Digital & lens sharpness

I've had a posting in the Nikon forum about lens sharpness & an offshoot of it

prompted me to post this in this forum. I'm not trying to cross-post.

 

When it came to lens sharpness & film. Am I being really picky about image

quality, or is it that I was lulled into a false sense of how good some of

these lenses were by viewing slides through an 8x viewer (about A4 size).

 

Whereas now I view images on screen at 100% (about 20x30 I think)and the lenses

that I once thought were sharp, weren't ever really that sharp at all?

 

And, some of the later lenses are outperforming some primes for digital? E.g my

Sigma 15-30mm f3.5-4.5 DG EX blows away my Nikkor 24mm lenses, both AIS and AFD

at all apetures!

 

Not trying to start a brand war or film vs digital war, just interested in the

feedback..

Hi Ross, I think it is much easier to find relatively small differences among lenses while looking at images at 100% using Photoshop. "Pixel Peeping" has had the same effect on many others as well, so you're not alone. But digital files, when shot at a sensor's "native" ISO (For many Nikons, I think that's ISO 200) seem to be much less grainy than most film. Kodak's Technical Pan B&W film - I think now discontinued - resolved better than most, so some of what you're seeing may be a combination of factors. Lastly, some Sigma lenses are very good but I'm still a little surprised that a variable aperture zoom does better than a Nikkor prime lens.

When you talk about "film" and "on screen" I assume you are projecting slides. If so, and you are using a beaded screen, I think you probably lose some sharpness because of that type of screen. A smooth surface would be better.

Unfortunately, most 35mm projector lenses are only marginal when it comes to resolution. If you want to really evaluate slide sharpness you would need a screen at least 72X72 and a professional grade lens like the Navitar or Colorplan.

Interesting subject and for me, yet unresolved. My experience has been opposite of yours. I have a few old manual lenses that I was never satisfied with using film. They have found new life with digital. With one of them, I can read the fine print on a moving ship a mile away handheld at 100%. The mysteries of digital processing, I presume.

Thanks for your replies everyone. I was actually comparing viewing Velvia and Provia 100 through an 8x loupe to a D200 100asa file on a computer screen at 100%.

 

Re; prime lenses. My 24mm AIS blows away my equivalent AFD lens, and both are beaten by the Sigma zoom on the D200. Those results surprised me too.

 

My 20mm AF is too soft wide open but good at f5.6+. My 50mm f1.8AFD and 180mm f2.8AF are fantastically sharp on the D200 (even wide open).

 

That's what I was meaning by digital highlighting the weaknesses of some lenses that were originally designed for film. And, that viewing through an 8x loupe means that you are viewing them at roughly A4 size, whereas I think that 100% on a computer screen is around 20x30 inch equivalent (i think!).