Seen on Ebay [Thread includes some lens tests.]

[rfcurry]

You might want to grab http://www.ebay.com/itm/181666680835?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

According to my lens list that model is a 4 glass lens.

[rfcurry]

I forgot, this is a visible-light photo of the subject from which each of the images above was cropped.

 

[Alex H]

So what is the meaning of these long-pass filters in your test setup, Reed?

[rfcurry]

Alex,

 

I find them interesting. If the range of UV is greater than the halogen lamp supplies, e.g., natural light through the window, each of the filters is a different color in UV. Also of interest, while the metal holders appear similar in visible light, in UV, you will note in shots above, the bottom holder is blue, not black. I have thirty or forty such filters, so I can try different combinations.

 

Below is the same subject as the images above, however the light source is solar, through a window; I lose a lot of UV that way, of course. The parameters are the same, f8.0, ISO 400, 3.5s, CopperU 3.0, and Tessar 50/3.5. Note the different colors.

 

[colinbm]

I have now received the, Carl Zeiss Jena Tessar Zebra 50mm f2.8 M42 mount.

It may be a nice lens for visible light photography, it tested poorly for UV :D

When I placed the lens on the UVProducts J221 meter it was only allowing 10% of the UV light from the MTE U301 to get through :)

Col

[nfoto]

Take some test shots with it before you discard the lens for further UV use.

 

Hunting for UV capable lenses means a lot of misses before good ones are found. Fortunately, most come cheap so you keep the fun of the occasional nice new find without going into bankruptcy. Once rumours spread about a given lens, prices tend to rise significantly, and that's a tell-tale sign for not picking up that item.

[colinbm]

Thanks Bjorn

Yeah, I already have a growing collection of legacy lenses that are OK for visible photography.

At least I now have the equipment to test them for passing 365nm. When I get a few good lenses I can save for a better camera for UV.

Col

[rfcurry]

Col,

 

What are the test results from your other lenses for 365nm transmission, using your light and recording device? What is your baseline?

 

IIRC, each air/glass interface can rob us of as much as 13% of the UV (differing wavelengths, of course). Further, assuming the crown glass to be a BK7 equivalent, which has at best 70% transmission (at 5mm thick) for approx 365nm, most crown-glass-based lenses will not pass a lot of 365nm light. For example, with a simple Cooke triplet with six air/glass interfaces providing reflection, scattering, and absorption, you might only have 43.4% UV transmission, best case. That is only my broad theory based upon a failing memory. :D

 

However, I have never tested the theory above with a reliable recording device, so I am eager to hear your results.

Thanks.

 

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

I just ran the numbers based upon WG360 glass, which is similar to NBK7. I used a combination of 2mm, 3mm, and 2mm for a triplet. The reflection factor of WG360 is 0.887. The effective reflection factor of the combination is 0.92. The transmission at 365nm is 22.7% (internal) and 20.88% after applying the reflectance factor.

 

So, while my memory of 13% reflectance is close, the results are worse than I supposed. Proviso: The above is run with planar glass, not non-planar lenses.

[colinbm]

Hi Reed & Andrea

For the record, I have run a test over the legacy lenses I have collected over the last 12 months or so.

 

First the test methodology & my reasoning for using this setup.

 

UVProducts, Blak-Ray, J221 LongWave UV 365nm radiometer. I think you only need a working radiometer, not calibrated, as it is only being used as a comparator, not absolute units.

This radiometer has two scales, 'A' scale measures 0 - 12, 'B' scale measures 0 - 60. There is a supplied perforated screen, that is used with this radiometer to, increase the scale by 5 times.

I have used the 'B' scale, with the supplied perforated screen, for this test.

 

MTE U301 UV 365nm flashlight. This is a powerful 365nm band pass light.

I have setup the MTE U301 UV 365nm flashlight, above the UVProducts, J221 LongWave UV 365nm radiometer & adjusted the lamps height, to make the radiometer read #60 on the 'B' scale with the perforated screen in place. In my case, the lamp's lens was 265mm above the perforated screen.

I have then placed each lens, to be tested, above the perforated screen on the radiometer & between the MTE U301 UV 365nm flashlight.

The radiometers reading was then recorded, as a number between 0 & 60. #0, is for no recorded UV light, at 365nm, passing to the, UVProducts, J221 LongWave UV 365nm radiometer. #60, is for all the available UV light, at 365nm passing to the UVProducts, J221 LongWave UV 365nm radiometer.

 

Showing the, Carl Zeius Jena Tessar, f2.8 / 50mm, recording #5 out of #60.

 

The results & the lenes tested (from the best to the worst) :-

 

:)

1/ #60, Schneider Kreuznach Radionar, f2.9 / 80mm, metal. From a Franka Solida III, folding MF camera.

2/ #26, EL Nikkor, enlarger, f2.8 / 50mm, metal body.

3/ #22, Helios, 44M-4, f2 / 58mm, metal body.

4/ #20, Petri, CC Auto, f1.7 / 50mm, metal body.

5/ #20, Vivitar, Anastigmat, f3.5 / 75mm, metal body.

6/ #18, El Nikkor, enlarger, f2.8 / 50mm, plastic body.

7/ #15, El Nikkor, enlarger, f5.6 / 80mm, plastic body.

8/ #12, Sigma, 105mm Macro, f2.8, DG.

9/ #8, Mitakon, Wide MC, f2.8 / 28mm. metal body.

10/ #6, Rodenstock, Rogonar-S, f4 / 25mm, enlarger lens, metal body.

11/ #5, Carl Zeius, Jena, Tessar, f2.8 / 50mm, metal body.

12/ #5, Sigma, DP2, compact camera, fixed lens, f2.8 / 24.2mm, plastic body.

13/ #4, Sigma, zoom, f4.5-6.7 / 100-300mm, DL.

14/ #3, Sirius, MC Auto, f2.8 / 135mm, metal body.

:D

 

Cheers

Col

[Alex H]

I can not believe that Helios will be better than El Nikkor. Did you account for the aperture differences and the fact that the light beam will be affected by the focal length of the lenses?

[colinbm]

Hi Alex

I'm just a simple guy, & I have used simple equipment, as simply as I could.

If it needs any maths or correction formulas, then I am not the person for this task, sorry.

A lot of these lenses fluoresce or go milky / cloudy, under the light of the MTE.

Col

[nfoto]

I think such a comparison can have some merits if similar class of lenses are used. for example, a bunch of 50 mm lenses set to a common aperture. Of course the ranking would be in relative terms and comparing widely different lenses (or with different light-gathering capability) will, for reasons already mentioned by Alex, be very difficult indeed.

 

I usually start any investigation by shining a Nichia LED torch into the lens to learn how "cloudy" the inside looks. If the rendition is very brown and/or cloudy, a quick photographic test using one of my Broncolor studio flashes (uncoated Xenon tube) is next before I write off the lens as useless for UV. It should not be down more than 3 EV compared to a UV-Nikkor or the Coastal 60. Field testing of passed lenses then follows to ascertain that they also can deliver adequate sharpness for UV captures. UV transmission is not everything and really doesn't matter much if sharpness suffers badly in UV. Most if not all of the UV-capable 35 mm class lenses do need to be stopped down to at least f/5.6 before they deliver acceptable UV quality photos.

[Alex H]

Hi Alex

If it needs any maths or correction formulas, then I am not the person for this task, sorry.

Col

 

In that case you will mislead yorself.

[colinbm]

Looks like I already have :D

[rfcurry]

Col,

 

I have enjoyed using the Ludwig Meritar and Peronar for years. They are very simple triplets - as is the Schneider Radionar - and pass more UV than my other lenses. You will note the one second of the Peronar as compared to the 2.5 or 3.2 seconds of my lenses above. However, if I wanted to capture fine detail, the Peronar is not the lens I would use. Even at f8 it lacks detail.

 

That said, if you just want fast lenses, the Cooke triplets will serve. Watch for model names such as triplet, triotar, isconar, iscotar, trioplan, trinar, helomar, telomar, color pantar, radionar, cassar, apotar, reomar, piesker, and geronar, to name a few.

 

If I were you, I would try the Tessar as a UV lens before tossing it in the dustbin.

[colinbm]

Thanks Reed

Where do they get these names from ?

I won't be throwing any out, not yet anyway. When I get a camera that is more UV capable, than the Sigma's I am using now, I will evaluate them again.

Col

[Andrea B.]

Col, refine your methods as needed and try again!

 

Bjørn's suggestion of grouping like lenses may be useful in the rankings.

 

I think you could find a used Panasonic GH1 very cheaply for conversion. If you are handy, you could DIY. The GH1 and a couple of adapters would give you a very nice set up to play with in UV.

[colinbm]

Thanks Andrea

Refine........how to refine ?

Grouping, I can understand, but how to group ?

Yes a camera like the Panasonic GH1is getting closer, I have been saying that for a year now.......

Everything will happen, in time :D

Col

[Andrea B.]

Beats me!!! Can't tests always be refined? :D

[JCDowdy]

What about a G3?

[JCDowdy]

Here are a couple of possible refinements doable within the constraints of your available tools.

 

1. Mount lens on an extension tube or helicoid, focused at INF such that the sensor window of the meter is at the flange focal depth. This places the detector the same distance from the rear of the lens as the image sensor.

 

2. Move the light further away, a good rule of thumb would be 10x the focal length of the lens, 20x the focal length of the lens would be better if you have enough light. If possible remove the reflector from the lamp so it acts more like a point source but be careful and only do that if it won't cause the LED to overheat and die.

[Damon]

I am so terrible at math/formulas and their ilk--I have been just mounting my lenses and shooting a sunflower when possible or another flower. I never really have any numbers or formulas to help anybody it seems but it's tough to beat a real pic--unless of course you decide to use a Blak-Ray! Or an unmodified camera! :D

 

What you did Col is exactly how I would have tried it. If you could take pics with these lenses then, without math and hocus formula pocus, you can come up with sound conclusions and then perhaps correlate to see if what you are doing really does work. If a formula says no that lens is not good for UV and you put it on your camera and it works great, well, there you go. I am NOT saying ignore what is already known or can be figured out with math.

 

I have to work within my limits--which is why I am out in my UV shack taking images because I am no good at the rest of it. My skill is taking the pics--the why's and such is where I fall apart. But that's where all you smart people come in!

If my 1D works in sunlight I will send my D70 to you free of charge for testing. It takes very excellent UV with the El-Nik 80 which you have. Although I am not sure about the plastic one. The plastic 105 does just fine I found out recently.

 

So Bjørn, using a proper UV LED can give a good indication of it's potential efficacy for passing UV? So if I am at a yard sale and see an old lens I could mount and use--Can I use my LED in a darkened space and look for cloudiness or brownish and have at least an idea if it has potential (passing UV).

 

Is there any other parameter that you would likely consider if you quickly picked up a lens to contemplate for UV use? Below is the sticky. I can see coatings but the rest in hand I suspect not. I am asking partly because we have a massive Flea market around here that has hundreds of outdoor tables and I recollect seeing a lot of old lenses on tables. I likely will have trouble mounting everything and taking a pic.

 

In the Sticky--UV-capable lenses is that they tend to have uncoated elements, little or no element cement, a small number of elements (3 or 4) and, ideally, at least one quartz or fluoride element, although that isn't often found.

 

Thanks so much!

 

-D

[nfoto]

Yes, always bring a UV torch with your for a 'sneak view'. It surely sorts the chaff from the wheat as it were and may help avoid some costly mistakes. Well, in a flea market perhaps not *that* costly, but you get the idea.

[colinbm]

Following along from John's refinements......

I haven't followed to the letter, but tried to be consistent too.

Now down to 12 Lenses, I took the two smaller enlarger lenses out as I have no idea of where their infinity point is yet & I have no connections to M42 for them either.

I modified the suggested set-up & placed the MTE U301 UV365nm flashlight at a point 1200mm away from the UVProducts J221 radiometer. This was the length of an aluminium channel section that I could align everything onto.

All lenses are set at the FFD of the Sigma SA mount at 44mm.

Again best to worse....

 

B)

1/ #50, Schneider Kreuznach Radionar, f2.9 / 80mm, metal. From a Franka Solida III, folding MF camera.

2/ #28, EL Nikkor, enlarger, f2.8 / 50mm, metal body.

3/ #20, Helios, 44M-4, f2 / 58mm, metal body.

4/ #20, Petri, CC Auto, f1.7 / 50mm, metal body.

5/ #13, El Nikkor, enlarger, f2.8 / 50mm, plastic body.

6/ #11, El Nikkor, enlarger, f5.6 / 80mm, plastic body.

7/ #8, Sigma, 105mm Macro, f2.8, DG.

8/ #7-3, Sigma, zoom, f4.5-6.7 / 100-300mm, DL.

9/ #4.5, Sirius, MC Auto, f2.8 / 135mm, metal body.

10/ #3, Carl Zeius, Jena, Tessar, f2.8 / 50mm, metal body.

11/ #2.3, Mitakon, Wide MC, f2.8 / 28mm. metal body.

12/ #1.75, Sigma, DP2, compact camera, fixed lens, f2.8 / 24.2mm, plastic body.

:D

 

Col

[JCDowdy]

Following along from John's refinements......

...........All lenses are set at the FFD of the Sigma SA mount at 44mm.

 

Col, I see the order changed for some of them. However, I meant the FFD of the lenses. This is so that the image circles will be correct for INF setting on the lens. The FFD of the EL-Nikkors is in the lens Sticky. The FFD of the M42 lenses is 45.46mm as is the Helios I think. The Petri breech lock is 43.5mm.

 

There is a method for determining the FFD of a lens that is posted on Dr Klauss Schmitt's extensive blog that you can use to get a ballpark FFD for your other enlarger lenses.

 

Once you mount that Rogonar-S I predict it will move way up the list. These sub frame enlarger lenses are interesting if one is using a crop sensor. That one will likely vignette heavily on a 35mm frame sensor and possibly on APS-C but I am thinking maybe not so much in µ4/3. Please let me know what the size of the image circle and FFD of that one is.

Was that you biding against me on that 25mm? :D

 

The light source distance of 10-20x the focal length is a way to somewhat normalize the effect of lens focal length. That will require you to measure with and without a lens at each set distance and then calculate a ratio of the meter readings to use in ranking.