Sunday, October 28, 2012

Hamamatsu A4869 UV lens f3.5/50mm for reflected UV photography

I got a loaner lens for testing, a Hamamatsu f3.5/50mm UV lens, made of quartz and fluorite, a 5e/5g design, with obviously uncoated lens elements (which might be the reason for the prominent hotspot that it shows in VIS and UV), as this is some 15-20 year old lens I have been told. It has a c-mount and was made for Hamamatsu's line of high sensitive and intensified UV cameras, hence its image circle is just 16mm as per its specs. I measured the latter and the real image circle is larger (certainly not as well defined), about 25-27mm, so it will not cover APS-C sensors, that require at least 30.1mm.

[click on image to see a larger one]

 First thing tested was vignetting, which it shows quite some wide open, if used with a 21mm image sensor.

Vignetting, fully open on a 21mm diameter imager:


Well, I was curious to see how it would perform in VIS and UV, so I took a few shots with it, using for UV my "work horse" UV filter, the Baader-U. This lens has a common 40.5mm filter thread, so mounting filters was easy, just a step ring was needed. Unfortunately the lens front rotates while focusing as do many other lenses. I used sunlight for the outside shots and Xenon flashlights for the studio macro shots, using a Rudbeckia fulgida flower as a target.

Outside shot, VIS, fully open:


Outside shot, UV, fully open:


Outside shot, VIS, stopped down to f8:
 

Outside shot, UV, stopped down to f8:
 

Stopping down significantly reduces blurriness that is visible wide open even in the image center as well as some curvature of field and enhances imaged sharpness considerably.

It gets quite obvious, that stopping down the lens (from about f8 onwards) makes visible a quite prominent hotspot that is has in VIS + UV in certain lighting situations:

Outside shot, VIS, stopped down to f11, central hotspot:
 

Outside shot, UV, stopped down to f11, central hotspot:
 


Now on to studio macro shots...

Macro shot, UV, stopped down to f11:
 

Macro shot, UV, stopped down to f11, detail :
 
The detail shows some strange artifacts which could either result from the flower being wet or lacking lens resolution. More research needs to be done on that.

Here is its transmission graph versus some normal and quartz fluorite reference lenses:

 
[Be reminded that this measuring setup used is valid to about 310-320nm onwards, so both quartz fluorite lenses transmit UV better than shown]

To summarize, this (rather expensive $$$$) Hamamatsu A4869 f3.5/50mm UV lens is certainly not a bad lens. That prominent hotspot it has needs carefully controlled lighting situations to avoid spoiled images, which in the field outside cannot be secured, so it's "hit and miss" unfortunately. So I would rather recommend it for studio work only. Also the lens needs to be stopped down to at least f8 to achieve a flat field and sufficient sharpness. In studio the lens performs much better, as my examples show and a thin c-mount extension ring added gives the needed close up/macro focusing distance, that this lens otherwise not has (closest focusing is 0.6 meters, 2ft). Infinity focus was perfectly adjusted and no re-collimation was needed.

P.S.: It has been confirmed by Hamamatsu staff that this lens is about 15 years old and was designed to match the needs of maximum 2-3 Mpix cameras. Hence the limited resolution and most likely the artifacts are diffraction effects. Further it was mentioned to me that the found hotspot may be the result of uncoated lens elements being used, so stray and reflected light bounces between them and the shiny sensor surface.

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

Colorful reflected UV ultraviolet photography II

I have been wondering why reflected UV photography would have to look so drab in terms of colors often. So here some more recent experiments with a bit colorful background and various UV lights, when shooting it in reflected UV light using my "work horse" UV filter, the Baader-U filter and a quartz fluorite lens. Well, I was using one of my last Rudbeckia fulgida flowers for that, as the first snow is coming...

[click on image to see a larger one]

Conventional, looking monochrome:
 

Added front light:
 

Colorful, wider band:
 

Colorful Variant 1:
 

Colorful Variant 2:
 

Now this is "artsy" playing with light, but still documents very well the wonderful and prominent UV pattern this flower has...

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

Thursday, October 25, 2012

Golden reflected UV ultraviolet photography VII

Today was one of these last sunny October days with golden sunrays in the evening, so I grabbed my UV equipment and went to the park for some more "golden" UV shots. I used the 94mm CERCO quartz fluorite lens for those. Also here my special "golden" processing for these shots has been used.

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Salvia leaf:


Delphinium seedhead:


iridescent blue Delphinium:


water droplets on leaf:


Quite amazing high resolution this type of UV photography shows.

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

Friday, October 19, 2012

Lens Resolution: Golden reflected UV ultraviolet photography VI

Today I would like to use those recent "golden shots" of autumnal Rudbeckia fulgida leafs to show the different performance of lenses, an older 50mm enlarger lens and the 94mm CERCO quartz fluorite lens. Distance to the leaf was chosen to achieve about matching images. Also here my special "golden" processing for these shots has been used.

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old enlarger lens:


CERCO lens:


Here a diptych to make comparison easier, Cerco lens is left:



It gets pretty obvious, that the Cerco lens delivers a much higher resolution and sharpness.

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

Thursday, October 18, 2012

Rudbeckia: Golden reflected UV ultraviolet photography V

Today more "golden shots" of an autumnal plant that I had shown before, Rudbeckia fulgida in that case. I was using this time an older 50mm enlarger lens and was playing around with some lighting situations.

I used my special "golden" processing for these autumnal shots that I have also used a few days ago.

[click on image to see a larger one]

normal UV:


"golden" UV:


And here now shown on a different leaf, in more detail...

normal UV:


"golden" UV:


Also this was some "artsy" playing with light then my usual documentary work...

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

UV photography - Inspired by old bromoil prints

I was inspired by some old bromoil prints and used my recently developed UV photographic technique for that.This is new territory for me, so bare with me...

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Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

Tuesday, October 16, 2012

Hydrangea: Golden reflected UV ultraviolet photography IV

Today more about those "golden shots" of an autumnal Hydrangea I was presenting the other day. I was using this time my CERCO 94mm quartz fluorite lens and was playing around with some lighting situations.

I used my special "golden" processing for these autumnal Hydrangea shots that I have also used a few days ago.

[click on image to see a larger one]





 

Also this was some "artsy" playing with light then my usual documentary work and I quite like the results.

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

Friday, October 12, 2012

Colorful reflected UV ultraviolet photography ?

I was always wondering if reflected UV photography would have to be so drab in terms of colors. We humans are so used to a wonderful world of colors, so I thought I should experiment a bit with that topic. Well, I was curious to see how that Rudbeckia fulgida flower I have here would look like, if I would create a bit colorful background for it, when shooting it in reflected UV light using my "work horse" UV filter, the Baader-U filter. Well, here an example for that...

[click on image to see a larger one]

Rudbeckia fulgida:
 

Now this is "artsy" and still documents the wonderful and very prominent UV pattern this flower has, very well still useful as a documentary.

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

Old enlarger lens: reflected UV ultraviolet photography

I was digging through boxes, when some older, but new in box  f4.5/50mm enlarger lens fell into my hands. Well, I was curious to see how it would perform in UV, so I took a few shots in the Hermannshof park with it, using my "work horse" UV filter that never let me alone, the Baader-U filter. How nice that this lens has a 40.5mm  filter thread, as not all enlarger lenses have that. A simple short M42 focusing helicoid served as a focusing aid and as it has a Leica thread mount (M39), so simple M39-M42 ring was all needed to make it fit. All shots were done at f8 in evening last sunlight with not much UV left to use.

[click on image to see a larger one]

Rudbeckia hirta, wild form from Illinois:


same, but closer:


Rudbeckia fulgida:
 

Quite impressive performance for a most likely simple Cooke triplet 3e/3g lens. Oh and I forgot to mention, is has no (or barely any) focus shift. Here is its transmission graph versus my usual reference lenses.

 

More research and testing needs to be done, but it could form the basis of a comparably cheap UV photography system; we'll see...

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

Thursday, October 11, 2012

X135 UV calibrated f2.8/135mm lens: golden reflected UV ultraviolet photography III

Today I wanted to make the difference visible of those "golden shots" of an autumnal Hydrangea I was presenting the other day. I was using this lens of mine that I have calibrated and used for reflected UV photography a while ago. It has a 5e/5g design and I have posted about it here and here.

I used my special "golden" processing for these autumnal Hydrangea shots that I have used a few days ago. That method I have also used earlier HERE and HERE.

So what you will see is the normal, visible image, the pure reflected UV image and the specially done "golden" shot.

[click on image to see a larger one]

Visual image:


UV shot:


"Golden" image without BG illumination:
 

This was some  more "artsy" playing with light then my usual documentary work, but it shoudl still be interesting.

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

Wednesday, October 10, 2012

X135 UV calibrated f2.8/135mm lens: golden reflected UV ultraviolet photography II

Today more "golden shots" of an autumnal Hydrangea using this lens of mine that I have calibrated and used for reflected UV photography a while ago. It has a 5e/5g design and I have posted about it here and here.

I again used my special "golden" processing for these autumnal Hydrangea shots that I have used a few days ago. That method I have also used earlier HERE and HERE.

[click on image to see a larger one]







This was some  more "artsy" playing with light then my usual documentary work, but it fits the season very well I thought.

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

Monday, October 8, 2012

X135 UV calibrated f2.8/135mm lens: golden reflected UV ultraviolet photography

Well, today I dug out this lens of mine that I have calibrated and used for reflected UV photography a while ago. It has a 5e/5g design and I have posted about it here .

So today about UV photography using this lens, executed using one of my last Rudbeckia fulgida flowers. Sunlight was used as a light source.

Oh well and I forgot to mention that I used my special "golden" processing for these autumnal shots, which I have already used HERE and HERE.

[click on image to see a larger one]







and here some autumnal leafs, Hydrangea in that case...




This was more some "artsy" playing with light then my usual documentary work, but still the very prominent UV pattern of that Rudbeckia gets nicely visible.

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

Tuesday, October 2, 2012

Carl Zeiss Jena Lamegon 38mm: UV ultraviolet photography II

Well, I dug out this lens last weekend and took a few shots with it again, when I remembered that it can also be used for UV (and IR) despite its complex 8e/4g lens design incorporating lots of glass elements and a few cemented ones, based on the famous Biogon design of Dr Bertele. In my first Blog entry about this lens about a year ago I was referring to my friends site about such special and rare lenses HERE and there are also some UV and IR shots.

So today about UV photography using this lens, executed using one of my last Rudbeckia fulgida flowers. Shots were done using the UV Baader-U and XNUV filter as well as the bee vision simulating XB4 filter. My modified Xenon flash was used as a light source. Oh, and no focus correction was done!

[click on image to see a larger one]

Visual image using UV/IR Cut filter:


Simulated Bee vision using XBV4 filter:


UV image using XNUV filter:


UV image using Baader-U filter (with usual whitebalance):


UV image using Baader-U filter (with special whitebalance to resemble a quartz fluorite lens):

Well, the UV transmission is not that great, as may be seen from the colors of the second to last image, but still quite useful and especially sharp. So, maybe you you understand why I was so surprised again about the performance of that lens - no wonder its larger brothers (8/110mm and 5.6/55mm) were used in cold war as a aerial imaging lenses. And btw. if you like to see how amazingly this lens performs in the visual, have a look HERE from 2011 and HERE from this year.

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos