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UltravioletPhotography

Dandelions & Speedwell


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Hiya... Spring has sprung and ultraviolety things are spouting.

 

Though its still cold at night, here some shots i took for everybody here to look over...im sure youre busting at the seams with dandelion photos.

 

Dandelions and the wildflower Speedwell.

 

Sony A6000 full spectrum

 

Tamron 17-50mm Nikon(adapter used)

 

-Hoya U-330 + S8612

 

-Hoya U-360 + S8612

 

-BG3 + S8612

 

In camera white balance

 

Sunlight for all

 

Last photo is a visual of Speedwell

 

Dandelion: Hoya U-330 + S8612

post-341-0-22739100-1619141737.jpg

 

Dandelion: BG3 + S8612

post-341-0-29437700-1619141764.jpg

 

Dandelion: Hoya U-360 + S8612

post-341-0-92102000-1619141777.jpg

 

Speedwell: Hoya U-330 + S8612

post-341-0-04537700-1619141817.jpg

 

Speedwell: BG3 + S8612

post-341-0-31622900-1619141833.jpg

 

Speedwell: Hoya U-360 + S8612

post-341-0-01295300-1619141978.jpg

 

Speedwell: Visible

post-341-0-06195800-1619141988.jpg

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I think it can pass whatever the modified A6000s ultraviolet limit is... Think someone here said 320nm or maybe a little lower.

 

For this Rose shot, i had a Hoya 340 and S8612 on the Tamron lens and a ZWB1 on a full spectrum flash.

 

5 seconds

250 iso

F/22

2 flash pops

 

And the Tamron just laughed and asked for more.

post-341-0-68826400-1619145111.jpg

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Tamron A16NII SP AF 17-50mm F/2.8 XR Di-II LD SP Aspherical for Nikon.

 

 

Also have a Tamron 70-300mm Nikon that likes UV...

Tamron AF 70-300mm f/4.0-5.6 Di LD Macro Zoom.

 

 

And i have a Tamron 18-270mm Sony A mount that does pretty good... provided it doesnt go past 150mm or so. Blade flares start to appear past 150mm in UV.

 

Tamron AF 18-270mm f/3.5-6.3 PZD

 

 

All these lenses i use manually with adapters and all use 67mm filters

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I think it can pass whatever the modified A6000s ultraviolet limit is... Think someone here said 320nm or maybe a little lower.

I like your images and your exploration of the wavelength region around 400 nm.

They are very nice. I especially like the last image in your first post, of the Veronica.

This flower has very interesting colouring in this colour region.

This shows that there are very much to look at in this wavelength band too.

 

I am sorry but I must make it clear that with that lens you have very little UV-reach.

It is very unlikely that the camera is the limiting factor for UV-reach here.

 

Modern zooms with complex optical design with many lens groups made by modern optical glass types and coated surfaces do not pass UV far below 400 nm!!

 

Beside lenses specially designed for passing UV-light we have only seen lenses with few thin lenses and simple design that pass UV down even close to 320 nm.

 

This is how your lens is built: https://radojuva.com/en/2011/11/tamron-17-50mm-f2-8-xr-di-ii-ld-aspherical-if/

16 elements in 13 groups is not a design that have any change to reach deeply into UV if the lenses are made of glass.

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I like the last 5th photo, that flower has a rainbow-like coloring with the filter you used.

 

Your dandelion has a similar "muted" yellow to mine in the photos taken with my old point-and-shoot. This confirms that that camera had a limited reach, probably around 360 nm. I can recognise the reach based on the false UV colors. A shallow reach gives brownish, almost "wheat" yellows and blues closer to blue, with little lavender. A deep reach gives strong greenish yellows and purples.

 

Ulf is right, your camera should reach UVB if the conversion allows it. It is the same camera Bernard used to take his tri-colo(u)r images.

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Sorry, but im inclined to disagree.

 

Its hardly a modern lens seeing as i bought it in 2006... Advanced multi coating isnt in its description.

 

You might have missed the info for the rose photo settings

 

U340 filter

F/22

Iso 250

And another 340 equivalent on the fs flash

 

There isnt any visible light forming the rose pic or violet or deep violet

 

I dont have advanced equipment to measure.... But i do have cds and the spectral shot with the flash coupled with the Tamron show an inch long yellow line starting at blue/violet in the resulting spectrum.

 

Thats UV, not a glare or an anomaly.... My UV line with a 1981 nikon 50mm 1.8 is slightly longer.

 

In fact, i can shoot with the 50mm nikon, change out to the Tamron, and use the same camera settings and get the same pic with just 1 stop wider aperture.

 

The 50mm nikon definitely isnt a modern lens

 

I dont have to shoot in seconds with the Tamron to make an image..i can go iso 800, f/11 and easliy get an image with the 340 at 1/100 of a second

 

The 16-50mm kit lens that came with the A6000 can hardly collect enough light to build an image with those settings and only shows a tiny slice of yellow after blue.

 

Real world, hands on experience on will always win over charts and theory and heresay. So unless you have said lens and have performed tests with expensive spectrometers and such to prove otherwise..the poormans tests win.

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Andy Perrin
....heh, Ulf DOES have expensive spectrometers. I don’t know if he has tested that lens in particular but I have trouble imagining that any lens with 16 elements (from any date at all) can be transmitting deeply into UV. These photos are definitely ultraviolet, the question is how deeply into UV they extend.
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No I have not measured that lens, but my experience with optical design and measurements is not based on hearsay, but real knowledge.

If you look here you will find some analysis of lenses that mostly work passing UV: https://www.ultravioletphotography.com/content/index.php/forum/645-uv-lens-technical-data/

All lenses with deep UV-reach are simple designs..

By modern lenses I would say anything after 1970, not 2006!

There existed multi-coating loong before 2006.

To get any light through a lens with so many optical groups you must use relatively advances AR-coatings.

 

You cannot draw any valid conclusion from a in camera WB image about UV reach.

This has been discussed may times on this forum.

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Your images look like 385nm to 390nm to me. I think you are significantly over estimating the UV depth of that lens.

If it was hitting 370 or 375, the background would be more yellow. Its not and clearly blue as you do have the white balance correct. If it was less than 350nm the background would be strong green. Its not.

Your images are good, don't sweat it.

I would say that about 85% of UV images are shot in 380 to 390nm. Most of the UV signatures are there and sunlight is strong with good sensor response.

You're not missing much going deeper.

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Also add I am finding quite a few Sigma lenses do transmit with a 375 to 380nm UV cut off.

My recently acquired Loawa 12mm f2.8 lens cut off at 380nm.

 

But don't expect deep UV. Thats much more specialized.

 

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I didnt say anything about white balance making it so.

And while we are on that subject...I was reading some threads here a month ago or so and you guys jumped another user here about white balnce and UV. And i mean ripped into him good about how you CANT draw any conclusions WITHOUT a proper white balance. Someone then said... This discussion is over until a proper white balance is made.

 

So which is it?

 

And im not some youngster that woke up one day and said im going to be an infrared and ultraviolet photographer. Ive been doing infrared for almost 25 years...and without the aid of full spectrum cameras, make my own filters with everyday materials, take my lenses apart and fix and clean them myself.

 

And i researched UV photography for decades, ive seen all the charts and graphs, read all the heresay, i know all about quartz lenses.

 

And 1970 is not modern...cameras and lenses are just like computers. After a few years they are considered obsolete. And my cameras and lenses are simple and old and cheap. Ill take a 150$ lens over a 2000$+ lens because i know, in my experience, that it wont have modern, multi coat, anti reflective, mumbo jumbo stuff.

 

 

Thats like the guy that said my v6 acura couldnt reach even 120mph, even though the speedometer goes to 160mph. So i stuffed him in, went to a straight country road, and was at 145mph before i had to slow because the road was running out. He went on saying that shouldnt have been possible because the specs charts and graphs say so. Well, charts and graphs dont dictate real world results.

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White balance can be all over the place. So very few have confidence in it. Also camera sensor used to use different dyes on the sensor. That has mostly changed. Most of the modern cameras with live view are mostly using the exact same Fuji RGB dyes on sensor. The color difference is normal photography is due to UV/IR blocking. So comparisons accross the board for our full spectrum converted cameras in UVA are easier now. UVB is trickier due to different coverglass used on some sensor generations. Newest sensors seem to have AR coatings on the actual coverglass, which isn't removable.

 

But I think your WB is ok as your dandelion looks good to me. It and the background look like a 387nm image I might get with my system and a 390bp filter, which I have recently found peaks at 387nm and not 392nm like I had thought.

It doesn't look like a 370bp image.

 

So for me I am comfortable with WB reference, since your images seem ok. Others will not be and want a spectrum of the lens.

 

I just looked at my Sigma's. My EF mount Contemporary 17-70mm f2.8/4 cuts off at 378nm.

My Sigma 10-20mm f4/5.6 lens cuts off at 375nm.

My Sigma 8-16mm f4.5/5.6 cuts off at 400nm.

My Tamron adaptall 17mm f3.5 lens with internal 80B filter cuts off at 350nm, but slow ramping peak.

 

My 77mm Bg39 filter looks to cut off the IR leakage from my 77mm ZWB2 filter. So I should be able to get some dandelion images with these when the sun comes out.

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Well.. the uploads didnt happen in the order i wanted. The visual Speedwell is mixed in there.

 

After the uploads are complete, then place your cursor in the text where you want a particular photo to appear

and then click "Add to Post" to the right of that photo in the uploaded photo list.

You must be in the Full Editor to see the uploaded photo list and the Add buttons beside them.

 

I cleaned it up a bit for you. But of course you can rearrange. :smile:


 

I can recognise the reach based on the false UV colors.

Stefano, no, just no.

You cannot do this from a white balanced jpeg. This stuff is not 1-to-1. Converters vary all over the place. White balance tools do not make the same WB. Saturation differences affect false colour. Contrast settings affect false colour. Not every demosaicing algorithm works the same.

Geez. C'mon.


 

But i do have cds and the spectral shot with the flash coupled with the Tamron show an inch long yellow line starting at blue/violet in the resulting spectrum.

IxnaX, no, just no.

You cannot make an accurate assessment of lens transmittance using CDs. There is just no control of the light.

Again, geez.


 

Most floral signatures do not vary by much over the short interval from 300 nm to 400 nm. Given that IxnaX has captured quite successfully the floral signatures of both Dandelion and Speedwell under broad UV-pass filtration, does it really matter whether that Tamron reaches past 375 nm or not? No, it does not.

 

This lens may have reach past that or it may not. But until I see an actual spectrographic measurement with proper equipment (which includes an integrating sphere), then I say we should hold off on staking any claims about the Tamron's "reach". All the informal methods we use to determine "reach" are subject to many pitfalls. They are fun and in many cases "good enough", but they are not accurate.


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And while we are on that subject...I was reading some threads here a month ago or so and you guys jumped another user here about white balnce and UV. And i mean ripped into him good about how you CANT draw any conclusions WITHOUT a proper white balance. Someone then said... This discussion is over until a proper white balance is made. So which is it?

 

Can you please link to this?

In reflected ultraviolet photography, white balance is used only to "standardize" the image. So I am not sure what conclusions were being drawn about UV transmission based on white balance.

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I can recognise the reach based on the false UV colors.

Stefano, no, just no.

You cannot do this from a white balanced jpeg. This stuff is not 1-to-1. Converters vary all over the place. White balance tools do not make the same WB. Saturation differences affect false colour. Contrast settings affect false colour. Not every demosaicing algorithm works the same.

Geez. C'mon.

Ok, my bad. Let's rewind the tape and pretend I never said that.
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well please just think it thru. There are an enormous number of variables involved in producing false colour. It is rather amazing that we do manage to standardize our reflected UV photos to the extent that we do. But if you look in the botanical section you will see variations in the appearance of the same flower because there is no way to be accurate/precise about WB.

 

I do not entirely dismiss the attempts to match up false colour with wavelength, but too often these attempts are made without taking into account *all* the variables. That, by the way, includes the structure of the flower for floral subjects. And also includes an good analysis of the camera's channels. (Do the channel lines cross in such a way that two different wavelengths can give the same false colour? Not in the visible, but what about the UV? Those pesky Bayer pigments.)

 

My personal opinion is that photographic false colour to wavelength correlations are not really needed given that the world has good spectrometric equipment which can provide a repeatable, accurate, precise determination of reflected wavelength. But if you are going to try to make such correlations, then you must list *all* the variables at play and account for how they might affect the outcome.

 

Am I being too demanding? too "scientific"? :devil: :devil: :devil:

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Andy Perrin
Andrea, why would you need an integrating sphere to determine just the lens cutoff? I think even Colin’s gadget can get the cutoff. Getting absolute transmission numbers needs the sphere probably but that’s not what the discussion was about. Ulf can check me on that. We do care a bit about the cutoff because it’s nice to know what we are looking at. I mean, I love pretty pictures but if that were the whole story I could just photoshop a visible light image to have any colors I wanted.
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Andrea, you are right. There are a lot of variables to consider, and false colors can not tell you the exact wavelength. What I said is that I can tell (more or less) the reach of the photo based on the overall palette. The yellows are not the same yellows, and the blues/lavender are not the same either. But this is not scientific, just experience.

 

I saw the same palettes in this Birna's comparison: https://www.ultravioletphotography.com/content/index.php/topic/4466-fun-with-rodenstock/page__view__findpost__p__44220

 

The yellows are more "turned-off" with a shallower reach.

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