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Thread: Samyang Rokinon HD8M 8mm fisheye focus issues

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    Samyang Rokinon HD8M 8mm fisheye focus issues

    Hello
    I am a proud new owner of the rokfish 8mm
    Its a very fun lens and it takes pans in 6 shots which is a huge benefit over my kit lens 18-55.

    However it is having focus issues. I have read some great threads about calibration of the Samyang FM 8mm model and am wondoring if the structural make up of the 1st gen and 2nd are the same and if the 1st gen technique would be the same for the 2nd gen.

    I tried to roll up the rubber focus band but it was very rigid and I felt it would break if I tried any harder.

    Thanks for looking

  2. #2
    dubaiphil's Avatar
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    Re: Samyang Rokinon HD8M 8mm fisheye focus issues

    I would have thought that at f8, everything would be in focus

    I had a Samyang 8mm fisheye and I didn't really need to bother with focus. When I shot 360 degree panos with it, I just focused short of infinity, f8 and I was there. Well, with it being a fish, you weren't there, you were everywhere...

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    Moderator GrumpyDiver's Avatar
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    Re: Samyang Rokinon HD8M 8mm fisheye focus issues

    I have the 1st gen version of the lens and would agree with Phil; I don't even worry about focus. Set the lens to infiity and everything is in focus, almost regardless of what f-stop I am shooting with. So far as I understand it, the only difference between the two generations is that 2nd gen has a removeable lens hood, while my version does not.

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    Re: Samyang Rokinon HD8M 8mm fisheye focus issues

    Hi guys
    This is what I have read as well. F8-11 set focus ring at 5feet and from 5 feet + should be in focus. However it is not the case for this lens.

    Please see this link re calibrationhttp://www.focusonnewfoundland.com/s...80_174000.html

    Im using an A57 and the exif data is not showing up. Could this be because it is a lens that is not chipped?

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    Moderator GrumpyDiver's Avatar
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    Re: Samyang Rokinon HD8M 8mm fisheye focus issues

    I wonder if you have a defective lens...

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    Re: Samyang Rokinon HD8M 8mm fisheye focus issues

    Hi,

    I am going to take some pics and post them up here shortly. I am a newb so I will try my best to get the data correct as the exif data does not show up in the files.

    Thanks

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    Re: Samyang Rokinon HD8M 8mm fisheye focus issues

    Quote Originally Posted by MetroRuss View Post
    Hi guys
    This is what I have read as well. F8-11 set focus ring at 5feet and from 5 feet + should be in focus. ...
    Er, no. Set focus to infinity (practically, halfway between 10' and infinity is probably fine).

    If you're shooting close subjects, or you really want to judge focus critically, the easiest way is to use liveview and magnification. Or, if you're shooting a Canon that can load up Magic Lantern, ML has focus peaking and magic zoom.

    BTW, even if your lens's focus ring was calibrated correctly, there could still be an issue on critical focus. My Sigma 8mm circular fisheye is notorious for being off at infinity.
    Last edited by inkista; 17th March 2013 at 07:36 PM.

  8. #8

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    Re: Samyang Rokinon HD8M 8mm fisheye focus issues

    Hi,

    This photo was taken at f22, focus at infinity and 1/30, iso 100 handheld.
    Does it look like it could be in better focus?
    http://360smb.com/images/largefiles/pano-mar17-2013.jpg

    The image was cropped.
    Oh and I forgot to mention that the lens does snap into the mount properly like my other lenses, but it wiggles a little, like maybe 1/2 millimeter to 1 mm.
    Last edited by MetroRuss; 17th March 2013 at 10:56 PM.

  9. #9
    inkista's Avatar
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    Re: Samyang Rokinon HD8M 8mm fisheye focus issues

    Um. f/22 may not be ideal for sharpness on a crop-body dSLR, if that's what you're shooting with. Diffraction. Bryan Peterson dismisses it as not a big deal, but you need to make up your mind for yourself.

    Secondly, at f/22, 1/30s, and iso 100, handheld, maybe you have some camera shake blur in there as well. Thirdly, you're cropping down to nearly nothing, so we're almost looking at this thing at 100% magnification. That's an extremely critical way of viewing any lens, let alone one as extreme as a fisheye.

    My recommendation would be to put the camera on a tripod. Stop down to f/8 or f/11. Then use liveview and 10x magnification to adjust critical focus and see where the ring ends up. Then tape it down there. Eliminate the other factors that could be causing softness before blaming the focus.
    Last edited by inkista; 19th March 2013 at 09:09 PM. Reason: whoops. Two secondlys.

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    Moderator GrumpyDiver's Avatar
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    Re: Samyang Rokinon HD8M 8mm fisheye focus issues

    That is one serious crop. There are better ways to do a pano and to retain some more data; you are down to around a 6MP image. That being said, I compared your shot with one I took with my version of the lens, it is okay sharpness wise, but certainly not in the same league as some of my more expensive glass.

    Samyang Rokinon HD8M 8mm fisheye focus issues

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    Re: Samyang Rokinon HD8M 8mm fisheye focus issues

    Hello and thank you for the comments. It all helps me so much and I appreciate it. Im a total newb and its hard to make the time up to read or get out to take some shots.

    I've got some shots Of my disastrous back yard at f8 that I can post later on this evening.

    I did what you suggested and it helped alot. Set to f8 then used digital magnification to see my area of focus better.

  12. #12

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    Re: Samyang Rokinon HD8M 8mm fisheye focus issues

    Hi there,

    Here are a few more pics, un cropped and right from camera.
    Samyang Rokinon HD8M 8mm fisheye focus issues
    Samyang Rokinon HD8M 8mm fisheye focus issues
    Samyang Rokinon HD8M 8mm fisheye focus issues
    Samyang Rokinon HD8M 8mm fisheye focus issues

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