First few with the SIgma 10-20

First impressions - love the ultra wide angle! But quite a tricky lens... it can be adequately sharp all the way across the frame, but some of my closer up shots were really quite soft at the edges despite being at f8+.

It's great for the money though! The final shot shows the sort of thing the lens seems most suited to... I had been here with my 16-45 and failed to get such an interesting angle on the falls (or even get the whole of it in shot).

The location is absolutely awesome by the way, especially if you like waterfalls and industrial archaeology. It's in Matlock.













All shots were at 10mm. Why can't Pentax make a 10mm DA* prime?

Nice shots, the 10-20 is indeed a splendid lens.

A Pentax 10mm prime, what guess the price for such a beast?
Premier League footballer salary springs to mind

Adrian

It's OK, he was only looking for an f1.4, not a 1.2...

I like the last of the series - well captured with the 'near-far' perspective giving an unbroken line between the top of the fall and water near the lens.

A great set from a great lens, have had some great results from this lens. We should start a sigma 10mm thread.

Here's my effort.

Not quite enough beer in there though S-C...

A nice series PP! The last 3 really show off the lens, looks like a great location.

Totally agree with you about the lens as well, along with my walkabout 17-50 the 10-20 is the one lens that never leaves my bag. I guess there are some minor variations across copies but mine seems to be sharp everywhere. It's also fantastic for big skies Incredibly value for money really.

Regarding your comment about softness at the edges in extreme closeups, I've also noticed this and after some investigation I think it is to do with the field curvature i.e. the view is so wide that sometimes objects right at the edge can be simply too close to be within the DOF. Here's an example (the top right is clearly OOF). I don't think it is inherent softness in the corners as in more 'normal' shots the corners seem to be nice and sharp.

An interesting set of pictures. I guess with a lens like that one can take shots in places you wouldn't even consider. My favourite is no.4 with great depth of field and sharpness: it must have been quite dingy in the woods.

A very nice set, I think the comment regarding field curvature sums up the softness at the edges. Many ultra wide lenses perform this way the older 10-20 4-5.6 has a lttle and the DA 15mm to a lesser extent. Looks like a really nice location, I've visited Matlock Bath many times, but less so Matlock itself.

Regards,

John

Would this not also be a characteristic of a completely flat field?

Euh, thinking about it makes my brain hurt - I'm not sure any more. If it was a flat field I think the corners would be even worse?

A wide view of the Tyne bridges
[IMG]http://i799.photobucket.com/albums/yy273/Davidtrout2/SteelAcrossTheTyne.jpg[/IMG]
I love my Siggie 10-20mm. Here's one of the Tyne bridges from the 'blinking eye' Millenium Bridge which links Newcastle and Gateshead quaysides. The view also includes The Sage music centre. I couldn't have got all that in with anything more than 10mm.
I like the excellent quality of your shots Will. I also enjoyed Snappy's fridge view.
David

At a guess, the field is supposed to be flat - it may not be anywhere near perfect, but it is at least supposed to be a rectilinear lens. There's tons of barrel distortion at 10mm, of course, but it's often not a problem.

I think your 'edge too close to be within the DOF' is a very real effect.

The other thing that complicates things with lenses this wide is that it's incredibly easy to have the camera angle such that (for instance) an item at the left edge of the field has its own left edge closer to the focal plane (even if that plane is perfectly flat) than its right edge, which means that the magnification of the left edge is greater than the right, leading to an apparent distortion.

This makes the 'frame, focus and reframe' technique of getting the bit you want sharp by only using the centre AF point very unreliable.

Added to which, of course, with the Sigma 10-20, there's the complication that the DOF is often so extreme that the AF doesn't feel it needs to adjust focus, when really it should.

It's definitely not the easiest lens to get the best out of, but I do like mine very much.

I really like the last shot, Pentaxophile. It's a fantastic lens, mine has hardly been off my camera since I got it! The three on my "Gotham" thread were taken with it. I've found that using it in manual focus can often get round the problem of softness at the edges (when I manage to guess the right distance to focus), so I guess it's something to do with the focus being different at the edges due the light travelling different distances to the sensor. But like Tim it hurts my brain thinking about it.

[IMG]http://i23.photobucket.com/albums/b399/philstaff/Marina1.jpg[/IMG]

It's a great lens so versitile but it does take some getting used to that fridge looks to have pretty much the same contents as mine ya cant beat John Smiths .
Ian