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01-26-2014, 08:23 AM   #1
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M42 Lenses - 'Green Hexagon' vs. Focus Peaking/Magnification

On cameras equipped with both (K-30. K-50, K-500 etc.), when using M42 lenses, which do you find is easier to focus manually and is more accurate?

Live view (CDAF) with Focus Peaking and Magnification (4x, 6x whatever) or OFV with the 'Green Hexagon' (PDAF)? Why? Any performance difference between focal lengths and aperture?

I use M42s only with my K-01. But there are certainly times when it would be nice to have the OVF. With the K-500 hitting $399 with the 18-55 kit (which I would sell) I am tempted to pick up a K-500 body for those times. (again - will use M42s only with it).

If you prefer Green Hexagon, any comments on exposure accuracy vs. Live View? (I find Live View exposure on my K-01 works just fine - but read there are 'problems' with M42s on the OVF bodies..)

(Adam if this is the wrong Forum, please move. But I put it here because it was M42 lens specific, and across a number of different bodies..)

01-26-2014, 09:39 AM   #2
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I use focus peaking on the K-01 for M42 lenses,
or sometimes just the distance scale,
e.g. for street work with the Super Takumar 20/4.5.

The big advantage of live view
is getting a useful image at a taking aperture of f/8,
without having to open up to frame,
and then stop down again to take the photo.

Also, for critical focusing with a lens like the 20/4.5,
(e.g. for extreme close-ups),
I wouldn't expect the green hexagon to be as good as live view.
01-26-2014, 10:09 AM   #3
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Doesn't the K-500 have the same LCD as the K-01, and the focus peaking function as well? So it kind of gives you both options. But it is a bit bigger and not as.. well, I like the way the K-01 looks. And the K-500 might have a stronger AA filter than the K-01? Maybe someone can do a sharpness test with the same lens, see if there is a difference between the two cameras

And regarding OVF, you have the additional advantage of using CiF (catch in focus, focus trapping), which is great for manual lenses.

That being said, I prefer to use manual primes on my K-01, instead of on my K-r. But I think the K-r has pentamirror and a smaller OVF than the K-50's pentaprism OVF. For me, the K-01 is just suited to manual primes. The whole package just.. works. Its fun, relaxing, and takes good photos. With the K-r and a manual primes, I never got quite the same feeling, even though the K-r offers some more functions
01-26-2014, 10:59 AM   #4
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QuoteOriginally posted by Na Horuk Quote
Doesn't the K-500 have the same LCD as the K-01, and the focus peaking function as well? So it kind of gives you both options. But it is a bit bigger and not as.. well, I like the way the K-01 looks. And the K-500 might have a stronger AA filter than the K-01? Maybe someone can do a sharpness test with the same lens, see if there is a difference between the two cameras

And regarding OVF, you have the additional advantage of using CiF (catch in focus, focus trapping), which is great for manual lenses.

That being said, I prefer to use manual primes on my K-01, instead of on my K-r. But I think the K-r has pentamirror and a smaller OVF than the K-50's pentaprism OVF. For me, the K-01 is just suited to manual primes. The whole package just.. works. Its fun, relaxing, and takes good photos. With the K-r and a manual primes, I never got quite the same feeling, even though the K-r offers some more functions
Great points, Na Horuk. Hadn't thought about the problem of a possible stronger AA filter. But CIF (if it works well?) would be great. Too bad its not possible on the K-01 - even moreso on the Q..

Yes - I too love my M42s on my K-01. Have to beat back the K-500 CBA..:>) Maybe someday we will get the 'K-02' with DVF and CIF - but not holding my breath..

01-26-2014, 11:01 AM   #5
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I had the K10, the K20 and still have the K5.
All of these were not reliable using the hexagon.

Now I have the K5IIs. This is the first one, were I can really rely on the hexagon.
I suspect it is because of the new f2.8 sensor, or perhaps some general AF improvement.
01-26-2014, 11:11 AM   #6
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Focus accuracy with green hexagon is not accurate; there will be a range in which the heaxgon will indicate that focus is achieved. The truth is somewhere in the middle With lots of practice you can probably get used to the behaviour, but if you're a fan of very shallow dof, I would not rely on the hexagon. You can opt for a third party split prism screen (e.g. katzeye or jinfinance) as a focusing aid; there was also a thread about the EE screen.

I can not really judge metering; if I get it wrong, I retake it or adjust in post processing.

ps I use a K100D with focusing screen if I really want the accuracy. On the K5 I rely on a mix of dof, what I see in the viewfinder and the hexagon with reasonable success
01-26-2014, 11:31 AM   #7
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Well, split prism screen is as inaccurate as the AF sensor, probably even less accurate due to a smaller basis (f5.6 or lower) and due to shim inaccuracies.
There was an LX screen with a larger basis.
01-26-2014, 01:11 PM   #8
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About the split screen not being accurate--yes you are correct you need to check if the stock shim still is correct, and you can buy a range of shims thicknesses cheaply from Pentax (anyway could w/ K20d--just buy one of each/should still be true).

Except for macro and/or slow lenses (where the split screen darkens) a properly shimmed split screen is likely only second to live view in accuracy, and a lot more convenient.

01-26-2014, 02:41 PM   #9
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QuoteOriginally posted by cahudson42 Quote
On cameras equipped with both (K-30. K-50, K-500 etc.), when using M42 lenses, which do you find is easier to focus manually and is more accurate?
Magnification > focus peaking > OVF green hexagon

A properly calibrated split-image screen in the optical finder should be as accurate as a magnified live view image.


Steve

Last edited by stevebrot; 01-26-2014 at 04:35 PM.
01-26-2014, 02:58 PM   #10
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So where are we:

It seems CDAF (Live View/Focus Peaking) is 'potentially' more accurate, as it uses the same 'film plane' that records the image.

PDAF (the Hexagon), by utilizing a separate sensor and mirror, requires +10/-10 'calibration' to compensate for manufacturing variances (and shim?) differences that cause the sensor plane to be different than the film plane. Apparently complicated further by needing to be calibrated 'per lens' - not possible on M42s.

Conclusion - pentaprism, mirror, separate sensor plane - are obsolete compared to EVF using the exact sensor-plane and CDAF - or CDAF/PDAF-built-into-the-main-sensor.

I should hold off buying any mirror-based DSLR until Pentax comes out with the equivalent of the K-01 with an EVF. (And hopefully, CIF based on the film/main sensor plane)

Please, correct my thinking?
01-26-2014, 03:01 PM   #11
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QuoteOriginally posted by blende8 Quote
Well, split prism screen is as inaccurate as the AF sensor, probably even less accurate due to a smaller basis (f5.6 or lower) and due to shim inaccuracies.
Reference?

My experience has been the exact opposite when shooting with anything even approaching fast glass.


Steve
01-26-2014, 03:25 PM   #12
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Manual focus confirmation (green hexagon) is twitchy on my K10D. It is very easy to go past the "in focus" zone with the slightest touch and sometimes requires some "sawing" (going back and forth) to lock the focus with legacy glass. Many times it just won't indicate in focus. When using the 18-55mm kit lens in manual focus it is quite easy to achieve confirmation.

I have the AF button set to disable focus confirmation in situations where I can't seem to get the green hex and just eyeball it.
01-26-2014, 05:27 PM   #13
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Conclusion - pentaprism, mirror, separate sensor plane - are obsolete compared to EVF using the exact sensor-plane and CDAF - or CDAF/PDAF-built-into-the-main-sensor.

Not usually and certainly not w/ lots of objects moving around (complex fast dance), or a small fast object (a flying butterfly), etc., for which nothings comes even close to prism+mirror (and likely ground glass screen).
01-26-2014, 05:46 PM   #14
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QuoteOriginally posted by dms Quote
Conclusion - pentaprism, mirror, separate sensor plane - are obsolete compared to EVF using the exact sensor-plane and CDAF - or CDAF/PDAF-built-into-the-main-sensor.

Not usually and certainly not w/ lots of objects moving around (complex fast dance), or a small fast object (a flying butterfly), etc., for which nothings comes even close to prism+mirror (and likely ground glass screen).
Or complex subjects in general.


Steve
01-26-2014, 09:51 PM   #15
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I use my K-30's OVF with manual focus 99% of the time. It has never failed to deliver a sharp image for me. But, I verified that I did not have front/back focus issues first which required lots of test shots and pixel peeping. Maybe I'm just too old school but framing a shot with an OVF can't be beat by a 3" LCD. Maybe there's something about the extra stability of bracing the camera against your face?

Even then... trust your eyes. Just make sure your diopter and/or prescription is right.
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