C-mount Lenses discussion
from John Lord
Hello Damien,
Yes, if you're using video surveillance lenses like the Cosmicars
you would get a pretty low opinion of c-mt lenses. Such lens were
made to be only as good as they had to be, which was not very good.
Even so, it was amazing what a difference replacing such lens with a
photographic lens made on the monitor image.
Of course, if the camera has a c-mount, one can use the many
c-mount adapters available that enable it to accept, for example,
lenses in Arriflex standard mount, etc. Arguably the best current
16mm prime lenses are the Zeiss superspeeds; a set of 5 runs around
$35,000 I believe.
To be realistic, one would look at the used lens market. Avoid all
the early uncoated lenses. Depending on one's pocketbook:
In the under $500 category:
- Zeiss Planars, Distagons (very rare in C-mt in the USA, but maybe in Europe...) Standard on the Arriflex.
- Cooke and Taylor-Hobson-Cooke (English), but not the early uncoated stuff, which you see a lot of on the used market.
- Kinoptik Apochromats (and the Tegea). Really nice lenses.
- Angenieux.
- Canon has made some fabulous 16mm zooms, and I hear they made non-video c-mts, but I never saw one.
In the under $200 category:
- Cine-Nikkors. Personally, I think these are okay but not great.
- Switars. Watch out for the RX lenses, which have a nonstandard flange to film distance to accommodate the reflex prism in Bolexes. Yvars are not as good.
- The 15mm Angenieux. These are plentiful, and so cheap.
- Century Precision Optics telephoto lenses.
In the under $100 category.
- Kodak Ektars (not the earlier, uncoated Kodak Anastigmats). These are cheap because they come with a strange mount that requires the Kodak C-mount adapter. These days, that adapter can cost more than the lens! I picked up a 63mm and 102mm Ektar last month for about $20 each, in perfect condition except for the helix lubricant being more than a little stiff.
- Bausch and Lomb made a line called Animars, which are greatly underrated and so very cheap (like, $10). The last, coated version of the f2.7 one inch Animar is a very sharp lens.
Brands best avoided: Som-Berthiot, Elgeet, Wollensak (except some extraordinary wide angle lenses made for the military)
This is of course, just an off-the-cuff selection from a universe
of glass, and most makers occasionally produce a dud.
Another thing that interferes with image quality: the flange to
focal plane distance in video cameras is not always what it should be.
Some companies (e.g., the Fire-i400) provide a means for the user to
adjust this, an excellent feature. What they should tell you and
don't is that the adjustment should be made with a wide-angle lens
known to be properly mounted (i.e., tested by an optician). The
greater depth of field of normal and long focal length lenses makes
finding the plane of focus more difficult.
Lastly, there is some talk that, unlike film, the wells in CCD
sensors are very sensitive to the angle at which the light hits the
sensor (i.e., vignetting beyond that caused by the geometry). If this
is so, one would think that a lens with a large rear element might
perform better than one with a small element, other things being
equal. One manufacturer has started to produce such lenses for
digital still cameras. We'll see.
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