Slow AF?


aminstar

Link Posted 14/02/2010 - 19:57
Anvh wrote:

Glad to make a Canon user jealous

ps another film K7 vs 7D link
The K7 isn't doing it that bad right, I wonder if they could throw more power over the contacts to make the SDM move faster.

Hmm, Stephan I think by showing that clip you just put one more nail on the argument about Pentax sluggish AF. Watch how quick the white 70-200 f/4.0 locks in, while with the K7 seems exactly what Mike mentioned, old age pensioner would have run a 100 meters flat before it had locked in
Amin Photo Gallery

RichardDay

Link Posted 14/02/2010 - 20:15
Anvh wrote:
aminstar wrote:
Quote:
the DA40 is a real speed demon, it can focus to close up to infinite and back in less then a second and it looks it's so because of the small focus throw.

Now this really nails the argument. If Pentax can make DA40 so fast at focusing why on earth wouldn't they make their newer and expensive SDM lenses fast also? This I fail to comprehend. In fact the sluggishness of the DA*60-250 was so annoying that I used to pull my hair everytime I tried to focus and now I have ended up with little hair. And if I had kept at it I would have lost the rest of it too.

I think it's because the DA* lenses have a longer focus throw to make it more accurate, that's why I was interesting in how it was with the canon lenses.

btw all the DA limited lenses seem to focus very fast, don't know about the FA though.
Here is a little review about the DA40 and the DA70 where you cans ee the focus speed. link
Around the 3:00 mark for the DA40 and around the 6:00 for the DA70 they go from close to infinite I believe or vice versa
Glad to make a Canon user jealous

ps another film K7 vs 7D link
The K7 isn't doing it that bad right, I wonder if they could throw more power over the contacts to make the SDM move faster.

SDM lenses don't all have a long focus throw. The DA 17-70 is very small and the DA*60-250 is not that much more either, the DA*55 is very long and is very slow end to end.

In decent light the 17-70 is about as fast as the DA 16-45, the 60-250 is maybe a bit slower. I compared my DA*60-250 againt the Sigma 150-500 HSM on a fairly dull day in December and I didn't notice much difference in the AF speed, both were fairly quick and positive.

Tha fastest focussing lens I ever had was the FA*24, it was faster than the DA 40 which is very quick. I've had, or tried, most of the FA and DA lenses (including *'s and Limiteds) at one time or another and would say that SDM has no speed advantage over screwdrive AF lenses or vica versa. AF speed seems very dependent on the rotational length and the mass of the focussing element, and, of course, the light levels and contrast.

I've used a Canon 1D mkII, the 70-200 f4 L and 100-400 L lenses and it was blisteringly quick with both, you almost didn't notice it focussing. I wish you could get the same performance in a package in less than half the size and weight! Some say the Oly E3 and their latest SWM lenses is a fast combo.

I find my K20D more than adequate with the 60-250 and I would say I get around 70% in focus shots when I'm birding and that's pretty high. The number of keepers is much less due to my inadequate skills!
Best regards
Richard Day

Profile - link - (click on About for equipment profile) - My Flickr site - link

Anvh

Link Posted 14/02/2010 - 21:00
aminstar wrote:
Hmm, Stephan I think by showing that clip you just put one more nail on the argument about Pentax sluggish AF. Watch how quick the white 70-200 f/4.0 locks in, while with the K7 seems exactly what Mike mentioned, old age pensioner would have run a 100 meters flat before it had locked in

Wasn't there a preproduction version of the K7 that was very fast, you and Mike I believed tried it at SRS.

RichardDay wrote:
SDM lenses don't all have a long focus throw. The DA 17-70 is very small and the DA*60-250 is not that much more either, the DA*55 is very long and is very slow end to end.

Tha fastest focussing lens I ever had was the FA*24, it was faster than the DA 40 which is very quick. I've had, or tried, most of the FA and DA lenses (including *'s and Limiteds) at one time or another and would say that SDM has no speed advantage over screwdrive AF lenses or vica versa. AF speed seems very dependent on the rotational length and the mass of the focussing element, and, of course, the light levels and contrast.

Richard it seems we got to the same conclusion.

Someone said something about seeking of the focus with the DA*50-135, is that something typical for the K7 since the DA*50-135 does not do that with on the K10D?
Stefan


K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
Last Edited by Anvh on 14/02/2010 - 21:00

aminstar

Link Posted 15/02/2010 - 09:12
Anvh wrote:

Wasn't there a preproduction version of the K7 that was very fast, you and Mike I believed tried it at SRS.


Yes that pre-production model was fast, but to be quite honest and after trying other systems I can categorically say that even that pre-production model wasn't fast to the same standards of 7D for example.
Irony is if the K7 released for sale was at least as fast as that pre-production model then I would be using one, and me and Unlocker and the likes wouldn't be complaining so much

Hardgravity wrote:
and having seen comments on here about speed/reliability I don't think I want one!

Is speed and reliability of AF inversely proportional? Hmm, in my short experience in the field at least I haven't noticed it, everytime I have heard that beep sound and released the shutter I have nailed the focus, and the times that the shots were OOF the problem was me.
So I hope Pentax is not using that as an excuse for not coming out with a faster AF, its a feeble one and non valid. You just have to see the examples like the one Mike-P mentioned about having a dog running towards you and then firing the shutter and checking what percentage of focused shots you got.

And yess the burst rate seems like a bonus but one that I haven't got into yet. And now that you mention may be I should give it a thought and try to take advantage of it. I just can't imagine situations where it could be well used. A few times I used I just ended up bored with the number of almost similar shots that I had to process so I stopped using burst mode. But may be I should have a go again and different situations and see. In my view though the burst mode of the K7 seems far adequate. So there you go, each individual has different priorities
Amin Photo Gallery

Greytop

Link Posted 15/02/2010 - 09:30
RichardDay wrote:
[quote:3496ace15f="Anvh"]Some say the Oly E3 and their latest SWM lenses is a fast combo.

Very much so, one of the quickest I believe.
In fact even the using an E-510 body my 12-60 and 50-200 SWD lenses were much faster (and very accurate with it) than the comparably specified 16-50 & 60-250 SDM. There again Oly (like Canon) use high torque ring motors rather than the geared micromotors that Pentax has opted for.
Regards Huw

flickr

George Lazarette

Link Posted 16/02/2010 - 00:26
Beats me how HCB and all those other so-called great photographers managed to take any good pictures at all.

I mean, everybody knows that fast auto-focus is the sine qua non of a good photograph. Especially for still-lifes, landscapes, reclining nudes, etc., etc..

Methinks some people spend too long reading advertisements - and, what is worse, believing them!

G
Keywords: Charming, polite, and generally agreeable.

Greytop

Link Posted 16/02/2010 - 00:39
I don't think there is much doubt that if Pentax lacks any capability in comparison to the competition it is focus speed.
Having said that and as George points out, this is really only an advantage with certain types of photography and even then it is possible to adapt and improvise to achieve the result (in a lot of cases), particularly if you have got to know your camera well
Regards Huw

flickr
Last Edited by Greytop on 16/02/2010 - 00:51

edumad

Link Posted 16/02/2010 - 10:33
I think a good camera is not one that forces you to gain additional technical skills not required for improvement of the aesthetic quality of your photography, but solely needed to overcome shortcomings of the mechanic instrument in use.

We might enjoy talking gear and specs, nerdy pleasure I suppose. But at least the one that are not consumed by brand fighting, do so based on facts and figures. And however much you want to look the other way and flash other qualities in peoples eyes, it does not take away the reality of the facts.
TWAPSI Blog

PG

Link Posted 16/02/2010 - 13:54
Quote:
Beats me how HCB and all those other so-called great photographers managed to take any good pictures at all.

Excellent point. For the majority of photographs people take, the Pentax AF speed is more than sufficient. The Sigma 70-200mm HSM on my Canon focuses really fast, but the 17-85mm USM is roughly the same speed as the 18-55mm WR on my K-7.
PhilipGoh.com - Wedding and Portrait Photographer

KZ

Link Posted 16/02/2010 - 19:35
Use/used K200/K20/K7 with 16-50/2,8, 50-135/2,8, 55/1,4, 200/2,8, all sdm lenses. Also C40d with C17-85/USM, C70-200/4/USM, Tokina 11-16/2,8/screw-drive and Sigma 30/1,4/HSM. Even the slowest lens on C40D (Sigma 30) is faster than the fastest SDM on any Pentax body. And the C lenses and even the screw-drive Tokina is a class faster than the Sigma. So yes, at least the SDM lenses above are very-very slow. Of course, if you shoot e.g. landscape it is not a problem. But if you have three ever moving children…

ChrisA

Link Posted 16/02/2010 - 21:36
George Lazarette wrote:
Beats me how HCB and all those other so-called great photographers managed to take any good pictures at all.

It's certainly amazing that sports photographers of old managed to take any sharp photographs at all. I suppose they practised and practised, and got very, very good, at the things that mostly we only need to do some of the time these days.

And good luck to them - but I bet the average amateur had nothing approaching that level of skill.

For landscapes and architecture, of course, AF is irrelevant, and for street shots where mood and subject matter are most of what is important, and wide angle with lots of depth of field takes care of most of the rest, it's very nearly so.

So citing HCB isn't perhaps the best example to choose here. A 1940s sports 'tog, much more so, maybe.

Quote:
I mean, everybody knows that fast auto-focus is the sine qua non of a good photograph. Especially for still-lifes, landscapes, reclining nudes, etc., etc..

Methinks some people spend too long reading advertisements - and, what is worse, believing them!

I don't think this is really fair, George. None, I suspect, of those engaging with this topic here, is foolish enough to suggest that AF speed is the be-all and end-all of all things.

If we only wanted a simple camera where we had to do everything ourselves, we could have one of those for twenty quid or thereabouts.

It's not that unreasonable, when paying closer to £1000, to expect that the automatics are both capable and reliable on the one hand, and on the other, to expect that they enable us (with a lot less skill than the uber-focusers of old) to do things we'd never consider attempting with the £20 alternative.

It's in that rarefied corner of the performance envelope that the arguments are relevant. And there are enough variables to make it a genuinely difficult thing to assess.

Your point is well taken, I'm sure, but it's a touch facile to rubbish the whole AF-speed argument just by saying "well HCB never needed all this new-fangled gimicry, so what's the fuss about".
.
Pentax K-3, DA18-135, DA35 F2.4, DA17-70, DA55-300, FA28-200, A50 F1.7, A100 F4 Macro, A400 F5.6, Sigma 10-20 EXDC, 50-500 F4.5-6.3 APO DG OS Samsung flash SEF-54PZF(x2)
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Last Edited by ChrisA on 16/02/2010 - 21:38

ChrisA

Link Posted 16/02/2010 - 21:45
Daniel Bridge wrote:
ChrisA wrote:
For aircraft in flight, the K10's AF is more than adequate. For birds, I really don't think it is.

https://www.pentaxuser.com/forum/topic/red-kites-at-rhayader-13176/p-0

Obviously it depends on the birds and the situation, but I wouldn't necessarily write the K10D off for bird pics.


Well those are very good, Dan, I remember them from when you posted them originally.

Certainly large birds, further away, will place less of a demand on the AF speed, than smaller, closer ones that are changing direction frequently and suddenly.

But technique is also, of course, paramount, and yours is clearly not lacking.

I didn't think mine was, at the time, either
.
Pentax K-3, DA18-135, DA35 F2.4, DA17-70, DA55-300, FA28-200, A50 F1.7, A100 F4 Macro, A400 F5.6, Sigma 10-20 EXDC, 50-500 F4.5-6.3 APO DG OS Samsung flash SEF-54PZF(x2)
.

aminstar

Link Posted 17/02/2010 - 09:03
George Lazarette wrote:
Beats me how HCB and all those other so-called great photographers managed to take any good pictures at all.

I mean, everybody knows that fast auto-focus is the sine qua non of a good photograph. Especially for still-lifes, landscapes, reclining nudes, etc., etc..

Methinks some people spend too long reading advertisements - and, what is worse, believing them!

G

You confuse me now with your comment George. Particularly with your latin phrase. If my translation is correct it stands for indispensable, essential, condition, or ingredient or if we go further and take the Wiki meaning of it "(a condition) without which it could not be" or "but for..." or "without which (there is) nothing" then you are just concurring with many of us in criticising Pentax for not having a faster AF.

Could this be a first where we see you criticising an aspect that Pentax really lags behind? Or was it just a mere confusion from yourself while using the latin terminology and what you really wanted to imply was that we who keep pointing the big AF flaw in the Pentax system should really just go and improve our technique.

And also I don't get it with regard to "still-lifes, landscapes, reclining nudes, etc., etc.." needing fast AF, I thought these are the types of photography where fast AF is not really needed.

But then again, what do I know? I am just a novice and I still have a lot to learn and worse still probably been spending too long reading advertisements - and, believing them!
Amin Photo Gallery

ChrisA

Link Posted 17/02/2010 - 09:08
aminstar wrote:
And also I don't get it

Perhaps you should also look up 'irony', Amin
.
Pentax K-3, DA18-135, DA35 F2.4, DA17-70, DA55-300, FA28-200, A50 F1.7, A100 F4 Macro, A400 F5.6, Sigma 10-20 EXDC, 50-500 F4.5-6.3 APO DG OS Samsung flash SEF-54PZF(x2)
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iceblinker

Link Posted 17/02/2010 - 09:55
Amin, I think the point is that you rarely need AF at all to take great photographs, let alone fast AF.

I know Pentax doesn't have the fastest AF and I DON'T CARE. So please stop going on about it and go and enjoy your Nikon or whatever it is.
~Pete
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