photo:lensmirror
super telephoto mirror lenses
introduction
mirror lenses are difficult to use and for most people are probably not the best option
they were popular in the 1970's and 80's as they mainly competed against manual focus big, heavy, f/5.6-6.3 telephoto lenses
in the 1990's, the advent of new high refractive index glass, computerised lens manufacture combined with a now mature autofocus technology and optical
image stabiliser, meant that mirror lenses were generally only for those whose budget could not afford a “real” telephoto lens such as a 400mm f/4 IS
catadioptric mirror lenses share the following characteristics:
-
fixed aperture
virtual elimination of chromatic aberration and lateral color fringes as uses mirrors rather than lenses
central mirror:
allows much more compact lens length as the optic path is reflected internally twice
by necessity, blocks some of the light and thus causes:
front filter thread if present, rotates with focus
significant vignetting
difficult to suppress stray light, ghost and flare
shallow depth of field (DOF) with low contrast makes accurate manual focus difficult, further compounded on most lenses by the lack of micro-focus gearing so that only small incremental changes to focus can be made
apart from their telephoto reach for such a small size, these lenses were difficult to use for film photographers using SLR cameras as:
they usually had slow apertures around f/8 and were thus dim in optical viewfinders making manual focus difficult and requiring bright sunny conditions for any action shots
they were not image stabilised, and the light weight actually worked against getting sharp images without camera shake - even the camera's mirror was sufficient to cause camera shake
mirror lenses on mirrorless cameras
mirror lenses
2000mm
1000mm or more
600-800mm
500mm
<500mm
cheaper designs
older cheap brands include Hanimex, Makinon, Soligor
contemporary cheap models with generally lesser image quality and build quality, and often marketed as Albinar, Vivitar, Rokinon, Bower, Walimex, etc, include:
comparison of 500mm mirror lenses
model | aperture | diam | length | length incl. MFT adapter | weight | optics | close focus | front filter | Infinity on Canon EOS |
Olympus OM | f/8 | 81mm | 97mm | 123mm | 590g | v. good | 4m | 72mm | YES |
Canon FD | f/8 | 90mm | 148mm | 170mm | 705g | v.good | 4m | none | NO |
Nikkor N | f/8 | 89mm | 116mm | 143mm | 823g | v. good | 1.5m | 82mm | YES |
Nikkor C | f/8 | 93mm | 142mm | 169mm | 1000g | good | 4m | 88mm | YES |
Sony/Minolta | f/8 | 89mm | 118mm | 142mm | 665g | v. good | 4m | 82mm | NO |
Tamron SP f/8 | f/8 | 84mm | 92mm | mm | 595g | good? | 1.7m | 82mm | YES |
Samyang f/8 | f/8 | 77mm | 88mm | 123mm | 320g | avg? | 1.7m | 72mm | YES |
Samyang f/6.3 | f/6.3 | 119mm | 98mm | 133mm | 705g | avg? | 2m | 95mm | YES |
ProOptic Maksutov | f/5.6 | 105mm | 220mm | 255mm | 1220g | good | 1.5m slow but microtune | none | YES |
photo/lensmirror.txt · Last modified: 2014/05/18 20:03 by gary1