the #3 has alot, seemed like hundreds when reassembling mine..Originally Posted by Ole Tjugen
erie
the #3 has alot, seemed like hundreds when reassembling mine..
erie
The Compound #3 that happens to be sitting next to me has 15 blades.
I think the older lenses that were meant to be sharp would probably give you the look you're after -- not soft focus or anything, but just smoother than a modern lens. You can always increase contrast on the file/print side to suit.
The other guys know more than I do about this, but I suspect the "sharp" vintage lenses start with Kodak Ektars...
I don't believe it, either, for the same reason mounting an old barrel lens in a modern shutter wouldn't make it a Super Symmar (or whatever). Also I don't believe the aperture shape has "the single most important influence on out of focus area rendition." Lens' aberration, for example, is also a big factor for OVERALL out-of-focus characteristics. I agree the aperture shape does affect the rendition of an image, but with a world of respect for what Mr. Perez has done, part of the quoted statements sounds too simplistic.
One instance where the aperture shape is very pronounced is the shape of bright spots (e.g. light bulbs, sun reflections). As a compromise, modern "polygon" apertures, at least in small formats, have curved edges for the first 1-2 stops from wide open (originally a Minolta patent, IIRC). For the curious, I've seen a Photoshop plug-in that can simulate DOF and even the number of aperture blades, though probably only for bright spots.
Not exactly. Petzvals are bitingly sharp within the design coverage, and the central 20 degrees of good Aplanats can give higher resolution than all but a very few modern lenses. One of my 18x24cm negatives shot with a 270mm Meyer Aristoplanat is limited by film resolution, not lens resolution...
So guys, any lenses that fit this description that is, and thanks Frank, exactly what I am after for this particular project.
Remember looking at 240mm and then one longer around 480mm + or thereabouts.
Enough coverage for some movements on 8x10
And fairly light and small.
Shooting on colour often at sunset / sunrise.
I don't ask for much!
Cheers.
A 240mm Dynar-type Heliar would do nicely, at least mine does. minimal movements on 8x10", but it does cover.
If you can find a Zeiss Doppel-Amatar, that might be even better (more coverage), but even the 150mm is rarer than hen's teeth.
For a longer lens a Rapid Rectlinear might do the trick, but most Aplanats will be too sharp (yes, I know they are supposed to be equivalent. Believe me, they're not).
I was told by a physics prof that odd vs even number of sides/blades in an aperture has an effect on the way a lens responds to specular areas. He seemed to think 'even', giving an example of a 6-blade iris, was largely the reason for a starburst look. I don't know if he meant those internal reflections you see in movies or a single one at a bright spot. He said the Fourier Transform (which is only a measurement or characterization tool that optics design predates) gives the different behavior...analogous to different waveforms with odd or even harmonics or both.
I can't vouch for whether history, collecting and usage support this or if there are innumerable exceptions. I see odd & even numbers listed in the postings in this thread.
murray
Your physics prof is correct, as far as "starbursts" go. A six-sided aperture will give a six-ray starburst, a five-bladed one will give a ten-ray starburst where each "ray" is weaher since there's no doubling. That's why there is a strong preference for odd numbers of blades, even if a 23-blade aperture has to be a lot more difficult to calculate exactly than a 24.bladed one would be.
This seems like the question "how many rocks make a pile?" or "how many grains of sand make a heap?" The answere is far to 'gray' to provide a definite answere. my sugestion would be to look at an old lens, that produces the desired effect, and count the number of blades.
yours;
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