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10-11-2019, 06:31 AM   #16
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QuoteOriginally posted by Digitalis Quote
This is probably the biggest issue with executing hyperfocal focusing with current lenses. The lack of an accurate hard stop point at infinity makes getting the hyperfocal point nearly impossible.
Exactly!

With a good infinity hard stop, a lens could run out to infinity and then back-off the appropriate number of ticks. The camera would still need some kind of user-entered CoC value.

The more general problem of knowing or controlling the distance setting of the lens requires some sort of highly accurate encoder inside the focus motion system. A 50/1,4 would probably need an 8 or 9 bit encoder (some 8 or 9 tracks with up to 256 or 512 on/off transitions) for sufficient accuracy for professional use on high-resolution cameras.

10-11-2019, 06:32 AM   #17
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QuoteOriginally posted by kypfer Quote
A reference I read quoted 1 stop as being necessary, which kind of made sense to me as the APS-C sensor is about half the size of a full-frame 35mm negative.


Which brings me to a sudden realisation !! The Industar-69 I recently acquired came from a half-frame camera, so the DOF markings should be good for an APS-C sensor and I don't need to compensate I should point out here that this lens isn't used on a Pentax but on a mirrorless body, and needed some mechanical modification to achieve infinity focus.
I usually treat it as a pixel size issue and the APS-C sensors until recently were much more pixel dense than full frame. With full frame camera now getting up in the 50MP range they now have similar pixel sizes to APS-C lenses. Film had grain and people were more forgiving with film shots and acceptable depth of field. That is why I usually go for the 1.5 to 2 stops more than the DoF gauge indicates with the K-3. If I had a K-1 or K-1ii I would probably go for 1 to 1.5 stops.
10-11-2019, 08:27 AM   #18
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QuoteOriginally posted by agukha Quote
I saw on another forum that Pentax had done it.. on a PZ-1p, it would be easy to do it again !
I own a PZ-1p. It has no such feature.
10-11-2019, 08:43 AM   #19
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QuoteOriginally posted by Ausable Quote
I own a PZ-1p. It has no such feature.
too bad...
Thank you for the information

So the solution to display the hyperfocal distance would at least be easy ^^

10-11-2019, 10:18 AM   #20
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QuoteOriginally posted by MossyRocks Quote
I usually treat it as a pixel size issue and the APS-C sensors until recently were much more pixel dense than full frame. With full frame camera now getting up in the 50MP range they now have similar pixel sizes to APS-C lenses. Film had grain and people were more forgiving with film shots and acceptable depth of field. That is why I usually go for the 1.5 to 2 stops more than the DoF gauge indicates with the K-3. If I had a K-1 or K-1ii I would probably go for 1 to 1.5 stops.
I have always viewed it like this. The coc the lens renders is exacly the same at the sensor. The more you "enlarge" the image * , the more your DOF decreases.

* in digital terms the statement should be "the less you decrease the image size."
10-11-2019, 11:23 AM   #21
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QuoteOriginally posted by photoptimist Quote
And then there's the change in CoC for pixel peeping instead of printing 8x10.
Yep...magnification defeats DoF such that DoF approaches zero as magnification approaches infinity. (Assuming systems with infinite resolution.)

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10-11-2019, 11:53 AM   #22
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QuoteOriginally posted by stevebrot Quote
Yep...magnification defeats DoF such that DoF approaches zero as magnification approaches infinity. (Assuming systems with infinite resolution.)
That's an extraterrestrian assumption. Since earth is spherical, infinite magnification would mean that to see the whole picture the observer should be send to infinity, perpendicular to the image plane, of course.

10-11-2019, 12:25 PM   #23
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With film, on any of my 35mm film bodies- MZ-S, PZ-1p, ZX-L, etc. I would sometimes use the DOF scale on a lens to determine hyperfocal settings. Although I rarely use it, I do still carry a handy, compact DOF scale in my bag for lenses that do not offer this feature.
10-11-2019, 02:08 PM   #24
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QuoteOriginally posted by mikesbike Quote
I do still carry a handy, compact DOF scale in my bag for lenses that do not offer this feature.
Is this a printed card or a slide-type calculator?


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10-12-2019, 09:08 AM - 1 Like   #25
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It's a slide-type calculator. Rather works much in the same manner as the scale seen on some lenses. FLs given starting at 20mm through 300mm are the most common ones found in prime lenses. Distances are given in feet. This one was made by "FotoSharp" and designed for 35mm SLR use, or now for a FF DSLR. One would've to extrapolate the reading to get an APS-C result, I expect. It is quite flat and only about 4 x 8" so it fits very easily in the zipper compartment of the inside top of a very modest-size camera bag I often carry. It was inexpensive.

I should get yet another that is made for APS-C use, which would also include a shorter FL range. I'm sure an outfit such as B&H would carry one similar to the one I already have for a FF camera.

Last edited by mikesbike; 10-12-2019 at 09:14 AM.
10-12-2019, 10:06 AM   #26
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Doesn't the GR offer a "Snap Focus" feature that seems to me a version of hyperfocal.. could Ricoh Pentax transfer this feature to our beloved dslr's..?

When my wife & I visited Venice, we were taking our 1st ride in a water taxi boat to our hotel, and the boat's constant movements & jostling made using an autofocus zoom lens... uhh.. problematic.. every time my hand/camera moved, it would try refocusing... so... I switched to a manual focus K 24 2.8... set up ISO and aperture so the hyperfocal distance scale indicated roughly everything between say 5' and infinity were in focus, and just started snapping away... worked like a charm too..!! Having no need to focus is faster than any auto focus system I have yet used.
10-12-2019, 10:27 AM   #27
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QuoteOriginally posted by hongman Quote
When my wife & I visited Venice, we were taking our 1st ride in a water taxi boat to our hotel, and the boat's constant movements & jostling made using an autofocus zoom lens... uhh.. problematic.. every time my hand/camera moved, it would try refocusing... so... I switched to a manual focus K 24 2.8... set up ISO and aperture so the hyperfocal distance scale indicated roughly everything between say 5' and infinity were in focus, and just started snapping away... worked like a charm too..!! Having no need to focus is faster than any auto focus system I have yet used.
Exactly. I rarely bother focussing , auto or manual when using an ultra wide angle. The physics are on your side !
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