f. stop V. Aperture value
Posted 04/02/2010 - 20:10
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I noticed that and wondered why but have always been too lazy to ask. The website's reporting of EXIF data is whacky, e.g., shutter speeds of 33333/100000 sec and so on.
K.
K.
Kris Lockyear
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.
Posted 04/02/2010 - 20:13
Link
I've no idea either....
They both say f/# so f-number or a better worth focal ratio since it's an ratio between the aperture and the focal-length.
Aperture itself is giving as a diameter and not as an f number, if I've it right.
Hopefully someone else can shine some light on this.
They both say f/# so f-number or a better worth focal ratio since it's an ratio between the aperture and the focal-length.
Aperture itself is giving as a diameter and not as an f number, if I've it right.
Hopefully someone else can shine some light on this.
Stefan
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
Posted 05/02/2010 - 09:06
Link
The aperture is the hole situated in the lens of the camera that controls the amount of light that is allowed to reach the sensor. Certain modes on a camera allow the user to change the size of the aperture therefore changing how much light is allowed through.
Apertures are represented by a series of numbers called f-stops, and, in reverse of what you might think, the larger the number, the smaller the hole. For example, an f-stop of f/2.8 would represent a large aperture and an f-stop of f/32 would represent a small aperture. As you can see from the illustration below, the largest hole is represented by the smallest number. Each subsequently higher f-stop number lets in half as much light as the previous number.
The f-stop of a lens is a number that represents the aperture opening. A large opening is a small f number, and a small opening is a large f stop. Lenses are rated in the range of f-stop numbers they can be set to. Pay particular attention to the lowest number. If a lens is rated, "f3 to f22," the f-3 is what you care about. This represents the lens' ability to pass light. The smaller the number the more light the lens can admit which improves the camera's ability to capture images in places with low light. Some of the best 35mm film cameras have lenses that are rated at around f1.2 and f1.8. In digital cameras you will do well to get a lens in the area of f2.8.
Simples eh!
Apertures are represented by a series of numbers called f-stops, and, in reverse of what you might think, the larger the number, the smaller the hole. For example, an f-stop of f/2.8 would represent a large aperture and an f-stop of f/32 would represent a small aperture. As you can see from the illustration below, the largest hole is represented by the smallest number. Each subsequently higher f-stop number lets in half as much light as the previous number.
The f-stop of a lens is a number that represents the aperture opening. A large opening is a small f number, and a small opening is a large f stop. Lenses are rated in the range of f-stop numbers they can be set to. Pay particular attention to the lowest number. If a lens is rated, "f3 to f22," the f-3 is what you care about. This represents the lens' ability to pass light. The smaller the number the more light the lens can admit which improves the camera's ability to capture images in places with low light. Some of the best 35mm film cameras have lenses that are rated at around f1.2 and f1.8. In digital cameras you will do well to get a lens in the area of f2.8.
Simples eh!
Regards
David
Retired at last - now all that time for photography - you would think: wink:
David
Retired at last - now all that time for photography - you would think: wink:
Posted 05/02/2010 - 09:21
Link
I had always assumed that the Aperture Value and Max Aperture Value in the EXIF were figures reported by the lens, and the f-stop is the number specified by the camera. I thought this was why the Aperture Value isn't always the same as the f-stop, e.g. Hasky's image here.
I'm probably completely wrong
I'm probably completely wrong
Tim
AF - Pentax K5, Sigma 10-20/4-5.6, Tamron 17-50/2.8, Sigma 30/1.4, Sigma 70-200/2.8, Tamron 70-300/4-5.6
MF - Vivitar CF 28/2.8, Tamron AD2 90/2.5, MTO 1000/11
Stuff - Metz 58 AF1, Cactus v4, Nikon SB24, Raynox 150, Sigma 1.4x TC, Sigma 2x TC, Kenko 2x macro TC, Redsnapper 283 tripod, iMac 27”, Macbook Pro 17”, iPad, iPhone 3G
Flickr • Fluidr • PPG • Street • Portfolio site
Feel free to edit any of my posted photos! If I post a photo for critique, I want brutal honesty. If you don't like it, please say so and tell me why!
AF - Pentax K5, Sigma 10-20/4-5.6, Tamron 17-50/2.8, Sigma 30/1.4, Sigma 70-200/2.8, Tamron 70-300/4-5.6
MF - Vivitar CF 28/2.8, Tamron AD2 90/2.5, MTO 1000/11
Stuff - Metz 58 AF1, Cactus v4, Nikon SB24, Raynox 150, Sigma 1.4x TC, Sigma 2x TC, Kenko 2x macro TC, Redsnapper 283 tripod, iMac 27”, Macbook Pro 17”, iPad, iPhone 3G
Flickr • Fluidr • PPG • Street • Portfolio site
Feel free to edit any of my posted photos! If I post a photo for critique, I want brutal honesty. If you don't like it, please say so and tell me why!
Posted 05/02/2010 - 12:53
Link
mayday wrote:
The aperture is the hole... Simples eh!
But not what we were asking. The web page is interesting too but on a quick scan through I cannot see the answer there either.The aperture is the hole... Simples eh!
What we were asking is why the EXIF shows two values. For example, with this image the website EXIF shows F stop f/9.5, aperture f/6.5. This image was taken with a lens with a maximum aperture of f/2.8 (the DA* 50-135mm to be precise).
Interestingly Photome reports the aperture as "6.5Av(F9.5)"
At this remove I have no idea what aperture I thought I had set the lens to, but clearly they are two separate things and not the lens' maximum aperture.
Still puzzled... I thought I understood this stuff!
K.
Kris Lockyear
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.
Posted 05/02/2010 - 13:05
Link
Perhaps one is the 'actual' aperture and one is the aperture as seen by the camera.
Tim
AF - Pentax K5, Sigma 10-20/4-5.6, Tamron 17-50/2.8, Sigma 30/1.4, Sigma 70-200/2.8, Tamron 70-300/4-5.6
MF - Vivitar CF 28/2.8, Tamron AD2 90/2.5, MTO 1000/11
Stuff - Metz 58 AF1, Cactus v4, Nikon SB24, Raynox 150, Sigma 1.4x TC, Sigma 2x TC, Kenko 2x macro TC, Redsnapper 283 tripod, iMac 27”, Macbook Pro 17”, iPad, iPhone 3G
Flickr • Fluidr • PPG • Street • Portfolio site
Feel free to edit any of my posted photos! If I post a photo for critique, I want brutal honesty. If you don't like it, please say so and tell me why!
AF - Pentax K5, Sigma 10-20/4-5.6, Tamron 17-50/2.8, Sigma 30/1.4, Sigma 70-200/2.8, Tamron 70-300/4-5.6
MF - Vivitar CF 28/2.8, Tamron AD2 90/2.5, MTO 1000/11
Stuff - Metz 58 AF1, Cactus v4, Nikon SB24, Raynox 150, Sigma 1.4x TC, Sigma 2x TC, Kenko 2x macro TC, Redsnapper 283 tripod, iMac 27”, Macbook Pro 17”, iPad, iPhone 3G
Flickr • Fluidr • PPG • Street • Portfolio site
Feel free to edit any of my posted photos! If I post a photo for critique, I want brutal honesty. If you don't like it, please say so and tell me why!
Posted 05/02/2010 - 14:05
Link
Perhaps it is all just like shutter speeds that show up in Exif
Regards
David
Retired at last - now all that time for photography - you would think: wink:
David
Retired at last - now all that time for photography - you would think: wink:
Posted 05/02/2010 - 16:36
Link
thoughton wrote:
Perhaps one is the 'actual' aperture and one is the aperture as seen by the camera.
Huh?
Perhaps one is the 'actual' aperture and one is the aperture as seen by the camera.
Stefan
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
Posted 05/02/2010 - 17:04
Link
This thread gets more confusing as it goes along... I, too, had wondered about the two different values shown in EXIF. The F stop on one of mine shows 5.6, I know this was true since I was in Av mode but the the other value is 4.97, shutter speed is 1/20 and the other value is 4.32. Confused? You will be!
Not an answer to the OP but until someone comes up with a mathematical answer, don't worry. My picture was taken at 1/20 at f5.6.... phew!
Not an answer to the OP but until someone comes up with a mathematical answer, don't worry. My picture was taken at 1/20 at f5.6.... phew!
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 -
“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 -
Posted 05/02/2010 - 19:05
Link
It isn't often the combined photographic knowledge of the PUG fora comes up with a universal "huh?"
K.
K.
Kris Lockyear
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.
Posted 05/02/2010 - 19:25
Link
Hmm makes me sorry I asked now
K-20D, Battery grip, Pentax 18-250mm & 50mm (Manual), 28mm (Bell & Howell) & Metz 'Mecablitz' 58 AF-1 flash. Manfrotto tripod with ball grip head.
Posted 05/02/2010 - 19:26
Link
Steve908 wrote:
Hmm makes me sorry I asked now
Don't be! It seems very odd but there must be an explanation out there somewhere...
Hmm makes me sorry I asked now
Kris Lockyear
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.
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