[HawaiianOnline]

For those of you that do IR photography with your Pentax cameras, what zoom and prime lenses have you found to work very well with an IR modified camera? My personal experience has been that the original 18-55mm kit lens and the WR version works reasonably well, and so does the Sigma 70-200 f2.8. However, I'm wondering about other people's experiences with other lenses.

[blackcloudbrew]

I concur with you on the kit lens with IR. I can tell you that the DA 12-24, DA 14, DA*55 are not good lenses for an IR camera.

[chickenandavocado]

may i know the reasoning why the other lenses may not work as well?

[HawaiianOnline]

may i know the reasoning why the other lenses may not work as well?

Some lenses have a tendency to have hot spots when used for IR. My Sigma 18-50 f2.8 has that problem. Some aren't very sharp in IR, or can have a nasty flaring problem.

[blackcloudbrew]

HawaiianOnline is correct. I've seen lots of flaring with all three lenses and the DA*55 has a definite tendency for IR hotspotting. It has to do - or so I've been told - with the coatings not being optimized for IR light. That has been my experience with these lenses over the past year or so. It doesn't happen all the time but it happens. Oddly the kit lens seems to be much more resistant to both IR flaring and hotspotting.

This past February, I shot all month with my IR converted K100ds and my Samsung 12-24 (rebranded Pentax DA 12-24). You can see my results here:
Single in February - a set on Flickr
Clearly sometimes it's ok and sometimes it's very not ok.

[creampuff]

There were previous threads on this topic.

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/66895-ir-infra...tml#post671922

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/33394-lenses-u...otography.html

[mano]

Thanks for the links to the older threads, Creampuff. I had been unaware of the lens problems when shooting IR.

I did experiment with a Hoya filter on an unmodified K5 this summer and seem to have missed the problematic glass by chance ;-).
I've been using the DA15, DA35 Limited and M28 2.0 so far, the last one not being mentioned in the older threads, I think - it works quite well.

[blackcloudbrew]

Wow, thanks for the links to those thread Creampuff. Quite helpful. I have to laugh that the kit lens is one of the better IR lenses in all of this. I'd gotten to that understanding in my work with my IR camera. As I haven't had much use for the kit lens in other stuff, it seems that the kit lens will be more permanently affixed to my IR camera now because of this. I'm glad it has found a useful roll. I'm not running the kit lens down, but I've aquired so many other lenses that are better that the kit lens has been gathering more dust and was moving into the sell off list. Thanks.

[creampuff]

If you guys think IR shooting is only about shooting landscapes, you should view the work of Jakarta based Pentax photographer Kesha (his nick). He's a very experienced portrait shooter and has a good following from his many Singapore based Pentax friends.

K10D Diva InfraRed

Diva Infrared in Studio (5 pics) (Not work safe)

[HawaiianOnline]

Thanks for the links!

[Digitalis]

Also the DA15mm f/4 isn't very good at IR either, it suffers from some pretty bad flare:



not to mention the image quality from the DA15 in the corners is really bad even at f/16 with IR light