Solar spectrum lens test - Olympus M.ZUIKO DIGITAL 45mm f1.8

[Dmitry]

Gear used:

Olympus e-pm1 body full spectrum converted myself.

Olympus 45 f1.8 lens.

More details in index topic

 

no filter

 

zwb1

 

zwb2

 

zwb3

 

zwb3+qb21

[Cadmium]

Looks like the UV+Blue+Green stack is leaking red.

[Dmitry]

Yes, zwb3 does leak some vis and IR

[Cadmium]

All of your stacks are leaking red/IR, from the looks of your tests.

Now, if you are 'pushing' the exposure too much, then you will see transmission of quite strong OD,

but if you are using a 'normal' exposure, one that exposes a UV scene shot normally using AP, for example, then the red/IR should not show up at all in any of the stack tests.

Otherwise, the stacks are leaking, and they need stronger (thicker) red/IR suppression glass (or a combination of thicker U and thicker BG/suppression glass).

[Andy Perrin]

I think this is meant to test the lens not the stack? So he doesn’t care if there is some IR as long as he can see the solar lines in the UV side.

[Cadmium]

Well, the lenses look good, I guess, but it is certainly showing me something about the stacks.

I care.

[Cadmium]

As far as the lens transmission... it is hard to say how deeply the lens is transmitting into UV using this method, it seems to me.

[Andy Perrin]

I gather his idea was to use the solar lines which occur at known wavelengths.

[Cadmium]

Might be nice to show some markings for that then. Regardless, the stacks leak.

[Dmitry]

Andy, you are right. Two very close dark lines are H and K Fraunhofer lines, wavelength is 393.366nm and 396.847nm.

Next to left is L line, wavelength is 382.044nm.

[Cadmium]

Can you mark those for me? Not sure which two lines and next line you mean... looks like a few of each to me.

Might be good to have reference makings at the bottom.

[Andy Perrin]

Yeah, it would be nice if you'd label the lines for us, Dmitry? (I agree the stacks leak, wouldn't want to use them for photography. I think they are okay for this purpose, however.)

[Dmitry]

Let me mark lines at 25mm lens test thread.

[Cadmium]

It would be nice to know two things, UV depth nm limit, and IR upper nm limit.

And, it would be kinda cool to have a few other nm points of reference also.

I really like how it looks and however you are doing it.

[Andrea B.]

Yes, we need to focus (no pun intended!) on the UV-capability of the lens which the ZWB filters can show us. Although we do all care about how these filters would perform for ordinary photograpy.

 

I'm going to help Dmitry organize his results. We will make sure that the leakage is commented about in proper context. :D