Video Assist recommendations?

Michael Mann · June 5, 2009

Hi,

I've been scouring the web looking for practical advice on how to setup Video Assist on a Konvas 1M. The info is thin on the ground: I know people do it, but they tend to sell it as a service afterwards, resulting in not too much practical detail...

I would like to do it myself, and am wondering if I can do it with off-the-shelf parts?

I would also like to post my results here as I go, so that we can document the steps necassary to get this going.

For the record I now have 2 Konvas cameras: a 1m and a 7m. I want to fit the 1m as a portacam, hence the need for assist.

Practical requirements:

I'm sticking with the "mount-to-eyepiece" method, as this is easiest to wangle: however we lose the eyepiece, so ideally we need a very accurate and high light sensitive (low lux)camera.

Specifically I would like some advice on the recommended CCD camera types, and lenses, as well as best practise for mounting to the eyepiece, from anyone who has tried it.

I've seen Sony and Pulnix cameras with lux ratings from 0.5 - 0.1 being used elsewhere.

What are your experiences?

Also: I've been told that this method is not good enough for fine focus, due to the low resolution and light density. Again: what are your experiences?

Why can't a Konvas get a high quality video assist? Has anyone built a video assist that they felt was good enough to replace the eyepiece altogether?

Step one: choosing a CCD:

So far the best bet for low-lux seems to be some "enhanced" sony cameras on ebay:

Simply put: If I choose the following camera:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...em=350199204524

.. we seem to be on a good path (supposed 0.0001 lux) for a monochrome CCD camera. Any thoughts?

For those that have already done it: what type of lens would you recommend to best fit the standard eyepiece. The crew that sell the above camera offer any lens down to 1.2mm to go with it.

Also: At what point along the eyepiece would you mount the camera?

Is there a better camera alternative (This one supposedly does 0.0001 Lux - which would be more than adequate for low light I believe, but needs to be taken with a pinch of salt).

Lastly: Would you trust such a solution for fine focusing?

Thanks for any help you can give.

Mike.

James Steven Beverly · June 6, 2009

Raf at rafcamera.com makes one "on demand" which fits into the hole where the viewfinder mounts. It costs something 273 bucks plus shipping and is a simple install and from the ads, looks like it works very well. The 1m requires an extra little clamp to use it in an orientable viewfinder type setup.

http://rafcamera.com/video-assist-for-konvas-p-55.html

Edited June 6, 2009 by James Steven Beverly

Bruce Taylor · June 7, 2009

Lastly: Would you trust such a solution for fine focusing?

I don't think you're going to find a tap you can rely on to focus with. Mostly I see taps used as a framing reference. Calibrate your lenses and focus with a tape measure, that should work. I had Steve Morton build a beam splitter type tap with the Pulnix camera. It allows the continued use of the optical viewfinder. The video image is framing reference only. I think Bruce a Aranda Film offers a beam splitter tap conversion too. Raf's unit I have heard works, as it goes in place of the optical viewfinder it is compact. It is also a framing reference, not for critical focus.

Good luck,

Bruce Taylor

www.indi35.com

Rafael Pankratau · June 9, 2009

I have heard that Kinor-35 factory made video assists were thrown to trash right out of the box since they were unusable too.

On the other hand, if you have a big monitor, focusing quality with video assist may be comparable to focusing with a viewfinder (all that our video assit do is just translates image from the camera groung glass), but I feel that viewfinder (that isn't split screen and gives you no any hint on focus) don't allow to focus perfectly, especially in low light.

So, most practical advice is from Bruce - have the lenses collimated, and use a measuring tape.