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03-28-2015, 03:35 PM - 2 Likes   #436
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Shooting sport is difficult with telephoto. Takes practice, familiarity with the sport/team/event, and some planning to do well.

I LOL at those critics who don't understand narrow depth of field, and further assume at a football game the camera can do face detection, and so blame every OOF shot on front or back focus.

---------- Post added 2015-03-29 at 09:44 AM ----------

QuoteOriginally posted by kenspo Quote
This new 70-200 is 2-3 times more heavy then the Sigma one
I pretty much always shoot big 70-200's on a small Manfrotto monopod. If the Pentax 70-200 is as heavy as you suggest, it might be worth adding one to the bag.

03-28-2015, 04:25 PM   #437
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QuoteOriginally posted by rawr Quote
I LOL at those critics who don't understand narrow depth of field, and further assume at a football game the camera can do face detection, and so blame every OOF shot on front or back focus.
I do understand shallow DOF, I shoot moving subjects at 200/2.8 often enough. Getting front focused shots, no matter if the action is moving towards you or the opposite is something that could be caused by FF. If the lens/camera can't keep up with the movement you usually get some back focused shots with the object coming to you and front focused when they are moving away. And yes, I know you don't focus on faces, Captain Obvious.
03-28-2015, 05:14 PM   #438
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QuoteOriginally posted by jaad75 Quote
I do understand shallow DOF, I shoot moving subjects at 200/2.8 often enough. Getting front focused shots, no matter if the action is moving towards you or the opposite is something that could be caused by FF. If the lens/camera can't keep up with the movement you usually get some back focused shots with the object coming to you and front focused when they are moving away. And yes, I know you don't focus on faces, Captain Obvious.
sorry about my strong words earlier, you made a fair observation...

Last edited by Stavri; 03-28-2015 at 07:50 PM.
03-28-2015, 05:23 PM - 1 Like   #439
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QuoteOriginally posted by jaad75 Quote
And yes, I know you don't focus on faces, Captain Obvious.
This won't be news, I guess, but the usual focus problem with an average sports event is that when shooting telephoto and wide open:

(a) you have a flat, narrow (and usually tilting, if shooting from above) plane of focus, so the target feature has to 'walk into' a often very small focus 'box';

(b) there's often a lot of colourful and contrasty stuff on the event field (other players, grass, fences, advertisements etc) for the AF to validly choose from, unless it is well directed and carefully set up (AF-C alone on the K-3 has about 7 options).

My point being that one shouldn't immediately assume front-or-back focus is the issue when shooting sports scenes. Maybe one can make that call quickly when shooting a lens in the studio or landscape, but dynamic scenes are harder to shoot perfectly, and harder to assess problems with.

03-28-2015, 05:27 PM   #440
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QuoteOriginally posted by kenspo Quote
This new 70-200 is 2-3 times more heavy then the Sigma one
Sigma 70-200/2.8 EX DG APO Macro HSM II: 1.37 Kg (chose older version since it lacks OS)

Pentax-D FA * 70-200/2.8: 1.76 Kg

1.76/1.37 = 1.28x (28% heavier...not 200-300%)


Steve

Last edited by stevebrot; 03-28-2015 at 05:35 PM.
03-28-2015, 05:55 PM   #441
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QuoteOriginally posted by rawr Quote
My point being that one shouldn't immediately assume front-or-back focus is the issue when shooting sports scenes.
I did not say it is front focusing lens, I just asked if he calibrated it, cause that could be the reason. There could be many different reasons too, of course, like swinging back while shooting, wrong focus point/AF configuration etc., but because of that repeatability that one was the first I'd like to eliminate.
And once again - I don't see slight FF or BF to be a problem at all, it's pretty normal for me to calibrate the lens and that is the first thing I do when I try the new one.

Last edited by jaad75; 03-28-2015 at 06:11 PM.
03-28-2015, 06:11 PM   #442
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QuoteOriginally posted by rawr Quote
This won't be news, I guess, but the usual focus problem with an average sports event is that when shooting telephoto and wide open:

(a) you have a flat, narrow (and usually tilting, if shooting from above) plane of focus, so the target feature has to 'walk into' a often very small focus 'box';

(b) there's often a lot of colourful and contrasty stuff on the event field (other players, grass, fences, advertisements etc) for the AF to validly choose from, unless it is well directed and carefully set up (AF-C alone on the K-3 has about 7 options).

My point being that one shouldn't immediately assume front-or-back focus is the issue when shooting sports scenes. Maybe one can make that call quickly when shooting a lens in the studio or landscape, but dynamic scenes are harder to shoot perfectly, and harder to assess problems with.
I don't shoot sports but my daughter often shoots running sports Manual Focus, zone prefocused or Catch-in-Focus for just these reasons. Some years ago an SI football line shooter coached her this way.
03-28-2015, 06:22 PM   #443
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QuoteOriginally posted by jaad75 Quote
it's pretty normal for me to calibrate the lens and that is the first thing I do when I try the new one.
All well and good.

But when you calibrate and test your lens, of course you do so:

- shooting with a tripod,
- under good light (and static WB),
- using a decent static [monochrome, high-contrast] lens test target like a Lens Align target,
- use AF-S,
- select focus priority,
- using spot AE metering, and
- select only one central AF point, or at best a central AF point grouping like the centre 9 on the K-3.

That may give you a baseline, but not all of those test conditions may apply when shooting sports.

For instance, when shooting football (or night rodeo...) you will most likely be shooting using AF-C; expanded-area AF (thus multiple AF points being dynamically engaged as the subject moves across the frame); release priority; under variable lighting, and with dynamic contrast and colour changes happening all the time in the scene in front of the camera.

03-28-2015, 06:42 PM   #444
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QuoteOriginally posted by rawr Quote
That may give you a baseline, but not all of those test conditions may apply when shooting sports.

For instance, when shooting football (or night rodeo...) you will most likely be shooting using AF-C; expanded-area AF (thus multiple AF points being dynamically engaged as the subject moves across the frame); release priority; under variable lighting, and with dynamic contrast and colour changes happening all the time in the scene in front of the camera.
Ummmm...yes, how does that change the AF calibration? Are you saying that the numeric bias is assigned in different ways depending on setting?


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03-28-2015, 06:58 PM   #445
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QuoteOriginally posted by stevebrot Quote
Are you saying that the numeric bias is assigned in different ways depending on setting?
I would say so. The centre points are more sensitive than the outer AF points, for example, to different types of movement and different light levels. If the AF-C has grabbed a AF point in the top right of the 27 points it might have at it's disposal, and you tested for the centre AF point, it wouldn't surprise me to see differences.

My main point is that for action shooting you are measuring your camera settings, the camera AF algorithms, the AF point sensitivities, the metering sensor's performance, and the general camera 'smarts' that stitch it all together to help give you a decent shooting result. Not one or two lens or camera body machining and adjustment tolerances.

Last edited by rawr; 03-28-2015 at 07:08 PM.
03-28-2015, 07:04 PM   #446
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QuoteOriginally posted by stevebrot Quote
Ummmm...yes, how does that change the AF calibration? Are you saying that the numeric bias is assigned in different ways depending on setting?


Steve
No. What looks like front focus in one shot may simply be what the focus fixed on in that specific dynamic scene. In the first shot it looked like the ball was in focus.

I would suggest it would be pretty well impossible to shoot a sports scene at f2.8. The depth of field in some of the shots doesn't cover the person's appendages let alone the other aspects of the scene. Carefully selecting a center point of the depth you want to capture may help, but there isn't time. Stopping down would help quite a bit, at the cost of noise.

It may also be that the K-3 is too slow, and the lens is faster than the body can control. With my DA*300 it is the other way, the focus mechanism is slow, but my Sigma 500mm f4.5 is much faster and sometimes the body lags. In both cases birds flying away either outrun the lens focus mechanism or the body focus control.

If we were worried about the Pentax upgrade cycle justifications, here we are.
03-28-2015, 07:58 PM   #447
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QuoteOriginally posted by rawr Quote
I would say so.
QuoteOriginally posted by derekkite Quote
No. What looks like front focus in one shot may simply be...
Glad we are all on the same page here.


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03-28-2015, 08:02 PM   #448
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QuoteOriginally posted by rawr Quote
For instance, when shooting football (or night rodeo...) you will most likely be shooting using AF-C; expanded-area AF (thus multiple AF points being dynamically engaged as the subject moves across the frame)
It depends on your preferences and what you actually shoot. With Pentax cameras I prefer to follow my subject with preselected AF point/area (one point is always more responsive, but it is harder to keep it on the subject). I shoot AF-C and BBF almost exclusively anyway, even in studio.
QuoteOriginally posted by rawr Quote
The centre points are more sensitive than the outer AF points, for example
Sensitivity is the same (-3EV), accuracy is different (f/2.8) for central points.
QuoteOriginally posted by derekkite Quote
What looks like front focus in one shot may simply be what the focus fixed on in that specific dynamic scene.
So now we need to wait for Kenneth to say something about his AF configuration and focusing technique he was using here...
03-28-2015, 08:06 PM   #449
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or we could just
03-28-2015, 08:09 PM   #450
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QuoteOriginally posted by monochrome Quote
or we could just

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