Double Invisible Vision 308nm filter - makes sense for UV-B only stack?

[lukaszgryglicki]

I'm considering moving my deepest sunlight stack a bit more into 310nm or 308nm... I'm considering buying another IV 308 filter to replace my UV-B stack.

Current one is IV 308nm + Hoya U340 4mm. Do you think this can give me an UV-B stack?

- GFX 50R mono + quartz coverglass + UV-Nikkor + 2 x IV 308nm filter?

I want to use this for outdoor photos using sunlight only...

I know there are people there who can save me costly mistake, is there anything that will make this setup impossible?

I've calculated transmission by just multiplying my current IV 308nm with itself here: https://docs.google.com/spreadsheets/d/1y2XAs5Y12vt_tVL7wj4EZregpfbQ8yrxny7_OY7qyrY/edit?usp=sharing

 

[dabateman]

I have no idea if a double stack will keep great UVB and reduce the IR.

U340 seems magical that way, in that you can stack it without loosing too much in UV, and removing all IR leakage. 

The trick with your imaging is your light source.  You want to us sunlight.  I like to image using the mercury lines. 313nm is a great line. 302nm is also fun, thats how I photograph, under controlled lighting. 

[lukaszgryglicki]

Yes but I want sunlight. I want to test how deep possible is to go with no artificial lighting.

 

[Andy Perrin]

Quote

I'm considering moving my deepest sunlight stack a bit more into 310nm or 308nm...

...

Yes but I want sunlight. I want to test how deep possible is to go with no artificial lighting.

 

My honest feeling is "not much further than you already did" with sun. Like, maybe you could push it a few nm further, but you probably won't see anything new, and it's going to be diminishing returns with the (lack of) sunlight. Advice is to stick with what you have and do more imaging with it. You cannot really defeat the fact that the world goes dark at that point, especially in a far-northern winter. 

 

The other thing you can do is what dabateman said and use another light source. I'm sure you could push it significantly further with artificial light. Doing trichromes like Stefano and Bernard have attempted seems like a good goal. 

[lukaszgryglicki]

OK, I will wait for more sunlight then and experiment with my current setup. 

[JMC]

Lukas, At this point the sensitivity defining issue is the light itself - there just isn't a lot around at 300-310nm especially if it's not full summer and bright sunlight. There is unfortunately quite a lot of visible and even IR around, so it makes imaging what little UVB there is even harder. Personally, I would not recommend you get another IV308 filter at this stage,

[lukaszgryglicki]

OK understood. I know that I can do more with artificial lighting, but this limits me to indoor and close distaances, while I really prefer to make photos outside.

I wonder if this is possible to make a portrait in UV-B - at least I'll try to do "UV-B selphie" :P

 

[ulf]

http://thephotopalace.blogspot.com/p/head-brace.html

 

[colinbm]

46 minutes ago, lukaszgryglicki said:

I wonder if this is possible to make a portrait in UV-B - at least I'll try to do "UV-B selphie" :P

 

What don't you understand Lukas ?
If you wear the proper eye, face & skin protection, you won't get a very good portrait !

[lukaszgryglicki]

I'm speaking about natural sunlight, I don't use sunscreen and I'm OK, making portrait does not change anything.

 

[dabateman]

Go for it in sunlight. 

Jonathan also attempted a UVB portrait,  but I think he had IR leakage.  Make sure to use the U340 to block the IR.

 

@ulf,

Thanks for the head brace link. I will have to look into those for a totally different purpose. 

[photoni]

1 hour ago, dabateman said:

 

@ulf,

Thanks for the head brace link. I will have to look into those for a totally different purpose. 

it's simple to build it, I used a microphone stand, on the arm I put a thick aluminum wire with a soft end.

in another I used two tablespoons.

[Andy Perrin]

Yeah, I mean, natural sunlight for reasonable (non-sunburn-causing) periods of time is not going to be that harmful. Like, he spends time outside anyway and unless he always uses sunblock, he's getting the same exposure. The real safety problems are with artificial lighting.

 

Actually, the real REAL problem will be that he may not like what he sees! 

[lukaszgryglicki]

Only talking about sunlight, and I know what to expect. I will need to be patient and motionless for maybe a minute or two.

 

[Andrea B.]

For max UVB, go up in altitude to about 6000 feet (~~1800 meters)  in the middle of summer at high noon. 

Preferably find this high altitude as close to the equator as possible. 

 

Just making a joke here....... "-)

 

The thing about remaining motionless is that you cannot stop your heart from beating. Sometimes heartbeat alone can cause a bit of motion blur. I've had this happen when I'm trying to handhold. (Why are we all so everlastingly stubborn about using tripods? I do not know. Maybe none of you all are like that, but I try way too often to handhold when I should just be sensible and take the tripod. Oh well.)

[Andy Perrin]

I wonder if a solution might be to take a lot of large aperture but high ISO shots and align the photos and average them together, using software like the Mac app "Long Exposure Stacker." Then you just have to not change expression.

[lukaszgryglicki]

I decided to get another IV308 anyway, will see how wrong I was.

 

[Stefano]

On paper it should work, I'm interested to see what you get.