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16mm C-Mount Lens for Beaulieu R16


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#1 Jon Wells

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Posted 24 September 2014 - 10:36 PM

I have a Beaulieu R16 with a Angenieux 12-120.   I'm looking for recommendations for a 25mm prime lens that is sharp with good contrast.  Any advice would be appreciated.  Apparently, I'm supposed to stay away from Bolex RX lenses.  My budget is up to about $400.

 

There are various cine lenses on ebay, some of which are quite expensive for vintage stuff.  Has the Micro 4/3 craze for c-mount lenses driven prices up recently?

 

Also, can c-mount lenses that are designed for video (TV, CCTV, machine, etc.) be used with good results?   B&H has a plethora of new lenses on their site that are fairly inexpensive.


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#2 Dom Jaeger

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Posted 25 September 2014 - 12:27 AM

Yes the M4/3 craze has indeed pushed up prices, along with some of the S16-sized sensor digital cameras now available.

 

You should avoid the RX branded lenses because they were designed to optically compensate for the reflex Bolex prism, and at wide apertures they will introduce some spherical aberration if used on your Beaulieu, but those manufacturers also made non-RX lenses. Some of the better names in C-mount were Kern, Kinoptik, Taylor Hobson (Cooke), Angenieux, Schneider and Kodak Ektars. Older lenses will generally have less contrast than newer ones, and manufacturers often had different quality series, so it can be a minefield. Sometimes lesser known brands like Elgeet or Zeika produced excellent lenses.

 

Personally I think anything over a couple of hundred dollars is over-priced when it comes to C-mounts. Some of the most expensive (Hugo Meyer, Dallmeyer, Ross) are more collectors items than optical gems, and anything very fast (like the various versions of f/0.95 25mm) tend to fetch prices way beyond their real practical value. A lot of people are looking for lenses that have an unusual look, and get sucked into paying thousands for an old lens that looks like you shot through a coke bottle.

 

One of my favourites is this particular 25mm lens:

http://www.ebay.com/...=item3395d66c9b

 

A lot of Som Berthiots are rather low con, but that one is a very nice lens that may not fetch the same price as an Angenieux or Switar. 


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#3 Jon Wells

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Posted 25 September 2014 - 12:33 AM

Thanks for the reply.  Very much appreciated.

 

Do you know if the video c-mount lenses are advisable for film cameras, specially the ones currently being produced?  They are often referred to as CCTV, TV or machine.

 

Also, in perusing ebay, it seems that for any particular make of old c-mount lens, they made numerous iterations.  So you really don't know what you are getting.  Like you say, it is a bit of a minefield.


Edited by Jon Wells, 25 September 2014 - 12:37 AM.

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#4 Jon Wells

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Posted 25 September 2014 - 12:59 AM

You mentioned som berthiot.  There is a model called Lytar  that seems to be very nice in a test i saw on you tube.  Is lytar a more recent or older model of berthiot?


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#5 Simon Wyss

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Posted 25 September 2014 - 01:38 AM

C(iné) Mount lenses made for film movie cameras should not be used on video cameras and vice versa. The designers have left a little axial chromatic aberration that colour films perfectly fit to. The uppermost colour layer is the one sensitive for blue, the middle one(s) for green, and the layer farthest away from the aperture plate surface, by about a mil, for red. Most black-and-white films have one or two layers thick enough to collect all colours, exception Gigabitfilm. Video camera sensors have virtually no depth of capture, if I may say so.

 

Most C-mount lenses of an inch or 25mm focal length produce sharp and nice pictures at f/4 and higher. The differences come out at wider apertures from f/2 to f/0.9. It takes more glass and more genius to correct those designs, so you won’t find an apochromatic lens in good shape for under $ 400.

 

Let me give you a general advice. Don’t bother too much about what lens you have but take care of it. Once familiar with a particular lens you can begin to discover the characteristics of others. In other words, an experienced cinematographer makes beautiful images with a triplet because he knows how to stop it down and how the light should be on the object. Four-element lenses of the Tessar variant produce sharp pictures at f/4. At f/8 little difference is noticeable among most lenses.


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#6 Dom Jaeger

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Posted 25 September 2014 - 07:37 AM

C(iné) Mount lenses made for film movie cameras should not be used on video cameras and vice versa. The designers have left a little axial chromatic aberration that colour films perfectly fit to.

I'm not sure about that, primary axial CA (red and blue) is corrected out on all the lenses I examine, including professional 16 and 35mm ones, the typical chromatic aberration you'll find in even some modern lenses is secondary lateral, which manifests as purple fringing. Where have you read that film lenses had deliberate axial CA left in the design? Professional 35mm lenses like S4s or Ultra Primes were designed for film cameras but have transferred just fine across to digital cameras, as have many others. The main issues tend to be telecentricity, which isn't an issue with film but is preferred by digital sensors, and aberrations introduced by digital camera optical low pass filters (a bit like the Bolex prism problem), but I've never heard of "film" lenses having built-in axial CA.

@Jon: The problem with most CCTV or machine vision lenses is that they are designed for different applications than film-making. Older ones had far lower resolution specifications than 16 mm film, newer ones are computer-designed to give the best resolution/mtf score for least cost, which results in lenses like the Red Pro Primes (only on a far cheaper scale) which nobody actually likes the look of. Personally I'd avoid them, but some people seem to find them OK, they can certainly be cheap sometimes. Watch out for CS mounts that look like C mounts but have a shorter flange depth and so won't focus past a few meters, and others that don't have an iris.

Regarding the Berthiot Lytars, they were a budget line, with pretty average build quality in my experience. One of the biggest determiners of lens image quality is whether the elements are centred relative to each other and the lens mount, something called centration. With small lenses like C mounts it becomes even more important, and the higher quality lines tended to spend more time getting that right. Others will be more hit and miss. Poor servicing can also introduce decentration, and many C mounts have focus thread wear, which can cause image shift as the focus direction is changed.

The reality is that buying 50+ year old lenses that were primarily made for amateur cameras is a gamble, try one and sell it on if it doesn't please you.
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#7 Jon Wells

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Posted 25 September 2014 - 08:37 AM

Thanks all for the information.  Really appreciate it.


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#8 Simon Wyss

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Posted 25 September 2014 - 12:43 PM

Dom, I’d never say built-in longitudinal CA. It’s just that a rest amount can be left, that the whole lens doesn’t need to be perfectly corrected.

 

They simply knew about the third dimension of the film emulsion as capturing medium.

 

 

Those were the days of artistic softness  . . .


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