Link Posted 29/10/2011 - 11:19
I suspect one thing which may have an impact on perceived sharpness is the fact that it's much easier to crop images to a ridiculous degree now. Rather than being limited by the height your enlarger head can go up to you can simply keep pressing the button. Lenses which were perfectly adequate in the days when the majority of people got their pack of prints back from the lab and never enlarged them further are left somewhat embarrassed when pushed to this level.
Matt

Shooting the Welsh Wilderness with K-m, KX, MX, ME Super and assorted lenses.
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