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cheap new c mount lenses


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#1 kevin jackman

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Posted 25 March 2008 - 01:15 AM

for those of you that didnt notice the posting in the 16mm forum i say have a look at this. new optical designs that i suspect are multicoated and cheap. as written by another...

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!!)
12.5mm f1.4
16mm f1.4
25mm f1.4
35mm f1.4
50mm f1.4
75mm f1.8

http://www.rmassa.com/manu/kowa.htm

http://www.rmassa.co...atalog_2007.pdf
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#2 Tony Terziev

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Posted 25 March 2008 - 04:38 AM

I have absolutely no idea about how lenses work (vinjetting e.t.c)
so my main question is: will they work with the Beaulieu 4008-series?
More specified: the Beaulieu 4008 ZM II?

Thanks in advance!

/Tony
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#3 kevin jackman

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Posted 25 March 2008 - 11:47 AM

they all should so yes at least the 1 inch ones. check the diameter of the 8mm image area and then look at the diameter of the image circle for each independant lens. that will tell you what they can do. but remember the centre of some of these lenses is 120 lp/mm
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#4 Bengt Freden

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Posted 25 March 2008 - 03:09 PM

[quote name='kevin jackman' date='Mar 25 2008, 07:15 AM' post='224018']
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.

Tony,

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.

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#5 Bengt Freden

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Posted 25 March 2008 - 03:32 PM

Kevin,

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.

Bengt
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#6 Tony Terziev

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Posted 25 March 2008 - 04:44 PM

Thank you for all the help Bengt!
Really appreciate it!
Best regards!

/Tony
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#7 Bengt Freden

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Posted 25 March 2008 - 05:09 PM

Hi again, Kevin and Tony,


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.

Best,
Bengt

Edited by Bengt Freden, 25 March 2008 - 05:10 PM.

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#8 kevin jackman

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Posted 25 March 2008 - 05:24 PM

Since im at work I cant go through the details on the brochure in detail but from what I recall there were no backfocus numbers that were 17.52mm. maybe I just missed it.

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.
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