Lovely. I can hear Clarky's teeth gnashing from the Sydney as we speak...

Well, so do I now.

Ordered two nights ago, shipped yesterday, received today, from LoobyLin's.

Perfectly clean front end now (with lens cap on.. )

Thanks for the other suggestions folks (couldn't easily find a supplier of the Kodak fluid - where do you get yours from, John?).

This is what was worrying me - the microfibre cloth was almost new, and that's exactly what I did.

I'll try the fluids suggested next.. thanks all.

I remember you said that - I'm really careful, actually (honest, guv - I know I talk as if I'm a bit lax, but as far as actual impacts go, I'm neurotically careful).

For instance, when I open the SD card door, I never let it ping open - I always catch it as it swings out. And to save wear on the catches, I rotate the release before pushing the door shut!

Ok, I admit it. I bought a Hoya 77mm Pro1 digital UV filter to protect (yes, goddammit) the front of my new 10-20.

I know I'm evil. I don't switch the camera off between lens changes, and I forget where the lens cap is quite often (that's one reason I like the transparent, screw-on type that says Hoya on the rim), and I'm not a good enough photographer to notice the alleged optical difference.

But let's get over that. Here's the issue...

I got something on the front of the filter that I can't get off with a microfibre cloth (an actual Pentax one) and huff.

I'm certain nothing worse than finger print grease has got on it. (It's actually nose grease from an annoying 11 year old that thought it was funny to get very close to the camera).

Yet I can't polish it clear anymore (it's very faint - I can't see evidence of it on the photo's from the Lakes).

Is it possible I've rubbed the coating off with the microfibre cloth? (I really haven't rubbed it all that hard, nor with anything else.

Any ideas? I'm thinking solvents...

K10D, SMC-A 400mm F5.6, 1/500 @ F11

Just as another example, here's my Sigma 10-20 at 10mm, first with the camera horizontal, then pointing up, then down:








Sorry about the flare etc, but it illustrates the point.

You can also see the barrel distortion in the first one - the house walls are actually straight! And yeah, I know the lawn needs mowing

I had a go at fixing the perspective in Photoshop.

This is with the maximum amount of correction available with one pass:




After 2 passes, it looked like this:




I haven't done any resizing, and I've not attempted to preserve the JPEG quality at all, so it may be better if you started with the full size image file.

It's not really correct to describe this as distortion - pointing the camera up as you have here means that the foreground is much closer to the plane of the sensor (measured at right angles to it) than the background.

Inevitably, therefore, everything in the foreground appears disproportionately larger than it should, compared with the background, and the result is the tilting verticals.

All lenses do this - but since with a wide angle lens you stand a lot closer to the foreground, the effect is much larger.

The Sigma 10-20 does display some barrel distortion at the wide end, but this isn't what you're getting here - this is plain old converging verticals, which you get whenever the camera isn't horizontal.

The OP is concerned with distortion more than sharpness. The pictures look sharp enough to him, and indeed, it's hard to know otherwise with pictures viewed on the internet. Let's help him sort out the distortion and its causes first.

Fact: the distortion in the photo presented is normal.

Fact: it's easy to fix without software (although not after the event).

Sharpness, or its lack, is much harder to establish.

First things first.

This is because the lens axis is not horizontal.

Tilting verticals are inevitable in such cases.

Without software, the only way of correcting this kind of distortion is to take the picture with the camera horizontal, and crop off the foreground.