The blog is here, over at my site.
http://tonopahpictures.0catch.com/Af.../Swirlies.html
Tell me what you think and then tell me how to
make the swirlies happen. I think I'm getting close. That one
of my wife's garden was breathtaking even in the ground glass!
Comments? Ideas?
Jim, your portraits are amazing even if they don't swirl. As far as the garden shot goes that photo makes me want a little dramamine. Very extreme. The other day I recieved a Dallmeyer Patent Portrait 3d put it on the 11x14 just to see coverage and the one thing I noticed was that foliage of some sort at a certain distance was the only thing I could get to swirl. I'm looking for the swirls too. I'm sure one of those wet plate guys will have some insight, they always seem to swirl. It might be the ether though.
Jim I have a Petzval but only get swirleys when the geometry of the subject is correct. Lots of verticals with horizontals growing off the verticals. Also from what I see, to really get the swirley going try a lens on a film size bigger than the lens is intended for. Or for that matter 2 sizes. A 5x4 lens on a 10x8.
Ether that or maybe it's how the plate is poured: first a pancake of collodion is poured at the center of the plate and when it spreads outward to the edge, we then start to tip the glass towards each successive corner in a broad circle. Having seen the care we take in doing this circular application of the chemistry, the subsequently applied photons follow suit and disperse themselves in a swirl around the edges of the plate.Originally Posted by photobulley
Next question?
I am with you Jim. Love the swirlies, but can't seem to make them happen with any regularity. They clearly seem to be as much subject dependant as they are aperture and focus distance dependant. That said, the examples you posted all have perfectly beautiful bokeh, even though the portraits don't swirl. What I think is you need is slightly oof specular higlights, or at least point-source highlights, near the edges to make them appear. I assume it is becasuse coma is what's making the swirlies, and the oof highlights allow the coma to be more easily seen.
Again, my compliments on those portraits, they are darn fine without the swirlies anyway!
Cheers,
Nice work Jim. The only problem I find in using a Petzval is that you have to center the optimal point of focus in addition to focusing on it. Your flowers picture may have real applications to the study of black holes. Perhaps there is a time/space analog to the lens comae aberrations? Are you near area 51?
I could tell him, but then I'd have to kill him
Jack, I've been looking through some old posts at photos that have swirls and here is a photo by William Linne http://www.largeformatphotography.in...1&d=1173825332 that has excellent swirl. Now I'm a little dense (like my negatives), if you could explain in laymens terms how coma creates curves? I've read a little and it seems coma is usually present and noticeable in highlights but this photo seems to be something different. I don't know if any tilts were involved but to my untrained eye this appears mostly like lens mojo.
Because coma affects ALL of the image formation at the outer edges of the IC -- it is usually just most visible with oof highlights in lenses where it has been partially corrected. The lens used in the link you gave was probably a simple design and had no correction for coma.
If you google "comatic flare," "spherical aberration" and "astigmatism," I'm sure you'll find several references and some should have diagrams and examples.
Cheers,
I wrote a long reply to your previous post but lost it all - my ISP is on the blink today.
However I have a prima example of coma here - maybe it works this time.
This image (hopefully) displays both astigmatism and coma, but coma is by far the dominating aberration. The result is just about the opposite of "swirlies".
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