Lens glass fluorescence

[Hornblende]

Ok, this one is pretty dramatic: Canon 8-15mm f/4 L fisheye.

UV light shined from above.

 

 

 

M̶͞͝͞͠ư҉̸s͢t͏̨́̕ ̵͡n̵̵͢͞o͠͝͞t̴̢̛̕͡ ̶̸͝͡ȩ̀͜͞n̷̨͜͡t̴̴͞é͢r̵̢͏ ̵͟t͞h̢̧̢e͘͢͠ ͏̛́͘v̴̡͜͠ò̷͢i̵̕͏d̨͡

[Andrea B.]

That's pretty!

[otoien]

+1, that must be the best one up to now (with the Tessar as #2).

For the record of the thread, here is the Nikon 105mm f/4 micro without and with a Nikon L39 filter attached to it, lit by my 365nm UV LED flashlight (filtered with 2mm ZWB1 on the front) ca 10cm above the lens.

 

Without filter on the depicted 105mm:

#1

Non-modified NIKON D5100, 55mm f/3.5 micro @ f/5.6, 8s, ISO 100 and 365nm UV LED light with 2mm ZWB1 filter. No filter on the 55mm.

 

With Nikon L39 filter on the depicted 105mm:

#2

Non-modified NIKON D5100, 55mm f/3.5 micro @ f/5.6, 8s, ISO 100 and 365nm UV LED light with 2mm ZWB1 filter. No filter on the 55mm.

 

 

(These were also posted here: https://www.ultraviol...0896#entry20896 )

 

[Guest]

I also accidentally discovered this phenomenon when I was walking around the house with my first UV torch rated at 365nm looking for things like uranium glassware. My entire collection of lenses just lit up, except for a few.

 

I started to connect the dots when I realized one of the lenses that did not fluoresce was listed here and elsewhere as UV capable. The lens that caught my attention was the Kyoei 105mm f3.5.

 

Afterwards, I went around and checked all of them. Here are some that I found that are clear through and through. Check from both front and rear.

• Takumar 55mm f2.2 Preset in M42. Non Cemented.
  
• Takumar 58mm f2.4 Preset in M42. Non Heliar. Non Cemented. Might be same lens as 55mm f2.2.
  
• Minolta P-Rokkor 75mm f2.5 Projector lens, there are two versions. Non Cemented.
  
• Kilfitt Kilar 150mm f3.5 in Exakta. I do not know the lens formula. No, it's not a tessar.
  
• Takumar 300mm f4 version 2 in M42. Lens formula unknown.
  
• Carl Zeiss Jena 12cm f1.9 protector lens. Heavy brass. Typically these contain two cemented doublets. I also have a similar copy of this lens 12.5cm which has some degraded glue on the front doublet and it glows white. Also the rear of the similar copy glows white.
  
• ​Takumar 200mm f3.5 Preset in M42. Lens formula unknown.
  
• Topcor 500mm f5.6 in Exakta. Clear except the slightest white fog on the front element only.
  

The lenses listed as non cemented I have disassembled and cleaned. I stand by that.

 

So far I have only step up rings for the Takumar 58mm f2.4 and have tested that by taking photos through the Baader U-Venus. I don't have a test bench, but I will post anecdotal photos with that lens soon.

 

[Andy Perrin]

I am not at all sure that lens fluorescence correlates to “good for UV” in both directions. That is, it might be true that no fluorescence is a good sign but we have plenty of excellent UVA performers such as the EL-Nikkor 80mm which are glowing brightly at the top of the thread.

[Guest]

Thank you for the reply. Also, I laid heavy on the suggestion the lenses I mentioned are not cemented.

If it is not worth pursuing then I will cease to publish any photos from these lenses. Even if the glowing does or does not play a role in possible color shift or positive transmission to the sensor. It's your world. I am new here.

[Andy Perrin]

It's always good to have more info? It doesn't have to be all or nothing, but you sounded like you were using this as major test of UV-worthiness, when I think it's maybe just an indication for more testing? Like, I would not discount lenses that show some fluorescence as useless for UV because we have good counterexamples like the EL-Nikkors. But at the same time, having no fluorescence can only be a good thing. Am I being logical here?

 

Uncemented is definitely a helpful trait.

[JCDowdy]

The old preset Takumars are some of my favorite vintage lenses!

Some of these are known to be UV capable, for example the 35mm f/4 (4 groups-4 elements).

The 100mm f/3.5 (3g-3e), 105mm f/2.8 (4-4), 200mm f/3.5 (4-4) are also non-cemented. source: http://www.klassik-cameras.de/Pentax_Takumar_e.html

I would like to see how your 200mm f/3.5 performs in good sunlight. I have long wanted obtain one to try but just have not gotten around to it yet.

 

The observation of strong internal lens fluorescence has been mentioned here as potentially problematic. So, you intuition is good on this.

[Guest]

It's always good to have more info? It doesn't have to be all or nothing, but you sounded like you were using this as major test of UV-worthiness, when I think it's maybe just an indication for more testing? Like, I would not discount lenses that show some fluorescence as useless for UV because we have good counterexamples like the EL-Nikkors. But at the same time, having no fluorescence can only be a good thing. Am I being logical here?

 

Uncemented is definitely a helpful trait.

 

I agree, absolutely. I just look for patterns when I don't have the proper equipment. It was more of a pathway to diagnostic for me.

 

Such as the un-cemented novoflex 35mm f3.5 is a good UV lens but does show some glow. However, it has been proven as having lower UV transmission than the Petri KC 35mm f3.5, which has no glow. So, in my mind I ask where is the price of UV transmission being paid.

 

Cheers

[Guest]

The old preset Takumars are some of my favorite vintage lenses!

Some of these are known to be UV capable, for example the 35mm f/4 (4 groups-4 elements).

The 100mm f/3.5 (3g-3e), 105mm f/2.8 (4-4), 200mm f/3.5 (4-4) are also non-cemented. source: http://www.klassik-c..._Takumar_e.html

I would like to see how your 200mm f/3.5 performs in good sunlight. I have long wanted obtain one to try but just have not gotten around to it yet.

 

The observation of strong internal lens fluorescence has been mentioned here as potentially problematic. So, you intuition is good on this.

 

Indeed! I nearly forget about that website. Very informative.

 

I will at some point try to get samples from the telephoto lenses once I put together a method to mount the 2" filter. I was looking into a rear mounted filter drawer. There're some that are shallow enough to work for SLR lens to mirrorless.

[Cadmium]

It is something to consider that lens fluorescence can come from both the glass and/or any adhesive used.

Some adhesives designed to transmit UV better can still fluoresce, and I have seen this with even the better UV transmitting adhesives, although they may transmit UV better than some other adhesive,

they may actually fluoresce more.

[Guest]

Thanks for the points regarding cement. I did try to avoid posting about lenses with cement, because I was unsure at the time. It was a variable I wanted to leave out, especially regarding lenses not dedicated to multispectral. I was focusing on coating or glass type.

 

However, I am guessing in the case of the Coastal Optical, Zeiss UV-Sonnar, Ultra Achromatic Takumar and the UV-Nikkor it was in their best interest to avoid adhesive altogether. Clearly the mineral is the most important factor in absorption or transmission.

 

It was obvious in my observation of the Novoflex 35mm f3.5 that the glowing of the rear element was due to either the coating of the glass mix itself, since it has no cement.

 

Your point opens a new can of worms for me. I want to test all my lenses!

 

[diant]

Cadmium, do you know anything about fluorescence of Canada balsam at the UVA excitation?

By the by, below I attach its transmission. Russian standards rate it as at least 73% at 360nm.

[Guest]

Interesting!

 

Without speaking for glass and coatings I would take a lens with final output of 73% at 360nm. That seems to be in the ballpark of the non-cemented Petri KC 35mm and the Novoflex 35mm. I wonder if the older El-Nikkor 80mm was cemented. Dr. Klaus Schmitt does mention on his blog that particular lens is double gauss, but I dont know if it is air gapped type or not.

[diant]

Without speaking for glass and coatings I would take a lens with final output of 73% at 360nm.

Blazer0ne, I don't understand your thought. please explain it more clearly.

 

Old El-Nikkor 5.6/80mm is cemented: it has 6/4 scheme. But there are a special cements (optical glues) for such enlarging lenses, transparent in UVA. It is very probable that something from their cohort was applied for EL Nikkor 80mm cementing.

[JMC]

Cadmium, do you know anything about fluorescence of Canada balsam at the UVA excitation?

By the by, below I attach its transmission. Russian standards rate it as at least 73% at 360nm.

Anton, thanks for sharing that. I've been looking for a transmission spectrum of Canada Balsam layers in the UV for ages (without success). Can I ask where it comes from please, in case I need to reference it in the future?

[Guest]

What I meant was that 73% at 360nm with Canadian Balsam doesn't seem that bad if that was theoretically the transmission at the sensor. However, that is probably not the case in cemented lenses of that type of adhesive. So, I was speaking only for the measurement of the glue. Assuming there was no other loss in the light path.

 

If you look at non cemented lenses commonly used on this site they have a transmission at the sensor generally similar to the number you mentioned. Novoflex 35mm and Kuri 35mm.

 

Again thanks for the diagram. I always appreciate the hand drawn plots of years past. Especially those by Volosov at GOI.

 

Cheers!

[diant]

Blazer0ne, ok, I understand. But the main blockers of UV (besides Canada balsam) in lenses are almost always flints. And the modern ones (with titanium and antimonium) are a dread blockers. Old flints with lead and arsenic often had a more deep UVA transmission - that is the clue to the mystery of old miracle 35mm (and other) UVA performers 4/4 or 5/5.

 

For example, I refer here at the transmission old F2 flint (with lead), compare it with the same flint in new generation - N-F2 (with titanium):

(all data at 10mm layers)

 

380 365 350 334 nm

F2 98.5% 97% 90.5% 54%

N-F2 76.5% 28% 9.5% nothing

 

And so in parallel with all new "N"-type flints.

 

Jonathan, it is Russian GOST 14887-80 data. You can see it yourself.

[JMC]

Thanks Anton.

[Guest]

Anton this was great!

 

Looks like we need Russian character OCR software to make some translation of the old scanned text. Anyway, I think everyone can agree it is good to have the reference shared.

 

As it might not be obvious with Japanese or German lenses how to indicate which used old flints with lead and arsenic can I have a date at which this conversion was likely to happen? For example, can I say any lens produced before 1960 is a better candidate for miracle transmission. Maybe it is regional though as this is related to environment.

 

Cheers,

 

B1

[diant]

Blazer0ne (what's your name?), yes, lenses produced before 1960, surely may be regarded as best candidate, may be even 1970s. I don't know exactly when there was a total change of flints on the planet. This was induced by ecological demands...

I see three main points for the lens to be a possible candidate.

1. Old flints.

2. Minimal elements with no cemented one (3/3, 4/4, 5/5 - no more).

3. No coating or early coating (single MgF2 is the best).

 

Second point is not absolutely, for in the middle of XX century we have already a lot of more UV-transparent cements. (See the same USSR GOST).

As for the third point, if we have a single MgF2 (usually have a light bluish color), the best is the one with a purple (lilac) hue. It give lower UVA reflects. Reddish single coating is better then all, but it is so rare.

Point 1 is almost absolutely. You can verify it yourself if you look into Schott, Hoya, Ohara or CDGM's catalogues.

[dabateman]

This reference was perfect. As part of the Lippman thread I was trying to figure out how deep historical images would go.

Since most Lippman plates used Canadian Balsam, its clear that the UV would only be at 360nm maximum.