A Question about Aperture
Mar 27, 2018 17:15:05 #
MaryFran
Loc: Front Royal, VA
All of these are welcome replies, though my brain is frying. I am not so good with technical information. I can't say it's exactly Chinese, but it comes close.
Mar 27, 2018 18:11:04 #
MaryFran wrote:
All of these are welcome replies, though my brain is frying. I am not so good with technical information. I can't say it's exactly Chinese, but it comes close.
Japanese! No, that is likely more confusing. Greek perhaps.
Mar 27, 2018 21:42:23 #
Guyserman
Loc: Benton, AR
JMCPHD wrote:
Maybe it will help to understand that the f number for aperture is based on the ratio of the size of the opening and the focal length of the lens. Thus in a zoom lens like the one you are using if you go from shorter focal lengths like 18 mm to 300mm the longer focal length divided into the size of the opening produces a smaller ratio and the amount of light reaching your sensor drops.
Glad to see someone mention that it is a ratio. If the lens opening is wide open it might be 1/3.5 of the shorter focal length. It you zoom out to the longer focal length the wide open lens opening would be a smaller fraction of the longer focal length, for example 1/6.3. Simple mathematics.
Mar 27, 2018 22:41:50 #
As you use the compression of the telephoto 300mm your depth of field should be shallow at f6.3
Anyway do some testing having your subjects background further away will help blurr the background.
Anyway do some testing having your subjects background further away will help blurr the background.
Mar 28, 2018 07:07:55 #
MaryFran
Loc: Front Royal, VA
Guyserman wrote:
Glad to see someone mention that it is a ratio. If the lens opening is wide open it might be 1/3.5 of the shorter focal length. It you zoom out to the longer focal length the wide open lens opening would be a smaller fraction of the longer focal length, for example 1/6.3. Simple mathematics.
Some people don't find mathematics that simple. I am one of those.
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