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POW Winner 23rd January 2011 Congratulations to Aggelos! Click to read reveal the full images.
When I received my 314L+ and Atik filter wheel a soon realised i was going to need a nice quality short tube frac to use for wide field, I had up until the ATIK arrived always used my favourite lens the Sigma 100-300mm F4 EX DG APO HSM ( that really is its name), this lens has seen of all the competition in the EF range of L lenses,[link widoczny dla zalogowanych], its simply superb,[link widoczny dla zalogowanych]!
The problem with Canon lenses is the registration distance between the rear mount and the film/cmos face. The lens registration is 44mm .
The first hurdle is the EF mount, Geoptik make a mount but you simply directly mount a ccd straight to the lens, no filter wheel
So here is my home brew adapter,[link widoczny dla zalogowanych], its cloudy so I miht as well give it a shot..
Materials..
1 x old EF macro extension tube
1 x 3” square piece of 2mm alloy sheet
1 x 1.25 nose piece.
Figure below shows the shortened EF macro tube, I took this down to the rear of the face plate. You can see the cut piece of ally sheet with the nose piece epoxy glued on.
Note the cut out, this was to allow the lens contacts to clear the ally sheet, I need to get the adapter as thin as possible in order to achieve infinity focus with the wheel attached
This is the top side, you can see how simple it looks
This image shows the rear of the lens, I have unscrewed and remove the internal baffle, as the nose piece has been measured and comes to within 3 mm of the re4ar element the shroud is not needed ( I’ve put it aside in a safe place)
This image shows a test fit, everything fits and nothing is fowling..
Here is the 2 main parts epoxy glued together.. I’ll allow 24hrs before testing it
This is lens side showing the shorten nose piece, its now hand dried so ive put it to one side to harden..
Part 2 next: attaching it all together
Hope you enjoyed this
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[link widoczny dla zalogowanych]

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[link widoczny dla zalogowanych]