telephoto options for Bolex Rx5

Jeremy Rumas · September 22, 2006

Hi all,

I am looking to get a telephoto or zoom lens I can use with my C mount Bolex Rx5 for use in filming surfing. I want a lens that's around 600mm, or the equivalent of a 1200mm 35mm lens. What are my options? Are there any C mount 16mm lenses fitting this description? Should I use a 35mm still lens with a mount adapter? Are there 2x extenders for 16mm C mount lenses?

thanks,

Jeremy Rumas

Mike Rizos · September 23, 2006

Probably the most economical choice for long focal lenghts are the Tele-Athenars from Century. Most of the time they are found in c mount, although almost all of them will cover 35mm still. The 385mm f4.5 is common and cheap. They come in many focal lenghts like 300,400,500,600,650mm, etc. all the way to 2500mm f16. The downside is they were made to order, so there is not too many of them around, so they are hard to find.

Long lenses for cine were also made in limited quantities, by Mayer, Kilfit, and Astro-Berlin.

I think using a still lens is a good alternative. I would avoid off-brand names, and definetly stay away from the generic 500/8 lens.

As far as extenders I'v seen 1.5x and 2x for c mount. Generally, extenders give acceptable results if they are used with the lens they were intented for. I wouldn't use them.

September 23, 2006

i would use a 35mm lens and adaptor as you mentioned. the quality and choice is there and its a no hassle way to do things. you also get the sweet spot.

September 23, 2006

I've used a Nikon F to C-mount adapter and 100-300mm f/5.6 Zoom-Nikkor on a Bolex H8 RX camera with very good results, although only in static applications. At these magnifications, I'm not sure if my fluid head tripod would allow me to produce steady images, especially if I had to pull focus while panning & tilting.

Bernhard Zitz · September 23, 2006

for use in filming surfing.

Slr lens with c-mount adpater should be ok, since your filming in bright daylight you can it stop down to decent sharpness. I shot some footage wide open with a crappy 80-200mm Slr-Zoom plus 2x extender with c-mount adapter on Bolex. It had little chromatic aberations and was a little soft, but still ok for Video (SD).

For C-mount extenders watch out that they fit your camera. I have a c-mount 2x extender (for videocameras), but it doesn't fit on a bolex, it reaches to deep in the camera and would touch the prisme...

Anyway; I would get a real tele.

On a tight budget I would get something like a 400mm or 500mm M42 and a c-mount adapter... If I could affort, a nikkor or canon...

Bernhard Zitz · September 23, 2006

for use in filming surfing.

again me...

Basicly I don't like zoom-lenses, but to film surfers, I found it usefull to have a zoom. It can be really hard to find that surfer, paning arround with a 500mm. Waiting on the wide-end of the lens to have an overview till a surfer is paddling in to a wave, then zoom in all the way to get him closer. It depends the break, on a clean reef you would point always the same spot for the take off, but on a crowded beach-break you'll be happy to have an overview and zoom in when something happens.

hang loose, Bernhard

Jeremy Rumas · September 23, 2006

Thanks for all the input everyone.

I am thinking that a lens designed for 16mm would be best, and would probably be smaller/lighter to travel with, plus easier to use due to size. I also should mention I have a goal of transfering to 35mm via an optical print, so sharpness is definitely a factor.

I have never used an extender before...will these soften the image noticeably?

About the Tele-Athenars or lenses by Mayer, Kilfit, and Astro-Berlin, were these made for 16mm? And any ideas where I can find one?

If I go with a C mount adapter plus 35mm lens, I would likely opt for a Canon FD lens, as this is what I shoot with for stills. But looking at say a Canon FD 600mm lens, that thing is like a telescope and I wonder if it even be possible to support that lens on a Bolex with a C mount adapter.

Bernhard, you bring up a good point about filming surfing, yes, a zoom makes it a lot easier. I had been shooting with a Canon XL2 with the 20x zoom lens, and I shot as you described. It is very difficult to shoot surfing if you can't zoom out between rides. So ideally, a zoom lens set up capable of magnification equivalent to about 1200mm in 35mm would be perfect. I have just been unsure if I can get a lens set up like this for my Bolex.

any other thoughts?

thanks

Jeremy

Mike Rizos · September 24, 2006

Thanks for all the input everyone.

About the Tele-Athenars or lenses by Mayer, Kilfit, and Astro-Berlin, were these made for 16mm? And any ideas where I can find one?

If I go with a C mount adapter plus 35mm lens, I would likely opt for a Canon FD lens, as this is what I shoot with for stills. But looking at say a Canon FD 600mm lens, that thing is like a telescope and I wonder if it even be possible to support that lens on a Bolex with a C mount adapter.

Jeremy

The Century lenses can be found at camera supply houses like Whitehouse, which has a couple right now. The others are more rare, being specialty items to begin with, and popular with collectors, they tend to be pricey. If you got patience, they show up on ebay from time to time, and a good deal can be found.

All the above telephotos except a couple Century lenses were NOT designed for 16mm only, but rather for 35mm academy, or 35mm still, or 6x6. You ordered the lens with the mount you wanted, and the manufacturer could cover all these formats with one design. Some common mounts are Arriflex, Exacta, M42. I think all can be adapted to c mount.

Check out this brochure from Astro-Berlin.

http://www.exaklaus.de/astrobj.jpg

Yes, it's mandatory to have a lens support(cradle).

Jeremy Rumas · September 24, 2006

http://www.exaklaus.de/astrobj.jpg

That's not a lens, that's an anti-aircraft cannon!!! Wow, I have never seen anything like that. Don't think that'll fit in my backpack. Someone has to use that image for a band poster.

Thanks for the info on where to find the lenses, along with explaining what they were made for. Much appreciated. I will definitely have to look into this option.

Jeremy

Bernhard Zitz · September 26, 2006

I have never used an extender before...will these soften the image noticeably?

I think if you get a good one it will be ok, the one I used was even worse than the zoomlens I used, so I can't tell. And mine eats around a stop or more...