'f stop' versus 'aperture value'
3,447 posts
Link
Posted 30/05/2015 - 07:08
Something that I don't get either, like tattoos, people carriers or owning a dog when you're not a sheep farmer.
Best wishes,
Andrew
"These places mean something and it's the job of a photographer to figure-out what the hell it is."
Robert Adams
"The camera doesn't make a bit of difference. All of them can record what you are seeing. But, you have to SEE."
Ernst Hass
My website: http://www.ephotozine.com/user/bwlchmawr-199050 http://s927.photobucket.com/home/ADC3440/index
https://www.flickr.com/photos/78898196@N05
Best wishes,
Andrew
"These places mean something and it's the job of a photographer to figure-out what the hell it is."
Robert Adams
"The camera doesn't make a bit of difference. All of them can record what you are seeing. But, you have to SEE."
Ernst Hass
My website: http://www.ephotozine.com/user/bwlchmawr-199050 http://s927.photobucket.com/home/ADC3440/index
https://www.flickr.com/photos/78898196@N05
Link
Posted 30/05/2015 - 08:49
I've asked various people to explain this and never got a straight answer. So, my best guess is that, given we have lenses with variable apertures, the f stop is what we set and the aperture value is the actual open aperture value at that setting. One does seem to relate to the potential largest aperture at the focal length selected.
It's a bit irrelevant really, and the EXIF on ePHOTOzine just shows the aperture. As the team cure the EXIF anomalies on PU no doubt that will be simplified.
Best regards, John
It's a bit irrelevant really, and the EXIF on ePHOTOzine just shows the aperture. As the team cure the EXIF anomalies on PU no doubt that will be simplified.
Best regards, John
Link
Posted 30/05/2015 - 10:26
The T stop was widely used at one time as uncoated lenses lose a lot of light due to internal reflections. A four element lens can lose 35% of the light in this way, meaning the f stop is accurate only for depth of field but not for exposure. With modern lenses and multi coating this is no longer necessary.
T stops continued to be used in cinematography, but rarely get a mention in still photography.
Best regards, John
T stops continued to be used in cinematography, but rarely get a mention in still photography.
Best regards, John
Link
Posted 30/05/2015 - 16:41
Lenses used in cinematography such as multi coated Carl Zeiss Distagons still have both T and F indices. T for aperture and F for calculating depth of field. However in real terms the physical difference between the two, especially on wide angle lenses, is miniscule; I've never believed there would be any noticeable difference and given the vagaries of the various methods used in the production of depth of field tables the whole thing becomes very subjective indeed.
Ken
“We must avoid however, snapping away, shooting quickly and without thought, overloading ourselves with unnecessary images that clutter our memory and diminish the clarity of the whole.” - Henri Cartier-Bresson -
Ken
“We must avoid however, snapping away, shooting quickly and without thought, overloading ourselves with unnecessary images that clutter our memory and diminish the clarity of the whole.” - Henri Cartier-Bresson -
Add a Comment
You must be registered or logged-in to comment.
michaelblue
Member
Shropshire
Regards,
Michael
My new website:link