Checking my lenses for UV capability

[colinbm]

First up is todays Sun spectrum for comparison, goes down to 321nm.

 

[colinbm]

Igoriginal refurbished lens, 35mm f3.5, Soligor III, goes down to 336nm.

 

attachment=19563:20200705 Igoriginal 35mm f3.5 Soligor III lens.jpg]

[Andy Perrin]

Amazing how Igoriginal can make the sun stronger than without the lens... (You should probably normalize these somehow?)

[colinbm]

Andy I am new to this, can you explain please ?

[colinbm]

Steinheil Munchen Cassar S 50mm f2.8 lens, goes down to 340.5nm.

 

[colinbm]

Novoflex Noflexar 35mm f3.5 lens, goes down to 345nm.

 

[Andy Perrin]

If you look at the peaks of the graphs, all those graphs have different peaks, and all are HIGHER than the case with no lens in the system (probably the lens is concentrating the light?). Anyway, point is that you can't compare one graph to another to see where it drops off if all the peaks are at different heights. So I'm suggesting that you normalize (divide by) the height of the maximum value so that all the graphs will be comparable. E.g. Divide the Cassar by 0.161, the Noflexar by 0.069, etc. Then you can plot them on top of each other to see what is going on.

[Cadmium]

http://www.optimumopt.com/?mod=product&col_key=product&cate_id=49&pro_id=42&t=prodetail&lang=en

[colinbm]

Sigma 30mm f2.8 Art lens, goes down to 360nm.

[colinbm]

If you look at the peaks of the graphs, all those graphs have different peaks, and all are HIGHER than the case with no lens in the system (probably the lens is concentrating the light?). Anyway, point is that you can't compare one graph to another to see where it drops off if all the peaks are at different heights. So I'm suggesting that you normalize (divide by) the height of the maximum value so that all the graphs will be comparable. E.g. Divide the Cassar by 0.161, the Noflexar by 0.069, etc. Then you can plot them on top of each other to see what is going on.

 

Thanks Andy

I think I can see what you mean, I don't know how to change this.

Does it make any difference to the lowest UV transmittance results ?

Cheers

Col

[Andy Perrin]

Not sure, your device seems to cut off at 350, and with all peaks at different values, it's hard to judge the lens by just looking where it goes to zero. Can you export the data to Excel and just do it there?

[colinbm]

Not sure, your device seems to cut off at 350, and with all peaks at different values, it's hard to judge the lens by just looking where it goes to zero. Can you export the data to Excel and just do it there?

 

Andy the device is supposed to be capable of down to 250nm, I don't have any UV lamps that go this low to check this.

The sunlight measured goes down to 321nm today.

I will need to learn this business of exporting the data to Excel & making the adjustments & re-displaying them. I am not a scientist or come from a science background.

Cheers

Col

[Andy Perrin]

Look also for the option to export to .CSV because Excel can open those. You don't need any math more fancy than division so it shouldn't be too bad.

[Cadmium]

They are going nuts outside with fireworks here right about now, not my favorite thing anymore.

His sunlight scan goes down to 325nm. His UV Illuminance Spectrophotometer SRI-2000UV goes down to 250-850nm. SRI-2000+, wavelength from 350-950nm, not sure which.

There are 4 ranges/models available I think.

[Cadmium]

[colinbm]

An oddie, O D Industries 50mm f4.5 lens, goes down to 341.5nm.

 

[Cadmium]

UV Illuminance Spectrophotometer SRI-2000UV

Fancy little piece of equipment.

[ulf]

Amazing how Igoriginal can make the sun stronger than without the lens... (You should probably normalise these somehow?)

Any magnifier can do that, locally.

A camera lens is normally acting like a very advanced magnifier.

Then the intensity at ground level can also vary quite a bit due to atmospheric disturbances.

[Stefano]

To avoid this, you should use a PTFE tile instead of the Sun as your light source.

[ulf]

The UV Illuminance Spectrophotometer SRI-2000UV is a specialised tool for analysing light sources like lamps and LED panels.

 

To get proper transmission measurements with reasonable accuracy will be tricky and need some other light source than the sun.

The math is simple and can easily be st up in an Excel sheet, but the opto-mechanical design of the device is not well suited for such measurements.

[ulf]

To avoid this, you should use a PTFE tile instead of the Sun as your light source.

A PTFE tile radiate very little light by it self and will disintegrate before it become a meaningful light-source, even in the visual range.

[ulf]

For transmission measurements in the UV-region light-sources with deuteriuml-lamps or continuous short arc xenon lamps are used.

https://en.wikipedia.org/wiki/Deuterium_arc_lamp

https://en.wikipedia.org/wiki/Xenon_arc_lamp

[colinbm]

Thanks Ulf

I am looking for suitable lamps.

[ulf]

Be VERY careful!!!

 

Those lamps can be very dangerous, in several different ways!!!

High voltages and temperatures, strong UV, including UV-C, High pressure and risk of explosions are some of the risks.

 

It is NOT well suited for any DIY.

[colinbm]

Yes thanks Alf, I would like lamps that have a housing.