How about a camera with a built-in ground glass?

[Ignacio Rodriguez]

Ok, a lot of us have expressed the desire for a low cost video camera with a sensor the size of a 35mm photo frame, thus we could use standard photo lenses, which are far far better than anything you usually get on a semi-pro video camera. But it seems that large sensors are expensive. So this might not be the best of ideas. The first such product for stills has a list price of US$8k and does about 3 fps.

Then, there are others of us who are trying to rent or buy things like the Mini35 (a gadget that interfaces 35mm lenses to DV cameras). This is also very expensive, so much that many people are trying to make their own such adapters. It also complicates things considerably because of the way it works. Here is a diagram of such a setup:

|ccd|--|video lens|-- |filter thr.|-- |optics|--|GG|-- |bayonet|--|ph. lens|

Pretty complicated, and thus quite expensive, even if it doesn't include a prism to invert the image.

Now I think there might be a third option: instead of waiting forever for Canon, Sony, Pana, JVC. etc. to implement large sensors on cheap cameras, we can ask them for something different: make a camera with a 1/2'' or less sensor array, placed behind a simple lens assembly and a ground glass, the size of a 35mm photo frame. This gets past two problems: (1) makes for a less expensive sensor design, similar to the one already on most of our cams, and (2) eliminates redundant optics that come from using a Mini35-like contraption. Thus, we could have a camera that accepts standard photo lenses at prices similar to what we pay today for semi-pro cameras.

This would be the diagram for the optics at work on such a camera:

|ccd|--|simple lens|--|GG|-- |bayonet|--|photo/video lens|

Simpler, less expensive, compatible with a wide range of existing low cost photo lenses...

Sony and JVC/ Pana might not want to do it because it would cannibalize their pro market... but Canon could really get away with something like this... and since Canon sells expensive photo lenses it would complement their current product lines already... imagine Canon selling photo and video cameras and high quality lenses with full intercompatibility... makes sense, doesn't it?

Now if such a camera could do MPEG2 1920x1080@30fps on MiniDV tape... wow!

[Brett Erskine]

Your basically describing the relay lens arrangement that the P+S Technik has for its mini35 setup.

It sound like a good idea and I hope something like it happens in the future but here are some reasons why we possibly havent seen it yet:
1)35mm DOF is so shallow that it requires the experience of a professional operator. What do you think is the percentage of 35mm professional focus pullers in Canons pro-sumer video market? We independent filmakers are a relatively small piece of the pie already. Then you have to find the even smaller percentage who shoot on video and who know and care enough about DOF to buy something like this.

Dont get me wrong. Im definately one of them and this forum has proved that it would be popular in our circle. But certainly not cost effective as a one piece camera quite yet.

Canon in the mean time might be more interested in making a EXTRA attachment not unlike their EOS adapter but instead with all the optics you described inside. That would be a winner.

[James Ball]

I think you're onto something.

A guy who has thought along similar lines is over on the DV.com board.

http://www.dv.com/jive3/thread.jspa?...001061&start=0

IF people were to try to develop a camera the first thing I think that needs to be done is to start a new forum, then divide the forum into topics for each of the camera's components.

Optics, CCD to analog out, compression and capture, monitoring, etc.

The guy in the link above essentially did this. Then as the camera needs improvement a group could work to upgrade just one component of the camera.

The real key to this project would be to have 8 to 10 people with some $$$. because each section would cost about 1 to 2 thousand to develop using off the shelf components.

I've been looking into doing this using the HD chip by Rockwell, It's in the JVC HD cameras.

[Brett Erskine]

I like to think of myself as some what resourceful but I sometimes passionately invests too much of my time but this is a whole new level. To all that have the time, money and know how to really MAKE a new camera....I wish you the best of luck. I rather build apon what exists and replace only what is not working for me. I dont know about you but I dont feel like reinventing the wheel when all that was needed was a air freshner in the first place.

In this specific case, a XL1 mount to EOS lens adapter tube with the optics found in the mini35 inside. Good luck.

[James Ball]

Thanks for the wet blanket.

WE all need to be brought back to earth at times.

If you check out the link above though, I think you'll find a nice compromise. The guy bolted together several things that you could get off the shelf.

A box camera. Has the camera head: CCD prism and electronic. He then digitized the output with an off the shelf product and sent it to Hard Disk with an off the shelf Hard Disk Drive recorder.

If you wanted 4:2:2 you'd just use a couple of boxes from AJA.com

Not to hard if $$$ is no object.

[Anders Floe]

I really want to get started on actually experimenting with homebuild adaptors. But I have the XL1 and need a macro. Perhaps I haven't been paying enough attention in the thread - but what macrolens would you recommend considering distortions? The centuryoptics are quite expensive!

Also there must be a way to construct some small lens or use a lens from another device on the XL-1 instead of the normal ones! Considering the lenght and balance of the camera - it really needs a smaller relay lens. Does anybody have an idea of what to try out??

Thanks

[Adam Bowman]

Hi Anders,

The main two factors you need to consider when trying to find a suitable relay lens for use with the XL1 to a 35mm filmback or 35mm filmgate target size is backfocus and focal length required.

Because the distance from flange to CCD is more than 30mm, (from memory) it means you cannot use any of the CCD C/CS-mount lens which would otherwise be perfect for the job (short focal length and coverage perfect for the 1/3 CCD's.

This means you're realistically left with only maybe some lenses for 8/16mm cine film cameras (varying degrees of flange back distance, haven't really looked heavily into this area, seems quite specialist), very wide angle 35mm SLR camera lens (can be expensive and speed can be a problem) or constructing your own relay lens from surplus.

The longer the focal length of your lens the longer your converter system will be, so although technically you could use a regular fast 50mm SLR lens you'd be left with a system quite a few meters long I'd expect. :)

I think I calculated somewhere around 12mm focal length was optimum for a compact system, but taking into consideration a mirror/prism flipping system (which would extend the optical distance from the front relay lens element to the groundglass) you could increase the focal length somewhat more, I think anything less than 30mm should be fine.

I'd be interested to see what the focal length of the mini35 relay lens for the XL1 is! :)

I've my surplus lenses in with a machinist who's making up a prototyping platform for my lens design, I'll be interested to see what my resultant lens will perform like! Should be fun. :)

Hope I was of help.

Adam Bowman

[Brett Erskine]

There should be XL1 only sites out there and plently of stories on what lenses will fit on the standard mount. You should be looking for a macro thats slightly on the telephoto side. That way you might not need to use any screw on macro lenses. Also look at what everyone is doing for macro photography. For example you can reverse mount a 50mm lens from a 35mm camera and all of a sudden you have a +20 achromat diopter. IF you end up using a screw on macro lens Hoya makes +10 achromats for about $70. I wish I had more but Im focusing on adapting my DVX100 instead. Good luck.

[Anders Floe]

Thanks for the info guys - it was exactly what I needed to know!

[Adam Bowman]

The XL1 is a long camera from the outset, I'm not even considering using the stock lens with such adapter system, operationally it would be quite defeating.

Considering the interchangeable lens mount on the XL1 it is both perfect for an adapter and also very difficult to implement such a system, but if someone gets it right, it should be brilliant.

[James Ball]

thanks for everyone messing up Ignacio's thread.

please post by topic.

please try to learn to use the search utility first if you want a piece of information

[Mike Tesh]

<<<-- Originally posted by Brett Erskine :
Canon in the mean time might be more interested in making a EXTRA attachment not unlike their EOS adapter but instead with all the optics you described inside. That would be a winner. -->>>

A little over a year ago Chris Hurd was supposed to (I don't know if he did) submit an XL2 wishlist thread to Canon that we all made here.

One of my suggestions was exactly what you suggested here Brett.

http://www.dvinfo.net/conf/showthrea...l2+suggestions

See the second to last post on the first page posted by me.
Perhaps Canon caught onto it.

I don't think anyone else caught on at the time but lets just say I was thinking ahead. ;)