Jump to content
videofilm

Power zoom pro video lenses on Sony Alpha

Recommended Posts

I found a lens mount adaptor that allows me to mount my Pro Broadcast Video Power Zoom Lenses on my Sony A7II Camera. I realize there is a problem with this adaptation as even in sensor crop mode these lenses cannot cover the camera's sensor. As a pro Video Person, I would love to have a Sony A7 tupe camera with a 2/3 inch sensor appropriate to my video lenses. Anyone who watches pro sports on TV has been watching the quality of imagery that can be captured with these small sensors that can Zoom from an image of a whole stadium to a close-up of the expression on the quarterback's face. This would make a great wildlife videographer's kit. There is no need for a giant video camera anymore to achieve great closeup imagery.  All you need is a Sony Alpha 7 series camera with a 2/3 inch sensor and a small battery box to power the Zoom lens and maybe even enable the auto aperture capability of the lens. There is another way to achieve this desired result. With the increasing density of sensor chips I can visualize a Sony with greater than APS crop factor and clear image zoom that could get the job done

Share this post


Link to post
Share on other sites

Sounds interesting. 8-). It also sounds like the adaptor you're using doesn't provide the necessary distance to the sensor, i.e. is too short. If that's the case. it might be worthwhile experimenting with some extension tubes, like one of those.

Could you please post a closeup of the naked adaptor only, plus one resulting image as shot with your setup?

Share this post


Link to post
Share on other sites

Distance to sensor is not a problem. Goes together perfectly. B4 lenses (The broadcast standard mount were designed for using three sensors for red, blue, and green colors mounted behind a set of prisms that separated the light into three beams filtered for the primary colors. The imagers were originally electron tubes wirh phosphors that were scanned by electron beams. These were either plumbicon or saticon tubes. The cameras were quite large and power hungry to power the high voltage electronics. The tubes were later replaced by CCD imagers. Due to the prisms, the imager is set pretty far back from the mount allowing adaptation to some mirrorless Still Camera lenses. Sensor technology has evolved such that prism separation for colors is no longer necessary and sensors can achieve HD video on tiny chips as evidenced by GoPro Cameras

Edited by videofilm
adjust image size

Share this post


Link to post
Share on other sites

Thanks for your detailed answer, which - frankly - leaves me more puzzled than before.

I see quite a "gap" between your sample image, which apparently covers only a fraction of the sensor, with heavy falloff towards the outside and less than perfect sharpness on the one hand, and the superb 4K image quality that you seem to be aiming at on the other hand. How are you planning to close that gap?

On an unrelated note: the adaptor seems to still have traces from some kind of machining on its inner surface, which would eventually taint the sensor of your camera, if not removed.

Share this post


Link to post
Share on other sites

The image  circle of a pro broadcast lens (even those monster lenses you see at football games is only 2/3 of an inch (17mm). That is all the sensor real estate that is needed for very clear ultra high definition video. I shoot HD video with cameras like that almost every week and it goes on giant screen Monitors in the hockey arena as well as out to cable TV.  The slightly speckled surface you see in the adapter picture is just the surface that the lens mount is locked to by a clamping ring. The inside of the mount is flat black. The upside of a small sensor size is that you can get tremendous magnification from a manageable size lens. 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
×
  • Create New...