New member's first attempts and questions

[ulf]

A 50% transmission peak at 365nm, and >25% transmission between 340-380 for high total light transmission.

Average out of band rejection is >OD 4.3 (0.005%), with a minimum rejection of>3.5OD (0.025%)

 

A glued filter stack with those specifications stated by Kolari, can be built with 1mm UG11 and 1.5mm BG39, based on Schotts filter calculator results.

I have not checked the vital specification data guarantied for those filter glass materials.

[montanawildlives]

Yeah, I think you should also find yourself a lens that passes UV better but also consider getting a new filter or a better one from Kolari. And buy some S8612 2mm. That will stop any IR dead.

 

OK, makes sense. I was hopeful that I might already have a lens that would work well, but that doesn't seem to be the case. This was the only UV pass filter available on Kolari's website, but it seems that they have other options hidden around the web for professionals that they don't sell to consumers.

 

It seems like no matter what UV pass filter I get, I will have to get something like the s8612 2mm to block IR leakage too. So there is really no way to do UV well without at least two filters (although I guess the acceptability of using just a UV pass filter on a full spectrum camera would go up to the extent that one's lens was very open to UV light).

 

I'm sorry for so many questions but as a newbie it is hard to find information like: a good starter kit is the Soligor 35mm lens (link to purchase), the Kolari UV pass filter (link to purchase), and an s8612 2mm (link to purchase). I know one size doesn't fit all, but I feel like I'm just going around in circles. Ahhhhh, learning curves. I've read the sticky threads and for an experienced user they look very well put together and informative, but it is an entirely new language for a newb. How about a sticky thread titled: "Three cheap starter kit options for UV photography."?

[nfoto]

1. Get a converted (full-spectrum) camera. 2. Get a Baader U filter, or a stack with S8612 + UGxx.. 3. Get a decent UV-capable lens (see Stickies). 4. Start amassing practical experience. 5. If not satisfied, go to 1 and try another camera/lens.

[montanawildlives]

If this is the filter:

https://kolarivision...ss-lens-filter/

Then it might be well within Kolari's specs and still fail our more elevated demand for a high OD

In their production specification they say:

"Our filter has a 50% transmission peak at 365nm, and >25% transmission between 340-380 for high total light transmission.

Average out of band rejection is >OD 4.3 (0.005%), with a minimum rejection of>3.5OD (0.025%), meaning there is a high signal to noise ratio and no IR contamination."

 

>3.5OD might be OK for landscape-UV or showing freckles on portraits, but we know it is not good enough for all floral photography.

Especially not with lenses that are not as good in UV-transmission as the UV-Nikkor.

 

Average out of band rejection >OD 4.3 is totally uninteresting if there is an IR leakage with a worse OD.

It is just boasting with numbers.

 

As their OD specification is like I quoted above, I would not recommend buying the Kolari UV pass filter as it likely would not be good enough in all situations.

 

Yes, I think that's the same Kolari filter, although mine has a distinct green cast (on the filter itself) that I don't see in those pics or for that matter, the pics of the filter on my order (I assume they're the same but I checked both your link and the "my orders" page). I actually purchased it through Adorama (for the return policy).

 

Well, their boasting with numbers certainly worked on a newb like me--that sounded so great! ;-)

 

Thanks.

[montanawildlives]

1. Get a converted (full-spectrum) camera. 2. Get a Baader U filter, or a stack with S8612 + UGxx.. 3. Get a decent UV-capable lens (see Stickies). 4. Start amassing practical experience. 5. If not satisfied, go to 1 and try another camera/lens.

 

Thank you!

 

#1, check.

 

#2, I will buy this:

 

Amazon.com : Baader Planetarium U-Filter 2" (Venus, Ultraviolet, ZWL 350nm) : Telescope Filters : Camera & Photo

 

#2a, I need to be able to mount this on my camera, and I think going with a 52mm lens standard seems wise (I have four old Nikkors to try, and then 52mm is a somewhat standard filter size for old DSLR lenses). The Baader website says I need two things to mount their telescope lenses onto camera lenses:

 

Baader DSLR-2" Filter Holder M48/SP54 - Camera Adapters - Adapters & Imaging Accessories - Accessories (baader-planetarium.com)

 

but I don't think I need that because the filter from amazon is already contained within a filter holder, correct?

 

Second, Baader says I need this:

 

Baader Hyperion DT-Ring SP54/M52 for DTAdapter II&III and Hyperion Eyepieces - Camera Adapters - Adapters & Imaging Accessories - Accessories (baader-planetarium.com)

 

and this will go between my lenses and the Baader U filter from Amazon (obviously).

 

I expect I'll see a bit of vignetting on some lenses, not only because I am going from 52mm to a 50.8mm filter, but also with the adapter (item 2 from Baader) it seems that the filter will be a good ways in front of my lens, further exacerbating the vignetting problem. (I wonder if there is another adapter that is shorter somewhere to help with this problem?).

 

#3, I'll test my current old Nikkors, then move on to the options in the sticky thread on lenses.

 

#4, this is the fun part!

 

#5, can I substitute "get frustrated, sell everything, and go back to IR photography."?

 

Thanks again.

[nfoto]

Forget about the Baader-specific rings. The U filter sits in a small ring all by itself, unfortunately perhaps with 48mm thread. However, do not despair.

 

Depending on the actual lens, you might get a step-up adapter to 48mm, or step-down if filter size for the lens is > 48mm. For example, the "Kuri" type 35/3,5 lenses often have 46mm front threads, so a 46-48mm ring will do. Or for a Noflexar 35/3.5, you need 49-48mm. All these are easily found on eBay for next to nothing price-wise.

 

You can also reseat the Baader into a 52mm filter ring. However, since I use my Baader U's in various ways,including inside 48mm based filter drawers, I kept the original configuration and just put the filter into a K-4 ring with either 48-52mm or another K-4 as a retainer. This will fit the front of my Coastal 60mm f/4 APO, or the UV-Nikkors, all of which are 52mm front size. (K-rings are also known as the proverbial 'Lego' bricks for photographers. Can be used for a plethora of applications. I probably have purchased 20-25 complete sets over the yers).

[ulf]

IMHO the Baader U is not the optimal filter, at least not if you in the future would like to expand the filter range for other types of photography that includes UV in the image.

The only good thing with the Baader U is that it is a single filter, but it is

1. rather expensive
   
2. designed for almost parallell light passage like in a telescope
   
3. thin and fragile
   
4. some versions sold are leaking IR
   
5. odd mounting thread
   

I have a Baader U but rarely use it.

Instead My UV-photography is based on filter stacks with one main component a S8612 2mm thick.

Then I add other different filters to get the effects I seek.

I have standardised on a 52mm thread as that often gives most alternative filters to chose from.

 

I would ask this seller how soon he will get 52mm versions in stock of S8612 2mm again:

https://www.ebay.com/itm/293721737361?hash=item44632e0891:g:GpsAAOSwFqJekbGO

https://www.ebay.com/str/uviroptics?rt=nc&_sop=16&_pgn=2

The seller is a member at this forum with the ID name Cadmium.

I am one of his customers without any further relations, beside technical discussions.

Over the last four years I have bought more than 30 filters from him and always gotten quality products.

 

A quick and dirty cheap alternative is to buy Chinese filters on eBay.

That might be an alternative while waiting for proper filters made from quality sources from Schott and Hoya.

 

I have good experience with this seller in China:

https://www.ebay.com/str/tangsinuo

[Andy Perrin]

Also very happy with Cadmium and his filters. I don’t own a Baader either.

[nfoto]

I join the appraisal of UVP member Cadmium. Always professional and helpful when you are on an outlook for specific filters.

 

My reason for the Baader is simply its usefulness for my line of work, including it being single-layer. The #1 generation, long since discontinued, did leak too much IR, however, the company listened to user criticism and rectified the design. The Baader filters are expensive, but last very long (unless they are dropped onto stony ground, which Andrea can tell all about -- I was just eyewitness and can say her language during that incident was much less foul than what I myself would have used).

[Andrea B.]

If we are going to mention any of our two member vendors, then please also mention UVR Optics/UVR Defense Tech and their SEU and AndreaU, both worthy UV-pass filters. The current AndreaU is around a 350 peak and leaketh not a bit o' blue as did past AndreaUs (which I still have!)

 

I like to give fair play to both of our vendor-members (who were "grandfathered" into the site because we knew them before they became vendors. Just to set *that* record straight).

 

KolariU -- mine does not leak IR. Go figure.

 

BaaderU -- working up close as I do, the BaaderU is excellent for floral photography. Only the old versions passed some IR. That was rectified back in about 2009, IIRC.

 

BaaderU thin and fragile --

Not at all. I've used BaaderUs since 2008. The incident Birna refers to happened when I directly stepped on my BaaderU after losing my balance after being scrunched up in some rocks trying to capture a floral signature. I'm pretty sure any filter I stepped on with full force would have also shattered. It was not a pretty sight. And broken filter shards are *sharp*. Wooee!

I've had BaaderUs fall into the dirt, get smeared with pollen, become scratched up, and still they keep on shootin'.

Agree that the BaaderU diameter is weird.

---

 

I'll run it down here on the UV-pass filter thing.

But I must omit the KolariU for now. Too many reports of leaks.

This is all in the Filter Sticky but nobody ever seems to read the darned thing. Oh well.

 

Need to fit in MaxMax here somewhere.

 

Professional, expensive "named" filters with good mounts.

Ask whether periodic maintenance is required for any non-dichroic versions.

• BaaderU (Baader Planetarium)
  
• SEU (UVR Optics/UVR Defense Tech)
  
• AndreaU (UVR Optics/UVR Defense Tech)
  

Professional, expensive, un-named filters from optical glass companies.

Ask whether periodic maintenance is required for any non-dichroic versions as

the filters may or may not be coated or clad.

• Google around. Lots on offer.
  

Glue-stacked, "named" filters, good mounts, less expensive.

Ask whether periodic maintenance is required for any non-dichroic versions.

I don't know whether anything coated is currently offered.

• LaLaU (UVIR*Optics on Ebay)
  
• LuvU II (UVIR*Optics on Ebay)
  
• MoonU (UVIR*Optics on Ebay)
  

Do-it-yourself stacking. Least expensive of the acceptable options.

Glass must be maintained periodically.

If you are going to roll your own,

then you must be sure you get authentic Hoya or Schott glass.

Fakes abound.

UVIR*Optics on Ebay sells authentic glass.

(Added: The next post has info on thicknesses. Read!)

• Hoya U-340 dual bandpass + S8612 blue-green IR-blocker
  
• Hoya U-360 dual bandpass + S8612 blue-green IR-blocker
  
• Schott UG1 dual bandpass + S8612 blue-green IR-blocker
  
• Schott UG5 UG11 dual bandpass + S8612 blue-green IR-blocker
  

Note: This is a purist's list of glass which can be used for UV-pass only when stacked with an IR blocker. So I have omitted the U-330 and UG5 which become UV+blue+green when IR-blocked.

 

Chinese low-cost Hoya and Schott Z-emulations

• You are on your own with this stuff. It might be good. It might not.
  
• You will also need a IR-blocker which Z-emulates some kind of BG glass.
  

• It is perfectly OK to begin with a Z-emulation stack!!
  If you continue in reflected UV or other multispectral photography,
  then you might want to upgrade to a quality filter or filter stack
  especially for scientific or documentary work.
  

All that said, I need to go look at where to put MaxMax. BRB.

---

 

I do not wish to hear one single comment about filter maintenance here in this particular topic. (You know who you are.) Here is the reference for Filter Maintenance. Don't Forget about Filter Maintenance !

[ulf]

Excellent list of different filters, Andrea.

 

One important detail missing is the thickness of the Hoya and Schott filters.

That is an important part of the formula that needs to be correct for a proper function.

 

Here is my modified list:

• Hoya U-340 2mm dual bandpass + S8612 2mm blue-green IR-blocker
  
• Hoya U-360 2mm dual bandpass + S8612 2mm blue-green IR-blocker
  
• Schott UG1 1 or 2mm dual bandpass + S8612 2mm blue-green IR-blocker
  
• Schott UG5 1.5mm dual bandpass + S8612 2mm blue-green IR-blocker
  
• Schott BG3 1.5mm or 2mm dual bandpass + S8612 2mm blue-green IR-blocker
  
• Schott BG25 1.5mm or 2mm dual bandpass + S8612 2mm blue-green IR-blocker
  

I have written 2mm thickness for all S8612 as that thickness works universally well, for attenuating the IR component.

Then the same filter can then be reused in all the combinations.

[Andrea B.]

I corrected my list to omit UG-5 and add UG-11. Sorry for the error!

(The substrate of the dichroic BaaderU is UG-11.)

 

*****

 

Ulf, yes, 2mm x 2mm works well. I have a set like that. Thanks for the addition.

I added a note to my post to refer to your post. La!!

 

You can use the Schott app to find optimal thicknesses for the stack in the sense of maximal transmission and best OD. That may vary from the 2x2. But why worry! The differences are not all that great.

[Andy Perrin]

KolariU -- mine does not leak IR. Go figure.

 

 

Have you ever tried it on anything but a quartz lens, Andrea? Remember the lenses most of the new people are attaching it to are substandard for UV. If you have a regular lens around with poor transmission, you could test yours on that and see if you get leakage.

[Andrea B.]

I can certainly try that tomorrow. If we have sun. It has been kinda cloudy today, so something might be brewing.

[colinbm]

I have never had any problems with the BaaderU filter in the strong sunlight in Queensland, Australia.

I have had lots of trouble with the S8612 filter with it getting a very sticky slimy poxy covering on the glass surface in humid locations.

[ulf]

I have never had any problems with the BaaderU filter in the strong sunlight in Queensland, Australia.

I have had lots of trouble with the S8612 filter with it getting a very sticky slimy poxy covering on the glass surface in humid locations.

OK, when in Queensland with strong sunlight and high humidity the Baaser U is OK, especially if you do not want to look after your filters from time to time and clean them if needed.

Then you get one type of filter characteristic, without any possibility to expand in the future.

 

Maintenance of filter glass like S8612, UG11, ... with hydroperoxide 3% is really very simple, effective and easy.

You must take care of filers in the way they need to stay in good condition, just as you have your car serviced from time to time.

Let us not restart that discussion again, please.

 

The main advantage with stacking S8612 with other filters is that you have many alternative interesting stack combinations to explore and can gradually expand the filter collection.

[Andrea B.]

I did not get to make an experiment today with the KolariU on non-UV lens because the SigOth dragged me off to look at furniture, of all things.

Hope to get to that filter experiment tomorrow.

 

Ulf makes a great point. With one IR-blocker of suitable thickness (say 2mm) and, say, a UG-11 and a U-340, you can have two nice UV-pass stacks for less than the price of one brand name UV-pass.

And there is room for expansion later with other interesting glass like, say UG5 one of my faves.

[rfcurry]

Don't they sell milk crates down there, Andrea?

 

I know I pushed the S-8612 many years ago, but there are cheaper alternatives, some which give you a better slope in the low 300 nms. Also, stacking has its disadvantages: you are cutting the transmission by introducing glass/air interfaces. A complete, cemented filter has two glass/air transitions (-8% total, iirc), but the ug11 and s-8612 has four (-16% T). Also, the Schott Excel program is designed for single filter, not stacking.

 

Anyway, another fun thread! Thanks.

[Cadmium]

The three I would get would be U-360 2mm, U-330 1.5mm, and S8612 2mm. Go to the store and get a nice bottle of hydrogen peroxide for about $1.50. you can keep your S8612 and U-330 clean with that, I don't think you will need it for the U-360 though.

U-360 2mm + S8612 2mm = UV (320nm to 400nm).

U-330 1.5mm + S8612 2mm = UV+Blue+Green (320nm to 520nm).

 

[dabateman]

Reed what is cheaper than the S8612 that has a good 300nm slope?

Only Alternative I know is stacking U340/ ug11/zwb1, but then you are getting thick.

 

The ug5/u330/zwb3 doesn't drop its IR signal as fast as the U340/Ug11/zwb1 filters and needs to be much thicker. But it does transmits deeper into UV.

[ulf]

I know I pushed the S-8612 many years ago, but there are cheaper alternatives, some which give you a better slope in the low 300 nms. Also, stacking has its disadvantages: you are cutting the transmission by introducing glass/air interfaces. A complete, cemented filter has two glass/air transitions (-8% total, iirc), but the ug11 and s-8612 has four (-16% T). Also, the Schott Excel program is designed for single filter, not stacking.

 

Anyway, another fun thread! Thanks.

Please, please tell us about the better alternatives Reed.

I would love to hear more about them. That sounds really interesting.

 

You are absolutely correct that cemented filters gain some transmission over air spaced filter stacks.

The loss of around 8% means that an exposure time of 2s for the cemented stack would be 0.16s longer.

I think that is a reasonable price to pay for the flexibility and cost reduction of buying just one BG-filter like the S8612, 2mm

At least if you want to explore the interesting possibilities with multiple filtration alternatives.

 

The Schott calculator is designed for calculating cemented stacks with up to five different filter glass components of any thickness, not just a single filter.

Normally it is enough to stack two filters and you can deduct the 8% from the result if the stack is air spaced.

[Cadmium]

Yes, mixing filters can be quite versatile, and worth using stacked single filters unglued. I do it all the time, and it works great, and saves some money.

If you want to plot single filters stacked, then the upper section of the program does that.

 

Single filter plot

 

And I think if you change the "combination filters" / "data input" / Peff data you can calculate unglued stacks.

Ask Andy.

[rfcurry]

Ulf,

You wrote:

"Please, please tell us about the better alternatives Reed.

I would love to hear more about them. That sounds really interesting."

 

Sorry, Ulf, I cannot in good conscience reveal those alternatives and sources. I have spent years having glass firms produce melts and dichroic filters for me to test, often buying a batch that is useless. I do not wish to sell filter components, only the best quality complete UV-Bandpass filters at the best price. Already today I provided a mechanism for home-brewing filter coating. If a person wished he could use that technology and market his ionic glass, coated, for a premium; with a substantial, but fair, profit margin. That is fine, I want people to do well and also advance UVPhotography. However, in order to provide any income in my dotage, I do need to retain some "trade secrets". I'm sure you understand. :)

 

Cheers!

 

P.S. - as the Schott program says - " Calculation of cemented glass filter combination (up to 5 types)"

so, it is ultimately, a single cemented filter. No big deal, just sayin'.

Thanks.

[ulf]

If you have your own melts custom made I fully appreciate that you do not want to share that information.

I was under the impression that such things was super expensive and totally out of reach for smaller companies.

 

I hope that you and your supplier have means to verify the performance of the filter passband and OD in the areas where it is not supposed to leak.

If not we have only your words on how they perform.

Proper scientific companies like ThorLabs, Edmunds, etc. provide such data that normally is reliable.

They cannot take the risk of bad publicity as their customers really need to trust the products they buy.

Unfortunately the UV-photography community is not that well equipped and more easily fooled by incorrect advertising.

 

I do not understand why you are twisting words about the Scott calculator.

You said "Also, the Schott Excel program is designed for single filter, not stacking."

 

A filter composed of several components, cemented or not cemented, is by my definition, built by stacking.

The Scott calculator can calculate stacked filters, but do not give the correct answer for the air spaced ones.

That error is very easy to correct.

For an air-spaced two filter stack, you just multiply all found transmission values T, by 0.92

"No big deal, just sayin'."

[dabateman]

Reed when you mentioned a cheaper better IR blocker than the S8612, I thought you meant an off the shelf ionic filter. If its a custom proprietary dichoic, no problem. You are entitled to your intellectual property.