Kalosat lens, DIY

[arri]

I´am planning to make a Kalosat aquilent lens for my self.

For this I want to order a fused silica meniscus lens.

Maybe some one other is interesting to get one of this lenses.

The meniscus lenses are available in Ø 2" (50.8mm) and focus length of 100mm, 150mm, 200mm, 250mm, 300mm, 500mm and 1000mm
Transmission is 185->2000nm

Prices for the lens element is around 400 Euros ± a little bit.

Further it needs a housing and a barrel with an aperture or a shutter, size II or III or maybe a Compound 3

Endprice will be much lower than an original lens but with the same optical results.

The lenses are available with special UV coating as well, makes the elements a little bit more expensive but has a few advantages.
Transmission is 285->1000nm

[Tin Can]

Had to look that up

https://www.smecc.org/soft_focus_len...ality_area.htm

I will not be joining

[reddesert]

I had not previously heard of the Kalosat lens. Using single meniscus lenses ("landscape lens") for a soft focus effect is a longstanding traditional use. LFPhoto member Reinhold Schable has meniscus lenses available made from (AFAIK) ordinary optical glass at https://www.re-inventedphotoequip.com/Formats.html The novel aspect of the Kalosat lens appears to be that it's made from quartz and thus has excellent ultraviolet transmission. I'd guess any effects of this would show up most clearly on blue sensitive materials (wet plate?)

Fused silica meniscus lenses are available from industrial optics suppliers, such as Thorlabs.

[Mark Sawyer]

Anyone have thoughts on whether a simple fused silica meniscus lens would suffer from chromatic aberration and (in blue sensitive processes) problems with focus shift between visible light and actinic light?

[reddesert]

I looked up the index of refraction and dispersion of fused silica before posting, to be not-completely-uninformed. The dispersion of fused silica is not much different from N-BK7 (most common crown glass). Like basically all glasses, the dispersion is much stronger in the UV. I assume that blue sensitive processes don't really go terribly far into the ultraviolet if one is shooting outdoors in daylight, but I don't have any personal experience with them. That is, I guess that the glass behavior at 380-400 nm might matter, but probably less so at 350 nm. Anyway, I'm sure it would have some chromatic aberration and focus shift, like any meniscus lens. It might have a little more aberration and shift because it's letting more near-UV light through.

My guess for the special pictorial properties of a fused silica meniscus lens, if it has a noticeable effect, is that maybe there's an enhanced soft-focus glow from the increase in near-UV light.

[jp]

With normal film it would probably have big chromatic aberration. It was probably marketed when film was more blue sensitive. With some blue sensitive Xray film, it would probably show freckles and such detail with portraits a little better.

[LabRat]

I would just try a glass meniscus lens first (which I am doing now) before paying for the other...

I suspect there will not be a difference between the two... (I think they will behave more the same as the optical design is the same...

One might be better for wet plate as it passes UV...

One is a few bucks, the other not...

Steve K