Initial impressions of K20D.....af seems poor.

Hi,

These are just my very first impressions about the K20D....I was expecting the AF to be worse than the Canon 40D I have been using...but it seems quite a bit worse. I compared the 40D + EFS 60mm macro to the K20D + FA-D 50mm macro. The 40D always locks on focus to anything in any light, both silently and within a split second. The K20D sounds very rough in comparison, takes longer and sometimes even with the subject in light shadow takes 2 or even 3 attempts to lock focus.

Is this normal?, I know many people rate Pentax's AF system as poor, but I did not expect a 'night & day' difference to the Canon. Is the FA macro poor? will different Pentax lenses improve the AF to any great extent, or is this one of the downsides of the Pentax DSLR's?

cheers Steve.M.

Many professional reviews of Pentax DLSRs (including K20D) describe the AF as "fast and accurate". The fact that AF may be even better in other cameras is of no relevance to Pentax users who are happy with their cameras. Personally, I'm happy enough with Pentax's AF (when adjusted properly).

AF is faster with some lenses than others. Also with practice you will get better at using the Pentax once you've learnt its quirks and what parts of subjects its best to focus on, etc.

Use the manual selection point rather than Auto.

By the way, the multiple attempts to "lock focus" is actually the camera refining the focus rather than snapping to an instant decision. This makes it more accurate than it would be otherwise.

I agree with iceblinker's assessment. Pentax AF is fine as far as I'm concerned - it snaps cleanly into focus on most subjects, hunts rarely, sometimes has a problem but then so do they all.

The final fine adjustment manually via the manual focus ring is superb and makes use of AF in many close up shots actually very efficient.

Th AF system is also quite old, I believe it was first used on the *ist D right or am I wrong?
They have updated the system along the way, if you compare the K10D and K20D site by site you notice the difference but still it's the same system.

It has the same name, but that's a bit like saying that a Spotmatic is the same as a K20D because it has the same name...Pentax.

A few things have happened along the way.

I've always found it to be very fast and accurate. The only lens I have that can take a while to find focus in low light is my Tamron 70-300, but that's usually because I've forgotten to put the focus limiter on. So it's got a huge range to cover. Even on a cloudy day it's usually almost instant.

But then the only other camera I've had was a bridge camera which was obviously considerably slower. If the sound and speed really bother you then you could always invest in some SDM lenses.

Not quite because the system is called SAFOX VIII
If there is a new version they would call it SAFOX IX right, since the version in the MZ-S is called SAFOX VII.

From that I concluded that the system is still the same but that they have tune it along the way so that it would preform better.

Maybe in the new cameras we will see a SAFOX IX.

Any light?

I have found the focus to be very accurate and reliable. But then I always specify which AF point to use, rather than using Auto.

The original Pentax AF system uses a motor in the body that drives a pin in the lens to focus. This will sound much louder. The benefit is the lenses are much simpler (and therefore cheaper) and often more reliable as a result. So that's where the noise is coming from.

The newer SDM focus lenses have an in-len motor much like the Canon. So these are near silent. But the lenses are usually larger and heavier (Pentax put weather sealing in the lenses with SDM as well).

As for the "attempts" - the Pentax AF does a refinement of the focus. So it will go for a coarse lock, then adjust to get accurate focus. Most other bodies will go with the coarse lock only - which is obviously faster but can result in slight off focus. The downside of the Pentax is that it's a bit slower... but not by much. It just sounds like it's taking an age.

As mentioned many times, my personal setup is to disconnect the AF from the shutter button (with the custom menu), and to engage AF using the rear "AF" button only. Coupled with selecting a single AF point I find this works extremely quickly and reliably in all situations, but especially low light

HTH!
Matt

If unsure about Canon V Pentax focusing just ask the technicians at Sigma for there unbiased opinion.
They have more problems with Canon than any other camera using their lenses, just because the 40D focuses fast does not mean it is accurate every time.

Thanks for all the responses..

...I always use manual focus point selection...I do not often use 'auto' anything...prefering to have as much control as possible. This was just my very first noticeable difference I found...I did expect some pros & cons...the same as any other camera. The reason I have moved back to Pentax is I prefer their combination of 'pros & cons' to the others....

cheers Steve.

Low light performance could be better, that is a fact allthough the K20D is a lot better in low light then my *ist-DS which on paper has the same AF system (version numbering) but in practice it has become better.

Just an observation and I'll add I've not used a Canon to compare but I can say that my K20D struggles a little with focus speed (and lock) compared with my E-510.
Now it's not such a gulf as to be a problem but there is definitely a difference.
Of all the K20D features this is probably one of the weaker areas. Having said that other features compensate to make it a thoroughly enjoyable and capable camera to use

Have you taken the lens cap off...... ?

shim

Somebody get out of bed the wrong side this morning?