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12-15-2014, 07:34 PM   #1
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Manual Focusing! Am I missing something?

Hello,

Another newbie question here. I recently got my K-3 and Rokinon 14mm. I took it out today to shoot some snow pictures. I followed usual steps of enabling the aperture ring and live view focus peeking in the menu. I am still having trouble focusing through the view finder. When I look through the view finder, everything seems to be in focus irrespective of where my focus ring is positioned. Live view magnification usually helps me get the proper focus. Am I doing something wrong while looking through view finder? Also, even in live view, I am having a hard time identifying areas highlighted by focus peeking. While reading about this online I came across couple of terms which I do not understand - "catch-in focus" and "focus confirm".

Am I doing something wrong or is manual focusing simply looking through view finder and turning the focus ring? Any help is highly appreciated. Thanks.

12-15-2014, 07:39 PM   #2
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Manual focus is just look and turn.

However, it sounds like the lens you are using is manual aperture, correct?
if the lens is stopped down the DOF will be greater, manual lenses do not allow open aperture focussing on a DSLR (you need to open it, focus, close, meter, shoot)

Wider lenses are also a bit harder to focus, as the objects in the viewfinder are smaller.


It doesn't help that DSLR viewfinders are really designed for auto-focus, and I find they all are substantially lacking in image brightness and quality compared to film cameras.
12-15-2014, 07:50 PM   #3
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QuoteOriginally posted by hks_kansei Quote
if the lens is stopped down the DOF will be greater, manual lenses do not allow open aperture focussing on a DSLR (you need to open it, focus, close, meter, shoot)
This is incorrect- it only applies to M42 lenses. The Rokinon 14mm supports open-aperture metering and has the "A" setting.

The reason everything appears in focus is due to the fact that the 14mm is so wide, hence it has a massive depth of field. It's hard to fine tune the focus without live view, but most of the time you won't even need to

Adam
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12-15-2014, 08:02 PM   #4
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QuoteOriginally posted by Adam Quote
This is incorrect- it only applies to M42 lenses. The Rokinon 14mm supports open-aperture metering and has the "A" setting.

The reason everything appears in focus is due to the fact that the 14mm is so wide, hence it has a massive depth of field. It's hard to fine tune the focus without live view, but most of the time you won't even need to

My mistake.
It's been years since I've used an M lens on my DSLR so I must have got them mixed up with M42.

12-15-2014, 08:26 PM - 1 Like   #5
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Long post. The important parts are highlighted.

The Rokinon 14 has an "A" setting on the aperture ring for Pentax mount. Just leave the ring on "A" all the time; Av mode can calculate exposure, and M mode also works with the 2 camera dials rather than turning the lens ring.

14mm is so wide that many details are tiny. That makes it tough to see details in the viewfinder and also tricks focus peaking into thinking everything is in focus. I rely on a combination of liveview and hyperfocal for my 14mm. With a tripod, I carefully focus on a foreground object then set aperture to make the background look in focus. For handheld use, such as walking around a city, I focus on something around 10 feet away, set aperture to f8 in good light, and everything from near to infinity will appear to be in focus. See Online Depth of Field Calculator or Google "hyperfocal distance".

"Focus confirm" is where the viewfinder highlights the focus point and the camera beeps when something is in focus. The 14mm is so wide that focus confirm might pick up the wrong object and tell you things are in focus when they really are not.

"Catch in focus" is a menu setting that won't let the shutter release until the camera detects that focus has been achieved. You can then hold the shutter button down, move the focus ring, and the shutter will release when something is in focus. This is subject to the same "14mm is so wide that everything looks in focus" limitations mentioned above.
12-15-2014, 08:38 PM   #6
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QuoteOriginally posted by uday029 Quote
When I look through the view finder, everything seems to be in focus irrespective of where my focus ring is positioned.
Welcome to the world of ultra wide-angle lenses. Everything in the viewfinder is sooooo tiny. As a result, the apparent DOF is huge making fine focus difficult. Here is what you can do:
  • Zone focus using the distance scale on the lens for casual shooting
  • Magnified live view with focus peaking for critical focus
You may want to confirm the accuracy of the distance scale using magnified live view with focus peaking. Samyang lenses are sort of notorious for the focus scales not being properly calibrated. In regards to the comment on focus confirm above, you will find that the AF system has poor sensitivity and very poor precision at the wider focal lengths when in the field. The same is true regarding catch-in-focus (CIF) since both use the same system.


Steve
12-15-2014, 10:02 PM   #7
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QuoteOriginally posted by stevebrot Quote
Welcome to the world of ultra wide-angle lenses. Everything in the viewfinder is sooooo tiny. As a result, the apparent DOF is huge making fine focus difficult. Here is what you can do:
  • Zone focus using the distance scale on the lens for casual shooting
  • Magnified live view with focus peaking for critical focus
You may want to confirm the accuracy of the distance scale using magnified live view with focus peaking. Samyang lenses are sort of notorious for the focus scales not being properly calibrated. In regards to the comment on focus confirm above, you will find that the AF system has poor sensitivity and very poor precision at the wider focal lengths when in the field. The same is true regarding catch-in-focus (CIF) since both use the same system.


Steve
Steve,

How do I confirm that my lens is properly calibrated? Measure distance to the object and check whether the focus ring pertaining to that distance makes it appear in focus?

Also, how do I sent the focus to infinity? I mainly intend to use this lens for landscape shots.

Thanks.
12-15-2014, 10:18 PM   #8
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QuoteOriginally posted by uday029 Quote
Measure distance to the object and check whether the focus ring pertaining to that distance makes it appear in focus?
Put the camera on a tripod at a known distance to the focal plane mark on the camera (or your best estimate. Focus using magnified live view and check the position of the distance scale against the known distance to the target.


Steve

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