DA 12-24mm advice

I bought this lens last Saturday from SRS as I wanted a wide angle lens for the airshows that I'll be going to this year and having read some of the posts on here it seemed to get very favourable reviews.

I've just been having a play with it and at first glance the images don't seem very sharp at all, in fact using my 18-55mm kit lens seems to produce sharper images.

This shot was taken at F4 using centre AF and multi segment metering, 1/250 @ 24mm & ISO 400 & SR was activated. The K20 was set to Premium JPEG setting. I've also included a 100% crop.

Some comments would be useful as to whether this is the type of quality this lens produces or whether it is the photgrapher!

[IMG]http://i477.photobucket.com/albums/rr139/RobbieB_album/mondeo1.jpg[/IMG]

[IMG]http://i477.photobucket.com/albums/rr139/RobbieB_album/mondeo2.jpg[/IMG]

Thanks

Rob

Hmmmm... shooting wide open isn't the best way to judge the sharpness of any lens
You really want to test around f/8 at least, and check both the centre and the edges (not just the edge as you've shown) since there can be differences in sharpness according to region.

I've had both very sharp and disappointing shots from the 12-24... and some of those cases were down to focus error (which I corrected in the K20D custom menu). Additionally, I wonder if it's best to turn off SR when using the 12-24 - as at this wide angle shake is hardly a problem

HTH!
Matt

I've been considering this lens for a while.

But most magazine reviews suggest its a soft lens. I'm not sure if the Tokina version is the same as the Pentax version but that also has had some unfavourable reviews when compared to the Sigma 10-20 in other mounts.

That said, all reviews have said that the 12-24 is decent at F8 - F11 though.

I know we are loyal to Pentax but at times I think we are too loyal and overrate some of their lenses.

There are lots of Pentax lenses and the poorer ones we note as such, but sometimes it depends on what the lens is designed for.

For example, the SMC Pentax-M 120mm f2.8 is soft at wider apertures. That's because it was designed to be so, as a portrait lens where cruel sharpness is not what we always want. I still don't like the lens, but that's just me, it doesn't suit what I want from a short telephoto.

The 12-24mm is a critically sharp lens - I use mine for landscapes and architecture. In the latter case it's ideal because the distortion is very low. But I would be using it to maximise DOF so generally f8 or smaller apertures. It's much sharper even at f4 though than your pictures suggest, so something else is awry.

I would run a test on a brick wall, making sure the camera back is parallel to the wall, at various apertures and with very careful focusing. On a tripod of course. Then see if the lens is sharp at all apertures and how much if any it drops off towards the edges.

This will give you a better idea of what is happening. If the pictures are not crisp then something else is definitely wrong. And when I say crisp I mean more than just in focus and sharp - I mean critically sharp.

It would be a mistake to just evaluate sharpness when considering a lens
There are other factors (some that are especially important in super wides like the 12-24).

The 12-24 is an excellent lens, and I wouldn't part with mine
Colour and flare handling is stunning. e.g. http://www.ephotozine.com/u16488/gallery/1026108
(BTW this looks absolutely fab at 18"x12" - and very, very sharp )

Mine suffered a knock some while back (the hood took most of the impact and cracked), and I've been wondering whether it could do with a bit of TLC & a service since then... (but that was long before the above shot!)

Matt

Absolutely right, but in the first instance I think we need to establish whether or not this sample is OK. The other factors are built into the design of the lens and help it give the sparkling results that it does.

I wouldn't part with mine either!

That is very true.

This is one thing Pentax glass is renowned for and is why im still consiering getting the DA16-45 and 12-24 instead of say the Sigma 10-20 and 17-70.

Although I still think we underrate non pentax glass on here. That said, as 2 expirenced members I'll trust your judgement that the 12-24 is a decent lens.

My 12-24 is pretty much permanently on my camera at the moment (in the absence of my 50-135mm). I found that I used the wide end of the kit lens mostly, and now I use the "tele" end of the 12-24... Nice to have 12mm when you want it though.

Rob, I'm not sure what your focus point was here but it almost certainly wasn't the rear light. As the others have said testing a lens at it's largest aperture is not a reliable way of testing a lens. Also iso400 isn't going to retain as much detail as iso100 due to noise control smudging the details.

Try a few tripod mounted shots at a smaller fstop & base iso. See what you then think.

Also a tip on your technique there. There is no need for such a fast shutter speed when you are not trying to capture things in motion. You could have lowered your shutter speed by one or two stops (maybe more depending on your technique) this would have allowed you to shoot at a smaller aperture &/or lower iso & resulting in a sharper image. (Apologies if I'm teaching my granny to suck eggs here)

Bob

Even though it may be sharper at smaller apertures, testing at the largest aperture is needed to ensure it is ACCEPTABLY sharp at the largest aperture.

In fact the 12-24 should be very sharp even at F4 accordng to http://www.photozone.de/pentax/133-pentax-da-12-24mm-f4-al-ed-if-review--test-re... - in fact near enough to F5.6 and F8 to notice hardly any difference.

I would also test other lenses at the same aperture or larger to test the camera's AF accuracy. With a K20D, try AF adjustment in the Custom menu to see if it makes any improvement.

Agreed about the focus accuracy Pete. In fact the first thing I do when I get a new lens is whip out the focus chart. I then make the necessary adjustments if required, before firing off some real-world test shots.

It would probably be better to test at 100ASA if possible 400ASA
is a bit too high. You might have to use a tripod at this time of
year or do it indoors with flash.

The exposure looks OK considering it's a black car and snow.

shim

Thanks for all your help and advice.

That's what I like about this forum, there seems to be an answer to everything!

I'll try all this out in the next few days and see how I get on.

Rob

Its difficult to tell exactly but it looks to me as if the centre of the picture (just below middle of rear door window) includes a REFLECTION. Centre point AF was used so focus could be on the reflection NOT the car - if so tail lights of car could simply be outside of the depth of field.
I would try again without any reflections to throw off the AF.

Good luck
Bob