Wide angle zoom - recommendations

I am looking at buying a wide zoom (10-20mm) for my K10D and rather like the sound of the Sigma 10-20mm f/4-5.6 EX DC but see that this is only available without the HSM for Pentax mount ( I assume this is still an Autofocus lens ). Anyone had experience of this lens or prepared to make other recommendations (happy to invest around £ 300 - don't tell the wife though !

Pentax doesn't use HSM - it's driven by a motor in the body.

It's only the forthcoming Pentax 16-50, 50-135, and 60-250 star (read expensive) lenses that have supersonic motors.

For the focal length you mention there are only two rectilinear options: the Sigma 10-20 and the Pentax 12-24. And in your budget that narrows it down to one

Note: There is also the Pentax 10-17mm fisheye that is around the same price. Note that it is a non-circular fisheye, and at 10mm it will have 180 degree angle of view - much more than even the Sigma.

So, it depends what you want to capture.

The other thing to take note is that both the 10-20 and 12-24 struggle with Cokin P ND grads. You need to shell out another couple of hundred quid for half decent Z-Pro or Lee filters to work with these lenses! The fisheye cannot take filters at all.


Depending on what you have currently, the SMC-DA 16-45 is available quite cheaply and is an absolutely cracking lens. Coupled with a set of decent P-sized ND grads you've got a really excellent landscape lens (different in quality to the 12-24 and in many ways easier to use).

Decisions, decisions
Matt

Thanks for the prompt response.

I am still a little confused though - you say the Motor is mounted in the body yet the latest lenses from Pentax will have supersonic motors, how will that work? Will this make the focus response quicker I assume.

I already have the standard 18-55 lens and surprised the 16-45 would give me much more in the way of field of view.

Looks like I shoould have bid higher for a Sigma 14mm that went on ebay for £ 160 recently!

Keith,

The new lenses will have internal motors that will work with the K10D only. (For all other bodies these new lenses can be driven by the body motor.)

It's supposed to be (a) quicker, (b) quieter.
But we'll have to wait and see
Having said that, the K10D has probably the fastest focus motor of the Pentax DSLRs and SLRs - so don't let lack-of-HSM put you off!

There's enough difference in AoV and quality to make the 16-45 tempting. The only niggle I have with the ultra-wides is I find I often have to switch lenses in the field because 24mm (or 20mm for that matter) is still too wide for a lot of shots I take.

But, as I said, it depends on what you want to take, and what style
There are a few on this forum that have the Sigma and can give you an idea of its performance (try doing a search here).
Matt

I sent an email to Sigma UK a couple of weeks ago asking if there were any plans in the works to start making HSM lenses in Pentax mount. They said they hadn't heared anything about it.

Since Sigma usually reverse engineer things I imagine we'll have to wait a while after the DA* lenses hit the streets before Sigma will have figured out the command protocols etc.

I wouldn't worry too much about HSM on a wide angle though, can't really see the extra focus speed being necessary for wide angle shots.

Hi Snappy,

I've got the Sigma 10-20, and find it a nice lens - certainly very well made and solid, like the other EX lenses. No play in the lens barrel at all, and feels lovely. Focusing is quick and smooth.

Having said that, I don't use it nearly as much as my Pentax 16-45, which I got to replace the kit lens (18-35) that I got with my istD. I was used to the angle of view I got with a 24mm lens on film, which is the same as 16mm on digital.

I got the 10-20 because there were situations when I needed a wider view, but couldn't justify the cost of the Pentax 12-24, and I felt that that lens overlapped a little too much with my 16-45 too. On the occasions that I've used it, I've been more than happy with the Sigma.

There is barrel distortion at the wide end, and it is noticable on horizons (see below), but I would assume software would correct this (PTLens?), not something I've investigated.

Image below taken handheld, at 10mm, 1/1000s at f/9.5, into the sun, using the supplied petal lens hood. Enlarged areas are shown 'full size', ie the same as if you were looking at them at 100% in photoshop. RAW file converted in C1 LE (no sharpening), USM of 120%, Radius 1, Threshold 0 applied in PS.




Form the bottom left hand corner:



From middle right:




As far as drawing any conclusions from this - you can't really, other than decide whether the level of detail is sufficient for your needs, distortion is excessive etc. You can't compare it to any other pics you might see on the web as the conditions would be totally different, but as an isolated example here it is!

Hope that helps,
Dan

As an extra consideration, just had a quick look at the Sigma, and noticed that the barrel distortion is all but gone by the time you've zoomed from 10mm to 12mm.

If this was a focal length that you needed a lot, then it this lens might give you better results from a drawing point of view than the Pentax, although that's purely based on the assumption that the Pentax will suffer from distortion at 12mm.

I am fully prepared to stand corrected!

Dan

The Pentax has a small amount of distortion - nothing that can't be fixed in Silkypix or PTLens
Likewise the Sigma.
Yes, the Pentax 12-24 is a great lens - superb flare resilience, very sharp, and superb on the K10D. It's also tiny compared to the Sigma. But it's expensive

To answer your previous question: going from 18 to 16 is like going from 28mm to 24mm in film. A definite difference. That's why I was suggesting you ask yourself how much you really use the very wide angle (I don't use it as much as I'd thought and often find I'm taking images in the 16 to 20mm region which are just fine on the 16-45.) And why I suggested that some ND grads might be a more useful investment if you are concentrating on landscapes...

HINT: Come mid-March there'll probably be some second hand 16-45's going as the 16-50/f2.8 comes along

Matt