Why do Pentax lag with autofocus?


dcweather

Link Posted 26/01/2013 - 15:27
Just been out in the lovely sunshine and again found my K-30 lacking in autofocus speed. I've seen an improvement over K-r but not massive.Two ducks we were watching took off so there wasn't a massive re-focus need by my DA* 300mm. Swung round and panned but just couldn't hit the focus. My friend with his aged Nikon D300 and also a 300mm prime got them both no problem. This happens time and time again and I have spoken to other Pentax birders who say the same. The question is, then, why can't Pentax match this old technology with their otherwise competition beating cameras?
Dave

Mike-P

Link Posted 26/01/2013 - 16:26
I don't think the actual af speed itself is lacking so much anymore, imo it's more to do with the speed of Pentax SDM lenses. If you compare Sigmas HSM lenses they are a fair bit faster. Where Pentax are lacking is in AF tracking accuracy and the lack of points (less points means they have to each cover a greater area and so are more likely to pick up on something other than the intended target.

Edit: The 18-135mm is also pretty nippy ... again a non SDM lens
. My Flickr
Last Edited by Mike-P on 26/01/2013 - 16:27

wvbarnes

Link Posted 26/01/2013 - 18:40
I agree the lens is the big factor. My 55 - 300 DA hunts around in high contrast skies when searching for birds, my 18 - 135 DA WR is however quick, accurate and quiet on my K5. I look forward to the former in the laters form factor, DC motor and WR please Pentax.

I always use centre spot AF and set a User mode up for action shots.

senn

Link Posted 26/01/2013 - 20:00
Mike
Some KAF mount equipped Sigma lenses are not equipped with HSM, .. question of technical compatibility (alas !..)

Dave
I've got the K-5 IIs just for 10 days. I took about 150 pics in the meantime by any daylight condition. Before that my best camera was K-x. So far I'm not really impressed by the improvement of AF speed and precision promised with K5 II. I wonder whether is there any significative one.
senn
my flickr gallery
my PPG
Last Edited by senn on 26/01/2013 - 20:04

sussexwolf

Link Posted 26/01/2013 - 20:26
I have the DA 60-250 SDM and find the focusing speed amazing. It's so quiet that sometimes you are listening to see if anything is happening.
K30, K-x, *ist DL. Pentax 60-250 F4, Sigma 18-125 & 70-300

Stuey

Link Posted 26/01/2013 - 20:45
I was playing with my K5 today whilst my son was sledging - only using the Sigma 70-300 APO DG macro - so not an expensive item but the af was spot on - no issues at all

Tracked my son without issue - followed a few birds as well for the hell off it and again focus locked no problem
K10D, K5 plus plenty of clueless enthusiasm.

My Flickr site link

Frogfish

Link Posted 27/01/2013 - 06:24
It is a complicated question and will undoubtedly depend a lot on exactly what is being tracked, how large it is in the frame, which lens and camera combination are being used and, for sudden changes in subject distance, where the focus was in the first instance (e.g. were you shooting at the MFD and then suddenly to a BIF at infinity) and of course the distance from the shooter (smaller object).

Having been paid to shoot a fair few sports events I would have no hesitation whatsoever recommending the K5 for rugby (which I shot),, football, tennis (which I shot), hockey, X games (which I shot), motor racing, moto-cross etc. etc. In my first year I used 2 x K5 with the Sigma 50-150 and DA*300 and they performed very well indeed, the failure to lock focus was relatively far and few between, I'd say a 90%+ success rate.

Last year I also used the Nikon D800, Sigma 500 and Nikon 80-200 in addition to the K5 kit. There is a distinct advantage in AF speed with the Nikon, even when used with the 500 (the 80-200 is lightening fast). I would often be shooting with the 500 and put it down to pick up the 50-150 (which with HSM is a little faster than most Pentax lenses) as the players came close to my pitch-side position and the speed difference is noticeable, but that said the K5 didn't fail me and no make/combination has a 100% success rate.

So yes, the Nikon AF is faster (and their 300 primes, whether f2.8 or the f4, are all very fast focusing lenses) and there are/will be instances where it will get the shot and the K5 would miss, but they are usually specific circumstances and the K5 will get 90% of the shots the D800 would. Of course that 10% is part of the reason I added a Nikon kit - birds are tough when they suddenly take flight from the bushes !
http://frogfish.smugmug.com/ Pentax. Pentax DA*300/4, Cosina 55/1.2, Lens Baby Composer Pro & Edge 80, AFA x1.7, Metz 50 af1.
Nikon. D800. D600. Sigma 500/4.5, Nikon 300/2.8 VRII, Sigma 120-300/2.8, Zeiss Distagon ZF2 21/2.8, Zeiss Distagon ZF2 35/2.0, Sigma 50/1.4, Nikkor 85/1.8, Nikon TC20EIII, Nikon TC14EII, Kenko x1.4, Sigma 2.0
Last Edited by Frogfish on 27/01/2013 - 06:28

Algernon

Link Posted 27/01/2013 - 09:55
I wish you'd stop telling us that you've
got a Nikon D800....ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ!

CZ Lenses ......ZZZZZZZZZZZZZZZZZZZZZZZZZZ!

Why don't you go off and buy a NEW CONTINENT!

-
Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi
Last Edited by Algernon on 27/01/2013 - 09:56

bettyswolloks

Link Posted 27/01/2013 - 10:19
Algernon wrote:
I wish you'd stop telling us that you've
got a Nikon D800....ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ!

CZ Lenses ......ZZZZZZZZZZZZZZZZZZZZZZZZZZ!

Why don't you go off and buy a NEW CONTINENT!

-

Hahahaha I'll have that one there please

giofi

Link Posted 27/01/2013 - 10:19
Algernon wrote:
I wish you'd stop telling us that you've
got a Nikon D800....ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ!

CZ Lenses ......ZZZZZZZZZZZZZZZZZZZZZZZZZZ!

Why don't you go off and buy a NEW CONTINENT!

-

I thought it was a quite useful post, and a very positive assessment of the K-5's AF capabilities. I think a comparison to a professional FF camera with a reputation for excellent AF speed gives a good measure of where the K-5 stands. And considering its price and other positives, it gave me a feeling that it's a great choice for everything except perhaps birds - but that we knew already.....
Giorgio

Pentax Photo Gallery

Frogfish

Link Posted 27/01/2013 - 12:22
Algernon wrote:
I wish you'd stop telling us that you've
got a Nikon D800....ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ!

CZ Lenses ......ZZZZZZZZZZZZZZZZZZZZZZZZZZ!

Why don't you go off and buy a NEW CONTINENT!

-

Everyone on here knows my opinion of you and your integrity so your views on anything have zero interest to me.

When is the last time you actually posted a shot you've taken on PU BTW ?

Do me a favour, if you see one of posts skip past it and you'll save us both making posts we'll regret.
http://frogfish.smugmug.com/ Pentax. Pentax DA*300/4, Cosina 55/1.2, Lens Baby Composer Pro & Edge 80, AFA x1.7, Metz 50 af1.
Nikon. D800. D600. Sigma 500/4.5, Nikon 300/2.8 VRII, Sigma 120-300/2.8, Zeiss Distagon ZF2 21/2.8, Zeiss Distagon ZF2 35/2.0, Sigma 50/1.4, Nikkor 85/1.8, Nikon TC20EIII, Nikon TC14EII, Kenko x1.4, Sigma 2.0

johnriley

Link Posted 27/01/2013 - 12:24
That's enough now please gentlemen....no slanging matches on Pentax User.

Many thanks in anticipation of an end to hostilities.
Best regards, John

Frogfish

Link Posted 27/01/2013 - 12:25
giofi wrote:
I thought it was a quite useful post, and a very positive assessment of the K-5's AF capabilities. I think a comparison to a professional FF camera with a reputation for excellent AF speed gives a good measure of where the K-5 stands. And considering its price and other positives, it gave me a feeling that it's a great choice for everything except perhaps birds - but that we knew already.....

Thanks Giofi. I'm not trying to blow any horn but in this instance at least I thought it was what the OP was looking for, a valid comparison.
http://frogfish.smugmug.com/ Pentax. Pentax DA*300/4, Cosina 55/1.2, Lens Baby Composer Pro & Edge 80, AFA x1.7, Metz 50 af1.
Nikon. D800. D600. Sigma 500/4.5, Nikon 300/2.8 VRII, Sigma 120-300/2.8, Zeiss Distagon ZF2 21/2.8, Zeiss Distagon ZF2 35/2.0, Sigma 50/1.4, Nikkor 85/1.8, Nikon TC20EIII, Nikon TC14EII, Kenko x1.4, Sigma 2.0

dcweather

Link Posted 27/01/2013 - 18:37
As the OP who has now having seen the result from Nikon 300D shot compared to my failed one could one of the experts suggest an improved technique or settings for me. I was, incidentally going from being focused on the ducks to them following take off so there wasn't a massive change in focal distance. My camera would still have been on AF centre spot. WOuld I be better off with lots of focal points and the 'C' setting. This was with DA*300 and K-30 by the way.
Thanks, Dave

michaelblue

Link Posted 27/01/2013 - 19:30
I was told by a professional wildlife photographer that when photographing birds in flight (with a plain sky background) to use ALL focus points, otherwise switch to ONE focus point-usually centre. If you think about it, it makes sense. It works for me.

Although I do agree, Pentax do lag behind when it comes to focus tracking. For me it's the only area where Pentax are behind the competition
Regards,
Michael
My new website:link
Last Edited by michaelblue on 27/01/2013 - 19:33
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