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Solar spectrum lens test - Lomo T-43 40mm f4


17 replies to this topic

#1 Dmitry

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Posted 17 May 2018 - 17:28

Gear used:
Olympus e-pm1 body full spectrum converted myself.
Lomo T-43 triplet lens.

Its shortest wavelengths I can see as for today (17 May 2018)

Note - far IR part is out of field of view.

Unfiltered full spectrum
Attached Image: P4308921.jpg

ZWB1
Attached Image: P4308922.jpg

ZWB1+QB21
Attached Image: P4308923.jpg

ZWB2
Attached Image: P4308924.jpg

ZWB2+QB21
Attached Image: P4308925.jpg

ZWB3
Attached Image: P4308926.jpg

ZWB3+QB21
Attached Image: P4308927.jpg

All photos processed from RAW without any color correction.

#2 Dmitry

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Posted 17 May 2018 - 17:35

zwb3+qb21 processed from JPG for colors comparison
Attached Image: P4308927.JPG

#3 Andrea B.

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Posted 17 May 2018 - 18:41

I commented the other Spectrum topic and requested thicknesses of the filters used, please. That is very important in analyzing these kinds of photos.

I'm so fascinated by these spectra.

Another question: When you say "processed from Raw without any color correction" what exactly do you mean? Thanks.
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#4 Dmitry

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Posted 17 May 2018 - 19:42

2mm thickness.

Processed using XnView, its know nothing about applying profiles or corrections to Olympus ORF files (file extension for its RAW format).

#5 dabateman

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Posted 18 May 2018 - 08:38

XnView uses dcraw for raw file conversion and will have a specific recipe of settings to tell dcraw. So there will be changes being made to the files. I think only Raw digger actually looks at unprocessed raw data.
If you want to compare open an orf in ufraw, infran viewer and xnview. All use dcraw and all are free and the output raw will look slightly different.

But more importantly how are you setting up your test?
What grading are you using? How many lines per mm?
What is your light source? If the sun what time of day or where is the sun position?


#6 Dmitry

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Posted 18 May 2018 - 09:09

Handmade adapter and jewelry spectroscope from China (about $30). Have no idea about number of lines. I point it to light white clouds around sun or to silver reflector if no clouds.
Direct sunlight is very narrow and does not lit full range.
Time of day 2-4pm local time.

Photo of setup.

Edited by Dmitry, 18 May 2018 - 09:16.


#7 dabateman

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Posted 18 May 2018 - 14:01

Thank you Dmity.
I am in process of setting up something similar. I have 1000 line/mm film that I purchased, which the spectrum of which was posted here. The advantage of using sun light is its free. But depending on time of day and your location, the available wavelengths will change. So not consistent, I am hoping to build something with consistent and reproducible measurements.
What I do find interesting is the sharp color seperation you see. Not really a full spectrum, but some filtering is going on there. I am not sure how that is occuring.
Keep up your tests, they are interesting. But don't forget to include all the details. Iso, shutter speed, aperture, lens, camera, light source, filters, filter thickness, subject, and processing for each post, as I and other may just stumble into a single post by using searches. I was not following your history.

#8 Dmitry

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Posted 18 May 2018 - 15:09

Its phase one - looking for best lens :)
Made index topic to move common questions. index

Edited by Dmitry, 18 May 2018 - 15:10.


#9 Dmitry

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Posted 18 May 2018 - 15:18

NOTE: right part of zwb+qb21 photo display misaligned lines and different color hue, compared to others. My guess its UV part of second-order spectrum.

Edited by Dmitry, 18 May 2018 - 15:19.


#10 Dmitry

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Posted 05 June 2018 - 18:34

zwb3+qb21 spectrum from another copy of T-43 lens
Attached Image: P5198994s.jpg

Edited by Dmitry, 05 June 2018 - 18:34.


#11 Dmitry

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Posted 11 August 2018 - 12:49

One more test

no filter
Attached Image: P8119202.jpg

zwb3+qb21
Attached Image: P8119203.jpg

unknown 315nm
Attached Image: P8119204.jpg

Edited by Dmitry, 11 August 2018 - 12:52.


#12 Dmitry

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Posted 11 August 2018 - 12:55

crop
Attached Image: P8119204x.jpg

my guess
Attached Image: P8119204xx.jpg

Edited by Dmitry, 11 August 2018 - 13:11.


#13 Andy Perrin

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Posted 11 August 2018 - 17:52

If I denoise and follow your guesses, this is what I get. By the way, as an experiment I also tried labeling only the 358 and 373, and the program then guessed 338 for the 336 line, so I think you are correct. By the way, all numbers left of the 336 line should be ignored -- when fitting curves, extrapolation is usually not very accurate, but interpolation between known points is good.
Attached Image: Lomo T-43 crop denoise.jpg

Edited by Andy Perrin, 11 August 2018 - 17:56.


#14 Dmitry

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Posted 11 August 2018 - 20:07

Thanks, Andy. Seems with proper filter it 330nm capable :)
Need to verify it with filter and mercury lamp.

#15 Dmitry

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Posted 11 August 2018 - 20:17

Googled confirmation for some lines http://www.coseti.org/9006-025.htm

#16 Ninjin

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Posted 06 April 2019 - 09:29

I would guess, if just to try setting the white balance in this photo ZWB1+QB21, from this test,
would be visible such gradient of transmission for the ZWB1+QB21 stack, for this T-43 test lens.

Attached Images

  • Attached Image: uvp test.jpg


#17 Dmitry

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Posted 13 April 2019 - 16:34

New test on e-m5 without dustshaker

zwb3
Attached Image: P4139260.jpg

#18 Dmitry

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Posted 15 April 2019 - 13:57

One more with direct sunlight using zwb2 4mm filter.
iso 200 1/2s shutter.

One dust piece somewhere on 350nm, another somewhere at 360nm

This one from in camera WB set on fullspectrum on white sheet target and 2.0 gamma applied
Attached Image: P4159268j.JPG

This one from ORF file converted without any changes using xnview
Attached Image: P4159268r.jpg