What is your favorite UV-pass solution, and why?

[Fandyus]

Might be a bit of a bold question, as I know that there are a lot of experimentators in here who are always looking for the next exotic thing that they can make by stacking different filters or such. But what is your favorite UV-pass solution, and why?

To make it a bit more clear what kind of question I'm asking. I really like the QB39+ZWB2 combination that I have recently acquired. It's affordable, doesn't leak (or at least so far I have not discovered any leaks, even when I used a halogen bulb for illumination with long exposures), and it passes light one stop better than QB39+ZWB1 which I used before. These are my reasons, which are yours? Do you like stacks or do you prefer the convenience of a Baader U Venus? Or do you use something else entirely?

[colinbm]

#1 Baader U Venus all in one filter & no problems with getting a sticky surface over time.

[dabateman]

The first UV filter I bought was the Baader u venus filter, as I wanted to buy one filter that I knew would be good for UV. That was 2008 or 2009.

Then I got back heavy into UV photography in 2017. I have since bought a whole bunch of various filters.

As a regular filter, doing the UV photography that others would be able to do. The Baader venus is still my favorite. It has a certain contrast that none of my other filters have.

But I also love my 313bp25 filter stacked with U330WB80 improved. That UVB is also my favorite. Then I do the 254bp25 because I can. So would be interesting to merge all three in my next series of images.

 

If you have full control over the lighting, a 2mm S8612 filter only and illuminating your subject with filtered 365nm light, also is my favorite. For a UV/visible look.

[Fandyus]

I heard mixed opinions on the Baader U, I know it's supposedly very crisp but also from what I've heard it leaks and is extremely expensive. Given the price I'd expect it to not leak at all. Though I have no idea what the characteristics of the leak are and if it's notable.

[colinbm]

Fandyus

There was an older version that had a slight leak, the 1-1/4 inch one maybe from the older stock, but the 2" is the latest & good.

[Fandyus]

I see.

I find that a good way to test for leaks is to use a halogen bulb so the UV to visible/IR ratio is very much skewed towards the latter and then doing a long exposure, as I mentioned I did. Would that work with the new Baader U?

[OlDoinyo]

All these filters leak if pushed hard enough; it is just a matter of degree. The leak in the Baader is most noticeable if you are shooting in light that has an unfavorable IR/UV ratio or if there are bright IR sources in the frame. It is most noticeable somewhere beyond 800 nm. I know less about the other stacks, but I would expect analogous findings. The main disadvantages of the Baader are not so much leakage as:

 

1) it is a dichroic filter and thus suffers from ring artifacts with wider-angle optics (FOV 40 degrees or greater;) and

 

2)It is available in only one size, which is useless if one needs something larger or much smaller.

 

I also have a U360/S8612 stack which performs well enough, and I used to have a UG11/S8612 stack on a lens which I no longer have. If I ever do photography below 340 nm, none of these will be suitable.

[ulf]

I see.

I find that a good way to test for leaks is to use a halogen bulb so the UV to visible/IR ratio is very much skewed towards the latter and then doing a long exposure, as I mentioned I did. Would that work with the new Baader U?

I would expect that it will fail as even if the version 2 is better than version 1 it is not super good.

A S8612/U-360, 2mm stack is measurably better and that is confirmed by the Schott calculator.

I have seen faint leakage effects with my Baader U at a few occasions where the S8612/U-360, 2mm stack performed perfectly.

[nfoto]

My standars choice is the Baader U. It can be remounted to 52mm filter threads in various manner. Because it is slightly smaller than 52mm filters it is much easier to insert into adapters etc. to give a rear filtration solution. This reduced the dichroic side effects to a large extent so even on my 21mm lenses /FX camera there is little chromatic unevenness.

 

The "old" gen.1 had too much IR leakage, which I for one quickly found out once full-spectrum cameras became the normal tool for UV photography. With earlier cameras such as Nikon D40 or D70, I used these unconverted since they had weak internal UV-filtration combined with sensible attenuation of IR. Baader responed with an improved Gen.2 version that had much better IR blocking. I have at present 3 of them of various ages and cannot detect much of a difference now.

[Andy Perrin]

The question, as Birna implied, is how much IR blocking you really need for everyday use. In sunshine the Baader will be fine, and under artificial UV one can choose the light source to not have too much IR.

 

The only real life situation that I know of where natural IR is big issue for a Baader is when taking UV photos under nighttime conditions. We have had several examples on the board of dubious nighttime “UV” photos that were probably IR contaminated. I found it is best to use extra S8612 (1.5+1.75mm) to fully block IR at night.

 

So under the majority of cases a Baader will be fine and gives very nice UV color rendering.

[Andrea B.]

BaaderU is my choice for close work. The filter is fast and sharp and puts the documentary floral signatures at a nice 350 nm peak. You can force IR thru it under some conditions. It is easily scratched. It's not quite wide enough so vignetting occurs. (Rear mounting is solution for that.)

 

For other work (landscapes or street, for example) I'll use the SEU (formerly StraightEdgeU) or a U-360 stack (either DIY or LuvU2). Both the SEU and a thick-enough U-360 + S8612 stack are very very good about not having IR-leak unless forced beyond anything reasonable.

 

So I have peak usage around 350nm, 360nm, 370/375nm. Very nice.

 

I still use an old AndreaU for a bit of violet pass which I really like in non-white-balanced UV fotos. (The newer AU is different.)

 

**********

 

Every UV-pass solution has its pros and cons for UV-peak, IR-leak, sharpness, transmission ("speed"), dichroic effects or not, reflections or not, speed or not, vignetting or not, flare or not. You get the drift. So just pick something and learn how to use it really well.

 

None of these filters last forever. Coatings, dichroic or otherwise, get scratched no matter how "hard" they are claimed to be. Glass oxidizes, chips and cracks. AR coatings wear off. Glued stacks develop weird spots (drying out?). And so forth. I've had everyone of those things happen in my filter set.

 

**********

 

I've recently realized that simply saying a certain UV-pass filter is, for example, "OD3.5 or better" is not quite enough to know. A lot depends on just how much of the filter's bandpass is OD3.5 and how much is not. If the filter only hits OD3.5 in a couple of narrow places, then there's not too much to worry about. If the OD3.5 is broader, then you might need to be more careful and supply extra UV illumination. I learned this lesson on my goofy mirrored Edmund 340BP10 which is said to be OD4 or better. However, there is too much OD4 and not enough "better". IR gets through this one more than I like. I'm about to give up on that expensive mess.

[Cadmium]

Using screwed together stacks, U-360 2mm + S8612 2mm. That stack white balances the same as Baader U.

U-360 can also be used for dualband IR, and S8612 2mm can be used for various other stacks such as UV+Blue+Green ('bee vision').

I prefer U-360 to any other U type filter glass. You can get glued together versions of that stack, but then you loose the versatility and experimental value of the two filters.

[Stefano]

Well, I like ionic stacks more because they usually have better blocking and look cooler in my opinion, but I never used a dichroic broadband UV-pass filter, so I can't say this by experience.

 

Narrow bandpass filters, like a 340/10 or UVB-bandpass filters are only available as dichroic filters. They are not terribile, but can have the disadvatages discussed above (such as color shifts at the edges with wide-angle lenses). As long as they don't leak, I like them.

[colinbm]

I will add that the BaaderU works better, in front of a lens, then most of the other dichroic filters I have.

[Fandyus]

I would expect that it will fail as even if the version 2 is better than version 1 it is not super good.

A S8612/U-360, 2mm stack is measurably better and that is confirmed by the Schott calculator.

I have seen faint leakage effects with my Baader U at a few occasions where the S8612/U-360, 2mm stack performed perfectly.

I see, thanks.