Anyone know how a Schott UG-11 and BG-99 stack performs?

[Andy Perrin]

As previously mentioned elsewhere in these fora, my converted Sony camera body came with quite a lot of dust in it. I mentioned this to eBay seller eeassa, who graciously offered to clean it for me, and is throwing in a Schott UG-11 and BG-99 filter stack by way of apology. (I am going to try to clean it myself first before risking the camera on the USPS two more times.) Anyway, I wondered if any of you have tried this combo and what the results were, if so. I should mention that eeassa is planning to sell these, so I have no doubt there are commercial instincts at play here too.

[Cadmium]

Hi Andy, I will make you a graph of whatever you want, but as far as I know there is no such thing as "BG99".

Perhaps you (or they) meant some other BG## ?

Also, if you want a combined graph, let me know what thicknesses of each glass type are used in the stack, and I will post a graph.

[Andrea B.]

Andy did this Eeassa do the conversion? If so, it sounds as though the conversion was not done in a clean room. Please let me know. We like to keep track of these things.

[Andy Perrin]

Andrea, yes. I got his name off of this forum and other people here seemed happy with his work. He said he did do it in a clean room but may have forgotten to clean the housing in addition to the sensor and some stuff fell off the inside of the camera after he did the conversion (probably when it shipped). The only other explanation I can think of is that dust got in when I was putting in the lens for the first time, but I tried to be pretty careful about that.

[Andy Perrin]

Cadmium, thanks, when I get the stack I'll have a look at it. He didn't mention the thicknesses so I would have to measure. As for BG-99, that was a direct copy and paste...at least I'm not paying for the stack, so if it doesn't work, it won't matter.

 

Edit- seems to have been a typo on seller's part. A previous email mentions BG-39. It's to block the IR leak in other glass.

[Andrea B.]

Andy, this converter "eeassa" is NOT listed in the Sticky.

Currently I can only recommend MaxMax, Kolari or LifePixel.

[Andy Perrin]

I didn't mean he was in the sticky! I saw him in comments here.

 

Edit: I saw him in Iggy's post here.

http://www.ultravioletphotography.com/content/index.php/topic/1106-under-300-nm/page__view__findpost__p__5404

[Andrea B.]

The thing is --- I am very skeptical that your Sony would have arrive with dust problems if this converter had actually been working in a Class 100 clean room.

[Andy Perrin]

Well there are two possibilities:

1) *I* could have gotten the dust in there myself when I put that first lens on. I did not check the back of the lens for dust, although it didn't look dirty to me.

2) Seller's explanation:

It would be negligent of me NOT to do a thorough dust check after each conversion (so that nothing is visible at f/16). And I typically do a very thorough cleaning between the lens mount and the sensor as well. The sensor was clean -- I know that --- so I must have missed the mark on the body cleaning. I'm more than happy to take care of the issue for you. I'll pay for shipping both ways! And as a matter of fact if there should be ANY issue with the camera in the future, I'd like the opportunity to sort it for you.

 

Thanks for the contact!

[Andrea B.]

As long as you get a clean working conversion !! Let me know. We all need to keep track of these things so that no one is mislead by any converter. At this point all I can say is that I'm not impressed by this particular seller.

[renaud]

Several members of this forum have converted cameras at home and can attest that it is possible to get a clean (or clean enough) conversion without resorting to a clean room. Therefore I wouldn't obsess on wether the seller has access to a clean room. However, not testing the camera after conversion sounds like a bigger sin to me.

[Cadmium]

Cadmium, thanks, when I get the stack I'll have a look at it. He didn't mention the thicknesses so I would have to measure. As for BG-99, that was a direct copy and paste...at least I'm not paying for the stack, so if it doesn't work, it won't matter.

 

Edit- seems to have been a typo on seller's part. A previous email mentions BG-39. It's to block the IR leak in other glass.

 

OK, well I would need thicknesses to calculate a combined graph. Glass type and thickness.

In many cases, UG11 is used to describe what might be something other than UG11, I am not saying this is the case, but it is something to be aware of and cautious about.

UG11 is the best for that kind of stack.

BG39 is very strong suppression glass, having the same suppression as S8612, but with far less UV transmission, so it truncates more of the UV transmission of the U-glass (UG11 in this case).

There are other versions of BG39 in other brands, so again, names and numbers can be deceptive.

So if you find out the thicknesses of the two glasses, then I will post a combined graph for you, assuming the glass is in fact what they say it is.

Schott UG11, Hoya U-340, and ZWB1 are all 'supposedly equivalent', so many times I see one used as the other, but they are only generally equivalent,

and of those UG11 is the only one I will use on a camera myself, although I will use U-340 on a light source if it is thick enough.

Many people have a concept that Hoya U-filters are better because they transmit higher UV and lower IR, this concept is only true in part, because when suppressing the Red/IR peak of a U-filter the suppression glass takes over.

With U-340 you gain nothing by using it, if adequately suppressed, you gain nothing by replacing UG11 with U-340.

With U-360 you do gain an advantage in using it instead of UG1. U-360 2mm + BG40 2mm is my personal favorite stack.

[Andy Perrin]

Yeah, I mean, I could calculate it myself if I had the spectra and thicknesses of the two glasses -- I was working on modeling artificial leaves for my postdoc and I wrote a MATLAB code using the transfer matrix method to calculate UV absorption in a TiO2 substrate with various electrode layers on top (ITO and stuff). That project was tangentially how I ended up on this forum. I was hoping to do some experiments in photographing the setup in the UV, and then I got side-tracked playing around with taking pictures of flowers and stuff. And the project got canceled too, so, bunch of wasted effort all around, but you lot are nice. :-)

[Andrea B.]

Well they say no knowledge is ever wasted. Hope that is true in this case.

Maybe what will come of it is an interesting UV "hobby". I kind of dislike that word, but "avocation" sounds too high-falutin'. :D

Good experiments in UV photography are always interesting - and welcomed. As are good UV photographs.