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04-04-2015, 12:41 PM   #1
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Pentax K-3 AF Speed Question

I was reading the staff review of the Sigma 30mm 1.4 DC HSM "Art" lens this morning, and it seemed like it would be a really great lens, until the reviewer described its autofocus speed as "sluggish". I believe it was tested with a K-3.


The three most important selling points that interest me are sharpness, autofocus speed, and a broad aperture range.

So I am wondering, instead of reading seven or ten reviews, what lens would you say, zoom or prime, from any maker, covering anywhere between 15mm and 35mm, would focus fastest on the K-3, give impressively sharp results, and provide the creative flexibility of a wide aperture range?


Thanks!


Last edited by DavidSKAF3; 04-04-2015 at 02:15 PM.
04-04-2015, 01:34 PM - 1 Like   #2
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I have the original Sigma 30mm f1.4, on my K5 it was a pretty much one to use MF only...on my K3, with a bit of AF correction dialled in, it is a revelation, snappy focus, even in poor light. Mostly hits correct focus wide open, but can sometimes miss....but 85% of the time it is spot on.


Here is a shot of a moving train in dark conditions at f2, 1/50th iso 12800


04-04-2015, 01:40 PM   #3
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I think the FA31, the DA 35 F2.4, the FA28 F2.8 and the new Sigma 35 F1.4 Art would be in contention for fastest focusing, with the added benefits of good quality in all other features.
04-04-2015, 01:52 PM   #4
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I have the 30mm f1.4 (with K-5 II), if you use the central spot it is focusing speedy and firmly, precis.

04-04-2015, 03:05 PM   #5
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I would probably go with the FA 31mm Limited (more compact, but loud AF) or the Sigma 35mm F1.4 (large, but has silent AF).

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04-04-2015, 06:35 PM   #6
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I would expect the not yet released D FA wide angle zoom from the roadmaps to be very fast. All indications from samples of the other new FF compatible lenses have pointed to these lenses being very fast focusing compared to past lenses even when used on current k3 bodies. But this is not yet released.
04-04-2015, 06:57 PM   #7
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QuoteOriginally posted by DavidSKAF3 Quote
what lens would you say, zoom or prime, from any maker, covering anywhere between 15mm and 35mm, would focus fastest on the K-3
The 40mm I think would be the fastest on any Pentax body, but I could be wrong

AF depends on a lot of things, particularly the lighting situation.
04-04-2015, 09:11 PM   #8
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If a photographer know his DoF, and knows to think, then no lens is slow.
Relying on AF alone to obtain a photograph is the worst decision one can make.

04-04-2015, 09:50 PM   #9
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QuoteOriginally posted by Uluru Quote
If a photographer know his DoF, and knows to think, then no lens is slow.
Relying on AF alone to obtain a photograph is the worst decision one can make.
++1

AF speed is the least of my concern in my photo-taking experience.. OTOH AF accuracy is much more important to me. I have never found any short comings in the AF speed in any of my k-5/II or k-3. In fact, k-3 is quite a pleasant surprise for me compared to k-5/II.

Having said that... I do even find my DA18-135 to be quite fast...
04-05-2015, 12:07 AM   #10
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QuoteOriginally posted by Uluru Quote
If a photographer know his DoF, and knows to think, then no lens is slow.
Relying on AF alone to obtain a photograph is the worst decision one can make.
Maybe a bit exagerated? Anyway that would be many photographers

I maybe made the worst decision one can make but nevertheless, all lenses I have tend to focus well, even the DA35 macro.
04-06-2015, 04:05 PM   #11
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Well, if we allow AF to sort out things for us, we enter into photography through a wrong door.

We must immediately establish our own deficiencies and drawbacks — where our skills and features are thin, so to speak, in order to compensate for them. Only after that we can speak about AF.

1. Perception time? A big problem, because not all people posses same speed in pattern recognition.
2. Reaction time? It is major drawback for many, to consciously decide upon an action. Getting rid of superfluous thoughts that inhibit faster response is a long and winding process.
3. Motor skills of our arms? We don't posses same strength and reflexes. Nor the same level of fine coordination.
4. Fatigue. Not all of us are born truck drivers. Not even short distance city drivers. Some have no stamina for photography, for being visually and consciously alert to such a level all the time. It improves with practice but still, some are not born for it despite desire to learn something new.
5. Visual literacy. What makes photograph worth considering? In the sea of chaos around us, how to see a scene worth taking? Some form of art and visual education is necessary.

So forth. When we sort out matters as those above, only then we can start thinking about how AF can help or impede our current moment, or how certain technology helps of cripples us in our work.
04-06-2015, 10:55 PM - 1 Like   #12
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QuoteOriginally posted by Uluru Quote
Well, if we allow AF to sort out things for us, we enter into photography through a wrong door.

We must immediately establish our own deficiencies and drawbacks where our skills and features are thin, so to speak, in order to compensate for them. Only after that we can speak about AF.

1. Perception time? A big problem, because not all people posses same speed in pattern recognition.
2. Reaction time? It is major drawback for many, to consciously decide upon an action. Getting rid of superfluous thoughts that inhibit faster response is a long and winding process.
3. Motor skills of our arms? We don't posses same strength and reflexes. Nor the same level of fine coordination.
4. Fatigue. Not all of us are born truck drivers. Not even short distance city drivers. Some have no stamina for photography, for being visually and consciously alert to such a level all the time. It improves with practice but still, some are not born for it despite desire to learn something new.
5. Visual literacy. What makes photograph worth considering? In the sea of chaos around us, how to see a scene worth taking? Some form of art and visual education is necessary.

So forth. When we sort out matters as those above, only then we can start thinking about how AF can help or impede our current moment, or how certain technology helps of cripples us in our work.
Sorry for all your theory man but it is much more basic than that: using the OVF I don't see the deph of field precisely enough to take the photo correctly. No more, no less. Typically I can turn the focus ring quite a bit before I see a difference. The only way I can do manual focus with current gear is to use live view with magnification and focus peaking. As to me for fine AF tuning manually I don't want to change the focusisng screen with issues arround metering, the risk to add OVF back/front focus and the limitation that many time when I'am after fine AF tuning, I don't want to focus on the center.

So even through you think I continuously make the worst decision one can make, I'll continue.
04-07-2015, 12:26 AM   #13
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I second your opinion. I have no problems with DA* 2.8/50-135mm or DA* 2.8/200mm focusing speed, this is bad-focussing (mostly back-focus with all +8 body micro-adjustment) and/or non-consistency which pisses me off.
More than half of portraits shoot with my copy of K-3 are focused on back-eye (regardless of micro-adjustment) when I was focussing the front-eye.
Question:
Did small Asian hands learn to make fake K-3s??

-----
QuoteOriginally posted by aleonx3 Quote
OTOH AF accuracy is much more important to me.
[...]
I do even find my DA18-135 to be quite fast...
04-07-2015, 03:44 AM   #14
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QuoteOriginally posted by Nicolas06 Quote
Sorry for all your theory man but it is much more basic than that: using the OVF I don't see the deph of field precisely enough to take the photo correctly. No more, no less. Typically I can turn the focus ring quite a bit before I see a difference. The only way I can do manual focus with current gear is to use live view with magnification and focus peaking. As to me for fine AF tuning manually I don't want to change the focusisng screen with issues arround metering, the risk to add OVF back/front focus and the limitation that many time when I'am after fine AF tuning, I don't want to focus on the center.

So even through you think I continuously make the worst decision one can make, I'll continue.
I am in a similar position. I have an eyesight condition which makes it difficult to fine focus even with glasses so I am reliant on the camera giving me a good bit of help. It can be a bit of a nuisance at times, even with liveview and focus peaking, especially with macro.

Theory and rules are all very well so long as they are not treated as "absolutes". They really only work when tailored to give you the artistic and technical outcome that you are aiming for, after recognising any physical limitations that you may have as an individual.
04-07-2015, 11:44 AM   #15
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QuoteOriginally posted by LoneWolf Quote
I am in a similar position. I have an eyesight condition which makes it difficult to fine focus even with glasses so I am reliant on the camera giving me a good bit of help. It can be a bit of a nuisance at times, even with liveview and focus peaking, especially with macro.

Theory and rules are all very well so long as they are not treated as "absolutes". They really only work when tailored to give you the artistic and technical outcome that you are aiming for, after recognising any physical limitations that you may have as an individual.
Me too!
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