as always...Originally Posted by jnanian
take a pinhole for example; although arguably then we are not talking lenses.
as always...
take a pinhole for example; although arguably then we are not talking lenses.
You are right, of course. As they say, one man's ceiling is another man's mirror!
Karsh of Ottawa also used an Imagon lens for some of his portraits.
https://www.google.com/search?q=kars...tIATcQ_AUIBigB
i'll have to remember that ...
Really? Do you have a reference for that? I would like to see which images were with an Imagon.
i had never heard of that either. from what i remember he loved sharp lenses like commercial ektars ...
daguerre complained that his meniscus lens was hard to focus ( it was what is known as a french landscape lens )
how is an image made by a lens like that where nothing seems in focus ... any more in focus than a lens that is defocused a little bit?
i've made and used chevalier achromat meniscus lenses, plano convex lenses, wollaston meniscus both as taking and enlarger lenses
and they are not ez to focus, no wonder why they made :f16 chokes for them. is the reason why a barely defocused modern lens is different than a soft focus lens because
a soft focus lens (like the 3 i have mentioned) is made to be unfocused, and i am manually defocusng a modern lens to give a similar image?
so one is by design and the other is not ..
i know a lot of people here on this forum collect and use a lot of vintage lenses, i am by no means
trying to suggest these lenses aren't worth collecting, using, having fun with, investing in &c, i am just trying to understand
why one is "accepted" and other is not ... since i was told there was so much of a difference.
With the Imagon there are certain conditions that have to be met to get the typical halo effect that the lens is known for.
1: you need a strong 5:1 lighting ratios.
2: you need a broad soft light source but not an umbrella or soft box.
3: you must focus at taking aperture as focus shifts with the aperture. The most commonly used aperture for portraits is 7.7 by using the second disk wide open.
4: you look for a strong highlight on the subject or have them hold a strong flashlight by the base of their nose. Focus on that highlight or flashlight until the light forms a cross. When you see the cross you are in focus.
Look closely at what the subject looks like at that point so you can recognize what a sharp image looks like when in focus.
thanks bob
so the imagon is an achromatic doublet ( which is like a french landscape lens right? )
it uses a sink strainer instead of a traditional single hole / iris ...
i know these lenses are stopped down ( as you said f7.7 ) but as you probably know
people use french landscape lenses and other soft focus lenses ( on this forum and elsewhere ) wide open, with
no correction/sharpening of the image by cutting the light ...
so the difference between using that lens wide open and a modern lens de-focused is ?
sorry to put you on the spot !
do you have any samples of this type of lens wide open without 5:1 lighting and all the "correct" ways of using it ?
A much simplified question I like.
A modern lens will be out of focus as you change the focus.
A SF lens has a blend of out of focus and in focus simultaneously. Typically, the perimeter of the lens focuses differently than the center of the glass. (look up spherical aberration) If the center is sharply focused, the rays going through the not-center parts of the glass will be out of focus, and you'll have a soft+sharp mix in the formation of the image. This makes a glow as a side effect. Old landscape lenses as mentioned fixed this by choking down to f16 or smaller to block the not-center rays. New normal lenses are designed without this fault and can't behave this way. The strainer in the imagon is a way to regulate the mixing of rays from center and non-center paths through the lens.
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