Am I crazy enough to try making my own lens mount from scratch? Yes. I've really just started, but I couldn't help posting.

After taking careful measurements from my L-series lens with a caliper and ruler, I started lathing... 5 or 6 more hours of work and I should be ready to mill away what I have to, and hopefully it will fit.

I hadn't originally planned on trying to make this, but I really don't want to spend the money on an L-series adapter I could use for the mini35 I'm working on (which uses relay lenses and will attach directly to my Xl2). At first I wasn't even going to attempt it because I figured I'd have to use stainless steel, and I wasn't about to try working with that stuff, but I'll be using rail support with this anyway, so the mount wont be for support as much as making a tight seal. If this doesn't work, I'm just going to omit the lens mount and have the mini35 sit up against the camera with a rubber o-ring to keep it light tight. In fact, I'd decided I might use that anyway, but now that I started this little sub-project, I want to see if I can do it.

Ok, some pics...

Objective:

To turn something like this
http://www.nysegwaypolo.com/images/p1010001b.jpg

Into this
http://www.nysegwaypolo.com/images/p1010003b.jpg

We have a cylinder!
http://www.nysegwaypolo.com/images/p1010006.jpg

And this is as far as I've gotten. It's difficult to see, but the detail of the outer edge is starting to take shape. I'd have had more done today, but the bit I was using broke (it was very thin -- 5/64"... I'll have to make another before I can go on).
http://www.nysegwaypolo.com/images/p1010013.jpg


Ok, comments welcome. I'll post more pics when it's approaching finished.

Looks fine from what I see.

If you dont want to bothered with drilling centre holes to turn out from, Bohler-Udderholm in Australia do a Flocast hollow bronze stock in various sizes of inner and outer diameters which saves a lot of work. It machines nicely too. It may be a bit brittle but I've had no issues with it so far. I imagine the same product exists where you are, probably anyone who does propellor shaft bushes for older timber hulled fishing boats would know where to get it if Bohler-Udderholm have not ventured into the US.

There is something I want to warn you before it's too late. Make sure the pins on the XL camera don't touch the metal part or you will end up have a dead XL body like I do :).

Quyen

So am I understanding you right and you're making your own relay lens for you adapter to run in between the lens adapter and the camera body? I have two XL1s camera and would definitly be interested if so.

Also just to let you know. I checked into something similar a year or so ago and if it doesn't work out you can order that part off the lens from canon for less than $100 bucks. I called last year. I don't remember the price, but i don't think it was more than $100. I wish I still had the product number, but I have no clue where it went off too.

Thanks for the comments...

Bob, I'd realy only considered either aluminium or stainless when thinking about this, and subsequently found that hollow aluminum stock is expensive, so thanks for the suggestion, but I'd just decided to make the center hole only as large as absolutely needed to make it a little easier task (I'm guessing around 3/4"). So at this point, if it doesn't work out I'll probably wind up not using a mount, but it's definately something to keep in mind if this does work and if I wind up making more (I'll be making at least one more).

Quyen, thank you! I hadn't thought of that -- in fact, like I said above, my center hole was going to be quite small, and the metal surely would have touched the contacts... I'm not sure I would have caught that while attaching the mount. I'll just lathe out as much as I need of that side of the center hole.

So am I correct in understanding you've done something like this, than? Did it work out, if you don't mind my asking?

Keith, yep... it's a relay lens direct from the GG to the XL cam. Though I wasn't planning on making them to sell or anything like that... I really don't have the time, unless I were to have the parts CNC milled and I don't want to get that far into it. I am planning on publishing a "how-to" with pics and technical drawings on my website for the mini35, if anyone wants to use them. There are a couple things about this adapter (besides the relay lens) that are pretty unique, and I don't want to post anything in that respect until I know I have everything working right, which probably wont be for at least another month. As for the XL mount, I have to admit, getting one direct from Canon hadn't occured to me, but even if it's, say, between $50-100, that would be more than I want to spend -- I've already gone way over budget on this, but it'll be worth it. I should also note that a rail support will be a must with this, as it's a bit of a monster, hence my nonchalance with the inclusion of the lens mount at all.

<<it's a relay lens direct from the GG to the XL cam.>>

Maybe I am not reading this correctly, but you say you are making a relay lens... ? This means you'll stick optics into your lens mount?

Because if you have no optics it's simply a lens mount and I don't see how the XL-2 can film the GG without a lens mounted to the camera body. The 35mm lens in front of the GG won't do, as it will be producing an image on the GG, not on the CCD's.

I should have been more clear -- it should be "...there is a relay lens..." instead of "...it's a relay lens...".

The lens mount itself doesn't have any optics, but the mini35 I'm working on that the lens mount will attach to indeed has two relay lens' between the GG and mount. The first one is embedded in the flipping mirrors (to save space), and the second (for fine focus, which should only have to be adjusted once, or at least rarely) is located right before the XL-mount, after the mirror array.

Don't worry, I think I know what I'm doing ;)

It's almost finished, I hope my measurements were accurate enough...

This is a progression starting right after I left off with the other pics.

http://www.nysegwaypolo.com/images/mini35/p1010020.jpg

http://www.nysegwaypolo.com/images/mini35/p1010041.jpg

http://www.nysegwaypolo.com/images/mini35/p1010050.jpg

http://www.nysegwaypolo.com/images/mini35/p1010054.jpg

http://www.nysegwaypolo.com/images/mini35/p1010060.jpg

A little difficult to see, but the two pieces appear to have the same dimensions. The outer edge (that would be facing the camera) is sticks out slightly more on the XL mount than on my replication, as you can probably see, but it appears that that edge doesn't even have to be there... all the "action" happens between the three protrusions and the back of the mount (sorry for the pun).
http://www.nysegwaypolo.com/images/mini35/p1010068.jpg


I just have to cut out those three sections, do a couple other little things, and hopefully it will fit. I don't know when it'll be done... I don't even know how I'll cut those pieces out yet, though I'm considering a dremel.

Looking good so far. Wish I could do machining like that. Keep me up to date on this one. I got two XL1s and would love to be able to not use the stock lens between the adapter and the camera.

Mind me asking what you're gonna use for the actual relay lens?

Ok, I thought I should give a little courtesy update...

After I'd removed the three sections of the piece, it didn't fit. I wound up using a dremel to get it into the right shape (and did a less than perfect job), and when I tried to put it on the camera, it would only seat half way in. The problem was my original measurements, I had made the piece slightly too wide in the area after the "three protrusions".

I'm going to get it back in the lathe eventually to see if I can't get it to fit, but I've really just gone ahead with the rest of the project since than. If I can't get the XL-mount to work I'm just going to use a thin hard-rubber O-ring to seat the adapter against the camera, sliding it in snug with the rail support I'm working on now.

UPDATE! I got it to work!

After thinking of a good way to mill away the excess material that couldn't be lathed without using a dremel, and after triming the various parts, I now have a completely made-from-scratch XL lens mount that works! I have one other very minor thing to do, but it fits.

http://www.nysegwaypolo.com/images/mini35/xlmount.jpg

http://www.nysegwaypolo.com/images/mini35/p1010008.jpg

Ha, now I'm not even sure I'm going to use it, but at least I have one for almost free (made from scap metal!)

Does the Canon EF mount have any electronics in it at all?

http://www.broadcaststore.com/images/model/large/651218.jpg

It looks like it only has a locking mechanism. Does this mean you cannot use autofocus with the EF lenses this piece lets you mount?

I messed with an EF adapter from a friend's XL last summer and unless I'm mistaken none of the electronic fuctions work through the EF adapter. You have to make all adjustments manually.

one question: does anybody know the part number of the original canon XL mount? only the male bayonet part...

the people at slovenia's only canon service said they can supply it, but i'd have to go there and SHOW them what exactly i mean :D
since they are a great deal away i don't want to make a pointless journey to Ljubljana if i can tell them the part number over the phone.

if the bayonet is expensive, i'll lathe one myself like justin

Does the Canon EF mount have any electronics in it at all?

http://www.broadcaststore.com/images/model/large/651218.jpg

It looks like it only has a locking mechanism. Does this mean you cannot use autofocus with the EF lenses this piece lets you mount?

yes, it has. there are terminals that connect the lens to a power source, terminals for autofocus, iris motor controls...
as far as i've worked with the one you posted, it decodes the iris commands from the camera body to allow you iris control. it also has it's own power supply, if i'm not mistaking - a battery