18 replies to this topic

[MLP]

Hi everybody, I'm new to the group. I just signed up and posted an intro.

I'm totally new to UV and I've really been struggling with getting enough UV light in my photos. Am I missing something - besides the visible spectrum I mean?

For my part, I purchased a Canon Rebel S1 and had it converted to UV by LifePixel (not full spectrum but UV). An expensive experiment to be sure. Since then I have used it with limited success. It seems the amount of UV light needed to get a decent exposure is hard to come by. In my experience even open shade is too dark. It needs to be direct sunlight or I'm not even able to focus using Live View.

The only time I was able to get a decent exposure was when I rented the Broncolor UV Attachment. Another expensive experiment. Luckily I live in NYC so I could rent one for the day to experiment. But even with the Broncolor, my ISO and Shutter Speed were painfully slow (ISO 3200, f2.8 at 1/30th). For people shots that is way too slow to be usable for most applications.

I have read about converting Vivitar 285 flashes but I'm wondering if that is enough power considering I was using a 3200watt Broncolor pack at full power and I'm still shooting painfully slow. I have also purchased, then returned, some LED UV lights that barely register either.

I'm sorry to sound so helpless but I'm just perplexed at how to get a decent UV exposure.

I would be grateful for any feedback. Thanks, Michel

Edited by MLP, 07 March 2017 - 18:17.

[Andy Perrin]

That is typical of UV exposure settings in ordinary sunshine, from my experience. 3200ISO, and 1/30" at F5.6 is probably my most common settings for handheld shooting. You probably need a lens that passes more UV, though. Check out the lens sticky for options. Many people also use modified flashes and UV torches. There has been much recent discussion about UV torches on here, but considering my own confusion on the issue, I won't provide guidance -- you can read the relevant threads.

To some extent, I think you need to adjust to the realities of this medium, though...

Edited by Andy Perrin, 07 March 2017 - 18:25.

[Alex H]

What lens are you using?

[Andrea B.]

Gotta be the lens.

Side Note: You don't want to be flashing that Broncolour UV at peoples' eyes. Harmful!

[JCDowdy]

Yes, what Alex said, what lens?

Also, please do not UV irradiate your eyes friend.

[nfoto]

Simple enough to get "UV Light": Use studio flash with uncoated Xenon tube. Forget about the Broncolor UV Attachment, it is really only suitable for film and even in this case not very efficient.

With a single Broncolor Minicom 80 head at 2 m, I can get perfect exposures at flash sync speed (up to 1/250 sec), f/11 and 100-200 ISO with the Coastal Optics 60 mm f/4 on my UV-modified Nikon D3200 or D600 using a Baader U 'Venus' filter. As the lens is parfocal in UV vs visible light, one can just focus as normal. No need for Liveview. which doesn't work well, if at all, indoors.

[MLP]

Great thanks everybody for the notes of caution, I am not flashing anybody in the eyes. Point taken.

Here is my entire equipment setup:

Canon Rebel SL1 (EOS 100D)
Canon Lens EF 50mm 1.8 II
LifePixel Dedicated UV conversion 360-400Mn
Broncolor 3200W Scoro
Broncolor G4 Head
Broncolor UV Attachment

If I could figure out how to shoot ISO 200, f11 at 1/250 it would be amazing!

nfoto - I'll look into studio flash with uncoated Xenon tubes. I'm not sure what that is yet but I'm eager to find out!

[MLP]

nfoto, on 07 March 2017 - 20:30, said:

Simple enough to get "UV Light": Use studio flash with uncoated Xenon tube. Forget about the Broncolor UV Attachment, it is really only suitable for film and even in this case not very efficient.

With a single Broncolor Minicom 80 head at 2 m, I can get perfect exposures at flash sync speed (up to 1/250 sec), f/11 and 100-200 ISO with the Coastal Optics 60 mm f/4 on my UV-modified Nikon D3200 or D600 using a Baader U 'Venus' filter. As the lens is parfocal in UV vs visible light, one can just focus as normal. No need for Liveview. which doesn't work well, if at all, indoors.

Does this mean I'm using the wrong lens and the UV light is being eliminated by the lens coating?

[nfoto]

The lens is probably not very suitable for UV. You need something that really lets UV pass through it. Check our stickies for suggestions. The Lifepixel UV passband figure you quoted is not very impressive but likely will suffice if you are into portraits.

Most studio flashes can be fitted with uncoated Xenon tubes. There are also independent suppliers available for such tubes. Some units use protective glass covers that cut UV and protect from a shattering tube at the same time. Thus you need either to use the naked flash (but with a reflector), or have a protector that also passes UV freely. Broncolor offers both alternatives depending on the actual studio head.

[Andrea B.]

Your Canon lens is probably coated to reflect UV away from the sensor.

I would recommend trying a rental of the UV-dedicated Coastal Optics 60/4.0 from Lens Rentals (link below) for a week in order for you to learn what is possible with your camera & filter in sunlight and with the Broncolor. This CO 60/4 is a quartz/fluorite, corrected (UV, Vis & IR) lens which is quite pricey. But the point is -- you will immediately see what you should be getting in a good UV photograph. Then you can begin to look for a less expensive lens which can operate in the 360-400 nm range and hopefully give you reasonable quality.

If you are not familiar with Lens Rentals, they are a top-notch deal. Keep their lenses in good shape, etc. (I bought a nice used CO 60/4 from them.)

LINK https://www.lensrent...=Coastal+Optics

[MLP]

nfoto, on 07 March 2017 - 23:23, said:

The lens is probably not very suitable for UV. You need something that really lets UV pass through it. Check our stickies for suggestions. The Lifepixel UV passband figure you quoted is not very impressive but likely will suffice if you are into portraits.

Most studio flashes can be fitted with uncoated Xenon tubes. There are also independent suppliers available for such tubes. Some units use protective glass covers that cut UV and protect from a shattering tube at the same time. Thus you need either to use the naked flash (but with a reflector), or have a protector that also passes UV freely. Broncolor offers both alternatives depending on the actual studio head.

Thanks Bjørn. I really appreciate your feedback. I'll look into uncoated Xenon tubes.

[MLP]

Andrea B., on 08 March 2017 - 00:43, said:

Your Canon lens is probably coated to reflect UV away from the sensor.

I would recommend trying a rental of the UV-dedicated Coastal Optics 60/4.0 from Lens Rentals (link below) for a week in order for you to learn what is possible with your camera & filter in sunlight and with the Broncolor. This CO 60/4 is a quartz/fluorite, corrected (UV, Vis & IR) lens which is quite pricey. But the point is -- you will immediately see what you should be getting in a good UV photograph. Then you can begin to look for a less expensive lens which can operate in the 360-400 nm range and hopefully give you reasonable quality.

If you are not familiar with Lens Rentals, they are a top-notch deal. Keep their lenses in good shape, etc. (I bought a nice used CO 60/4 from them.)

LINK https://www.lensrent...=Coastal+Optics

Thanks for the link Andrea. I'm learning so much about where I've made mistakes with my UV. The more I learn the less I seem to know. Cheers, Michel

[MLP]

Okay, I guess I need to check my assumptions about how UV works. Please feel free to let me know either way.

If I understand correctly, there are three primary variables in determining UV camera exposure, just like visible light photography: ISO, Aperture and Shutter Speed. However, there are also three other variables of that are UV specific.

The UV transmission rate of the filter over the lens or sensor (in my case I did the LifePixel UV dedicated conversion with 99% UV transmission).
The amount of UV coating on the lens that may block some of the UV from reaching the sensor.
The amount and quality of UV from the light source (that is why uncoated Xenon tubes work better than UV coated flash tubes).

[Andy Perrin]

Don't forget how much glass (and the type of glass) in the lens. Quartz will pass a lot more than ordinary lens glasses, for example. More lens elements = more glass to pass light through = less UV getting through. Also more glass/air interfaces for reflection losses.

Edited by Andy Perrin, 09 March 2017 - 20:42.

[nfoto]

A final consideration is that most lenses really need to be stopped down quite a bit to make acceptable quality UV images. The exception of course being the UV specialist optics, that often perform excellently almost "wide open" (mostly f/4 or thereabout).

[Andrea B.]

The UV transmission rate of the filter
The amount of UV coating on the lens
The amount and quality of UV from the light source

Also the type of glass in the lens, the type of glass forming the sensor microlenses,
& the type of glass used to protectively cover (vis fusion) the sensor.
The number of elements in the lens is a factor - the fewer the better for UV unless the elements are made of fluorite or quartz.
And the type of glue holding any fused elements together.
Also the possible reflectivity of the interior of a lens.

Also note that your Live Pixel UV-pass filter has a peak transmission of approximately (I would say) 96%-97% at about 375-380 nm. But the transmission falls off to the sides of that peak. Therefore you need to be sure your UV illumination covers that range. Using a 365nm torch or other such lamp will probably get you enough UV light but won't be quite as useful as it would if a lower peaked filter were used. However, on the plus side, there is always sunlight which should easily handle this peak. On the minus side, sunlight varies in its UV quantity by time of day, time of year, geographic location, altitude and other factors. Whew!!

At ISO 400 in really strong sunlight at f/11 (my common aperture for botanical documentaries), I cannot easily obtain 1/250". Indeed, outdoors, I almost always use a UV-flash to boost the sunlight even when I'm getting strong readings (in summer between the hours of 10am-2pm of between 4-5 mW/cm2 on the Solartech UVA/B solar meter. My lenses used to get settings like f/11 @ ISO-400 for, say 1/30", are UV- dedicated like the Coastal Optics 60/4, the Zeiss UV-planar 60/4.0 or the UV-Nikkor 105/4.5.

Now, in a studio setting with UV lamps (Broncolor or Blak-Ray, etc), I have no experience. So I can't offer up anything to guide you except to say look at what some of the other portraitists here have done.

Here's the Life Pixel chart.
The sides of the transmission peak are fairly steep giving a nice, wide half-bandwidth.

[MLP]

Andrea, I'm grateful to you and the forum for all your insight into the many many complexities of UV photography. There are way more complications than I expected. The glue used in the lens elements can be a factor.... Yikes. I read it elsewhere on the forum, UV has a steep learning curve. So I am learning.

Thanks for helping me through the first few steps.

Edited by MLP, 10 March 2017 - 18:20.

[Andy Perrin]

You certainly start to appreciate the engineering that went into making our equipment work in visible light (as intended) when you are trying to fight the equipment to make it work out of the visible spectrum! I am beginning my own learning curve with shortwave infrared (SWIR) photography, here defined as 1400nm-3000nm, which, on top of all the same kinds of issues UV brings (lens not transmitting SWIR light, etc.), also has the major difficulty that our silicon sensors don't work there AT ALL. One either needs a specialized InGaAs sensor camera, or you do what I'm doing and project the image on a fluorescent screen that emits 900nm light at inconveniently low intensities when SWIR light hits it.

[Andrea B.]

Everything is pretty much summarized in our Stickies.
<> Sticky :: UV Photography Intro, Cams, Mods, Lights, Links <>

<> Sticky :: UV/Vis/IR Filters <>

<> Sticky :: UV-Capable Lenses <>

<> Sticky :: White Balance in UV/IR Photography <>


Our member David Prutchi has a recent book about UV photography which you might find useful.
Look here: UVIRimaging

In the first Sticky look under Links for other good UV websites from members Enrico Savazzi, Bjørn Rørslett and friend Klaus Schmitt.

[Disclaimer: UVP has no financial association with vendor-members and does not permit advertising.]