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LED lights


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In a recent post Alex H gave a link to a LED light (Ultron ....)

 

as I also happen to have this torch and also a different one (Polarion ...)

I did a comparison last year

The Ultron is much more powerfull both are said to give 365nm peak light both show some visual violet

 

I did a shot with both in parallel and then on a dry flower with each seperatly

(Camera panny G2 full spectrum Noflexar 35mm lens and Baader U filter)

 

With Photo Ninja I developed all three shots one time with white balance on the Polarion and one with WB on the Ultron

 

Here is how it looks:

 

 

post-21-0-38504500-1406235910.jpg

 

 

Werner

 

(Corrected spelling of Polarion)

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Alaun,

This is an interesting comparison but I am a bit confused by your captions.

I likely am misunderstanding the labels, but the beam images or flower diptychs seem transposed?

John

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Sorry if it is a bit confusing:

 

The Polarion has Polarion PL-3U on its nameplate and UV 365nm

 

The upper two pictures are from the same raw file

the left with WB #1 on the Polarion

the right with WB #2 on the beam of the Ultron

These two WB settings were used on the two next shots:

 

 

The middle two pictures are also from the same raw file

lighted with the Polarion

left with WB #1 and the right one with WB #2 (corrected)

 

The lower two pictures are again from the same raw file

lighted with the Ultron

left one with WB #1 and right one with WB #2

 

My first thougths when I got the Ultron (I own the

Polarion a bit longer) were targeted at the influence

of the different power of the torches, but eventually

I assume as well, that they have a slightly

different spectrum, though both are sold as 365nm lights.

It seems the Ultron is "more into the UV"

 

The point is: I should not use them at the same time,

because I will get problems with the WB then

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Row one is self explanatory.

You define WB #1 as WB on the Polarion (row one left) and WB #2 as WB on Ultron (row one right)

Row three agrees with row one, Ultron WB on Polarion looks yellow while Ultron WB on Ultron looks white.

 

Sorry to pick a bone, but to me row two still appears transposed.

If the middle two pictures are lighted with the Polarion then should not your whiter one on the left be Polarion WB#1 on Polarion?

Likewise shouldn't your bluish one on the right then be Polarion WB#2 on Ultron as in row one right?

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Thanks John, yes, I correctd it.

(writing with this editor is a pain, normal speed looks like this:

witingwith tis editor is a pain, normal speed looks like this)

So I have to do a lot of editing

So I hve to do a lot f editing

because many key hits are lost

becuse nany key hits are lost

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What browser are you using Werner?

I don't see lost key hits using Firefox and I type fast.

 

Are you using an iPad ? It is terrible for losing key strokes.

 

 

*********************

 

Performing a white balance on that yellow should give a lot of blue.

Does the yellow flower at the bottom left go with the blue flower on the right?

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Andrea, usually I use IE11 with Win7.

This now is with Firefox, and you are right, it seems to just work fine.

 

Maybe the reason is, I have switched of some Java stuff in IE (so also many videos do not show up).

What I see in IE is, that it seems to communicate with the server for every key hit.

 

Thanks for the advice!

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which one matches the true UV color under the sunlight? I like blue ones (middle, right) better but it might not be "real". thanks for posting the LED results. Price seems to vary quite a bit. from $10 to $500.
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No UV LED torch can match sunlight. The LED has too narrow a bandwidth.

 

UV LEDs are not the best thing for illumination of a photographic subject if you want a false colour range

because they tend to produce a monochrome response in the camera.

 

UV LEDs are useful for inducing fluorescence when making UV-induced Visible Fluorescence photographs.

But for this you want to have a torch which does not leak violet or blue.

This can be accomplished by putting a UVIR blocking filter over the torch.

 

UV LEDs are useful for shining on the subject in order to focus when using Live View and an external UV-pass filter.

 

Many Ebay UV torches do not have powerful LEDs, so try to look for the specs and choose one with more power.

 

My particular UV LED has a "designer" titanium case which was why it was so expensive. Hardly necessary, just a whim because I wanted a long-lasting tool.

 

The Ultron which Werner demonstrates above looks like it might be a good choice. (But I have not read about it or worked with it.)

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Werner, I have no way to make the IE browser behave with this Invision software package, so perhaps using Firefox for UltravioletPhotography.com may be the best way to go.

 

You might investigate the preferences and settings for IE to see if there is anything which could be tweaked to make IE behave better.

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No, thank you Werner,

 

It is easy to get switched even without browser problems. I abandoned IE and after some months of running Firefox -vs- Chrome, I went with Chrome.

 

I had a similar but opposite problem with UV LEDs. I went the cheap route and purchased two 110V AC medium lamp base (regular light bulb) types from a re-seller. These were supposed to be 3W 365nm and 3W 385nm but when I measured them with my spectroradiometer what I really got was 374nm and 377nm. Where I was trying for variety and got essentially the same thing you went for consistency and got unexpected difference! LEDs are typically classified by a binning method due to manufacturing variability. The bins are normally named for the lowest wavelength, so a bin 365-375nm would be called "365". Seems to me it should be the mid or mean. Don't know how I got 377 for 385....

 

Having seen white light LED arrays composed of red, blue and green LEDs, I think it might be interesting if you superimposed your beams onto a subject with a complex UV signature that included both false UV-yellow and false UV-blue. The resulting image should not be monochrome with the degree of false UV-color separation observed between your two sources.

 

John

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Do I understand this correctly, the Polarion (or Polaron, not sure) have more emission towards the visible?

 

That would be my assumption also.

The Ultron is probably really 365nm and I would estimate the Polarion 20-25nm longer.

That may be why the Polarion looks weaker, if it is emitting into a lower transmittance part of the Baader U range.

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As said, I just will stay with Firefox, no problem, I have it on all of my computers (but not yet on my Ipad).

 

@msubees. I fully agree with Andrea. But a very good light close to sun light is just using a flash.

 

@John: I did try to combine the torches, but -beside the obvious different main wavelength- there

is a clear difference in the power between the two, also visible when I shine the light at a fabric or

something like that cleaned with a whiter, so I get some kind of flurescence. The Ultron then causes

a much brighter and larger blueish white spot.

 

(Side note: this is an easy test for torches, and you also see how the UV-beam is spreading/looks like)

 

And yes, I rate the Ultron is a good one for focusing even/also outside (and though it is not cheap it also not that expensive).

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Just for the different light and colors, a quick comparison (Camera GH3 modified)

 

(a bit windy outside and all by hand, camera in the right and torch in the left hand B) not ideal for getting a focus :) )

The sunlight is not direct sunlight.

First one with WB done on each picture individually trying to get the same black of the pollen

upper two with the UV Nikkor

lower two with the Olympus 45/1.8 µ43 lens (though only slightly into UV thanks to aperture of 1.8 similar exposure times and even the AF works)

 

post-21-0-52435100-1406483586.jpg

 

 

second one as the pictures came out of the camera (all with the same uncalibrated WB setting in the camera):

post-21-0-73242200-1406483601.jpg

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