Canon XL-1 Relaylens (original, now merged w/ consolidated XL1 thread)

[Valeriu Campan]

I have posted in an an another thread this suggestion:
A macro lens, C mount for 16mm cameras. I think EdmundOptics have something in the relay lens section. The mount can be built in a camera body cap getting the right flange distance. A 16mm camera lens covers a bit more than 2/3" diagonal, so for the XL1 that has a 1/3 chip, will use only the central part - a very sweet spot.

[Stephen Birdsong]

There is such a vast amount of information out there on building some sort of home built mini35 system. I've read much of Agus and Aldu's posts, but they do not address the concerns for an xl1s. Im an owner of an xl1s with a 14x manual lense. I cannot focus on anything closer than 4 feet, and with anything but the widest setting, even farther. I understand the concept of the static ground glass setup, but I have no idea how I can acheive focus on the flange depth of a 35mm lens with my lense. Additionally, I've heard so many tings about fresnels, acromatic diopters etc... Are these all really necessary? What have other Xl1s users found? What sort of lense do I need to be able to focus with a longer focal length at less than 6 inches? its so hard to sift through all the posts out there on this topic, especially when much of the information does not apply to the xl1s. Would anyone be so kind as to give it to me in a condensed form? Im ready to put down the money for the materials to start expirementing, but Im not sure where to start.

Thanks,
Stephen

[Charles Papert]

Stephen, not that this is necessarily the info you are looking for, but the 14x manual does have a macro feature, enabling close focus down to the front element.

[Stephen Birdsong]

Im familar with the macro setting, but, it is at widest setting, and you will see the entire ground glass rather than the projected image full frame.

Perhaps with some sort of telephoto in front of the lens, with the macro setting on it would be possible. I wouldnt know where to start without simply expirementing with different lenses, which I dont exactly have the opportunity to do.

Stephen

[Charles Papert]

Gotcha. Thanks for the clarification.

[Valeriu Campan]

<<<-- Originally posted by Stephen Birdsong : I wouldnt know where to start without simply expirementing with different lenses, which I dont exactly have the opportunity to do.

Stephen -->>>

You can adapt a cMount adaptor in to the camera body cap and attach a small macro lens for 16mm.
or get an adaptor for a 35mm Nikon macro lens from:
http://www.lesbosher.co.uk/XL1.asp
or
http://www.zgc.com/zgc.nsf/active/200471117190AB9E85256B81000CB326.
You will get a lot of distortion and unpleasant focusing problems with various diopters and third party attachments.
Even an enlarging lens with a M39 thread will give a better result than the myriad of attachments suggested. Also the size of a rig of your XL1 with standard lens and adaptors will put a Panavision camera to shame.

[Stephen Birdsong]

Ok, I've started on my first prototype, and wanted to post on it.

I found that Hollywood Frost works great as a substitute for ground glass. If your not familiar with it, hollywood frost, also known as opal, is a gel used in production.

What I did was take a somewhat sturdy box resembling a shoebox (it held a iron at one point).
I cut it in half, and rigged it so that one end went into the other so I essentally had a box that I could shorten or lengthen.

I then measured my flange distance (im using an olympus OMG 50mm lense) and placed a large cut-out of hollywood frost at the flange depth.

When I pointed the box at an object, I got a very crisp image projected onto the hollywood frost.

Now, I took my camera, and inserted the lens into the other end of my box, and drew focus. Obviously, Im not going to have a full frame at this point, because Im required to use the macro setting which is equivilant to a 35mm focal length (i think).

So, my problems are this: Im getting a serious hot spot, with major vignetting, and I need to be able to fill the frame with the image.

Im not sure if I understand the difference between a close up filter and a tele.

I do know that I need to be able to focus at less than 3 inches (which I can already do), and I need to be able to zoom to something like 600mm.

Any ideas?

Stephen
Ill try to post pictures of what Im talking about soon.

[Anders Floe]

To: Valeriu Campan

I might have misunderstood your post but:

Are you suggesting that you could build a relay lens (like the one the mini35 uses) out of a lens-mount and a macro lens?

I'm danish and I'm having difficulties interpreting what exactly a camerabody cap is? Do you mean the plastic dustprotector you can put directly in front of the ccd chip - where you would normally mount the lens??

I think I'm getting more and more confused every day on how to get started on my adaptor!

Thanks

[Valeriu Campan]

To Anders,
Yes, I meant to get a spare llens cap and adapt a cMount. Start with palstic, get the flange distant and upgrade to metal later

[Anders Floe]

Ok - that sounds great! Do you know where or how I can get a hold of a c-mount adaptor for the XL-1?

About the macro - do you mean a complete 16mm macro lens or just a macro glass for 16 mm??

Thanks

[Valeriu Campan]

Anders,
I don't know of any Cmount > xl1 adapters. My suggestion was to make one from a spare camera body cap and a metal adaptor you will incorporate in it. You can find some info about the flange distance of various mounts here:
http://www.gregssandbox.com/gtech/filmfacts/flange.htm.
Also I suggest to get a macro lens for, let's say Bolex, a Kilffit Macro lens. It is better to use a lens that is designed to work at close range in flat field environement. You can even consider an enlarging lens with M39 thread, but I will incline for lenses made to cover a small format closer to the 1/3 sensor of the XL1.

[Stephen Birdsong]

So here is an update on my progress.

I bought some pvc pipe, and found that 2" fits my 35mm lense like a glove. 58mm thread size will fit inside the pipe, and I used 2 uv filters to sandwich a piece of 216 (a different kind of diffusion, which seems to work a little better than hollywood frost)

So, I have a decent image in my ground glass, still a little vignetting happening, hopefully using real gg will solve that problem.

As far as the relay lens goes, this is what I've discovered:
even with +7 close up lens in any setup, whether wide, or tele, it is not enough to fill the frame. Having that much glass between the still lens, and my ccd is just stupid. So, I scratched the idea of trying to find something to put inbetween my lens and the gg.

And I tried something new. if you grab a still lense, and remove your lens from your camera, holding the still lens in front of the cdd, you can actually get a clear image. Problem is, its magnified so much, that its useless. I used a 50mm macro lens to no avail. I was able to get a full frame, but it was so telephoto it was worthless.

So, I grabbed a 16mm motion picture lens. This yeilded much better results. Still somewhat telephoto, but not nearly as much as 35mm.

So, my problem is, I need to figure out what 16mm lens I need. im not sure if I need a macro, because the lens I used seemed to already be functioning like a macro.

Any suggestions?
Anyone know where I can find any 16mm motion picture lenses?

Stephen

[Valeriu Campan]

<<<-- Originally posted by Stephen Birdsong : Anyone know where I can find any 16mm motion picture lenses?

Stephen -->>>

Have a look on eBay. There are plenty. Also, EdmundOptics have a selection of close range lenses for 2/3 cameras.

[Anders Floe]

Would an 8mm Bolex macro lens do? Or is it too small??

[Valeriu Campan]

I don't know the size of the 8mm frame. If it is larger than 1/3 XL1 canon sensor, should be fine.