cheap new c mount lenses
Posted 25 March 2008 - 01:15 AM
Well, here is some new and interesting news. Kowa has a new line of industrial C-mount lenses called the 1" Megapixel Series. They boast an astonishing and nearly unbelievable 120 lp/mm in the center!!!!
And they sell for somewhere around $300 each. They have an image circle of 16mm (so plenty good for S16), and they come in the most excellent lengths:
8mm f1.4 (holy snot! 8mm!!)
Posted 25 March 2008 - 04:38 AM
so my main question is: will they work with the Beaulieu 4008-series?
More specified: the Beaulieu 4008 ZM II?
Thanks in advance!
Posted 25 March 2008 - 11:47 AM
Posted 25 March 2008 - 03:09 PM
8mm f1.4 (holy snot! 8mm!!)
Thanks for the tip, Kevin,
There aren´t that many good C-mount wide angle lenses around, that are short enough to be used for Super 8mm.
Judging from the list, the people at Kowa also make an 1.4/6mm wide angle (at $119) and a slightly more expensive (and slightly 'slower') 2.8/5mm wide angle (at $413), both C-mounted and both of the high-resolution type, which is all the more interesting. This list of lenses looks a lot like a similar one from Fujinon, by the way.
A 5mm prime wide angle lens would be very nice - that´s roughly equivalent to a 28mm in 35mm (24x36mm) photography. A 4mm lens would be something like a 24mm SLR lens - I have an aspherical wide angle attachment lens for my Schneider Optivaron 1.8/6-66mm zoom and it gives a focal length of 3.9mm. I have compared it to a 24mm lens on my Nikon FM3A and they are very similar in field of view.
Those lenses would probably work beautifully on a Beaulieu 4008 ZMII camera, provided the back focus (the flange focal distance) is properly collimated, that is, exactly matches the distance from the C-mount flange to the film.
This is particularly critical when it comes to very short focal lengths at infinity, especially if used wide open (at f=1.4).
rofessional camera operators typically carry a field collimator (ARRI or equivalent), to be able to check the back focus of the lenses every time it is mounted to a camera.
A lens that covers a 1/2" size chip will leave a lot of space for the Super 8 frame and will, as an extra benefit, use the 'sweet spot' in the center, where the lens has it´s highest capability of resolution. That means that these lenses that are manufactured for much larger 'frame' sizes than Super 8, can probably be used at full opening (f=1.4 or 2.8) and still be extremely sharp - that´s very good for low or available light situations. Or if you´d like to use a selective, short depth of focus with some of the longer lenses.
/ Bengt in Stockholm
Edited by Bengt Freden, 25 March 2008 - 03:11 PM.
Posted 25 March 2008 - 03:32 PM
I discovered in the KOWA PDF catalog/brochure that there are three more very interesting focal lengths:
a 3.5mm (super) wide angle
a 4.5 mm wide angle and
a 6 mm wide angle
all of them are extremely fast (f=1.4) high resolution (HR) lenses for the 1/2" video format, in C mount (a distance of 17,52 mm from the back lens flange to the film). According to the text, they are able to procuce a detail of 100 lines/mm at the center of the image (the 6mm even 120 lines/mm).
Check out the 'LM -4 thru 6- NCL' lenses on page 6 of the KOWA catalog/brochure.
Posted 25 March 2008 - 04:44 PM
Really appreciate it!
Posted 25 March 2008 - 05:09 PM
Re. the KOWA 3.5 and 4.5 mm wide angle lenses:
Upon closer inspection of the KOWA brochure, it seems that some of the lenses might not be useable on a Beaulieu Super 8 reflex camera. On for example the 'LM4NCL' 1.4/3,5mm lens, the rear lens element section protrudes too far back it seems, about 5mm or more beyond the C mount thread, which would perhaps be too narrow for the window of the guillotine mirror/shutter. One would have to try the lens physically on the 4008 ZMII camera body to be absolutely sure that the rear-most lens element doesn´t touch the edges of the window in front of the mirror.
I will try to measure up the exact distance in my cameras.
The threaded mount is called CS (not C) and is probably mainly intended for non-reflex cameras with a separate viewfinder or for cameras that allow for such a short distance. According to the HR f=2.4/3.5 mm lens specifications, the distance is 4.5 mm.
Some of the lenses might not be highly color-corrected (mainly intended for black & white use) or are specifially manufactured for 3 CCD cameras, with a beam-splitter that directs the light beams to three different image chips, each with slightly different back focus, depending on the image distance of each of the colors Red-Green-Blue.
Re. the 1/2" format:
I am no expert on this format but at a chip/frame size of 4.8x6.4mm, it is nearly 1mm higher and 1 mm wider that the Super 8 mm frame, which has a projected/masked image of 4.01x5.46 mm (according to SMPTE). The full frame of the camera is slightly larger, depending on camera type and gate. The 'Super-Duper 8' or 'MAX-8' 1.58:1 'widescreen' camera format is roughly 1mm wider than Super 8, perhaps slightly less.
Thus, an image circle of 8 mm is clearly sufficient to cover both the Super 8 and the wider 'MAX-8' gates.
Edited by Bengt Freden, 25 March 2008 - 05:10 PM.
Posted 25 March 2008 - 05:24 PM
As for the colors?I think they list lenses for 3 ccd cameras so I would expect they would not be good choices for us. Im not so much interested in the wide lenses, I like the idea of having a choice of lenses for a wide variety of work, the 16mm being what I would use as a standard lens. Im wanting to stick to the lenses that have the 120 lines. I also hope the small super8 image area will be wholly covered with 120 line resolution.
These units could just do the job. I wouldn?t assume that they are designed for black and white because there is a heap of colour machine vision cameras out there. I guess somebody will just have to test and see. I just wish I could get 150 or 200 lp/mm.