Posted: Sat May 29, 2010 10:17 am Post subject: Re: Tele-extenders - any experience? |
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Scheimpflug wrote:
kansalliskala wrote: |
EDIT: btw the "Product description" on the link is .. ? I don't even understand what they want to say. Nice duck anyways. |
ebay auction wrote: |
Product Description :
1). Teleconverter Telephoto pitch, also known as mirror, it is a body installed in between the lens and the camera optical attachment is to be extended to two times the focal length or 2.2 times the lens of subsidiary device. Teleconverter lens installed on the first and then use them. |
I've never used the screw-on tele-extenders, but I've used the screw on wide-angle & fisheye converters. In my experience, they come in three categories:
- 1) Designed for a specific camera & lens by the same manufacturer, performing reasonably well on that camera/lens. Performs OK on other cameras/lenses.
- 2) Designed for a specific camera & lens by the same manufacturer, performing reasonably well on that camera/lens. Performs horribly on other cameras/lenses.
- 3) Designed as a "universal" conversion lens by a third-party manufacturer, with the same lens performing anywhere from decent to horrible depending on which camera/lens it is paired with.
So, it is a bit of a minefield...
I do remember reading a discussion once about how front-mounted tele-extenders and rear-mounted tele-converters make the light form different optical paths through the lens. With a rear-mounted TC, the center part of the image is expanded to fill the frame and the outside part of the image is not used... whereas the front-mounted conversion lens changes the angles for the light entering the main lens such that the main lens uses its entire optical path as normal. It was a good discussion, although I can't remember the conclusion... _________________ Sigma DP1, Nikon D40 (hers ), Polaroid x530, Pentax P30t, Pentax P50, (P30t/P50 K-A to Nikon F body mount conversion)
Nikon: 18-55/3.5-5.6 "G ED II DX" (F) Soligor: 28/2.8 (FL->F converted), 135/3.5 (F), 3x TC (F, modified) Kalimar: 28-85/3.5 (F)
Vivitar: 70-210/2.8-4.0 Version 3 (F), Tele 500/6.3 Preset (F), 19/3.8 (F) Minolta: 300/5.6 (SR/MC/MD pending F conversion)
Tamron: 28/2.8 (Adaptall) Panagor: 28/2.5 (FD) Aetna: 300/5.6 (F) Osawa: MC 28/2.8 (F)
Vintage Lenses: Dallmeyer: 1940s A.M. 14in 356mm f4 (ULF->M42) 1930s Adon Telephoto Taylor, Taylor & Hobson: 1880s Rapid Rectilinear 8 1/2 x 6 1/2 11.31in f/8 (LF->?)
Parts Lenses: Nikon 35-135/3.5-4.5 (F), Sigma 70-210/4.5 (F), Nikon 50/1.8 Series E (F) |