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UltravioletPhotography

Infrared leak?


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New to the UV photography. I'm ordering a bunch of filters to create a 2 stack cheap UV filter. Does anyone have a formula for ir leak? Say if the stack allows for light 300nm to 400nm at 65% transmission and it from 680nm to 850nm at 8% transmission. The UV curve is rounded at the peak and the ir has a triangular shaped curve. In my IR experience I'd have no issues with such a difference. But I know there is much less UV light than IR. Tia!
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Yes can get complicated if you want to parse it out to specific UV wavelength.

 

But short answer first: for UVA work 350nm to 400nm, buy a 2mm thick S8612 filter and your done. That will work with U340/UG11 filters, and U360/Ug1 filters and U330/UG5 filters.

 

For deeper UV you need to think about camera QE response curve, light source emmission, lens coating and then look at IR blocking range.

 

Range of filter is important as well. A UV filter with tight band of say 370 to 375nm will need different IR blocking level than one that includes 370 to 400nm.

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enricosavazzi

As a first approximation, the IR peak of the filter you mention is roughly 12% the height of the UV peak. This is way too much IR transmission for UV imaging in solar light on a silicon sensor. A D=4 (i.e. 0.01%) IR transmission or D=5 (i.e. 0.001%) IR transmission is generally regarded as good enough for a UV-pass filter.

 

Then another question is the width of the peaks, not just their height. A low wide peak may contain a similar amount of radiation as a tall but narrow peak, so a measurement of the area under a peak (or in a given interval of wavelengths) is probably more significant than just peak height.

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Deleted

 

Colin offered a reality check here. Don't always speak whats on your mind. Your Audience will not always care or know what to do with the information.

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My personal favorite is Hoya U-360 2mm + Schott S8612 2mm (or even 1.5mm, 1.75mm, 1.75mm makes a perfect OD5 suppression).

UG1 is like U-360, but I think U-360 is better. U-340 is like UG11, but I think UG11 is better (especially when thinner than 1.5mm, I would not use U-340 1mm, it leaks in the 500nm range, where UG11 is more suppressed at the same thickness).

UG11 or U-340 can be used if you want to cut a little deeper below 400nm. This will look slightly yellower when compared using the same WB,

but when individually WB'ed from RAW, they will be virtually impossible to differentiate from each other or a Baader U.

 

LUV U is a UG11 stack, U-Vee is a U-360 stack.

Compared with Baader U, using Kuribayashi 35mm f/3.5(M42 threaded) lens.

post-87-0-45492500-1579129693.jpg

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dabateman,

Why are you introducing, Namestom, who says they are ' New to the UV photography ' to this deadly stuff, when they asked a simple question about 300nm - 400nm UV photography ?

Not only is your suggestion deadly, I think it should be removed from this answer, please ?

Not looking for a fight or loosing your friendship, but this is deadly stuff for a newby.

Col

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Yeah, I'm thinking we should quarantine the UV-B and UV-C stuff to their own threads (or even start a new section?). I mean, not that I'm against experimentation out there — I would love to try it sometime — but let's try to avoid suggestions that might hurt people who don't know what they're dealing with yet. Andrea??
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"Say if the stack allows for light 300nm to 400nm at 65% transmission and it from 680nm to 850nm at 8% transmission."

 

The 300 to 400 sounds good, more realistically 320 to 400.

If you want a higher percentage then get Baader U (not abiding to your "cheap" criteria, but having a higher transmission % and slightly faster exposure) or do a U-360 2mm + S8612 1.5mm or even cheat a little bit and do a 320nm to 405nm stack using U-360 1mm + S8612 2mm (about the same exposure as a Badder U).

 

The "680nm to 850nm at 8% transmission" that you mention, I don't know if I am understanding you correctly.

You don't want anything above 400/405 to have 8%. You want at least OD4, preferably OD5 which is 0.001% transmission.

You want everything above 400nm suppressed to OD5.

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dabateman,

Why are you introducing, Namestom, who says they are ' New to the UV photography ' to this deadly stuff, when they asked a simple question about 300nm - 400nm UV photography ?

Not only is your suggestion deadly, I think it should be removed from this answer, please ?

Not looking for a fight or loosing your friendship, but this is deadly stuff for a newby.

Col

 

Both previous quick response from me have been edited. My thoughts should rightfully go into a separate post with oh so many warnings. Maybe more warnings than content.

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Just to add something about the dangers of short-wave UV...

 

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.hongkongfp.com/2017/10/26/partygoers-left-burns-light-sensitivity-hypebeast-event-landmark/&ved=2ahUKEwiHvbGByYfnAhWEC-wKHeZlDKUQFjACegQIDxAN&usg=AOvVaw3zkVfN1CT9V5u4hYls6k1z

 

Someone apparently bought the wrong type of UV lamp, and this were the results.

They glow a nice cyan-blue color (436 and 546 nm lines).

 

Looking at one of them for one minute or less is enough to have eye damage (hopefully not permanent). Symptoms are not immediate, they start to appear hours later.

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Yes know your audience. First rule I forgot. Don't teach quantum mechanics to a high school student, they just know enough to have their brain melt. Teaching to kindergartners, you just look at you and say you just said some silly words.

 

There are two types of Germicidal bulbs. So be very careful. The common type will emit mostly 254nm light that is dangerous and are low temperature and low pressure. Then there are the super dangerous Ozone germicidal bulbs that emit mostly 185nm and 254nm light. These are medium pressure and/or high temperature. Its not always marked if you got a super dangerous one. But if you smell ozone, an odd smell after 5 seconds of turning it on and the smell gets stronger, then turn it off and clear the area. You may have gotten an ozone light.

 

If you can smell ozone you are actually above the OSHA safety level.

 

Never look at a germicidal light. Amazon is filled with reviews of people whom have been blinded.

 

Best never to really use or buy a germicidal light. I will test mine in my shower to see if it can kill the mold and anaerobic bacteria I have growing under the silicon seal. But I doubt it and they aren't useful for anything.

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"two types" ?

Lets simplify that, both types are in the 100 to 320 range, and we want to stay away from all that stuff entirely. Agreed?

And anything above 320nm, up to 400 +/- is not good for us either, especially our eyes. Agreed?

So, if you want to play around with UV, I suggests you keep it in the 320 to 400 range unless you wear a tent made out of leather.

And wear protection (especially for your eyes) in the 320 to 400+ range also.

UV is especially bad for your eyes, it causes cataracts and skin damage, and can burn out your eyes also.

Be extremely cautious about attempting to use UVB or UVC. That is dangerous stuff, never intended for life to be used on, seen by, or exposed to.

Keep in mind there is no UBV or UVC in sunlight that reaches the surface of the earth (and thus will open a whole new thread of discussion, once again, as has happened before).

 

There really should be an EXTREME DANGER WARNING (in RED) at the top any topic that deals with UVC or UVB, and some kind of warning also with any topic that deals with UIVA even.

But UVC and UVB 100-320nm is really off limits.

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I am interested in exploring such things but I think we need to isolate posts on these issues to some special corner of the site, with all the appropriate hazard warnings.

 

I messaged Andrea so maybe we can get an official discussion going.

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Well, isn't enough to just avoid exposing eyes and skin to UVC and avoid breathing the ozone that may be synthesized? Is there something else to know?

 

Yes, every UVP member (and every person really) should know that UV, especially UVB and UVC are dangerous, can cause skin cancer and so on. So is this just to make sure that everyone REALLY knows this?

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Yes everything Cadmium said.

 

And from what I have seen, in general people should avoid mercury based compact fluorescent bulbs. End stop. All of them.

Switch over to LED lights now. When you turn them on there is a burst of light at low pressure and low heat and you will be exposed to dangerous UV. Not all inner coatings, especially the cheaper bulbs are good.

 

For your health switch to LEDs. You will also save more money in your house.

Incandescent bulbs are ok but very rare today. Cheap hallogen bulb in an incandescent looking frame that are cheap actually are also unprotected and go down to 350nm.

 

Leds seem to be the safest, UV free light. Unless specificly design for UV.

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Well, can't they make CFLs with a "normal" glass? If you buy them from a "trustable" seller they should be fine. Today even halogen car headlights have a UV filter, they fluoresce blue when exposed to UV. Their quartz envelope is still quite transparent to UVA. But chinese bulbs don't have this UV filter, and that's why I like them (for UV photography).

 

Also I read that they want to make white LEDs with a UV LED "pump" instead of the classic blue LED. They would be basically solid-state CFLs. Even those could be dangerous if UV is not shielded.

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I have a "funny but actually not" story:

My mother had a UV tanning lamp (probably mercury, 313 nm), and it was very powerful. She used to use it at ~2 m away and only a few minutes were enough to make her skin red (healthy, right?). There was clearly written that you could use it for max x minutes, I think 5. Any more than that and you would have gotten a nice sunburn. She had a colleague at work. She didn't really like her, but thats another story. She asked my mum if she could borrow it, because she saw that my mum was suntanned. She did borrow the lamp to her, but warned her that she could't use it for more than 5 minutes. It was Friday I think. On monday, she didn't go to work. On tuesday, same. Finally, on wednesday, she went to work, and guess what happend. She had been seriously sunburned, she had to go to a doctor and I think that her eyes swelled or something like that. She was also a bit angry, but my mum reminded her that she warned her not to use the lamp for too much. She said that she used it like the other lamps, for 15 minutes.

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Well, isn't enough to just avoid exposing eyes and skin to UVC and avoid breathing the ozone that may be synthesized? Is there something else to know?

 

Yes, every UVP member (and every person really) should know that UV, especially UVB and UVC are dangerous, can cause skin cancer and so on. So is this just to make sure that everyone REALLY knows this?

A lot more people read our site than are members, and in fact many people don't really appreciate danger at a gut level until they are actually burned. Teenagers in particular are notorious for this...

 

As far as whether there is something else to know, yes, I would actually quite like to know how people SAFELY handle UVC. I have been thinking of building some kind of fish-tank-like container to hold the equipment with a UVC-absorbing glass or plastic, and also perhaps semi-automating the camera and light source so it can be remotely controlled. Things like this could be discussed.

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A lot more people read our site than are members, and in fact many people don't really appreciate danger at a gut level until they are actually burned. Teenagers in particular are notorious for this...

 

As far as whether there is something else to know, yes, I would actually quite like to know how people SAFELY handle UVC. I have been thinking of building some kind of fish-tank-like container to hold the equipment with a UVC-absorbing glass or plastic, and also perhaps semi-automating the camera and light source so it can be remotely controlled. Things like this could be discussed.

Luckily blocking UVC is very easy. The difficult part is transmitting it (quartz lenses).
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Luckily blocking UVC is very easy. The difficult part is transmitting it (quartz lenses).

That's a little short-sighted. A lot of materials absorb UVC indeed, but they also tend to break down. I don't want some kind of plastic that's going to turn yellow or crack or something after it's been exposed a few times. I also have to think about how to make sure it's not leaking light anywhere. And then there's the automation. The light source needs to be able to be remotely controlled. And preferably with an automatic shutoff so that it can't be accidentally left on. And ventillation seems to be a big issue -- one needs to get rid of the ozone and also have a sensor to detect if there is too much in the room air.

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My personal favorite is Hoya U-360 2mm + Schott S8612 2mm (or even 1.5mm, 1.75mm, 1.75mm makes a perfect OD5 suppression).

post-87-0-45492500-1579129693.jpg

I tried to find graphs for U-360 stacks but I couldn't find them. It would be interesting to see the Hoya U-360 2 mm + Schott S8612 1.75 mm. OD 5 at 3.75 mm is quite impressive. That's probably because U-360 has the IR peak moved slightly forward (>700 nm) in comparison to the U-340 (>~680 nm). 20 nanometers can do a lot in that delicate region.
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