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UltravioletPhotography

UG2A and four other UV-filter pass filter combinations.


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I finally got my UG2A-filter

 

The wether has been very nice lately, sunny and with less wind than usual.

I have spent the last days in the afternoon outdoors with my camera and a pile of filters to test.

 

The camera used is a full spectrum modified EOS 60D at ISO320, with an EL-NIKKOR 80/5.6, oldest Nippon Kogaku metal-type.

Date of photography: 2018-05-07

Location: Billebjer, southern slope, a nature preserve close to Dalby Söderskog, Skåne, Sweden.

 

One of the plants I found is the Green Strawberry, (Fragaria viridis).

I din't know it existed until last week.

The Wild Strawberry, (Fragaria vesca), is the one I have seen before. This more common here, I think.

 

The white flowers of this plant show the different behaviour of the filter stacks quite well.

White balance: selection of the bottom half of the pictures below the flowers, from side to side.

No other colour tweaking is done, to keep the result as true as possible.

 

post-150-0-29823900-1526052430.jpg

Picture #1, Visual reference, filter : BG38, 2mm, 1/100s

 

post-150-0-52843200-1526052637.jpg post-150-0-30558800-1526055439.jpg

Picture #2, filters: S8612, 2mm + UG2A, 2mm, 6s

 

post-150-0-78740900-1526052736.jpg post-150-0-95850000-1526055460.jpg

Picture #3, filters: S8612, 2mm + UG1, 1mm, 10s

 

post-150-0-63073500-1526052799.jpg post-150-0-51727500-1526056110.jpg

Picture #4, filters: S8612, 2mm + Hoya U-360, 2mm, 10s

 

post-150-0-24311300-1526053546.jpg post-150-0-44165500-1526055857.jpg

Picture #5, filter: Baader U, 10s

 

post-150-0-46989100-1526053619.jpg post-150-0-56551000-1526056009.jpg

Picture #6, filter: Omega surplus filter 330WB80 eBay, 10s

https://www.ebay.com/itm/151058919420

 

I have tried to process the raw files to get a similar intensity in the foliage by adjusting the exposure control.

The U-360 and Baader U needed an adjustment of 0.66EV to get a matching result.

 

The UG2A show the result I imagined when I found the material and compared the transmission graphs with the graphs for an UG1 1mm-filter.

 

I am quite happy with the UG2A-filter.

Thank you Steve, for making it possible for me to use a new unique filter!

 

Edit: Added date of photography and location.

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Andy Perrin
Interesting test. My favorite of this set of photos is the "Picture #3, filters: S8612, 2mm + UG1, 1mm, 10s" one, with the intense (false???) blues. It is hard to tell if this is because you adjusted the photos differently ("I have tried to process the raw files to get a similar intensity in the foliage by adjusting the exposure control.") or because of the filter. Could you show us tiny versions of these WITHOUT any edits but with (identical) white balance? I am curious about exposure.
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Andy,

 

I can do that if you think it would give some meaningful information.

The reason for adjusting the exposure level when processing the Raw-files was to try to cancel out the effect of the transmission of the different filters and how the camera has responded to the difference in the spectrum. I also shifted the exposure level a bit in the middle of the sequence when I finally checked the histograms and realised that I could exposure more to the right. The last two have more exposure time even if the transmission is better for the Baader U than the U-360 stack.

 

Same filter sequence as above. Now identical raw-processing parameters except for the white balance.

 

Now the leafs are more shiny in the second image, but still the flowers are more pale in the first image.

 

I hope this helped.

 

I f you want I can send you the raw files too, but each file is 20-25MB.

 

post-150-0-97484500-1526063754.jpg

post-150-0-95789600-1526063777.jpg

post-150-0-57258800-1526063806.jpg

post-150-0-16075400-1526063825.jpg

post-150-0-04298200-1526063841.jpg

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nice... i wish i could WB my D800 that nicely for the UG-2a

All these images are processed from RAW in my computer.

 

I have given up trying to get WB working in the camera, especially as I normally am going through most of my UV-related filters for many subjects.

I often do more than 10 different filter combinations. Magnetic filter holders is mandatory to make it possible.

Just VIS and UV is quite spartan for me.

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Ulf, great pics! I like the first set subject, just as art, but also about the test comparisons.

Overall, I like the UG2A stack example at the top best, but it is arguably close to the UG1 stack, the second example down.

It is not a wonder that those two are so close, given that UG2A 2mm is equal to UG1 0.66mm thick. So with this comparison, with these thicknesses, the UG2A shot is 3/4ths the strength of the UG1.

Shows up mostly to me in the exposure time you noted.

 

Also interesting now close the U-360 2mm + S8612 2mm stack looks to the Baader U shot, and the exposure time is the same also.

I can't even see a difference.

 

Thanks for showing these comparisons.

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Steve, the same exposure time between the U-360 2mm + S8612 2mm stack and Baader U is just a coincidence.

 

I had a too conservative setting on the camera when shooting with the U-360 2mm + S8612 2mm stack.

When I changed to the Baader U I noticed that and shifted the camera exposure compensation setting to get less noise. ( The expose to the right rule. )

 

Then when I processed the U-360 2mm + S8612 2mm stack I had to do a similar exposure compensation to get a matching intensity in the foliage.

The change needed was +1/2EV.

This is a reasonable shift for the difference in transmission between Baader U and the stack.

I can measure the two with my spectrometer and give a more correct transmission value of the filters.

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Ha ha ha...

Ulf, I am confused now! ;-)

Well they all look good.

Basically, the UG2A and the UG1 look about the same, but I like the UG2A best of those. I think we should try some UG2A 1mm, what do you think?

I like the U-360 and Baader U shots, and I don't see any difference between those shots.

That is my basic philosophy on the whole thing.

All of your shots look very nicely white balanced.

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Just wanted to add... Ulf, made this filter happen, asked me, and was not something I even thought about making, convinced me, and Ulf is responsible for that.

So thank you Ulf, for making this happen.

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Sorry if I what I wrote was confusing.

Sometimes it is difficult to convey ones thoughts.

I can also be biased seeing what I expect to see, but I think not, this time.

 

I like the idea of trying some UG2A 1mm. It would be quite interesting to see what images they produce.

 

If you see only small differences between UG2A and UG1 it might be due to your screens gamut.

 

I also clearly saw a hue shift in the corners in the foreground of Bobs first UG2A images too.

I could verify the shift by checking the RGB values in Photoshop.

 

My monitor has a rather big gamut and I clearly see that the UG2A images have paler blue flowers.

The difference is not dramatic, but still clear. I could easily have gotten that result by manipulating the UG1 image too.

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I have my UG2A filter now so if there is some interest, I will make some standards & color checker photos and look at their raw composites and raw histograms. These might help show how the UG2A differs from the UG1.

 

I would be careful about judging hue shifts in corners. Common vignetting (light fall off) might play a role?

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(typo above, no such thing as 'UG1A')

 

Here is a comparison between the following stacks.

UG1 2mm + S8612 2mm

UG1 1mm + S8612 2mm

UG2A 2mm + S8612 2mm

UG2A 1mm + S8612 2mm

 

UG2A 1mm starts to become more of a mild form of UV+Blue+Green

(what I call 'bee wearing shades vision', or BWSV for short, a popular look among famous Hollywood bees, such as Betty Bee, Cecil Bee DeMille, and the lead singer in The Buzz).

post-87-0-54752000-1526246751.jpg

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Compare UG2A 1mm and standard UG5 (or U-330) 1.5mm UV+Blue+Green ('Bee Vision') stacks.

Interesting, and so would be the non stacked dual band use I would imagine.

post-87-0-94957300-1526247512.jpg

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