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11-21-2022, 02:13 AM   #16
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QuoteOriginally posted by PJ1 Quote
Yes, the lens in question is the 55-300 PLM.
Thanks … missed that

A point to consider, the minimum aperture for "reliable" a/f performance is generally considered to be f/5.6 … unfortunately this lens is f/6.3 at the long end.
Whilst, under good light with a "normal" subject, this isn't usually a problem, factor in a couple of considerations, like the rippling water and/or overcast skies, and the camera can start to struggle, especially with a moving subject.
This observation is based on my extensive use of my Sigma 150-500mm, also with an f/6.3 aperture at the long end, taking many hundreds (if not thousands) of similar pictures from the local 300ft cliff tops of seabirds on or over the ocean.
Having compared performance both with an FA 100-300mm f/4.5-5.6 and a Sigma 70-200mm f/2.8 with 2x fitted (again, effective aperture f/5.6) my experience shows that the f/5.6 aperture allows the camera to be more responsive and accurate … unfortunately, in my circumstances, the reduction in "reach" is rather more than I'm willing to accept.
There's probably good reason that the DA 560mm and the FA 150-450mm were both designed as f/5.6 lenses … customers paying those prices wouldn't want a lens that was only totally reliable when the sun was out

11-21-2022, 02:33 AM - 5 Likes   #17
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QuoteOriginally posted by kypfer Quote
A point to consider, the minimum aperture for "reliable" a/f performance is generally considered to be f/5.6 … unfortunately this lens is f/6.3 at the long end.
If it's struggling to focus, I sometimes wind back to about 260mm where the maximum aperture is f5.6, even if it means cropping a bit more.


11-21-2022, 03:39 AM   #18
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QuoteOriginally posted by sebberry Quote
I'm noticing a frustrating pattern with AF in both Live View and OVF.
You are too far away from the subject. Subject is too small relative to each AF point area, that's why AF is confused. My rule of thumb for good photos, is to have relative subject size 1/4th of the image frame, which makes it easier to nail focus and while also enjoying the full resolution of the camera sensor (no cropping). If your subjects are too small in the frame, you are never going to get your bangs for the bucks you spent on the camera system. Get closer to subjects, or get a longer lens.

---------- Post added 21-11-22 at 11:39 ----------

QuoteOriginally posted by clackers Quote
I think the main thing is to be the photographer, emulate the pros by taking control from the camera, choosing in these instances single point AF focus (there are additional advantages to BBF when taking a series of shots).
That's not the issue.
11-21-2022, 03:59 AM   #19
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QuoteOriginally posted by Des Quote
If it's struggling to focus, I sometimes wind back to about 260mm where the maximum aperture is f5.6, even if it means cropping a bit more
Wow, those are excellent shots.

11-21-2022, 04:59 AM - 1 Like   #20
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QuoteOriginally posted by clackers Quote

I think the main thing is to be the photographer, emulate the pros by taking control from the camera, choosing in these instances single point AF focus (there are additional advantages to BBF when taking a series of shots).

When using a 'high tech' Sony A1 to shoot surfers, I was told by the instructor to make the zone fields as small as possible because algorithm driven autofocus ended up concentrating on nearby waves.

Cheers,
Ian
I've heard a few long-time professionals recommend spot focus, they themselves largely ignoring eye-focus and zone settings on their flagship MILC's. I know for myself as long as the situation seems appropriate, BiF being an exception for me, I still use a single centerpoint and recompose as needed on all my cameras irrespective of brand.

I'm also guilty of avoiding manual focus as much as possible. Yup, I'm lazy and impatient.
11-21-2022, 06:03 AM - 2 Likes   #21
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QuoteOriginally posted by clackers Quote
I think the main thing is to be the photographer, emulate the pros by taking control from the camera, choosing in these instances single point AF focus (there are additional advantages to BBF when taking a series of shots)
Agreed

I find in situations like these where you may want AF-C one minute, then AF-S the next, it can be useful to set up at least two of your USER modes to allow for quick changing between functions. I have a USER mode for action shots (TAv; AF-C; Expanded Area AF Points Small). The next USER mode is set to TAv; AF-S; Spot AF Point. This makes it very easy to move from a panning/tracking set-up to a static subject set-up.

The same can be achieved with Back button focus. Just find out which method works best for you.
11-21-2022, 06:36 AM - 2 Likes   #22
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QuoteOriginally posted by pschlute Quote
I find in situations like these where you may want AF-C one minute, then AF-S the next, it can be useful to set up at least two of your USER modes to allow for quick changing between functions. I have a USER mode for action shots (TAv; AF-C; Expanded Area AF Points Small). The next USER mode is set to TAv; AF-S; Spot AF Point. This makes it very easy to move from a panning/tracking set-up to a static subject set-up.
As this is a K-3iii thread, it's possibly prudent to recommend the use of the SFn (Smart Function) wheel for things like this.
I've got AFS/Single Point, AFC/Single Point and AFC/Zone set as my three a/f options and can flick from one to the other using my thumb with the camera to my eye Ö the various options appear briefly in the viewfinder, so no matter which way I rotate the wheel I'm never more than two clicks away from where I want to be
The SFn isn't quite as comprehensive on the KP, as I remember, (it's been a while since I used it), but the K-70 can have the three User Modes configured appropriately and again, can be accessed with the camera to the eye, but using the trigger finger rather than the thumb

11-21-2022, 06:53 AM   #23
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QuoteOriginally posted by kypfer Quote
As this is a K-3iii thread, it's possibly prudent to recommend the use of the SFn (Smart Function) wheel for things like this.
I've got AFS/Single Point, AFC/Single Point and AFC/Zone set as my three a/f options
Exactly the same as mine.
11-21-2022, 02:07 PM   #24
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QuoteOriginally posted by pschlute Quote
Wow, those are excellent shots.
Thanks Peter. Of course you need to be fairly close to get a viable bird shot at 230mm or 260mm. The more so with a tiny bird like the thornbill (second shot).
QuoteOriginally posted by biz-engineer Quote
You are too far away from the subject. Subject is too small relative to each AF point area, that's why AF is confused. My rule of thumb for good photos, is to have relative subject size 1/4th of the image frame, which makes it easier to nail focus and while also enjoying the full resolution of the camera sensor (no cropping). If your subjects are too small in the frame, you are never going to get your bangs for the bucks you spent on the camera system. Get closer to subjects, or get a longer lens.
There is a point here, although I don't think the answer is "row onto to the lake or give up and go home". We need to have realistic expectations, but it's still worth trying to get the most with what you have and the situation you are in.

@sebberry your second and third samples are taken at 190mm and the fourth at 230mm. (EXIF not available for the first one.) As @biz-engineer says, the AF will work better (including spot AF) if the subject is bigger in the frame, so try at 300mm. In light like that, f6.3 should be OK. (The point I was making about winding back for f5.6 is where the light is poor.)

Last edited by Des; 11-22-2022 at 01:08 PM.
11-21-2022, 02:50 PM   #25
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QuoteOriginally posted by biz-engineer Quote
That's not the issue.
It sure is, BE.

The OP has already said he's using Zone Auto.
11-21-2022, 03:35 PM   #26
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Hopefully my article helps...
Pentax K-3 Mark III Continuous Autofocus Demystified - Articles and Tips | PentaxForums.com
11-21-2022, 04:12 PM - 3 Likes   #27
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Yeah, for that scenario I agree with both clackers and biz-engineer. Switching to a single AF point for a subject that small and far away is the way to go, but so is accepting that it's pretty far away and you need to get closer or wait until the bird comes closer if you want a better shot. The AF tries to grab the closest high contrast spot under the AF point but those points are larger than the little confirmation square in the viewfinder would suggest. With the AF point on the bird it sees the water in front of the bird too. You can try with single spot placing the AF point high on the bird or even just slightly above so it is seeing the bird and the water behind it and choosing the bird because it's closer, rather than the bird and the water in front of it. It's a challenging scenario for any AF system. Solution, get closer, which might seem impossible. It's not, just maybe harder than you are willing to do for that shot.

---------- Post added 11-21-22 at 04:19 PM ----------

I should add that angle matters here too. If you can get lower down close to the surface of the water you change the distance to background which makes the bird stand out more to the AF system. At the angle of your shots the foreground and background are the water right around the bird and are only inches apart. If your lens is inches above the water then the background becomes the far shore and gets nicely blurred away and while the foreground will still be the water and some waves the bird should stick up above them enough to let the AF pick out the bird.



Last edited by vector; 11-21-2022 at 04:41 PM.
11-21-2022, 05:31 PM - 5 Likes   #28
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I use single point focus, and focus on the eye. AF-c and multi-point focus is used only for birds in flight. When I can, I focus on the eye. Or part of the head neck on the same Focal Plane as the eye.

You can futz around with other methods, and I do at times, but it always comes back to single point focus, pick a convenient spot. In situations where there are branches in front of the bird, I find something nearby on the same focal plane, so focus doesn't switch to the foliage as I engage the shutter release.

Since that's my experience of the 9 years with my K-3, at this point, I don't often entertain other methods.

Another point would be lining up your shot and then shooting a burst. Birds can move thier heads quickly, the pose that was there when you started to depress the shutter release may not be there when you fully activate the shutter. With a one or two second burst, the bird has time to move it's head out of the frame and then move back in again, and I do not refocus for that as long as the body hasn't move. Any body movement requires a complete refocus, and even in a long burst a quick refocus is preferable, just in case you didn't nail it the first time. This often produces 8 to 10 times the number of times the number of images you actually need, sometimes 8 in the exact same pose, but for especially small birds it's absolutely essential. There's a lot of head bobbing and tilting, there is very quick unanticipated motion blur, and the head of the bird may move in and out of the Depth of Field.

IMHO single point focus, focussed on the eye (although you may choose to move that point, but it must still remain a single point) and burst is the best way, especially for smaller birds.

Last edited by normhead; 11-21-2022 at 07:44 PM.
11-22-2022, 07:19 AM - 1 Like   #29
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QuoteOriginally posted by normhead Quote
I use single point focus, and focus on the eye. AF-c and multi-point focus is used only for birds in flight. When I can, I focus on the eye. Or part of the head neck on the same Focal Plane as the eye.

You can futz around with other methods, and I do at times, but it always comes back to single point focus, pick a convenient spot. In situations where there are branches in front of the bird, I find something nearby on the same focal plane, so focus doesn't switch to the foliage as I engage the shutter release.

Since that's my experience of the 9 years with my K-3, at this point, I don't often entertain other methods.

Another point would be lining up your shot and then shooting a burst. Birds can move thier heads quickly, the pose that was there when you started to depress the shutter release may not be there when you fully activate the shutter. With a one or two second burst, the bird has time to move it's head out of the frame and then move back in again, and I do not refocus for that as long as the body hasn't move. Any body movement requires a complete refocus, and even in a long burst a quick refocus is preferable, just in case you didn't nail it the first time. This often produces 8 to 10 times the number of times the number of images you actually need, sometimes 8 in the exact same pose, but for especially small birds it's absolutely essential. There's a lot of head bobbing and tilting, there is very quick unanticipated motion blur, and the head of the bird may move in and out of the Depth of Field.

IMHO single point focus, focussed on the eye (although you may choose to move that point, but it must still remain a single point) and burst is the best way, especially for smaller birds.
Excellent advice Norm. I've seen fellow photogs use continuous focus on relatively static birds and not getting the results they expected, with wayward leaves or branches becoming the focus not uncommon. As you say, single-point AF-S pretty well fixes that.
11-27-2022, 08:05 AM - 2 Likes   #30
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QuoteQuote:
As you say, single-point AF-S pretty well fixes that.
Not to mention that Pentax AF-s is right up with anyones. It's tracking where the Pentaxes are typically weaker (now addressed with the K-3iii). For the way I shoot, there's actually no advantage to other systems. I simply don't have many opportunities to use tracking.

Most of the time when I use tracking, it's for practice and to prove it can be done. In the last 10 years I've used it maybe three times in real life.

Even my Snowy Owl is AF-s. And with a slow focussing lens. The DA 55-300 is a comparative dream in AF speed. And to a certain degree it was less that the speed focussing of lenses, most of the cameras had more capability than the lenses could take advantage of. Which you can see when T is using the DA 55-300 PLM (without Aperture control, but hat's never been problem.) One of their oldest cameras has vastly increased AF speed, with a fast focussing lens.


Pentax used to produce only "Field" cameras. The K-3iii and DA 55-300 changed that.

Last edited by normhead; 11-27-2022 at 08:16 AM.
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