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Thread: Query about IQ on focal length (FL) of 200mm and 300mm

  1. #1

    Default Query about IQ on focal length (FL) of 200mm and 300mm

    Hi bros, I have a query on cropping of photos taken from FL of 200mm and 270mm.
    I recently took a photo of the moon from my Canon 70-200 F4 L lens (FL @ 200mm)and cropped the photo when doing PP.
    The IQ was not as sharp compared to the same shot taken from the Tamron 18-270 PZD (FL @ 270mm), same cropped size as well.
    Is it due to different FL despite the Canon being a 'superior' lens than the Tamron?
    Or should I get the calibration done?
    I am using the 550D body.
    Thks!

  2. #2

    Default Re: Query about IQ on focal length (FL) of 200mm and 300mm

    200mm and 270mm will definitely have a noticeable difference. The longer focal length will result in the moon having a higher "magnification" on the sensor, thus giving the appearance that it's sharper.

    Also, you should know that lenses are generally sharper when stopped down - the 70-200 would be sharper at f/5.6 or f/8 than at f/4.

    Try shooting with the Tamron at 200mm, f/5.6 and the Canon at 200mm, f/5.6 and compare. That would be fairer.
    Alpha

  3. #3
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    Quote Originally Posted by Rashkae
    200mm and 270mm will definitely have a noticeable difference. The longer focal length will result in the moon having a higher "magnification" on the sensor, thus giving the appearance that it's sharper.

    Also, you should know that lenses are generally sharper when stopped down - the 70-200 would be sharper at f/5.6 or f/8 than at f/4.

    Try shooting with the Tamron at 200mm, f/5.6 and the Canon at 200mm, f/5.6 and compare. That would be fairer.
    If I'm not wrong, I think the aperture has reached F/6.3 @ 200mm for tamron.
    Equipment: D800|D700|11-16|28-75|105 Micro VR|50 F1.4G|85 F1.8G
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  4. #4

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    Quote Originally Posted by Rashkae
    200mm and 270mm will definitely have a noticeable difference. The longer focal length will result in the moon having a higher "magnification" on the sensor, thus giving the appearance that it's sharper.

    Also, you should know that lenses are generally sharper when stopped down - the 70-200 would be sharper at f/5.6 or f/8 than at f/4.

    Try shooting with the Tamron at 200mm, f/5.6 and the Canon at 200mm, f/5.6 and compare. That would be fairer.
    Thks for the simple but vy clear explanation.. Much appreciated. Been trying to get it as sharp as the Tammy the whole night..

  5. #5

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    Quote Originally Posted by Cowseye

    If I'm not wrong, I think the aperture has reached F/6.3 @ 200mm for tamron.
    Not sure as I hv since sold the Tammy.. But at 270mm it's f6.3

  6. #6

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    I am also aware that each lens hv their own 'sweet' spots. Meaning being IQ being sharpest at a particular f. I tried by taking a scene at different f but could not really tell the diff between f8-f16 for most of the Canon lens I own. From the collective experiences here, is there a better way to do this?

  7. #7
    Senior Member giantcanopy's Avatar
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    Default Re: Query about IQ on focal length (FL) of 200mm and 300mm

    Quote Originally Posted by Omahom View Post
    I am also aware that each lens hv their own 'sweet' spots. Meaning being IQ being sharpest at a particular f. I tried by taking a scene at different f but could not really tell the diff between f8-f16 for most of the Canon lens I own. From the collective experiences here, is there a better way to do this?
    All i usually gather about sweet spot info from lens reviews and testings. I usually use the required aperture for my shots.
    I guess if you really want, you can shoot a same scene with a wide variety of apertures and identify 100% pixel peep from there.

    However the effects of the aperture is probably more important than fine print sharpness.

    Ryan

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