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Thread: Rayqual and Infinity is...

  1. #1
    ajuett
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    Rayqual and Infinity is...

    Well, see for yourself

    All using the Canon FD 50mm f/1.2 at infinity focus.

    #1 and #2 are at f/8, #3 is f/11

    Burrard Street bridge


    Fairly large crop;


    City of Vancouver
    Last edited by ajuett; 11th February 2009 at 16:09.

  2. #2
    Super Duper
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    Re: Rayqual and Infinity is...

    Looks good. I can understand the necessity to stop down in order to get foreground and background elements of the scene in focus for a nice picture, but to really test for infinity focus you should have the lens wide open. Do you know if the skyscrapers in the background of #3 were in focus with the lens set at infinity and at f/1.2?

  3. #3
    ajuett
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    Re: Rayqual and Infinity is...

    Carl, the City image was taken at F/11. I'd never think to use f/1.2 in this situation, if the image is sharp, it's sharp. The fstop really shouldn't matter. I'm not trying to prove if you are right or wrong it's just my opinion. Can you explain more, maybe I'm missing something.

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    Re: Rayqual and Infinity is...

    Quote Originally Posted by ajuett View Post
    Carl, the City image was taken at F/11. I'd never think to use f/1.2 in this situation, if the image is sharp, it's sharp. The fstop really shouldn't matter. I'm not trying to prove if you are right or wrong it's just my opinion. Can you explain more, maybe I'm missing something.
    I agree that you wouldn't want to use f/1.2 for this scene. My point is for a purely technical test of the adapter you can't really tell if the lens/adapter can achieve accurate focus at the infinity setting with an aperture of f/11 because the depth of field is so great. You don't even have to take an image for this test. Just set the lens to the infinity mark and set the aperture to f/1.2 and look at a very distant object to see if it is in focus or not.

  5. #5
    ajuett
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    Re: Rayqual and Infinity is...

    OK, I get it now, its been a long day I'll give it a go tomorrow.

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    Re: Rayqual and Infinity is...


  7. #7
    Ranger 9
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    Re: Rayqual and Infinity is...

    Quote Originally Posted by monza View Post
    One note about this trick: The longer the lens, the better the results you'll get.

    Professional collimators are usually in the 500-1000mm range, I think.

  8. #8
    Member JimBuchanan's Avatar
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    Re: Rayqual and Infinity is...

    I couldn't have said it better than scho.

    You want to test and confirm infinity focus, open it up and take photos at far away objects and compare 100% crops in LR or another program. I do this all the time.

    The stopped down lens will camouflage the infinity focus accuracy.

  9. #9
    ajuett
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    Re: Rayqual and Infinity is...

    Quote Originally Posted by JimBuchanan View Post
    I couldn't have said it better than scho.

    You want to test and confirm infinity focus, open it up and take photos at far away objects and compare 100% crops in LR or another program. I do this all the time.

    The stopped down lens will camouflage the infinity focus accuracy.
    While I will try (for curiosity sake only) the wide open test on a distant object I'm not a fan of pixel staring, to me that kills the fun of photography.

    Let's take the City image I have there. If I zoom in on the buildings they are about 400 to 500px high. In the real world I'd never crop that much, not even close. So what is so important about this being razor sharp at 100%? I have my screen set to 1680x1050, that is about 2MP or about a 10"x18" image. That is slightly over the size of an average portrait which gives me an excellent idea of how the print would look. As for the net, I generally post 1000px on the long side for landscape mode and about 800px for portrait mode.

    "Camouflaging" is not in play, viewing the image in a realistic manor is. Just my opinion though

  10. #10
    Member JimBuchanan's Avatar
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    Re: Rayqual and Infinity is...

    Do you want true infinity focus or not?

    This is not killing the fun of phtography, its calibrating your equipment.

  11. #11
    ajuett
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    Re: Rayqual and Infinity is...

    Jim,

    Would you say the the 3 images I posted at infinity focus are not sharp?

    #1 was 800ft to the bridge
    #2 was 200ft to the boat
    #3 was 4 miles to the buildings
    Distances approx. as measure by Google Earth

    Even if the infinity focus was noticeably out of focus 2 facts remain; the adapter is made, the lens is what it is, therefore, how on Earth would I calibrate it? Would Panasonic or Canon, maybe Rayqual? lol. Sorry, I find it funny.

    I didn't do the f/1.2 test today. Maybe over the weekend.

  12. #12
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    Re: Rayqual and Infinity is...

    I am not sure what the point of starting this thread is if you are not going to do the things necessary that actually confirm the Rayqual is accurate at infinity.

  13. #13
    ajuett
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    Re: Rayqual and Infinity is...

    Quote Originally Posted by monza View Post
    I am not sure what the point of starting this thread is if you are not going to do the things necessary that actually confirm the Rayqual is accurate at infinity.
    Necessary or just technical pixel peeping? I'll ask you the same question I asked Jim; Are the 3 infinity focus images I posted out of focus?

  14. #14
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    Re: Rayqual and Infinity is...

    Heh.

    These photos, even though sharp, do not necessarily prove that the Rayqual is calibrated for infinity. The Rayqual could be completely out of whack and still these images could be tack sharp.

    Other posts have shown how a proper test can be done.

    The question is, based solely on these images, can it be definitively said that when the G1 is focused on something (using the 'pixel peeping' focus assist of the G1) at say 5 feet at f/1.2, will the lens actually indicate 5 feet?

    The answer to that question is 'no.'

    If you want to show the Rayqual is accurate at infinity, which would mean it would also be accurate at other distances, then please follow the other suggested tests and report the results.

  15. #15
    ajuett
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    Re: Rayqual and Infinity is...

    Quote Originally Posted by monza View Post
    Heh.

    These photos, even though sharp, do not necessarily prove that the Rayqual is calibrated for infinity. The Rayqual could be completely out of whack and still these images could be tack sharp.

    Other posts have shown how a proper test can be done.
    To me, simplicity sells. If the photo is sharp, etc. then what is there to be questioned? I see no need to test this lens any further. It wasn't a "test" anyway it was more like a conclusion to me that all is good. I'll leave the charts and graphs testing for those who wish to take photography to a level I don't deem necessary.

    In a earlier post I explained I went through my first FD 50mm f/1.2. It not only had fungus but it also didn't focus at infinity, more like 300 odd feet. Anything beyond that was a blur at any aperture.

    Quote Originally Posted by monza View Post
    The question is, based solely on these images, can it be definitively said that when the G1 is focused on something (using the 'pixel peeping' focus assist of the G1) at say 5 feet at f/1.2, will the lens actually indicate 5 feet?

    The answer to that question is 'no.'
    To clarify, I don't use the focus assist. Personally, I don't like focus assist and its an extra step that to me, doesn't help much. Also, it bugs my eyes out coming from a 15x zoom to a normal viewing ;-) Especially when trying to catch the kids running around.

  16. #16
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    Re: Rayqual and Infinity is...

    All that is well and good, but again, I don't see the point of having a thread about Rayqual and infinity, if the post doesn't prove anything one way or another with regards to, well, Rayqual and infinity.

    Not to worry, I have confidence in Rayqual and other users here have the FD adapter. I'm sure it works fine and lens scales can be relied upon accurately.

    I'm glad you got a good un-fungused lens and are happy with it.

  17. #17
    ajuett
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    Re: Rayqual and Infinity is...

    Me too, I missed having a bright/fast lens. I'll have to save for the next 2 FD lenses I have my eyes on. ...maybe sell the mitre saw that is sitting in the garage

  18. #18
    Member JimBuchanan's Avatar
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    Re: Rayqual and Infinity is...

    To each his own.

    I know that adding an adapter between a different brand camera and lens may or may not focus at infinity. On less than infinity subjects, as illustrated above, the G1 with its optical VF, you will get sharp in-focus photos, even if infinity is off due to a too thick or thin adapter. The only exception to that, is if the lens has floating elements, where there can't be any variance between flange and sensor.

    Infinity subjects present the problem. I know that I want my lens/camera setup to focus precisely on infinity, when I crank that focus ring all the way. Thats my reference point, and that is indicative of a properly calibrated lens/camera system. If one has to stopdown to get sharp infinity objects, the system is compromised. At that point, what is the point of using expensive lenses?

    And to know if your lens/camera does accurately focus infinity at wide open, is not a big deal, with compared 100% crops of far off objects.

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