[barondla]

Wondering how much the 645 digital format crops the fisheye. Not sure which 120 format the Arsat was originally designed for?

Thanks,
barondla

[maw]

Hi barondia,

Wondering how much the 645 digital format crops the fisheye. Not sure which 120 format the Arsat was originally designed for?

The Arsats are (good) clones of the Kiev machines, a Soviet copy of the Hasselblad, the Arsat 120mm of which you ask has an angle of field equivalent to 31° (about 120 mm),
so a medium tele. Considering that in the 6x6 and/or 6x4.5 format, the 80mm is considered the normal equivalent of about 50mm in the 24x36 format.

Ciao Mario

[johnha]

I've tried the P6x7 35mm fish-eye on my D - the FE effect is greatly reduced - if you're careful with straight lines it might not even be obvious. The Arsat is wider, I can't comment on how much of a difference that would make.

The shot below is the P6x7 35mm FE on my D - the 100% crops were to test how badly the built-in red filter attenuated the Green & Blue channels - notice how the 'horizon' is pretty much centred to minimise the distortion of straight lines:

[kaseki]

These two images, taken of a neighborhood scene from a fixed tripod at f/11 and manual focus, may help show the differences in linearity and field of view. It appears that even though the 25mm DFA has a shorter focal length, the ARSAT can see a bit farther into the corners, but as expected, not quite as far in the horizontal and vertical central axes.

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[barondla]

These two images, taken of a neighborhood scene from a fixed tripod at f/11 and manual focus, may help show the differences in linearity and field of view. It appears that even though the 25mm DFA has a shorter focal length, the ARSAT can see a bit farther into the corners, but as expected, not quite as far in the horizontal and vertical central axes.

Thanks for this excellent comparison of the Arsat 30mm fisheye and 645 DFA 25mm rectilinear lenses. Really illustrates their differences.

---------- Post added 08-12-20 at 03:36 PM ----------

Hi barondia,



The Arsats are (good) clones of the Kiev machines, a Soviet copy of the Hasselblad, the Arsat 120mm of which you ask has an angle of field equivalent to 31° (about 120 mm),
so a medium tele. Considering that in the 6x6 and/or 6x4.5 format, the 80mm is considered the normal equivalent of about 50mm in the 24x36 format.

Ciao Mario

Thanks for the information.

---------- Post added 08-12-20 at 03:44 PM ----------

I've tried the P6x7 35mm fish-eye on my D - the FE effect is greatly reduced - if you're careful with straight lines it might not even be obvious. The Arsat is wider, I can't comment on how much of a difference that would make.

The shot below is the P6x7 35mm FE on my D - the 100% crops were to test how badly the built-in red filter attenuated the Green & Blue channels - notice how the 'horizon' is pretty much centred to minimise the distortion of straight lines:

Interesting to see the Pentax 67 fisheye on the 645D. Looks sharp and you did a great job keeping the horizon centered to reduce the fisheye look.

Thanks everyone for posting,
barondla

[rdenney]

Sorry for the late hit. The Arsat is intended to be a full-frame fisheye on the 6x6 format, providing a 180-degree field of view diagonally, corner to corner.

Typically, a fisheye has an image circle of 180-degree coverage that is a little less than three times its focal length. So, a 15mm fisheye’s image circle is a hair larger than the 24x36 frame, and an 8mm fisheye fits entirely within the 24mm narrow dimension.

Thus, a 30mm fisheye covers the 6x6 frame diagonal, and a 35mm fisheye covers the 6x7 frame diagonal. The 30mm fisheye would produce a circular image on the 4x5 large-format frame, and dint think I haven’t been tempted to try and make that work.

Here’s a 30mm Arsat photo on 6x6 film, displayed without cropping:



Rick “who misssd this thread earlier” Denney

[kaseki]

... The 30mm fisheye would produce a circular image on the 4x5 large-format frame, and dint think I haven’t been tempted to try and make that work. ...

The hood baffle shape might make the useful image slightly truncated on the horizontal and vertical axes.

[rdenney]

Yes, but only slightly.

But the chances of me actually doing it are pretty low. Being able to do something isn’t the same thing as having a real reason to do it.

Rick “who would probably never expose a single sheet with it” Denney