Leveraging the Digital Advantage

Started Jan 6, 2013 | Discussions thread
John Michael Winterbourne
Junior MemberPosts: 41Gear list
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Re: Resolution and magnification
In reply to PK24X36NOW, Jan 19, 2013

I confess.  It was I who did "the poorly done "test" you referenced show that you are, despite your protest to the contrary, confused by pixel pitch vs. resolution. The "test" proports to show a 10.6MP D60 outresolving a 12.1MP D700, something it couldn't do without the disadvantage of having a sensor less than half the size! This alone should be enough to tell you that the "test" result is flat out wrong, and that the test itself is garbage!"

Garbage, eh?  I hope I'm allowed a comment (after pausing to work out that by "proport" you really meant "purport".. not something that I'd normally comment on, but this does seem to be an argument verging on the pedantic.)

My "test" wasn't a test trying to pin down resolution in any absolute way - the Atkins charts can't do that, as Mr Bob says himself on the link that Gerry provided above, I think Gerry's mention of 12% refers to the difference between the 2.5 and 2.8 lp/mm.

It was a cheap and cheerful trial in my ongoing effort to investigate the optical effect of using M42 lenses with the required optical converter on Nikon bodies, both FX (my main interest) and DX - in this particular case, to help decide which body to use when I get around to doing things properly.**

Whatever you think of its usefulness or relevance in this thread, the exercise was helpful to me.  I am now confident that all else being as equal as I can get it, the output on screen or print of the same lens at the same aperture with the camera in the same place will show higher Atkins numbers being resolved by the D60 than the D700.  You might not like it, and you may be able to argue about its significance, but I believe it to be true.  Although it won't stop me using the D700 when I get down to doing the serious business of pinning down the effect of the OC.

The stupid thing is that I've happily been using M42s on the D700  for several years (OK, I'll stop teasing, they do include various efforts by Pentax - even including all 4 versions of the 50/1.4 Takumar.)

It was only when it really started to irritate me in Nikonland, when anyone asks the question "are these old lenses any good?" some bright spark will pop up to say "they may or may not be any good, but you'll have to use an optical corrector to get infinity focus and because of the inevitable IQ loss that will negate any benefit" that I wanted to try to quantify things.  And to try to stay true to the OP's point, the negative IQ impact of the OCs "may be even more pronounced in the corners on FX".

I do have some interim subjective results.  If there are any of you wondering how an 8-element Super-Takumar 50/1.4 (plus OC) performs on a D700, my advice would be that the soft-focus 'glow' so often described when the lens is wide open is somewhat exaggerated and may not be to your taste, but stop down to f/2.8 and it's really rather nice.  I doubt it would be much different (wide open) on a D600 or D800, or a D7000 come to that.

** Please don't anyone leap to point out that it wasn't an M42 lens I used in my "test" - I wanted to compare the Atkins chart using the two bodies with the "sharpest" lens I currently own, which is an MF Tamron Adaptall SP 35-80 @ 80mm stopped down to f/8.

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