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X80QF - a f3.2/80mm apo lens for UV-VIS-NIR

Dr Klaus Schmitt

Well-known member
Here I officially introduce my X80QF f3.2 / 80mm apo lens. This is a lens made to order in very limited quantity, camera mounts available are basically all
DSLR and mirrorless camera types up to APS-C sensor format (FF needs optical modification, on request).

Apochromatic Quartz Fluorite lens system specs:
Lens data: f3.2 / 80mm
Useful spectral range: 200 - 1200nm (and beyond)
Focusing helicoid: infinity - macro (range as per request)
Mount: M42, on request: Nikon, Canon, Pentax, m4/3, Sony E
Aperture: variable, declicked f3.2 - f64 (click in on request)
Aperture calibration: on request, F-stops or T-stops
Weight: 290 grams (0.29 kg) in M42 mount version
Filter thread mount: 52mm standard

Specs are also here: http://www.macrolenses.de/ml_detail_sl.php?ObjektiveNr=385

Lens front - open aperture, 52mm filter mount:
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Lens rear - open aperture, micro 4/3 mount version:
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Lens focusing helicoid infinity position, retracted:
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Lens focusing helicoid macro position, extended:
large.jpg


Spectral transmission (310-400nm: >75%, 400-800nm: >65%):
large.jpg


(Btw. there was a decline in transmission below some 310nm, caused by my current measurement setup, not the lens, which should transmit flat to 200nm,
as it consists only of pure fused silica and calcium fluorite. I have therefore removed that part until I have more reliable data to show ...)

This X80QF lens is meant as a tool for the ambitioned amateur or researcher on a budget, who cannot allow to be restricted to the shortcomings of a lens based on optical glass,
limited to around 350nm cut off (some very special ones reach a bit lower), but need a flat transmitting lens down to 300nm or even beyond that. It certainly should not be compared
to such very pricey high performing quartz fluorite lenses such as the Coastal Optical Systems 60mm or 105mm Apo, the CERCO 94mm, the UV-Nikkor 105mm, the Pentax Ultra
Achromatic 85mm or the Zeiss UV-Sonnar 105mm. It cannot reach those in terms of sharpness or contrast wide open, but stopped down to the usual working apertures f8 - f11,
it delivers acceptable sharp and useful VIS, UV, IR or multispectral images with acceptable contrast and very little focus shift for a reasonable price.

More and larger images are here: http://photographyoftheinvisibleworld.blogspot.de/2014/03/x80qf-made-to-order-f3280mm.html

Should there be interest in such a lens: Inquiries are welcome using my email or PM.
 

Dr Klaus Schmitt

Well-known member
The following sample shots were done aside from visible photography in reflected ultraviolet using Baader-U filter and in simulated bee vision using my XBV filter.
Light source was sun or a modified Xenon flash. All shots were done at f8 - f11.

Triptych of Tussilago (in situ, light source sun), visible, reflected UV using Baader-U filter, sim. bee vision using XBV filter (left to right):
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Triptych of Tussilago (lab, light source Xenon), visible, reflected UV using Baader-U filter, sim. bee vision using XBV filter (left to right):
large.jpg


Diptych of Gazania (lab, light source Xenon) Visual image using UV/IR Cut filter - X80QF (left), Cerco 94mm (right):
large.jpg


Diptych of Gazania (lab, light source Xenon) reflected UV image using Baader-U filter - X80QF (left), Cerco 94mm (right):
large.jpg


Diptych of Gazania Detail (lab, light source Xenon) Visual image using UV/IR Cut filter - X80QF (left), Cerco 94mm (right):
large.jpg


Diptych of Gazania detail (lab, light source Xenon) reflected UV image using Baader-U filter - X80QF (left), Cerco 94mm (right):
large.jpg
 
Here I officially introduce my X80QF f3.2 / 80mm apo lens. This is a lens made to order in very limited quantity, camera mounts available are basically all
DSLR and mirrorless camera types up to APS-C sensor format (FF needs optical modification, on request).

Apochromatic Quartz Fluorite lens system specs:
Lens data: f3.2 / 80mm
Useful spectral range: 200 - 1200nm (and beyond)
Focusing helicoid: infinity - macro (range as per request)
Mount: M42, on request: Nikon, Canon, Pentax, m4/3, Sony E
Aperture: variable, declicked f3.2 - f64 (click in on request)
Aperture calibration: on request, F-stops or T-stops
Weight: 290 grams (0.29 kg) in M42 mount version
Filter thread mount: 52mm standard

Specs are also here: http://www.macrolenses.de/ml_detail_sl.php?ObjektiveNr=385

Spectral transmission (310-400nm: >75%, 400-800nm: >65%):
large.jpg


(Btw. there was a decline in transmission below some 310nm, caused by my current measurement setup, not the lens, which should transmit flat to 200nm,
as it consists only of pure fused silica and calcium fluorite. I have therefore removed that part until I have more reliable data to show ...)

Hi Klaus,

Congratulations with the new lens, it's specs looks very interesting and seem to be very useful for your type of imaging. I do wonder about the UV sensitivity in combination with a silicon based sensor though. The spectral sensitivity of silicon based sensors drops very fast for wavelengths shorter than 350-380 nm. Of course it helps if the lens doesn't limit that even more, but the sensor will set the limit.

The lens is of an APO design. Does that mean that it is corrected as traditional, Red+Green+Blue, or are different wavelength bands (UV and IR) corrected as well. I assume one would confine oneself to either UV or IR for specific eye sensitivity studies, but it could perhaps be nice if UV + IR could be focused well simultaneously. I don't know, but such a dual band might reveal some interesting patterns, although I would not know which creature could benefit from the visual clues it might provide.

Cheers,
Bart
 

Dr Klaus Schmitt

Well-known member
Thanks Bart!

Indeed, sensor sensitivity declines rapidly, especially for Nikon CCD based cameras, I had that tested out a while ago. But the newer models have Sony CMOS sensors and those (D7000 for instance I know quite well) work at least to 320nm, maybe a bit more.

This Hexaptych shows in sequence (left to right, top to bottom - 1st one is VIS) deeper and deeper reflected UV images, the last one being shot at 290-330nm, effective filter peak approx. 310nm and about 12 stops under visible light (VIS) exposure. (So far I haven't seen anyone recording reflected UV images that deep)

large.jpg


Details are here: Winter Jasmine - Jasminum nudiflorum using X80QF for deep UV reflected ultraviolet photography

About APO correction, this is within the whole useful area, but I have no specific data which three points were used for that, I just know that focus differences are very small, less than 1/2mm
 
Wow, what a lens. By the look of spectral transmission graph I wonder if it's transmission actually extends into the vacuum ultraviolet below 200nm. I've never seen pictures done with this part of the electromagnetic spectrum. A sensor that certainly works in this region is film and indeed film works at much shorter wavelengths too. Think of the tons of xray film exposed before the adoption of fluorescent intensifying screens.
 
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