UG2A + S8612 UV+Blue Stack

[Cadmium]

Quick landscape comparison of the following:

Baader U (left), UG1 1mm + S8612 2mm stack (center), UG2A 2mm + S8612 2mm stack (right):

 

All setting the same: ISO 200, Kuri 35mm @f/8, exposure as noted.

Each individually white balanced on gravel driveway.

 

Baader U (1.3s)

 

UG1 1mm + S8612 2mm stack (1.3s)

 

UG2A 2mm + S8612 2mm stack (1s)

 

 

UG1 1mm + S8612 2mm stack, vs UG2A 2mm + S8612 2mm stack:

[OlDoinyo]

The graphs show UG1 and UG2A having virtually identical shortwave limits. But the UG1 shot seems to have better bandpass, or at least it has better contrast and chromaticity. The color looks better defined.

[Cadmium]

Clark, the basic different I see between the UG1 and UG2A stack above is the color of the sky, blue is also slightly different, but not sure I see a contrast difference.

 

More thoughts... for UV+Blue+Green...

[Cadmium]

Clark, I understand what you are saying, but below is the straight 100% crop comparisons, and I don't see a contrast difference, in fact these look identical to me.

Perhaps the green sky casts some kind of optical illusion on the difference, but these crops are the real deal.

I might like them to be more different, but other than the sky, there is very little difference from what I see.

 

Close crops, 100%, actual pixels, UG1 and UG2A stacks.

Note: there is a bit more blur in the UG2A shot, was not using a cable...and wind... so...?

These shots don't show any sky.

Can you see much difference between these first two?

 

 

Here is a corner to corner, half and half overlay, can you tell where it is spliced?

 

Here is a hint, the corner showing is the UG2A stack.

 

OK, I gotta go watch a movie now, this stuff is driving me nuts. ;)

[Cadmium]

Here again are the pics from the top, with the sky cut off.

 

UG1 1mm + S8612 2mm stack (no sky)

 

UG2A 2mm + S8612 2mm stack (no sky)

[Andy Perrin]

I like the UG2A 2mm + S8612 2mm. Sky color is very similar to what I see with the Omega 330WB80 filter, which passes shortwave well.

[Cadmium]

Personally, I am not crazy about the UV+Blue stack using UG2A... I don't like the green sky, and I am not sure why it is green. Actually it looks blue with yellow in it, what I might expect from some UG5/U-330 stack,

but this doesn't have that much visual in it, so I don't know...

It would depend on where it is white balanced of course, but I was just expecting the sky to be bluer if anything.

Time will tell...

[Andrea B.]

Cadmium, those cyan and green skies probably result from a blown highlight which could not be properly recovered. I've seen that a lot. Usually Photo Ninja can recover that cyan/green. NX2 sometimes could, sometimes could not. So it is very dependent on converter app.

 

If you like I could check the raw composite to see what is really there. (Excuse me if you already have RD. I'm not able to remember everyone's apps!)

[Cadmium]

Perhaps. I have done little testing with UG2A so far. The green is reminiscent of overexposed PTFE sheet... this is a good point.

You will be test it soon enough.

[ulf]

I'll try to show the effect I hope to get with a stack of S8612 and UG2A, when my filter finally arrives.

(I got a note today that it is at the customs office.)

 

The following blurry pictures of some Anemone Nemorosa, from last Sunday, are taken with an EOS 60G and an EL-Nikkor 85/5.6, old model.

The slightest wind moved the flowers on their thin long stems during exposure.

 

Picture #1, filter BG38 2mm, visual reference:

 

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

 

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

 

Picture #4, filters S8612, 2mm + UG2A, 2mm, is missing as the filer has not yet arrived.

I think the flowers in this picture would have been more towards sky-blue and brighter, as the next step in the trend in the UV-pictures above.

 

I saw a similar behaviour with blackberry flowers last summer.

[Andrea B.]

Nice comparison.

 

How did you perform the white balancing step?

 

(Interestingly this pretty Wood Anemone just came up in another topic (linked). I had to look it up to find Anemone nemorosa as I do not see that flower often over here. http://www.ultravioletphotography.com/content/index.php/topic/2628-some-very-basic-lens-test-with-dandelion/page__view__findpost__p__20379)

[ulf]

I white balanced the UV-images by selecting a big part of the leafs in the foreground, avoiding the flowers.

For the VIS-image I just klicked on the white flower.

In hindsight I think gave the U-360 image a bit more saturation.

With less sloppy processing the blue-purple difference would be even greater.

 

This flower, Vitsippa in Swedish is quite common in the beech forests here in southern Sweden.

The location where I shot the images is interesting bothanically:

http://www.nationalparksofsweden.se/choose-park---list/dalby-soderskog-national-park/

[Andrea B.]

Ulf, yes, clicking on leaves usually works for informal white balancing. Flower leaves usually are false-grey.

 

If you should ever want more "precise" white balancing, remember we have collected some info here: Sticky :: White Balance in UV/IR Photography

 

What a lovely park! I hope I can visit it someday. Thanks for the link.

[ulf]

Ulf, yes, clicking on leaves usually works for informal white balancing. Flower leaves usually are false-grey.

 

If you should ever want more "precise" white balancing, remember we have collected some info here: <> Sticky :: White Balance in UV/IR Photography <>

 

What a lovely park! I hope I can visit it someday. Thanks for the link.

 

Thank you for the white balance tip.

I already have both a simple diffuse PTFE device and a few homemade UV-neutral grey ones, for white balancing, similar to what Jonathan wrote about last summer.

However this was at the end of the day after some hundred multispectral exposures elsewhere, close by, where, I used my grey 20% reference in the first series. I was too tired to do everything correct.

 

If you should visit the park, the spring is the very best time of the year, even if it is interesting other parts of the year too.

If you do visit, please let me know. I live 20-25km from there. It would be nice to meet you in person.

[OlDoinyo]

Other approximate white/grey targets:

 

-the bottom of clouds on an overcast day

 

-unpainted metal objects

 

-many kinds of tree bark (not lichen-covered!)

 

-limestone gravel

[Andrea B.]

Here is an an example of an unrecoverable highlight which goes cyan in a converter. See post #8 above. This photo was a lost cause, but does at least serve to show where the cyan comes from when comverting UV photographs.

 

This is a UV photo of a Lapsana flower which was overexposed under a 365 UV-Led. Most of the petal areas are "blown" in the red and green channels.

 

Raw photo - has a lot of blowout glow!

 

Conversion in Capture NX2 - cannot get rid of the cyan/green.

 

Conversion in Photo Ninja - can recover the highlight color. (But photo still not useable.)