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UltravioletPhotography

I'll show you my Baader, if you show me yours.


dabateman

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In the introduce yourself area a discussion broke out about Baader Venus U filters.

 

I think this deserves its own thread for discussion as it always seems confusing how many different versions there are.

 

I bought mine new from Company 7, located in the USA, back in October 2008. At that time it was called the new version.

 

On the side it says:

Baader U-Filter 2" (HWB = 325-369nm) Optically polished #2458291.

 

Its greenish yellow on one side and redish magenta on the other.

 

Label:

post-188-0-01720300-1580715921.jpg

 

Green side:

post-188-0-16518200-1580715932.jpg

 

Red side:

post-188-0-58448500-1580715942.jpg

 

Transmission spectrum recorded when I worked in a lab, back in Sept. 2009:

post-188-0-05851200-1580715955.jpg

 

Absorbance spectrum recorded back in 2009:

post-188-0-84842600-1580715965.jpg

 

 

Would be great to know what the most recent ones look like as you can see from my image it cracked and fixed with tape. I still do like the contrast from this UV filter the best. Too bad its not available in 25mm.

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The earlier Baader U had a greenish-blue shine on one side, light magenta/pink on the other. That version leaked a lot of IR, though. I still think there is one or two floating around here in the smaller 1.25" size.

 

The current ones in my possession are unmarked on the bezel. The box and plastic case had labels. They show reflections similar to your pictures: golden(very slight greenish cast) and pink on either side.

 

I do like the Baader the best of my UV passband filters. It gives a "snap" to the image that many other filters tend to lack. Using it in a rear-filtration setup mitigates the peripheral colour shift for most lenses.

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I bought mine in May 2019 from Microglobe Optics (a.k.a. optics-land), London.

 

It has the same part number (or what I assumed to be the part number) of 2458291, but the specs. on the filter mount and box are different to David's. The colour image below doesn't do the flter justice - it's more of a goldeny green than the bluish-green shown below.

 

True that it's not available in 25mm, but the 1.25" (around 32mm) version isn't too far off - depending on why you want 25mm.

 

post-245-0-86805500-1580722703.jpg

 

post-245-0-02304000-1580722714.jpg

 

post-245-0-11317200-1580722728.jpg

 

post-245-0-20233900-1580722735.jpg

 

post-245-0-87494000-1580722745.jpg

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Bernard,

From what I have read. They stopped making the 1.25" Astrophotography version at the point of switching to version 2. So if you see a 1.25" version, it will leak a lot of IR and should be avoided.

This is why there is still new old stock.

 

However, I have heard there are new owners for the Baader filters. They may have rerealsed it. I am not sure. Hopefully someone knows. But I wouldn't buy a 1.25" version without knowing its the new 6 layer blocked version.

The company 7 website still is alive even though I think the company is gone. It explains the 1.25" discontinuation in 2007. You can see the IR leak in the spectrum.

http://www.company7.com/baader/options/u-filter.html

 

These are the spectrum they provised. First is original and second is the newer version with IR leak shifted to 1150nm.

post-188-0-54097800-1580733702.jpg

post-188-0-27464500-1580733716.jpg

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Interesting.

 

The folks I bought my 2" filter from are advertising a 1.25" version - https://www.ebay.co....AQAAOSweNpdk354

 

If you look at the images, they actually show the 2" version - same as I bought. The blurb says "The filter features higher transmission in 300nm to 400nm and improved out of band blocking with a peak transmission of 80%." "Higher" than what, I don't know - but the implication is higher than the previous version. It also says "coating: dieletrical coating, 20-layers"

 

The Baader website is still advertising the 1.25" version (with part number ending in 2 instead of 1): https://www.baader-p...-and-uv---350nm).html [uPDATE: the pasted URL isn't working but if you go to https://www.baader-planetarium.com/en/ and search for "baader u venus" you'll find it.]

 

So I don't know what to think - and it may be that my 2" filter is of the old type. It would be great if someone who knows for sure that they have the new version could post images - then I would know what I have.

 

Looking at your blue graph, the IR leakage starts at about 1120nm, which is where a typical CMOS sensor's sensitivity ends: even if the sensitivity extends beyond 1120, it will be very low. So the leakage shown on the graph may not have any effect in practical terms.

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I just purchased a new 1.25" Baader U .... Baader-Planetarium wouldn't let me buy directly from their web store as before -- some non-EU discrimination taking place evidently. However, I got it from a Swedish dealer. Price isn't cheap around 210 Euro.

 

The reason for my choice this time of the 1.25" version is it will be easier to use for my rear filtration setups. .

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That's about the same as the £185 for Microglobe Optics.

 

What does it say on the box and the filter mount - are these similar to my images or quite different?

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Just ordered the filter (5 minutes ago ...). The illustration on their site states the same info as you gave.

 

I'll test the filter in due time. If it has an IR leakage, this will be immediately obvious.

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Bernard,

You have the newest version. When I cracked mine. The 2" was cleared out on back order. An other UV member had one on back order and when it arrived in 2018, it had the same markings as you described.

 

Birna,

Please keep us up to date on the 1.25". I now have a 9 slot 1.25" filter wheel and would like to add a compact UV filter.

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Forgot to mention the asking price for the 1.25" Baader U was 210 Euro excl. VAT, thus add 25% if the Norwegian Customs get their hands on the parcel (...).

 

There is no indication the 1.25" is any different from the usual 2", apart from its size.

 

I can do rear filtration with the 2" Baader on many lenses provided they are put on m43- or Z-mount cameras. Using the smaller 1.25" will open additional options.

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I've got 4 package/filter variations of the 2" BaaderU.

I also have the old original IR-passing Venus-U in the 1.25" size as well as a newer 1.25".

Will try to get some fotos up this evening or tomorrow.

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If they leak outside the 680-800 nm region, stacking them with a 1 mm Hoya U-340 should fix everything.

 

No if I am remembering correctly the bumps where 690nm, 725nm, 800nm and 900nm.

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Steve I got the Google cache from 2007 .....

"Baader Venus Ultraviolet Transmission Filter IR leakage comparison

Comparison of the 1.25" and the new 2" Baader Venus Ultraviolet Transmission Filter showing minor infrared leakage on the 1.25" filter at 737, 813 and 872nm, and no significant leakage on the new 2" filter"

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I found my stored 2" Badder U filter & it was purchased in 2012, & has 60nm HBW of 320-380nm.

The side we put to the light has a magenta mirror surface & the side facing the camera has a gold/green mirror surface.

Here is the current Badder U chart....Do we know the OD figures on the Badder U ?

post-31-0-19022200-1581085172.jpg

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Steve I got the Google cache from 2007 .....

"Baader Venus Ultraviolet Transmission Filter IR leakage comparison

Comparison of the 1.25" and the new 2" Baader Venus Ultraviolet Transmission Filter showing minor infrared leakage on the 1.25" filter at 737, 813 and 872nm, and no significant leakage on the new 2" filter"

 

Yes, I tried the cache, but it did show the graphs... not sure if I have any copies of Shane's graphs. Don't know why his site is not working (still not working today).

Yes, your graph above looks about right, but his was more detailed.

 

Well, I can't find Shane's graph on my computer, but here are some graphs I generated based on Shane's graph of the Baader U NEWER version:

These only show the most prominent part, there is a smaller blip in the 700 range not shown on my graph.

 

post-87-0-21035400-1581118838.jpg

 

post-87-0-45793600-1581118860.jpg

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I found Shane's document on my phone. Called "UV_IR filter spectra.pdf". Shane would have tested the same generation of Baader venus U filter that I have, and reported the peaks at 737nm, 813nm and 872nm. Ulf recently scanned the CWL350 BaaderU filter and had different leakage points.

 

Update: Shane Elen, said it was ok for me to share his spectrum obtained with specific permission from his website:

http://www.beyondvisible.com/BV3-filter.html

 

Here are cropped images from the Baader graphs.

post-188-0-49706700-1581137937.png

post-188-0-04362100-1581137947.png

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In the same light of sharing other people's data. This is the BaaderU venus CWL350 absorption spectrum that UlfW shared somewhere on this site. I can't find it anywhere. Have no idea what post it was uploaded to.

But I pulled it on October 10, 2018

post-188-0-04473100-1581140158.png

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Just comparing the old "new" Baader with the new new baader (CWL350) the IR blocking in UlfW filter looks much better. So looks to be an improvement.

 

Were Ulf scan shows OD4 blocking and Shane's shows its OD 3.8ish in the 900's.

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Godaddy fixed my site but wouldn't tell me what happened or how they fixed it.... kind of suggests they screwed it up somehow. I have been absent due to ongoing family health issues in England. It hasn't left much time for fun stuff.
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  • 2 weeks later...

I tried to take some photos of the 4 versions of my BaaderU filters. This proved to be not so easy to do. (And that should be no surprise.) Finally I hit upon photographing the filter as it was reflecting off a Spectralon rectangle. The only value of these photographs is comparative. I wanted to compare the filter colours because one of my BaaderU filters has an anomalous colour.

 

First here is the labeling and boxes of the 4 versions.

The measurement of the filter ring height excludes the threading.

 

1. OLDEST BaaderU

The mate to this one was the unfortunate BaaderU which got stepped on during the Desert Safari 2012.

 

White cardboard box labeled:

  • # 245 8291
  • Baader U-Filter 2"
  • (T=300-390nm)

Thin (5mm) filter ring labeled:

  • Baader U-Filter 2" (CWL 350nm)

2. (or maybe this is #3?) BOUGHT AFTER the Oldest above. The Anomaly.

This version has a kind of yellow-gold colour instead of a lime-green colour.

This filter has the newer labeling on its ring and the newer thick filter ring,

but was sold in the old white cardboard box.

 

White cardboard box labeled:

  • # 245 8291
  • Baader U-Filter 2"
  • (T=300-390nm)

Thick (7mm) filter ring labeled:

  • Baader U-Filter 2" (HWB=325-369nm) optically polished #245891.

3. (or maybe this is #2?). BOUGHT BEFORE the Newest next.

Plastic sliding tray box with Blue rectangle holding 2" designation and with photo of filter.

This filter has the older labeling on its ring and the old thin filter ring,

but was sold in the newer plastic box.

This box had never been opened until this experiment.

So I am dead certain that a filter with the old CWL label was in this box.

 

Box top labeling:

  • BAADER U-Filter
  • 60nm HBW/320-380nm
  • Fully blocked VIS & IR
  • planeoptically polished/hard coated Item No. 2458291
  • Schott UG 11 substrate with super stack
    dielectric coating for pure UV-transmission

Filter photo on box top labeled differently:

  • Baader 320-380nm U-Filter 2" (optically polished) #245891.

Thin (5mm) filter ring labeled:

  • Baader U-Filter 2" (CWL 350 nm) #2458291.

4. NEWEST version, currently being used.

Plastic sliding tray box with Purple rectangle holding 2" designation and with photo of filter.

 

Box top labeling:

  • same as preceding

Filter photo on box top labeled:

  • Baader U-Filter 2" (HWB=325-369nm) optically polished #2458291

Thick (7.5-8.0 mm) filter ring labeled the same:

  • Baader U-Filter 2" (HWB=325-369nm) optically polished #2458291

So there are three possible labels?

  • Baader U-Filter 2" (CWL 350 nm) #2458291.
  • Baader U-Filter 2" (HWB=325-369nm) optically polished #2458291.
  • Baader 320-380nm U-Filter 2" (optically polished) #245891. [This is from one of the plastic box photos.]

And 3 filter ring thicknesses: 5mm, 7mm and one between 7.5-8.0mm

 

And some mixed up packaging.

 

****************

 

The photos of the green side of my 5 living BaaderU filters showed that one filter, #2 above, the Anomaly, has a slightly different colour. As mentioned the actual photos were difficult to make. By catching the reflection of the Spectralon in the mirrored filter, I could at least assure that there was some comparative value in the photos. I did manage to show that the Anomaly is a different colour from the other 4 BaaderU filters. But, please, do *not* take this colour analysis as anything absolute. It most certainly is not.

 

Old box, old ring label, thin ring.

NZ7_1129colFilterOne.jpg

 

 

Old box, new ring label, thick ring. The Anomaly.

This is quite definitely a different colour than the other 3 filters.

NZ7_1135colFilterTwoAnomaly.jpg

 

 

New box, old ring label, thin ring.

NZ7_1131colFilter3.jpg

 

 

New box, new ring label, thickest ring.

Those dark marks are scratches in the dichroic surface. This filter has seen extensive, hard field use.

NZ7_1144colFilterFour.jpg

 

 

This was the set-up from above. Spectralon rectangle on the right.

NZ7_113901setUp.jpg

 


 

Probably way more information than anyone really wanted to know about BaaderU filters, boxes and labels!

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