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UltravioletPhotography

Canon 5D unmodified for UV


Damon

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Another Canon for the UV chopping block?

 

"Do you have any final words, Mr. 5D Classic"?

"Yes I do--it's not my fault, I was designed that way".

 

Achilles heels:

--Need max iso to get somewhat acceptable image--with 3 modified Vivitar flashes blasting it (I don't know how much UV is coming off the Vivitar's though to be truthful)

--using max iso inherently no good for UV

--images "soft" when captured

--no live view

 

 

Exif data says iso 1600 but it was iso 3200--don't know how this can be but it is. This captures the classic sunflower UV signature ok, not bad actually--but we have to be realistic. When zoomed in just a bit, the professional level UV detail falls away. For the web I suppose it looks just fine--good actually. The longer I stay on this site--the pickier I am becoming though. The fact remains however--it does capture the UV bulls-eye of this sunflower. Just a note for the archives.

You might be able to "get away with it" if you wanted to. However, dark less reflective subjects may cause you angina.

 

 

UV: Canon 5D Unmodified, EL-Nikkor 80mm f5.6, 3 Modified Vivitar 285 HV's Unfiltered, Incandescent light Unfiltered, 1/250 s @ f/5.6 ISO 3200, Baader U filter, WB color temp 2500K, 1 Click Photo Ninja

post-51-0-27472600-1424581624.jpg

 

 

BTW--with many of these shots--it makes little to no difference if I shoot at 80 or 250 shutter speed--the image looks the same. Are my Vivitar's firing hotter at 250?

 

 

-D

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Check the synch speed of your camera. It probably is 1/250 sec.

 

With a shutter like a DSLR, and fast-acting electronic flash, there will be little difference at most reasonable speeds up from synch speed or below. That is, until background illumination starts to become a significant part of the overall exposure, which for shooting in UV tends to entail very slow speeds. Thus, in my indoor studio, whether I shoot at 1/250 sec or 4 sec for a UV capture really doesn't matter compared to the settings of my studio flash(es).

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With the D600 I can get varying amounts of light with some flashes - depending on whether the flash is all synced up on the hot shoe (as opposed to a manual firing) and on how the flash menu items are set. The usual stuff. So just read up in your Canon manual and your Vivitar instructions to see how they might behave.

 

BTW, Damon......it is OK to perform some of the standard editing trickery which all photographers employ in either film (whatever that was) and digital: burn, dodge, contrast boost, sharpening. When I popped your 5D sunflower into NX2 and laid a color point over the center to raise the shadows, lo-and-behold, I found some detail. In green. So I added a tiny bit of high-pass overlay to the flower and a very minor contrast tweak to the petals. Very simple, legitimate edits. The photo does now offer a bit more of interest. Unfortunately the dodging also showed up a tad bit of center muzziness. But we already know that the unmodded 5D is not ideal for UV work.

 

Now, where did that green come from? It could just be a white balance issue? I would expect blue instead with a sunflower.

 

post-51-0-27472600-1424581624.jpg

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Thanks Bjørn, the shutter sync is 1/300 s.

 

Andrea, that green is a WB problem for sure. My standard teflon was out of the edge of the frame and I didn't notice it until I opened it up on my computer so I did the best I could with basically just the image to WB.

So you found my goof! :)

 

Thanks for the edits. I do usually process the images some. I didn't do much with that one obviously. It can become tricky because with software today, as programs have become very powerful, it is not difficult to make the image something it is not--or was not originally. So with UVIVFL, I take special pains to try not do that because it is not a true representation of what I saw--which most times corresponds to reality. :D

 

With UV though for me, it is a tad more difficult because I can't see it beforehand very well. Live View is limited apparently and needs a lot of light to work in a useful fashion and my flashes produce that light but only for a moment. With the Blak-Rays I can see the flower, but I haven't used them so much for UV, mainly UVIVFL. I am hoping sunlight is an improvement in that regard.

 

 

Looks like my old vivitars do not E-TTL, TTL, or any of that. There is not any of the communication that modern flashes have. However, there are a fair amount changes one can make using different dials etc. right on the flash.

I just have my on manual mode at full power all the time.

 

 

-D

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Live View is limited apparently and needs a lot of light to work in a useful fashion and my flashes produce that light but only for a moment.

 

Which is why we use a UV flashlight for setting up in Live View, dialing in focus, etc. Then turn off torch and shoot with flash. I have various clamps to hold the torch in place shining onto the subject while I fool around with focus & settings in LV.

 

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

 

I spose we should take a moment to remember that getting green in UV is not necessarily a sign of white balance error. There can be greens - usually dark greens after a click-white-balance step. Also if using a filter like the Andrea-U, greens are quite possible. And, after all, all colour in UV is false. But for most of the work you have been doing so far Damon, I guess that green indicates wb shift.

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There is also the possibility of a changed response for example in the outer areas of the transmission curve when a slightly diffrent filter is used. In my present (not yet published) investigations, I came across this quite frequently. The passband difference might be quite narrow yet more than enough to make significant false colour changes. This might occur even when nearly everything is rendered similar.
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Are you saying this green could be a characteristic of the Baader U I used?

Would someone please make a brick-wall filter already?

 

It's weird because I can take a simple piece of proper cheap polycarbonate and it blocks 100% UV. And yet they can't put a coating on a filter that blocks all of a certain wavelength?

 

-D

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Damon we have listed elsewhere all the variables which conspire to create false colour in UV photographs. There is not any way to be totally sure where a false colour comes from. Just one of the little joys of UV photography!!

 

Go make some nice photographs. Enough testing for awhile. That's what I'm thinking for myself right now, too. I can spend hours over a flower or a landscape or a nice still life. But I'm bored silly after 20 seconds in a dark closet with a UV light and a spoon.

(....o man that sounds soooo weird at this late hour of the night......and I have jury duty tomorrow too...goodnight everyone....ttyl)

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Damon: it is not hard to attenuate ('block') something more or less complete, as long as you don't care what happens at the borders of the passband. However, our UV passband filters are not designed this way, because we *do* care about the transition between passband and the outside of it. We want of course the transition to be as sharp and narrow as possible, but 'possible' is the operational word here. You cannot have a very steep transition without side effects. Filters in practice cannot be but an approximation to the ideal 'brick-wall' (on/off, 0/1) filter.
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