Originally posted by Barry Pearson
As a result of this thread, I'm considering having my K-3 (superseded by my K-3ii) converted for Full Spectrum. Being superseded, I will not want to use it for visible-light photography.
I have a Hoya Infrared R72 which would appear to be useful on such a camera for IR photography.
But what filters would be useful for UV photography?
The B+W 77mm UV Black (403) Filter has been discontinued.
Hi @Barry Pearson, The R72 will give very nice results. I also use the older 29F for faux color and my favorite is the #87 for more of a monochrome effect.
If you're wanting to have a great learning experience try the UV but be prepared to do your homework before shelling a lot of money out. I'm glad I did.
As @dtrego mentions there is a very nice site for UV information.
Filters are not the initial cost, more it will be a lens that has good UV transmission.
True UV lenses are very expensive but the site mentioned by dtrego has several "accidental" lenses that perform well.
None of my Pentax glass (even vintage K and M series or coated Taks) transmit good UV due to the excellent coatings.
If you are wanting to photograph hand held or on a tripod with shorter shutter speeds and low iso then the lens will be your biggest obstacle.
Older basic triplets seem to be the best and a few 4/4 configurations work too, several older enlarging lenses transmit very well if you have a helicoid to focus with.
I was lucky enough to find an old M42 mount Steinheil Cassarit 50mm in great condition that does well down to 340nm. My old Domiplan 50mm does alright at 360nm. Also I have a Zeniton 35mm I picked up on the forums that works well at 360nm but the longer focal length Zeniton I have performs poorly even though it is still a 4 element 4 group lens.
Oddly enough my old Lensbaby Soft Focus optic transmits down to 340nm (none of my other Lensbaby's have good transmission though). Depending on the lens, the cement used in combining elements into groups can deter the UV transmission quite a bit too.
Filters from uviroptics are of good quality. Note you will also need an S8612 or BG38, 39, or 40 to stack on top. UV pass filters also transmit a lot of IR and will give you more of the IR effect due to contamination if you don't use a second filter to cut out the IR. Check filter transmission charts to see which you might prefer..
One of my post using the Steinheil:
Needing a challenge - UV340 - PentaxForums.com
and one using the Soft Focus optic:
UV attempt with Lensbaby - PentaxForums.com