Call for Comments: LENS STICKY

[OlDoinyo]

It might be interesting to compile a sublist (or subtable) of all lenses (other than purpose-made ones) which are known to transmit at 340 nm or below. I imagine that list would be reasonably short.

[Andrea B.]

I wish I had more transmission information about the various lenses. I'm in the process of gathering up what we do have.

And it would be easy enough to make a couple of Transmission Sub-Lists when I'm done. Thank you for this suggestion!

[enricosavazzi]

The difficulty with existing lists of transmission data is that only photographers with access to spectroscopes or filter arrays would be able to contribute original data, and only for the lenses they own or can borrow.

I think a more pragmatic type of list could be compiled by arranging the lenses in categories, depending on the UV-pass filters with which they are known to produce acceptable (or better than acceptable) images.

The list might also include a qualitative assessment of performance with a given filter (e.g. good, acceptable, marginal) and/or a thumbnail of a test image (to limit the amount of memory taken up on the site). Test image could be restricted to a couple of types of well-known subjects, like flowers with UV patterns and sunlight-illuminated landscapes.

 

For example:

 

Asahi Spectra XRR0340

CoastalOpt 60 mm Apo, good, [thumbnail]

Soligor 35 mm f/3.5, acceptable, [thumbnail]

EL-Nikkor 63 mm f/3.5, marginal, [thumbnail]

...(more lenses)

 

Baader U

...(list of lenses)

 

Prima Luce U

...(list of lenses)

 

...(more filters)

[lost cat]

For image based only submissions what ought the metrics be?

 

Camera body

Filter stack

ISO

f stop

Exposure time

WB target

Light source

???

 

For those of us with limited equipment would benchmarking to a well documented component (e.g. a "new" lens to a comparable focal length el nikkor) and adjusting exposure time is the easiest way to go?

[Andy Perrin]

Why not standardize the test species also? Dandelions seem to be pretty popular.

[Andrea B.]

Thank you everyone for the suggestions !!

 

Standardization Is Difficult

One of the difficulties in testing UV gear is that not everyone has access to the same filters, cameras, lenses, and white/color standards. Then too, UV varies by date, season, elevation, time of day, weather, distance from subject and illumination. So we have many variables which cannot be standardized in order to ensure any uniform, repeatable tests of UV equipment. It is even impossible to suggest a "test flower" because not everyone has access to the same flora due to geography or season.

 

Measurement Is Almost Impossible

As for actual transmission and sensor measurements, nobody has access to any kind of complete, formal spectrographic equipment except for a couple of members who work in laboratory settings. And that work equipment is not meant to be used for non-work related testing. But all is not lost because simply using filters and cameras, then presenting the photos gives us good information about those properties. And the various filter-based tests (Cadmium's Sparticle Board) give us some information about lens transmission. We have had some very creative efforts also by OlDoinyo and Timber for determining relative lens transmission capability. You could say that lack of formal testing equipment spurred creativity which might not have happened otherwise. "-)

 

So???? Shoot It & Show It!

So what are we left with? Well, informal, yet practical testing made by simply shooting UV photographs and posting the results along with good documentation of the experiment. We have gathered lots and lots of great information about gear this way. This kind of informal data has given a good start to a lot of folks wanting to try UV photography.

 

When submitting a post about testing a lens or a camera, suggested useful documentation would be data such as the following:

• Gear
  
  • camera
    
  • lens
    
  • filter
    
  • illumination
    

  [*]Exposure

  • f/w for xx" @ ISO-yyy with EV+/-z.z
    

  [*]Setting

  • subject
    
  • location
    
  • date
    
  • anything else relevant to the gear or image
    

  [*]Conversion/Edit

  • converter
    
  • white_balance
    
  • brief description of processing
    

  [*]Comparison/Analysis

  • to known lens
    
  • using exposure times
    
  • Sparticle boards, etc
    
  • Raw Digger
    
  • other
    

Recently I have created Tag Links so that readers can access more information about UV-capable cameras, lenses and filters posted here. I have also attempted to put some links into the Lens Sticky linking to test posts both here and on other websites. This is time-consuming, but I have made a bit of progress.

[lost cat]

How about a lens wish list? There are lenses that have potential for the list but have not yet been officially verified.

 

Fro instance the Vivitar 135/3.5 and 2.8 listed here have T2 mounts and 4/4 and 5/5 construction respectively.

 

http://boggys.myzen....s_DS_400dpi.pdf

 

There appear to be many clones of these lens out there as well. Prices are still reasonable on these ($20-35 shipped on Ebay)

 

A lens wall of shame containing lenses that have been tested and found to be not so good for UV would be helpful.

 

EDIT: In revisiting the list I see Andrea has already tested what I expect is a clone of the 135/3.5 Vivitar:

 

http://www.ultravioletphotography.com/content/index.php/topic/1030-lens-field-test-f-mount-close-visiruv/

 

Andrea can you confirm this?

[Andrea B.]

Lens found not to be so good for UV are so marked in the Lens Sticky. I suppose we could also list them separately.

 

There is a problem of subjectivity in assessing a lens' UV performance. Where do we draw the line between "transmits UV" and "does not transmit UV too well" ? The characterization of either is quite dependent upon illumination used, filter used, camera used and whether camera is converted or not. As Bjørn often reminds us, you can force UV through almost any lens with enough exposure time and enough UV light.

 

Also, most folks testing lenses for UV-capability do not have a dedicated UV-lens (UV-Nikkor, UAT, CO60, etc) against which to make meaningful comparisons.

 

What Lost Cat and others have done *is* useful. He compares a lens against one of the non-dedicated favorites, and we do get an idea that way of relative performance.

 

**********

 

I don't know if my Lentar 135/3.5 is a clone of the 135.3/5 Vivitar. How do you know which one came first?

 

**********

 

Do start a Lens Test Wish List if you like. We can Pin it.

[lost cat]

 

I don't know if my Lentar 135/3.5 is a clone of the 135.3/5 Vivitar. How do you know which one came first?

 

I'd guess Tokina is the original maker:

 

http://forum.mflenses.com/sears-tokina-135-3-5-preset-thanks-andy-t10473,highlight,sears+135.html

 

 

Do start a Lens Test Wish List if you like. We can Pin it.

 

Will do.

[Andrea B.]

Jim, I'll set up something this morning. Just help me out with a good Topic title please if the current "Lens Test List" doesn't work.

 

Also, I was thinking that in the Lens Sticky I could change the "not so good for UV" comments to Red to emphasize them?

 

Thoughts?

[lost cat]

Jim, I'll set up something this morning. Just help me out with a good Topic title please if the current "Lens Test List" doesn't work.

 

Also, I was thinking that in the Lens Sticky I could change the "not so good for UV" comments to Red to emphasize them?

 

Thoughts?

 

Something along the line of "Lenses with UV Potential". Ask for as much information as possible including:

• Multiple pictures showing main unique physical characteristics of the lens to help identify clones
  
• # elements / # groups
  
• # blades
  
• Apeture range
  
• Version #
  
• Known clones (especially the parent)
  
• Filter size
  
• Mount (especially underlaying)
  
• Links to reviews and data on other sites
  
• Manufactures data if available (sales brochures, optical layout diagrams, color corrected fro UV, UV friendly coatings, etc).
  
• Known good "related" lenses (e.g. Enna Munchen 35mm/3.5 and Enna Munchen 135/3.5, Helios 44 and Carl Zeiss Jena Biotar, Industar 50 and Carl Zeiss Jena Tessar, etc)
  
• Any special attributes e.g. good (or swirly) bokeh, minimal focal shift, high resolution even wide open, etc.
  
• Current prices on ebay?
  

The more evidence there is that a lens is likely to be good for UV the more likely it is someone will bite the bullet and give it a shot. Especially if its cheap, like a ten cent Helios 44 :D.