Thread: Crop Factor Lens Database

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  1. #21  
    I'm sure John said it's scaled. It would make no sense to crop it, because it'd be a crop of the raw sensor, which would then necessitate having to debayer that, meaning you'd end up with a mushy 720p's worth of data. I'm pretty sure that's not what they're doing, I'm pretty sure they're debayering and then scaling down the full sensor.
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  2. #22  
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    That's good news!
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  3. #23  
    Senior Member nickjbedford's Avatar
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    For EF-S body users, multiply the focal length you want to test by 1.5 and do a test shoot. 24mm on the BMD is equivalent to 17mm on my 60D's crop factor.

    I found that 17mm on my EF-S 17-55mm F/2.8 wasn't that wide, but was still within the field of view I would use when framing a shot. I plan on buying a super wide angle lens to cover those times when I need something moderately wide. I'm going to be shooting narrative / music video shots so the medium to long crop is exactly what I want.
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  4. #24  
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    Quote Originally Posted by nickjbedford View Post
    For EF-S body users, multiply the focal length you want to test by 1.5 and do a test shoot. 24mm on the BMD is equivalent to 17mm on my 60D's crop factor.

    I found that 17mm on my EF-S 17-55mm F/2.8 wasn't that wide, but was still within the field of view I would use when framing a shot. I plan on buying a super wide angle lens to cover those times when I need something moderately wide. I'm going to be shooting narrative / music video shots so the medium to long crop is exactly what I want.
    So is the Tokina 11-16 then really the widest, fastest option?
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  5. #25  
    Thanks everyone- really helpful information. Great spreadsheets as well!
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  6. #26  
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    Sorry but I have doubt about that croping nightmare. Since a 50mm is still a 50mm and a 21mm is a 21mm and a 100mm is a 100mm, does the 21mm have the same specs or it gets a 50mm properties.

    To be more clear does the 21mm have the wide lens look or instead flatten like a 50mm? If the answer is that it remain having the 21mm properties the crop factor just affect the distance where you put the camera to get the same frame as you will do in a full frame sensor, no?(I also read in Ken Rockwell that also affects in a slightly way the DoF).
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  7. #27  
    Senior Member laco's Avatar
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    Quote Originally Posted by Fabián Matas View Post
    Sorry but I have doubt about that croping nightmare. Since a 50mm is still a 50mm and a 21mm is a 21mm and a 100mm is a 100mm, does the 21mm have the same specs or it gets a 50mm properties.

    To be more clear does the 21mm have the wide lens look or instead flatten like a 50mm? If the answer is that it remain having the 21mm properties the crop factor just affect the distance where you put the camera to get the same frame as you will do in a full frame sensor, no?(I also read in Ken Rockwell that also affects in a slightly way the DoF).
    A 50mm 1.4 lens will have a same DOF on every camera. But because - to have the same picture - you will have to go further from the object, that's why it would be like that the depth of field will be larger.

    A 21mm lens on a 5D has a wide angle look. You won't get that look, because with a smaller sensor you will crop inside that picture.
    To get the same wide angle field of view, you would have to use a 9mm lens. (sigma has a 8-18mm lens)
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  8. #28  
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    Thanks men!!!!!
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  9. #29  
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    In my understanding the crop factor can be calculated by this math

    full format =36mm width
    Bmc format =15.6mm width
    So 36/15.6= 2.3x is the crop factor when you using a full format lens on a Bmc camera.similarly an aps-c camera width=24mm.so, 24mm/15.6mm=1.5x Crop.
    The focal length (ie) [The distance between the optical center of a lens & the sensor when its focused at infinity] wont change.But, the magnification of the lens will change based on what sensor we use that particular lens on.
    So i made my calculations for the existing popular 5d lenses
    Aps-c Lens:
    1.Tokino 11-16 = 17mm-24mm on a Bmc Body
    2.Canon 17-55 = 25mm-82mm on a Bmc Body
    3.Sigma 30mm = 45mm on a Bmc Body

    Full Format Lens:
    1.Canon 16-35 = 37mm-80mm
    2.Canon 24-70 = 55mm-161mm on a Bmc Body
    3.Canon 50mm = 115mm on a Bmc Body
    4.Canon 85mm = 195mm on a Bmc Body
    5.Canon 100mm= 230mm on a Bmc Body
    6.Canon 70-200= 161mm-460mm on a Bmc Body

    I see lot of ppl calculate Tokino 11-16mm lens with 2.3x crop factor. It is made for Aps-c Body which is 24mm Width & 18mm Height so the crop factor must be 1.5x
    If my calculations are wrong correct me
    Thank you
    Hope this will help you to find your right choice of lenses with BMC Body
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  10. #30  
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    Quote Originally Posted by manigandan View Post
    In my understanding the crop factor can be calculated by this math

    full format =36mm width
    Bmc format =15.6mm width
    So 36/15.6= 2.3x is the crop factor when you using a full format lens on a Bmc camera.similarly an aps-c camera width=24mm.so, 24mm/15.6mm=1.5x Crop.
    The focal length (ie) [The distance between the optical center of a lens & the sensor when its focused at infinity] wont change.But, the magnification of the lens will change based on what sensor we use that particular lens on.
    So i made my calculations for the existing popular 5d lenses
    Aps-c Lens:
    1.Tokino 11-16 = 17mm-24mm on a Bmc Body
    2.Canon 17-55 = 25mm-82mm on a Bmc Body
    3.Sigma 30mm = 45mm on a Bmc Body

    Full Format Lens:
    1.Canon 16-35 = 37mm-80mm
    2.Canon 24-70 = 55mm-161mm on a Bmc Body
    3.Canon 50mm = 115mm on a Bmc Body
    4.Canon 85mm = 195mm on a Bmc Body
    5.Canon 100mm= 230mm on a Bmc Body
    6.Canon 70-200= 161mm-460mm on a Bmc Body

    I see lot of ppl calculate Tokino 11-16mm lens with 2.3x crop factor. It is made for Aps-c Body which is 24mm Width & 18mm Height so the crop factor must be 1.5x
    If my calculations are wrong correct me
    Thank you
    Hope this will help you to find your right choice of lenses with BMC Body
    First: Welcome
    Second: Your BMC sensor width is off. It is 15.81mm not 15.6mm. It has changed since it was first announced.
    http://www.blackmagicdesign.com/prod...era/techspecs/
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