Canon EOS 6D 35mm and CanonEOS Rebel T7i parfocal?

Discussion in 'My Astrophotos' started by ROBERT T SCHAEFER JR, Aug 24, 2018.


    ROBERT T SCHAEFER JR Cyanogen Customer

    May 13, 2018
    I had to have a green Monster drink after last night which is today ... Last night the Moon was out but I wanted to try the TeleVue 2XPowerMate with
    step-rings added to it to use a 35mm T-Ring into a 4XPowerMate ... and then hook my Canon EOS 6D DSLR and see if I could "PinPoint Astrometry"
    'solve' a star field . I tried M13 but it wouldn't 'solve' but I images it anyway .... then I took the 6D off and put on the Canon EOS Rebel T7i and
    to my surprise!!!! it was parfocal with the EOS 6D ... or pretty close . Eventually I found a star field in M57 and M27 and both DSLRs
    'solved' at 9360mm F/L to surprise!!! ... . The 6D should have 'solved' at the 152mm A+M Refractor Telescope of 1200mm F/L times
    6X for the PowerMate combination to be 7200mm F/L but they must be seeing differently . So now I believe the power of magnification is 188xpwr .
    I 'stacked' 24-Autosaves of the Rebel T7i in SigmaClip in MaximDL Pro V6.16 and 8-Autosaves of the Canon 6D the same way and they are two separate
    images as jpgs .
    At a 12.5% view .. the Rebel image was larger than the 6D image with both in the 'buffer' of MaximDL Pro / Next I did a "Resize" from 3.72 size pixels
    to 5.75 micron pixels to make the M13 look the same size as the EOS 6D M13 ...which is real close .
    The jpgs of the Rebel are larger in the Photos view and the EOS 6D must be expanded a few time to look the same size in Photos .
    The first image is the Canon 6D , the second is the 5.75 resize , and the third is the original Rebel image and all of them are at Bin1 size .x
  2. Colin Haig

    Colin Haig Staff Member

    Oct 27, 2014
    Why are you surprised? All Canon EOS cameras can use EF lens, and have the same 44mm back focus distance. It has to be the same for you to be able to use EF lenses on both.
    Your plate solving problem could be caused by several issues - did you change the pixel size /configuration? Plus you may find it works better if you bin 2x2 to avoid the bayer matrix.

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