Infinity focus setting DAL 18-55 Supplied with KR

Arrived at high point near Clee Hill (Titterstone) yesterday just as storm was approaching. Followed my old film camera practice of taking a few snaps quickly in case storm arrived too fast to set up properly (it did!) Usual practice is - onto manual, check exposure, set focus to infinity (ie turn focus ring to max) and off we go.

Disaaster! - image quality awful!

So I did some tests, the upshot of which is that if I point at a distant object (block of flats) and take picture with focus set to infinity, focus set to recommended distance, then autofocus, the results are acceptably sharp from the auto and recommended focus shots, but everything - and I mean from 20 feet away into the distance- is blurred when the focus ring is turned to its full extent! Tried again with shake reduction switched off, same result. All on a tripod of course.

Similar tests (infinity v. recommended focus) using older 200mm F4 and 28-80 lens from MZ5N did not show this trait (and gave sharper images anyway).

Lens at fault is the 18-55 DAL 3.5-5.6.

Question 1)Do I have a faulty 18-55 lens which just produces rubbish when the focussing ring is turned to its fullest extent, or is there something I should know?

Question 2)Can anyone recommend a better quality replacement, preferably that does not have this trait?

Not sure if this is relavant but i have recently purchased a K-x with kit lens 18-55 DAL 3.5-5.6 When using manual focus i found the same and have found a slight tweak to the left (i think it full right for infinity) seems to sort the image out.

I have read that the kit lens is a cheaper quality version so assumed (I Know its wrong to) that this was one of the effects.

For recomendations i think the 18-55 DA 3.5-5.6 will be better but i'm new to Photography so i'd ask someone else to advise you. I've just joined here but i think someone will comment soon and sort you out,

and of course Welcome to the forum. (If i'm not too new to say that)

Will

Ah well, its back to leaving on autofocus, or just keeping the 28mm SMC on!
Thanks to all for your info

The DA L 18-55mm lens is excellent optical quality (take a look at the pictures by morpheus71 in the gallery).


The recommendation above is not necessarily correct as the DA L version is optically identical to the DA version. I have had excellent results with this lens which is sharp and typically 'Pentax' in terms of colour and contrast. I always rely on my eyes if focussing manually and have had no issues with the lens. I think the other guys above are basically correct in stating that many lenses focus past infinity and I would also guess that unless you are unlucky and have a 'bad' copy of the lens, there's probably nothing wrong with it.

Regards
David

Which is not 100% correct to my knowledge The DA version is the first generation, the DA II / DA-L / DA WR are the second generation with improved optics.

Well, you could run your own test...

I have just checked the 18-55 DAL that was fitted to my own K-x, using some leafless trees about 100 yards away as 'near-infinity'. Set to midpoint (35mm) I found that:

(a) autofocus on distant trees, then switch to manual focus: the ridged focus ring can be moved about 2 mm further before reaching the mechanical stop. Difference in the viewfinder only just perceptible.

(b) in LiveView (with the image magnified as much as possible with successive presses of the 'INFO' button) best focus at about 100 yards was again a couple of mm short of the end stop. This was true whether I was in MF the whole time, or if I used Liveview AF before disengaging the AF into MF, to allow the focus ring to move. Again, the defocussing at the end stop was very slight.

If you find a big difference between infinity autofocus, in any mode, and the mechanical end-stop, I would think that you have good grounds for claiming a replacement lens.

BTW: I seem to remember that there is still a lot of ironstone ore in Titterstone Clee - enough to make compass bearings unreliable. Is it wise to be up there in a thunderstorm?

Take care,

Martin

An afterthought: I can recommend karma mechanic's method for checking the accuracy of autofocus. It was in the Lens Fine Tune Adjustment thread, on 21/07/2011.

Martin