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UltravioletPhotography

Fused Silica single lens tests


dabateman

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The day before Jonathan posted his results with his 40mm Plan convex lens (PLCX) I purchased 25mm diameter elements being focal lengths: 50mm bi convex (BICX) and 75mm Plan convex lens (PLCX).

I have using super high tech techniques for attachment, with some black 3M electrical tape to directly tape the elements to a 25mm to 52mm ring. Then placed an equally high tech aperture disc behind it. This was a 25mm filter ring with black electrical tape filling the hole, then cutting an about 6mm hole. I then placed my 254.3bp25 filter behind that aperture disc and attached it to a 35mm to 90mm helicoid for focusing with my UVC Imager.

 

Results:

Using a single 254nm germicidal 15W bulb.

50mm BICX lens wide open:

post-188-0-97347500-1583820966.jpg

 

50mm BICX lens with roughly 6mm aperture disc:

post-188-0-21033900-1583820982.jpg

 

75mm PLCX lens wide open:

post-188-0-56104000-1583821011.jpg

 

75mm PLCX lens with roughly 6mm aperture disc:

post-188-0-62751500-1583821034.jpg

 

Using a single Exoterra UVB bulb:

75mm PCLX lens with aperture disc and 1mm UG11 filter:

post-188-0-34017200-1583821054.jpg

 

 

 

Camera EM1mk1, full spectrum modified with 75mm PCLX lens, roughly 6mm aperture disc, single 365nm LED and 1mm UG11 filter (6 seconds, ISO400, F12-14?):

post-188-0-15199900-1583821071.jpg

 

With a M43rds camera and close up focusing these lenses might actually be quite useful for UV work. I have ordered a 25mm, 200mm BICX and 100mm and 150mm PLCX lenses to play with further. These were all super cheap.

https://www.ebay.com...a+lens&_sacat=0

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I have no idea. I will compare them to my UAT. The 25mm diameter Plcx 75mm focal length lens element actually looks sharper than my 60mm f3.5 KSS macro lens.

 

I ordered a cheap Chinese aperture m42 control adapter. So in a month or so will be able to properly control the aperture.

 

Wait did you mean will the uv nikor be as sharp or go deep into UV?

Jonathan has posted the spectrum of the Nikkor and its good for deep UV, looked a little better than my UAT.

As for sharpness, I don't own the Nikkor UV.

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David, that last one looks pretty sharp.

So would a UV-Nikkor transmit basically as well as these?

No this single lens transmit better than the UV-Nikkor as there are only two silica to air transitions.

I would guess 10-15% better.

 

My 150mm Plano-convex fused silica lens show the same improvement when stopped down.

Already at f/8 there is a dramatic improvement. At f/22 it is sharp at the corners too on a a full frame sensor.

I will post the results when I get time to write more about it.

 

I suggested this type of setup already a few yeas ago:

https://www.ultravioletphotography.com/content/index.php/topic/2992-infrared-block-broad-uv-and-visible-pass-filter/page__view__findpost__p__24038

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Fantastic technology Dave, very do-able...

I really like the last one so sharp, is this the full frame or a crop ?

Col

 

With all my images, straight from camera.

Only proccesing I do for posted images is open in InfranViewer, resize to either 600x800 or 1024x768 save low quality jpeg, l think 70% and post. No cropping, no removal of that hair now on my imager, and no color tweaks. Straight from camera, as I haven't proccessed any thing.

Still need to do that.

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Fantastic technology Dave, very do-able...

I really like the last one so sharp, is this the full frame or a crop ?

Col

The reason it is sharp is the combination of a narrow bandwidth LED light and a good lens.

With other light-sources there will be more fuzziness. It is still a very interesting tool to explore UV.

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The reason it is sharp is the combination of a narrow bandwidth LED light and a good lens.

With other light-sources there will be more fuzziness. It is still a very interesting tool to explore UV.

 

I think my photos 4 and 5 in the original post help to illustrate that.

Photo 4 is monochromatic 254nm light with 254nm filter.

Photo 5 is broad spectrum UVB light with broadband 1mm UG11 filter.

Photo 5 is a little softer. I should show the same subject, but I liked the stems in the area and shot that.

 

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I think my photos 4 and 5 in the original post help to illustrate that.

Photo 4 is monochromatic 254nm light with 254nm filter.

Photo 5 is broad spectrum UVB light with broadband 1mm UG11 filter.

Photo 5 is a little softer. I should show the same subject, but I liked the stems in the area and shot that.

Yes that is very clear and illustrative. I just wanted to highlight the facts with some words. (pun intended)

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eye4invisible

I ordered a cheap Chinese aperture m42 control adapter. So in a month or so will be able to properly control the aperture.

That's optimistic. I ordered some basic items from China back at the start of February, and they still haven't been shipped (this vendor usually ships within a week).

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Here are some images of my home made lens. You can see the high tech precision razor blade aperture ring I made for these images. I probably should measure and make a better one.

 

post-188-0-78892700-1583864984.jpgpost-188-0-19192100-1583864993.jpgpost-188-0-45387800-1583865001.jpgpost-188-0-71990800-1583865009.jpg

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  • 5 weeks later...

Update on my Single lenses. I have made a whole bunch now and have attached them more securely.

 

Using a 5mm C-mount spacer ring, I grind down the threads as you can see here:

post-188-0-39794300-1586416806.jpg

 

This shows the 5mm C-mount ring, then the filled down ring, then paint the shinny aluminum black.

 

Here is an image of a 50mm focal length, 25mm diameter fused silica biconvex lens element glued in place:

post-188-0-75280400-1586416936.jpg

 

This is a possible lens assemble:

post-188-0-44960700-1586417104.jpg

bottom ring is C-mount/M42 dual mount to M43rds adapter

Then 25mm to 1.5mm aperture control ring which has M42 Male and female sides

Then M42 to M52 step up ring

Then Raf camera M52 to Center M25 adapter, which also has female M52 threads. So a 52mm filter can be mounted above when a C-mount adapter is cross threaded into the 25mm threads.

 

There is just enough space to mount the lens up as shown, or reversed below the Raf adapter, just above the aperture control unit. So a Biconvex lens can be flipped and my 25mm filters can easily be switched out above or a spacer can be added and 52mm filters can be mounted above the lens. Also possible is mounting the filter behind the lens just above the aperture unit. This works best for my 254.3bp25 filter which I now have mounted into a C-mount ring as well.

 

Close up of the rear aperture blades:

post-188-0-99857500-1586417433.jpg

 

They look much more professional now. With helicoids and spacers I have been testing out various elements. I may also test various combinations of elements as I have a couple biconvex, planar convex and concave elements mounted into C-mount rings.

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