As I have tested many of my 35mm F3.5 lenses for its UV-imaging capabilities, I thought I would also look at other focal length lenses which I own which were bought over the years. Some of these lenses are listed on some sites as UV-transmitting lenses (to varying degrees). The question is whether are they worthy to be on that list?
The 5 lenses I am testing here are: Meyer Optik Domiplan 50mm F2.8 (my first UV-capable lens), Tokina 28mm F2.8 RMC, Nikon 100mm F2.8 E series, Petri 135mm F3.5 breech lock, Helios 58mm F2.
Camera: full spectrum Olympus E-PL5
UV-pass filters: Baader U 2011, 330AF20
Subject: Rudbeckia fulgida
Settings: ISO 200 F8 for Baader U with 1/4 power Quantum X2D, F4 for 330AF20 with full power Quantum X2D
Processing: Baader U images were white balanced by clicking on the sintered PTFE in the background. All Baader U images have + 1.0 EV. The 330AF20 images had +3.0 EV for Nikon 100mm F2.8 and Helios 44mm F2, +1.5 EV for Tokina 28mm F2.8, and no change to exposure for Meyer Domiplan 50mm F2.8 and Petri 135mm F3.5 breech lock.
Distance from subject: The Meyer Domiplan 50mm F2.8, Tokina 28mm F2.8 were placed the same distance away from the subject, with the Helios 58mm F2 just slightly further away. The Nikon 100mm F2.8 E had to be placed much further away from the subject in order for it to be in focus. The Petri 135mm F3.5 had to be placed the furthest away from the subject, and in fact had to be hand held at the end of my table-top as I could not move my Kirk Low Pod any further (hence the two Petri images were not exactly the same).
The Petri 135mm F3.5 despite being the furthest away from the subject, did very well in terms of UV transmission, easily producing the brightest green image of the sintered PTFE with the 330AF20. The Meyer Domiplan 50mm F2.8 faired second best.
The Tokina still exhibits a tiny amount of UV in the 330AF20 image, as you can just about see a little green in the sintered PTFE with +1.5 EV. The Nikon 100mm F2.8 E and Helios 58mm F2 both only exhibit IR-leak with the 330AF20 images boosted up by +3.0 EV (i.e. no UV below 340nm).
So while all these lenses can transmit enough UV to capture the UV pattern of the Rudbeckia using the Baader U, (other than the Petri 135mm F3.5) they don’t transmit much lower UV, unlike the majority of 35mm F3.5 lenses I have tested.