[rdenney]

...you need a Kiev-88 to Pentax 645 adapter to use it, you don't have to sell the lens. However, Kiev-88 adapters are hard to find, Pentacon-6 (P6) adapter are easier, and you can use that and a Kiev-88 to P6 adapter (which is a thin ring).

I had forgotten about those Kiev 88/P6 adapters. I see several for sale on ebay right now, from an old acquantance. Those will indeed work, in conjunction with a P6-Pentax 645 adapter. Those are on ebay at the moment, too, from Hartblei and Arax.

I'll edit my previous post.

Rick "who has forgotten stuff over the last 15 years or so" Denney

---------- Post added 04-20-18 at 08:02 PM ----------

The focus was at infinity with the aperture at f5.6. This lens is for the Kiev camera with the Pentax 645 adapter.

That won't be enough for much depth of field with the Arsat. It's wide on the format, but the depth of field goes with the focal length if you measure the effect at the tilm plane. Try f/11.

Rick "who uses f/22 for a fixed-focus 65mm lens on a 4x5 point-n-shoot camera" Denney

[PhilRich]

That won't be enough for much depth of field with the Arsat. It's wide on the format, but the depth of field goes with the focal length if you measure the effect at the tilm plane. Try f/11.

Rick "who uses f/22 for a fixed-focus 65mm lens on a 4x5 point-n-shoot camera" Denney

How do you account for the field of view close to the lens being in focus and not that far away? I'm missing something ... shouldn't everything within 2 meters to infinity be in focus for a fisheye?

[rdenney]

How do you account for the field of view close to the lens being in focus and not that far away? I'm missing something ... shouldn't everything within 2 meters to infinity be in focus for a fisheye?

Don’t trust the depth of field scale on the lens. It’s about two stops too optimistic, but they were probably assuming a much smaller print than I do. But even the scale doesn’t claim depth of field from 2 meters to infinity at wide apertures.

I would think you’d need f/8 or f/11 to get that depth of field, and even then you will see lack of exact focus looking at it at 100% on your monitor. And it assumes you set the focus to the hyperfocal distance.

Rick “noting that even within the range of acceptable sharpness, nothing is as sharp as the focal surface” Denney

[itsdoable]

The focus was at infinity with the aperture at f5.6. This lens is for the Kiev camera with the Pentax 645 adapter.

Adapters are notorious for not focusing to infinity at the stop, most focus pass infinity, some don't reach infinity. The mechanical tolerances for proper infinity focus at the mechanical stop is pretty tight for the price they are charging for these things. Check where the lens is focusing on the screen.

How do you account for the field of view close to the lens being in focus and not that far away? I'm missing something ... shouldn't everything within 2 meters to infinity be in focus for a fisheye?

There are many DoF calculators apps available, for a 30mm lens at 5.6, you are looking at ~5m to infinity. Keep in mind that DoF is dependent on format size and print size, and the scale on the lens was calculated for film and an 8x10 print. Pixel peeping on a P645z is equivalent to viewing a 120x160" print. Rick's rule of thumb (2 stops optimistic) is what I use for digital.

[texandrews]

Here is a backyard scene (de-rezed by the forum upload mechanism):

Hey, could someone comment on that, please? Adam? Another mod? I uploaded one photo here a couple of years ago, and it looked so bad here (looked fine on my monitor...) that I've never tried it again. I notice that several folks' images seem to come out fine, and then others don't look nearly as good. Is there a trick some of us are missing specifically for uploading here. I've had the same problem elsewhere, although Zenfolio is ok (but still not as good as home).

[rdenney]

First impression based on 16x zoom on the LCD: Arsat is plenty sharp in the center by 5.6, and as good as it gets by f/11, before diffraction emerges. A bit of field curvature keeps the foreground in the bottom corners sharper that distant trees in the top corners.

I also saw what I would call mild lateral color in the corners.

Pentax 67 fisheye does not appear to be sharper, but I’ll need a better test than my quickie to have any confidence in that conclusion. But the 67 lens has noticeably more lateral color in the corners than did the Arsat. No significant difference in rendering that I could detect on the LCD. My lighting was flat and so were the images.

The Arsat looks like a winner to me, so far. Of course, I already knew that, based on my experience with it on film cameras.

I’ll do something more detailed in the next few days, if possible.

Rick “55mm Arsat PCS does okay, too, by f/8, except that the meter doesn’t seem to work at full shift” Denney

[PhilRich]

First impression based on 16x zoom on the LCD: Arsat is plenty sharp in the center by 5.6, and as good as it gets by f/11, before diffraction emerges. A bit of field curvature keeps the foreground in the bottom corners sharper that distant trees in the top corners.

This is the feedback I was looking for. My copy definitely is NOT sharp by f5.6. I have sent it back for repair or replacement. They explained that the problem could be rectified by adjusting the lens to allow focus beyond the infinity mark.

I also saw what I would call mild lateral color in the corners.

Please educate me concerning "mild lateral color in the corners". What is that?

Mine has very prominent CA in the outer portion of the picture.

[rdenney]

I’m in a busy period, but I will eventually show samples. Lateral color is very easy to correct in software, but in any case my Arsat has significantly less of it than the Pentax 67 fisheye.

Rick “who judges things at print magnifications, not at 100% on a big monitor” Denney

[kaseki]

Hey, could someone comment on that, please? Adam? Another mod? I uploaded one photo here a couple of years ago, and it looked so bad here (looked fine on my monitor...) that I've never tried it again. I notice that several folks' images seem to come out fine, and then others don't look nearly as good. Is there a trick some of us are missing specifically for uploading here. I've had the same problem elsewhere, although Zenfolio is ok (but still not as good as home).

The file I uploaded was an ~ 10 MB jpeg. It was a derived from an ~ 50 MB tiff file taken by a Noritsu HS-1800 scanner at 4824 x 3533 pixels.

Firefox claims that the Forum image presented on my monitor is "1,229px × 900px (scaled to 1,127px × 825px)."

I think it would require a significantly higher income stream for the this forum to save and present images in the source file resolution (which in any case few will have the monitor resolution to view). I need a 5k IPS monitor, it seems. I don't recall what the user's photo storage here will allow, but I'm willing to upload the image to there if anyone cares.

Additional information is that the photo was taken about ~ 2m from the near edge of the redwood table in the foreground. Camera was handheld and the LOS roughly level. Focus was via the 645N matte screen, and as I recall, the somewhat yellowish distant branches at the center of the field of view were what I focused on, while checking that the closer rhododendrons were still sharp.

[kaseki]

One other point that may be worth mentioning to help candidate buyers: While the lens is described both here and at Araxfoto's web site as having a 180 degrees field of view, the horizontal field of view with my 645N seen in my image earlier in this thread is observationally roughly 110 degrees. (I don't have a theodolite to measure it accurately.) If the lens design is f-theta (instead of the usual f-tan theta of longer lenses), the angular width should be 107 degrees for a 58-mm film width.

[rdenney]

One other point that may be worth mentioning to help candidate buyers: While the lens is described both here and at Araxfoto's web site as having a 180 degrees field of view, the horizontal field of view with my 645N seen in my image earlier in this thread is observationally roughly 110 degrees. (I don't have a theodolite to measure it accurately.) If the lens design is f-theta (instead of the usual f-tan theta of longer lenses), the angular width should be 107 degrees for a 58-mm film width.

The 180-degree field of view is corner to corner of a 6x6 frame. It won’t achieve that with the 645 frame.

Rick “a full-frame fisheye for 645 would need a shorter focal length” Denney