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Thread: A7r, Actus and Canon 'dumb' mount

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    A7r, Actus and Canon 'dumb' mount

    Recently got to try the Actus and a 'dumb' mount for the EF lenses thanks to Charles at Cambo UK.
    It's of interest to me for the rear stitching as I do a lot of stitched interior shots with the 24mm TS-E currently, but often having to fix errors.

    While I was at it, thought I'd see what would happen if I put together a 4 shot stitch, but with rise applied on the lens.
    Now I didn't make notes, to busy gabbing, so not 100% exactly how much rise I put on, also the body Charles brought was a pre-production version with no rise/fall markings or indents, so had to guess that on the rear.

    But from memory it was something like
    10mm rise on the lens
    8-10mm rise & fall on the rear
    10mm shift left & right (positive on that one)

    Click image for larger version. 

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    Anyone got any thoughts on why the bottom right is so heavily cut off?? I expected the bottom corners to be darker than the top from the shifted circle but not so unevenly. Was using the short bellows so shouldn't be those, unless it kinked a bit to much on that movement and I didn't notice. Has anyone else seen this with the 24mm on other platforms (MF!? Arca??)?

    It's not a deal breaker as it's beyond the amount of shift I'm likely to need for most of my work, just curious why it might be so uneven.

    Unfortunately going to have to wait till the new year to pick up an Actus after spending the last of my gear budget on something else
    Last edited by craigosh; 2nd November 2015 at 13:23.

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    Re: A7r, Actus and Canon 'dumb' mount

    A couple of things come to mind. First it looks like the Canon 24 TSE does not have enough coverage thus all four corners are out of the image area. Two possible explanations. First, bring the front and back standards closer to one another. This will bring the chip closer to the lens and increase the image area available. Second, figure out where the lens manually focuses providing the largest image area. Actually flip one and two. If you figure out the manual focus point that gives the largest image area, you can adjust the front and back standard for focus and maybe this will be enough.

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    Re: A7r, Actus and Canon 'dumb' mount

    i have shifted the TSE 24 to the max on the A7 with no vignetting; looks like your lens shift plus the cambo shift is too much

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    Re: A7r, Actus and Canon 'dumb' mount

    Oh yeah knew I would hit the edges of the image circle. Just a bit unsure as to why the lower right is so much more clipped.

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    Re: A7r, Actus and Canon 'dumb' mount

    Quote Originally Posted by craigosh View Post
    Oh yeah knew I would hit the edges of the image circle. Just a bit unsure as to why the lower right is so much more clipped.
    Given that the lower right vignette is so asymmetrical I would have to guess that a bit of the bellows or possibly even the camera body cavity is getting in the way. I have a custom dumb mount for my Arca. I'll look at my 24 tomorrow to see how it vignettes on the A7r2.

    -CB
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    Re: A7r, Actus and Canon 'dumb' mount

    You get a chance to try it Chris?

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