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First use of Kolari UV filter in portrait

Filters UV Lens UV Portrait

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#1 DonPilou

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Posted 04 January 2017 - 18:26

Hi everybody!
Long time whithout posting something here. I have just received a new ultraviolet filter designed by Kolari Vision, perfect opportunity to test a new 50mm lens by the same way.
To compare the properties of Kolari UV filter, I have also used my LUV U2 filter with the same adjustments. Let's see the results :

Attached Image: Test_UV_3.jpg

Canon 6D + Yongnuo 50mm F/1.8 + Kolari UV filter

50mm, F/5.6, 400iso, 1/10s


Attached Image: Test_UV_4.jpg

Canon 6D + Yongnuo 50mm F/1.8 + LUV U2

50mm, F/5.6, 400iso, 1/10s


As you can see, the Kolari UV filter offers very sharp and detailed result, contrary to LUV U2 filter which provides foggy effect.

I have also tested the same filters with the Nikkor E 50mm F/1.8 that I was using since now.

Attached Image: Test_UV_1.jpg

Canon 6D + Nikkor E 50mm F/1.8 + Kolari UV filter

50mm, F/5.6, 400iso, 1/10s


Attached Image: Test_UV_2.jpg

Canon 6D + Nikkor E 50mm F/1.8 + LUV U2

50mm, F/5.6, 400iso, 1/10s


Here, the Nikkor looks a bit less sharp than the Yongnuo, with same global exposition.

As a conclusion, I am really pleased by the Kolari UV filter. I have just bought 3 new lenses to test for large portrait : an Optomax 35mm F/3.5, a Soligor 35mm F/3.5 and a Steinheil EDIXA 50mm F/2.8. I hope I will achieve a better exposure time with them. So more to come ;).

#2 Andy Perrin

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Posted 04 January 2017 - 19:36

All of them are very nice! I always enjoy your portraits.

#3 Mark

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Posted 05 January 2017 - 02:24

Very good exposures with the Kolari UV filter. I think your new filter will serve you well.

#4 Andrea B.

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Posted 05 January 2017 - 19:06

Thanks for posting this comparison test!!
I have the new Kolari UV-pass filter but holiday activities got in the way of testing it. Soon I hope.

Did you remember to re-focus after each filter change? That's important.

[I'm sure you did, "-) but I mention it for possible newbs who might not realize there can be minor focus changes sometimes between different UV-pass filters due to coatings or layers or filter type.]
Andrea G. Blum
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#5 DonPilou

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Posted 08 January 2017 - 18:53

Many thanks to all of you. Indeed Andrea, I use a UV LED flashlight to focus, both of these lenses have an important focus shift in UV photography.

#6 Reed F. Curry

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Posted 09 January 2017 - 17:15

It is not just a difference in softness; as well, there are more visible melanin deposits using the Kolari UV Pass filter.
Best regards,
Reed
http://www.uvroptics.com

#7 Andrea B.

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Posted 11 January 2017 - 18:04

Looking at this again....

All shots were made at f/5.6 and 1/10", the exact same exposure. Thus, the only fair thing to conclude (until further tests are made) is that the LUV filter passes more UV light than does the Kolari filter -- all other things being equal (same light, same filter peak wavelength, no flare, etc). If one shot is brighter than another because that filter passes more UV light, then of course there will be some difference in how dark the melanin deposits appear.

To make a proper comparison between two filters, it is necessary to try to find the correct exposure for each filter (and each lens). I do this using some exposure bracketing. When I shoot filter comparisons, I bracket several steps around the presumed correct exposure in 1/3 stop increments. Then I look at the raw histograms and choose the two photos having histograms "most-pushed-to-the-right-but-not-overexposed" for the comparison. It can often happen that the two most nearly equal exposures have different exposure times at a given aperture due to differences in filter thickness, coatings or other construction.

Another possible explanation for the differences is because of different filter peaks between the two filters. I don't know the UV range in which melatonin absorbs UV, but it shouldn't be too hard to find. If one filter has a different wavelength peak than another, then one of the filters might show something legitimately different than another. So the transmission charts should be consulted to find what the approximate peak is for each filter in the comparison.


I have the Kolari filter but have not yet been able to find time to test it. Soon, I hope. :D
Everyone please think about my remarks here and let me know what you think about the best way to compare two filters.

DonPilou's tests are useful, but the conclusion is slightly wrong. DonPilou, can you try a reshoot with variation in exposure times? We love these kind of tests here!
Andrea G. Blum
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#8 Andrea B.

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Posted 11 January 2017 - 18:17

Looking for charts, etc. I found the following.

I was correct in that the two filters do not pass equal amounts of UV light during the same exposure interval (all other things being equal).

The two filters also have slightly different peaks and 25% transmission intervals, but that likely does not play much of a role. So when comparing these two filters, there will be differences in exposure length to get the "same" photograph.

I will be testing this out myself ---- eventually. :D

Kolari:
This filter has a 50% transmission peak at 365nm and >25% transmission between 340-380 nm.
Minimum rejection of >3.5OD (0.025%).
Coated.
LINK: https://kolarivision...ss-lens-filter/

LUVU2:
This filter has a 65% transmission peak at 360nm and >25% transmission between 330-385 nm (approximately).
Minimum IR supression is OD4.
Uncoated.
LINK: http://www.ultraviol...dpost__p__13718
Andrea G. Blum
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#9 Andrea B.

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Posted 11 January 2017 - 18:47

Melanin -- wow, this was interesting!
Somewhat of an exponential chart with peak absorption at 335 nm.

Am I correct in assuming that a 330 nm peak filter would show melanocytes at their best?

Zeise, L. et al. (ed.) Melanin: Its Role in Human Photoprotection, Valdenmar Publishing Co.
See pp. 31 - 38.


Attached Image: melanin.jpg
Andrea G. Blum
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#10 DonPilou

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Posted 11 January 2017 - 19:51

I agree with all what you say, Andrea. However, the fact is I have the same histogram with both filters, using the same power of flash and the same EXIF. And I processed the two pictures exactly the same way. I agree that this is not logical, so we have to find what parameter could explain this similarity. Maybe the use of absorption based glass for Kolari. I will do the exposure time tests as soon as possible ;).

#11 Andrea B.

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Posted 12 January 2017 - 02:22

Thank you for the quick reply about the same histograms. Now I am really puzzled. :lol:

We will look forward to further tests to see if the results are repeatable.
Filters have many characteristics that affect the photo but which are difficult to pin down. Coatings and glass types and so forth can all affect the results - creating different contrasts, tones, micro-contrasts, etc.

I had an interesting time thinking about this. And also enjoyed looking up info and reading about melatonin.
Andrea G. Blum
Often found hanging out with flowers & bees.

#12 Reed F. Curry

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Posted 19 January 2017 - 20:11

Cement might be another factor. Is the LUVU2 cemented? What is the type of cement used by the Kolari? Obviously, some optical cements pass UV better than others. I used one cement that passed 83% at 350nm, but switched to a cement with both lower viscosity and 90% at 350nm. And the RI is a factor as well, of course.
Best regards,
Reed
http://www.uvroptics.com

#13 JCDowdy

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Posted 19 January 2017 - 21:47

View PostAndrea B., on 11 January 2017 - 18:17, said:

Looking for charts, etc.......

Based on those rough numbers the Kolari may be passing ~4 times more relative out of band radiation. Not a lot in either case but enough to account for the observed difference?

Also, I was not under the impression that either of the two lenses transmitted as deeply into the UV as either filter, so the relative peak transmission of the filter is likely also clipped even more. This should have the effect of pushing the relative out of band signals even higher than what would be inferred from the filters alone.

Melatonin and melanin, while while related are not the same thing B)
Spell checker strikes again?

#14 JCDowdy

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Posted 19 January 2017 - 22:20

The plot of melanin absorbance is from a chapter in that book entitled The Spectroscopy of Human Melanin Pigmentation by my late friend and prominent photobiologist Nik Kollias who passed away the day before Thanksgiving. He did a lot of interesting spectral remittance spectroscopy of skin pigmentation.

Incidentally Nick held several patents including some on various aspects of UVIVF photography.

Edited by JCDowdy, 19 January 2017 - 22:21.


#15 Andrea B.

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Posted 20 January 2017 - 17:48

I'm sorry for the loss of your friend. Professor Kollias had a very distinguished career.
Andrea G. Blum
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#16 JCDowdy

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Posted 23 January 2017 - 14:13

Thank you Andrea.

#17 Hornblende

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Posted 26 January 2017 - 01:51

I am saving to convert my canon 6D into full spectrum, I am happy to see thas this camera seems to work well with UV! I have read so much things saying Canon is a bad brand for UV.
I think the Canon 50mm f1.8 II could be usable since it is a cheap two element lens (but light coated).

Edited by Hornblende, 26 January 2017 - 01:52.


#18 JCDowdy

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Posted 26 January 2017 - 13:20

View PostHornblende, on 26 January 2017 - 01:51, said:

I think the Canon 50mm f1.8 II could be usable since it is a cheap two element lens (but light coated).

Is this the lens you are talking about?

#19 Hornblende

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Posted 26 January 2017 - 14:00

View PostJCDowdy, on 26 January 2017 - 13:20, said:


Yes! Wait... I am wrong, Dpreview says there is 6 elements in this lens.
When I disassembled my lens I could only see two pieces of glass, that means the elements must be glued together..

#20 JCDowdy

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Posted 26 January 2017 - 14:08

They say 6 elements in 5 groups.

So perhaps it has 2 optical blocks one of which contains a cemented group?

Edited by JCDowdy, 26 January 2017 - 14:10.




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