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Thread: Afocal and AFOV

  1. #1
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    Default Afocal and AFOV



    My set of Orion Q70ís showed up last night, these are my first 2 inch EPís.
    I was hoping to take them out tonight and see how imaging through the 32mm Q70 compares to imaging through the 32mm Tele Vue Plossl, but the chances of that happening tonight or any time soon isnít looking good. As soon as I unpacked the new EPís I did a test on how the EP image is going to look in the camera, the results are attached. Not only does the EP image fill more of the camera frame but it should also show about 0.5 degrees more true FOV.
    Increasing the magnification of my camera doesnít get the EP image to fill the camera frame, instead it increases the magnification of what is shown in the EP, so increasing the AFOV is the only way to fill the camera frame.
    Canít wait to field test the new EPís with some afocal shots. It sure would be nice if my 2 inch dew heaters would show up before I get a chance to test the new EPís, the 1.25 inch dew heater may not be able to handle the mass.
    Attached Images Attached Images
    Name - Verne / Call sign - KF7UHL
    Scopes - Orion Atlas 10 EQ-G GoTo / Orion 130ST on an AstroView Mount with RA Drive
    EPs - Orion Plossl (10mm, 25mm, 32mm, 40mm), Tele Vue Plossl (32mm), Orion Stratus (5mm), 12.5mm Orion Illuminated, 7-21mm Orion Explorer II, set of Orion Q70's
    Camera Adapters - SteadyPix Deluxe, Orion Universal, Digi-Kit DK118, T-ring, 2 inch EOS
    Camera - Canon 5D Mk II, Canon T6i, Panasonic FZ35, Celestron NexImage


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    Default

    What are you shooting, square grid paper? That looks like a huge amount of pincushioning on both EPs.
    Zhumell Z10,
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    114EQ, 10x50 and 15x70 Binoculars
    Zhumell 2" UHC Filter
    Hyperion 8mm GSO Superview 30mm and a whole case full of Plossls

    Saskatoon, SK - 106W, 52N

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  3. #3
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    Default

    The EP's aren't in the scope. They're in a fixture that I made up for putting together my afocal setup. They're pointing at my laptop screen which is displaying a grid pattern. I was using just a white screen for the setup but adding a pattern showed when the camera was tilted in relation to the EP. I still end up doing fine adjustments when the afocal setup is mounted on the scope.
    Last edited by pederv; 01-26-2011 at 03:19 PM.
    Name - Verne / Call sign - KF7UHL
    Scopes - Orion Atlas 10 EQ-G GoTo / Orion 130ST on an AstroView Mount with RA Drive
    EPs - Orion Plossl (10mm, 25mm, 32mm, 40mm), Tele Vue Plossl (32mm), Orion Stratus (5mm), 12.5mm Orion Illuminated, 7-21mm Orion Explorer II, set of Orion Q70's
    Camera Adapters - SteadyPix Deluxe, Orion Universal, Digi-Kit DK118, T-ring, 2 inch EOS
    Camera - Canon 5D Mk II, Canon T6i, Panasonic FZ35, Celestron NexImage


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  4. #4
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    Default

    Finally!
    It took 31 days but we got a mostly clear night.
    Had a chance to do some experiments and to look through the 32mm Q70. The added FOV of the Q70 works well with M45. I made a Bahtinov mask out of cardboard and tested it out through the 32mm EP, it worked. I set the scope up for some afocal shots through the 32mm Q70 to compare with the TV 32mm shots I've done. When using the Bahtinov mask for focusing the afocal setup I couldn't make out the pattern, even when using the camera manual focus zoom function. I focused by eye through the EP, which is how I've done it in the past. Took some shots of M31, M45, M33, and M43 to compare to previous shots when I noticed some issues with the M45 and M43 shots. At the time I thought that the 1.25 inch dew heater wasn't able to keep my optics from frosting up but when I got home and looked at the shots on the computer I realized all of the shots had issues. It's easier to see camera to EP misalignment in the camera LCD with the TV 32mm than it is with the Q70 32mm, so I'm going to need to come up with a system to accomplish that.
    Tonight is forcasted for better viewing than last night, so I just need to figure out if I'm going to use a seeing 5/5 for attempting to nail down a camera to EP alignment process or do some viewing.
    Name - Verne / Call sign - KF7UHL
    Scopes - Orion Atlas 10 EQ-G GoTo / Orion 130ST on an AstroView Mount with RA Drive
    EPs - Orion Plossl (10mm, 25mm, 32mm, 40mm), Tele Vue Plossl (32mm), Orion Stratus (5mm), 12.5mm Orion Illuminated, 7-21mm Orion Explorer II, set of Orion Q70's
    Camera Adapters - SteadyPix Deluxe, Orion Universal, Digi-Kit DK118, T-ring, 2 inch EOS
    Camera - Canon 5D Mk II, Canon T6i, Panasonic FZ35, Celestron NexImage


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    I came up with a way to help better align my camera to the EP. I put a black circle every ten squares of the grid image I was using, centered the circle in the EP then centered the camera on the circle while assembling the afocal setup.
    I mounted the afocal setup on the scope, flipped the camera out of the way and focused on a star then went to M31 and centered in the EP then flipped the camera back into place. I took a 60 second exposure and there it was, the shadow of my secondary in the middle of my image. I moved the camera as close as I could to the EP, still had the shadow. Since I was using the 32mm Q70 for the shot I thought that maybe the 38mm or the 26mm Q70 would return better results but when I looked at how far the EP lens was recessed into the EP body I realized none of the Q70's would work. The 38mm Q70 has a longer eye relief than the 26mm Q70 but is recessed almost twice as far.
    As an experiment I tried different F-ratio settings on the camera, all that got me was darker images at f/8 than at f/2.8. The next experiment was to try the LX7 in my car instead of the FZ35. The outer diameter of the LX7 lens in smaller than the inner diameter of the 32mm Q70 so I was able to get the camera lens closer to the EP lens than with the FZ35. Took a 60 second exposure and no more secondary shadow. The LX7 has no manual focus, takes only jpg image files and will go through a set of batteries every 20 shots, not a good choice.
    Until I get a DSLR it looks like I'm limited to using my TV 32mm Plossl for my afocal shots with my FZ35.
    Name - Verne / Call sign - KF7UHL
    Scopes - Orion Atlas 10 EQ-G GoTo / Orion 130ST on an AstroView Mount with RA Drive
    EPs - Orion Plossl (10mm, 25mm, 32mm, 40mm), Tele Vue Plossl (32mm), Orion Stratus (5mm), 12.5mm Orion Illuminated, 7-21mm Orion Explorer II, set of Orion Q70's
    Camera Adapters - SteadyPix Deluxe, Orion Universal, Digi-Kit DK118, T-ring, 2 inch EOS
    Camera - Canon 5D Mk II, Canon T6i, Panasonic FZ35, Celestron NexImage


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    Default

    I forgot to mention that the image filled the camera frame of the LX7, no dark corners like in the images shown at the beginning of the thread.
    Name - Verne / Call sign - KF7UHL
    Scopes - Orion Atlas 10 EQ-G GoTo / Orion 130ST on an AstroView Mount with RA Drive
    EPs - Orion Plossl (10mm, 25mm, 32mm, 40mm), Tele Vue Plossl (32mm), Orion Stratus (5mm), 12.5mm Orion Illuminated, 7-21mm Orion Explorer II, set of Orion Q70's
    Camera Adapters - SteadyPix Deluxe, Orion Universal, Digi-Kit DK118, T-ring, 2 inch EOS
    Camera - Canon 5D Mk II, Canon T6i, Panasonic FZ35, Celestron NexImage


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