Large format fisheye lens(es)?

[Dr Klaus Schmitt]

Got one with 165 degrees coverage and about 80mm image circle, seems custom made. Any others known here? (Not the Hill cloud camera lens etc - that I know. Real fisheyes I mean)

[Peter K]

Any others known here? (Not the Hill cloud camera lens etc - that I know. Real fisheyes I mean)

I've seen only a drawing from the Fish Eye Komura 33mm f/4.5 for 4x5".

[rdenney]

Got one with 165 degrees coverage and about 80mm image circle, seems custom made. Any others known here? (Not the Hill cloud camera lens etc - that I know. Real fisheyes I mean)

I've never heard of a large-format-style fisheye, where the lens is mounted as front and rear cells in a typical LF shutter.

But the cheapie Ukrainian Arsat 30mm fisheye will do what you describe above, except with a 180-degree coverage (though the integral "shade" might invade the full circle a bit). It was designed for 6x6, and most fisheye lenses seem to produce an image circle roughly three times their focal length, so it has the 85-90mm image circle. It is a barrel lens, but it is also a retrofocus design which would leave room for a shutter. But you would have to set up a camera carefully--if any part of the camera sticks out the front, it will become part of the picture.

I prefer full-frame coverage, though, so an image circle of 160mm would be my preference. With the above lens there is no advantage to putting it in front of 4x5 unless you want the circular image.

Rick "thinking a real LF fisheye would have a 55mm focal length and cover 180 degrees across the corners of 4x5" Denney

[Struan Gray]

F-theta lenses for laser scanners should, in principle, give a fisheye view of objects at infinity. They are often made for single wavelengths and assume a narrow entrance pupil (the width of the laser beam), but the f-theta mapping is the same as some photographic fisheyes and the focal lengths are right for LF use.

They crop up quite often on eBay, but always seem to go for more than my tinkering budget allows.

[Dr Klaus Schmitt]

Thanks guys, this is good info. F-Theta lenses I have a few since some time already (the longest having 1200mm focal length and about 20 pounds heavy, but the lack of chrom. correction makes them hard to use. I'm looking for a circular field of view indeed. Thats for the tip about the Arsat, I had forgotten about that, but it only fills 6x6 medium format.

[rdenney]

Thats for the tip about the Arsat, I had forgotten about that, but it only fills 6x6 medium format.

When I get my house back in order, I'll take another look at my Arsat fisheye (which is an excellent lens, by the way). Yes, it is intended as a full-frame fisheye for 6x6, but I don't see anything in its construction that would prohibit a circular image if you put it in front of a bigger piece of film. The only possible interference would be the "shade", which is just four tabs mostly to keep the cap from scraping the glass, near as I can tell. These could be cut off easily enough if they interfered too much with a circular image. There are no square baffles inside the barrel, however.

But 6x6 requires an 80mm image circle, just as with the example you described. And I'll bet that Komura is no better than 90 or so.

A more expensive possibility might be the 35mm full-frame fisheye for the Pentax 6x7. It will be more expensive, and I don't know whether it is baffled down to the 6x7 frame (I rather doubt it). But it should fill the 4" dimension, and maybe even spill over a bit, when used as a circular fisheye.

The only difference between a full-frame fisheye and a circular fisheye, excepting any barrel limitations, is the relationship of the focal length to the format diameter.

Rick "who would like a 4x5 full-frame fisheye" Denney

[Peter K]

I'm looking for a circular field of view indeed.

You can also use an afocal fisheye converter normaly used for video cams together with a LF-WA lens.

[Dr Klaus Schmitt]

Thanks again Denny!

Peter, are you sure that would not severly limit? Arently these constructed for 35mm size lenses (the older ones) and the newer ones for even much smaller sensor format?

[Maris Rusis]

Well, I just held my 37mm Mamiya RB67 fisheye on the front of a Tachihara 4x5.

The circular image all but touches the short edges of the format which implies an image circle near 95mm. The four "lens hood" tabs that protect the front element intrude on the image and would have to be cut off for a pure circular image. I believe the Mamiya 37mm fisheye to 4x5 adaption has been successfully executed by others.

As far as I know the Mamiya 37mm fisheye delivers the largest diameter fisheye image of any regularly obtainable lens.

[Peter K]

Peter, are you sure that would not severly limit? Arently these constructed for 35mm size lenses (the older ones) and the newer ones for even much smaller sensor format?

Such converters are afocal. And can be used with any lens focussed at infinity.

Of course to avoid vignetting it works only with lenses with filter threads similar to the one used with such converters, often M 46 mm or 52 mm.