Saturday, March 1, 2014

X80QF - a made to order f3.2/80mm apo lens for reflected ultraviolet, visible, infrared and multispectral photography

Today I will officially introduce my X80QF f3.2 / 80mm apo lens. I have previously shown here and here results using a prototype 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

[click on image to see a larger one]

Lens front - open aperture, 52mm filter mount:

Lens rear - open aperture, micro 4/3 mount version:

Lens focusing helicoid infinity position, retracted:

Lens focusing helicoid macro position, extended:

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

(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 ...)

The following sample shots were done aside from visible photography in reflected ultraviolet using Baader-U filter and in sim. bee vision using my XBV6 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):  

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


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


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



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


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



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 as shown acceptable sharp and useful VIS, UV, IR or multispectral images with acceptable contrast and very little focus shift for a reasonable price.

I will make only very of those, so should there be interest to purchase such a lens: Inquiries are welcome using my email on the top right corner of this site.


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