“I think a lot of the time these days people are so concerned about having the right camera and the right lenses and all the special effects that go along with it that they’re missing the key element.”—Herb Ritts
Distagon is the name that Zeiss gives to its wide-angle lenses that have a retrofocus design. Short focal lenses are typically composed of glass elements whose shapes are symmetrical in front of and behind the diaphragm. As the focal length decreases, the distance from the rear element to the film plane or digital sensor decreases and could even protrude into the mirror box requiring the camera to be in mirror lock-up mode in order to use the lens. A retrofocus lens solves this problem by using an asymmetrical design that allows the rear element to be further away from the plane of focus than its effective focal length might normally suggest.
This digital IR shot was made at Barr Lake State Park the day before a big snowstorm was due to blow most of those leaves away. Camera was an LifePixel IR-converted EOS Digital Rebel Xti and 18mm Distagon T* f/3.5 and the balance on the lightweight Xti body was superb. The Digital Rebel’s 1.6x multiplication factor changes the angle-of-view to the equivalent of a 29mm lens (on 24x36mm format.) Exposure was 1/125 sec at f/16 and ISO 400 with a plus one-stop exposure compensation. RAW file was converted to monochrome using Silver Efex Pro.
The Distagon T* 18mm f/3.5 lens, that I used to make the above photograph has been replaced with the Milvus 18mm f/2.8 ZE Lens. The 18mm Distagon is surprisingly small and light (1.12 lbs vs. 1.59 lbs for the Milvus) for its wide 90 degree angle-of-view with full-frame sensor cameras where’s it capable of delivering true wide-angle lens performance. (I’ve seen the Distagons on sale for $1405,95 vs. the Milvus at $2299.)
My book, The Complete Guide to Digital Infrared Photography is currently out-of-print but used copies are available from Amazon starting at $14.36, as I write this. Creative Digital Monochrome Effects has a chapter on IR photography and is available from Amazon with new copies under $10 and used copies selling for $2.55 (plus shipping) one of the best book deals out their for what is my personal favorite book.