K3 Focusing. Fault or too high expectations.


dcweather

Link Posted 03/03/2014 - 12:21
I have now had the K3 long enough to think that the AF seems more hit or miss than my previous Pentax DSLR's in certain conditions up to and including the K30.
WHen it is right it is stupendous. But it often seems to front or back focus as well as get it spot on. In fact it seems to be in about equal proportions. I doubt the camera is faulty and I have shot a large number with the Tamron 18-250 with few issues. So could it be the DA*300?
This is the scenario. Mainly shooting furry birds in good light with more high contrast adjacent. I could see it missing focus in these difficult conditions but I am using centre spot focusing (back button focus) and do not press the shutter till I get the focus confirmation bleep and I can visually see the focus point on the bird's head or body.So to summarise:-
With DA*300 (calibrated) it misses focus a lot in AFS mode centre spot focus despite positive confirmation. Is this possible?
We can eliminate camera shake/movement due to shutter speeds, tripod, or the static object nearby being sharp.
Examples below:-

1. In focus



2. Back focus



3. Front focus



Any thoughts welcome,
Dave

Gravelrash

Link Posted 03/03/2014 - 12:42
Wow thats some narrow depth of field your working with! I don't shoot birds but I reckon you're expectations may be a little high at 300mm (what's that in old money, 400?)

Strange that you should get front and back focus though. Certainly would seem to eliminate the lens.

Did you allow for wind, bullet drop and curvature of the earth?


Steve

Sometimes I'm serious and sometimes not, but I consider sarcasm an artform. Which is it today?

cbrog

Link Posted 03/03/2014 - 13:01
I had a similar problem with my DA*300 (from new). I was very disappointed with it and came in for a certain amount of stick on the forum for suggesting my 55-300 produced better results (Frogfish even choking on his breakfast!)
The lens was back-focusing badly but, more importantly, it was jumping randomly in and out of focus and this was not always apparent until viewing a shot.
It went to Johnsons via SRS and the AF motor was found to be at fault and replaced under warranty. Since when it has performed perfectly.

Roger

Fletcher8

Link Posted 03/03/2014 - 13:17
Dave, do you know anyone who could lend you a DA*300 so you could compare each lens? If you have other telephoto lenses, are these hit and miss as well?

I don't own the DA* 300, but I have not had any issues with the DA* 200, or the FA* 80 -200 with my K3.
Perhaps the DA*300 needs servicing?
Fletcher8.

dcweather

Link Posted 03/03/2014 - 15:25
Good idea Gareth. NeilP is a friend on here and lives nearby and he has one and now a K3. Will have to get together with him.
... and Roger, yes maybe it should be sent back for a check over. It is well used and coming up to two years old. Sounds like a very similar fault to mine, except when it is correct which is still quite a lot, the quality is second to none.

Fletcher8

Link Posted 03/03/2014 - 15:39
Dave, forgot to state that image 1 is superb. when the DA* hits the mark focus wise it looks like a very nice lens.

I think i need to start saving my pennies and lot of them.
Fletcher8.

dcweather

Link Posted 03/03/2014 - 19:48
It certainly is a cracking lens Gareth - check out the ones that are in focus in my gallery!

davidstorm

Link Posted 03/03/2014 - 21:50
Hi Dave

I haven't noticed any focus issues with my K-3 yet, although I've yet to test it on a wildlife shoot. My old K-5 Mk1 used to behave as you describe, although funnily enough it was with the 17-70, not with my telephoto lenses and it was unerringly accurate on my Siggy 150-500!

That first Crossbill shot is indeed superb, but I would get the camera and / or lens checked out if I were you as it seems odd that it is this variable.

Why not send me your DA*300 and I'll check it out for you

Regards
David
Flickr

Nicola's Apartments, Kassiopi, Corfu

Some cameras, some lenses, some bits 'n' bobs

dcweather

Link Posted 04/03/2014 - 00:18
I would David, just to get some nice Dipper shots, which I'm sure you have around your way

Mannesty

Link Posted 04/03/2014 - 08:35
Gravelrash wrote:
I reckon you're expectations may be a little high at 300mm (what's that in old money, 400?)

I'd agree, DOF seems to be very narrow. 300mm on a K3 = 450mm on FF (1.5x)
Peter E Smith

My flickr Photostream
Last Edited by Mannesty on 04/03/2014 - 08:36

dcweather

Link Posted 04/03/2014 - 20:26
Not sure why this would affect focus? It is fine DOF but why would it confirm focus on something clearly out of focus? It demonstrates it is perfectly capable a lot of the time. I think people like David and Alan Wennington are getting higher success rate under similar conditions.
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