Radioactive lenses

Started May 20, 2012 | Discussions thread
ProfHankD
Senior MemberPosts: 1,657Gear list
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Re: Radioactive lenses
In reply to Carlgo, May 21, 2012

Carlgo wrote:

Thanks for the great insight on these interesting lenses. One thing that surprised me is that a 35mm was the widest angle listed.

Er... I listed the 28mm f/2.5 Rokkor SI.

Two reasons why fewer very wide:

1. The aberrations that the radioactive glass helps minimize are not that big a deal unless the lens has a relatively large aperture diameter -- making the lens slower also reduces aberrations. Few SLR lenses much below 28mm are very fast.

2. Most wides were either 35mm or 28mm. Some shorter ones are probably radioactive too (perhaps my Canon FD 24mm f/2.8 SSC, for example), but with far fewer around, the probability that anyone notices these lenses are hot is lower.

Also, remember that these lenses were not designed for a 1.5X crop body. 18mm on APS-C gives the field of view of a 28mm on "full frame" 135 film. Designing and building short focal length lenses for a long back focus (i.e., retrofocal) and coverage of "full frame" is hard.

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