Lens f numbers

Some great info. thanks
 
i posted a link showing the effect of aperture and DoF in post #8
which as you say is the point - but the question was on the maths of aperture calc

in the days of film when I first started, i purchased some short dated slide film and went into the garden and wrote on a piece of paper all the focal lengths/apertures i was going to use and shot away
that the best way to understand the kit
these days - not costly to do that and you get the exif - so this would be very easy and i highly recommend as you learn your kit and your lenses at different focal length
 
Wayne,
You have made a good point about using the camera and gaining experience, I study the combinations the camera makes on auto and try to understand why it has chosen them. Since the invention of the digital camera photography as a hobby has become quite cheap compared to other hobbies. I would like to see if anybody has had experience with bad photographers, I paid a photographer to take pictures of my family he had us under a tree and he was in the sunshine, I questioned this and he said it was an expensive camera and would be fine, when we got the pictures we were all in the shad and could hardly see us, would it be possible to take pictures when you are in the sun and the subject is in the shade?
 
would it be possible to take pictures when you are in the sun and the subject is in the shade?
i would expect so - flair maybe an issue and exposure , also in the sun everyone can get very hot and squint in the sun, also can be very contrasty - but that is after all what you expect the photography to know and get the best out of the situation, clearly your experience is not
could hardly see us
because everyone was dark ?
 
I'm new to all of this but I'm finding it all a bit much to take in, at the moment I just play around with the settings till I get the picture I want. I need it explain in 100% dummy terms, as in how an f number works, aperture and ISO etc. I have been watching videos and I am starting to understand slightly but I find it a lot to take in

Some good info on here to though for sure but I think it has confused me more reading different examples all at one go lol
 
I'm new to all of this but I'm finding it all a bit much to take in, at the moment I just play around with the settings till I get the picture I want. I need it explain in 100% dummy terms, as in how an f number works, aperture and ISO etc. I have been watching videos and I am starting to understand slightly but I find it a lot to take in

Some good info on here to though for sure but I think it has confused me more reading different examples all at one go lol

I quite like this as basic explanations go.

http://dallaseye.blogspot.co.uk/2011/10/photography-basics-exposure-aperture.html
 
yes. I agree. In my experience when I zoom in, it always seems to be on a subject with lower luminosity than the surroundings as windows and other light sources are lost from the frame. Therefore I need to compensate for that...but I understand your point, well made.

If your primary subject has not changed while you are zooming in then your exposure should not change, as the light reflecting off your subject does not change in any way just because you have zoomed in on it. If you do have to change your exposure then that means your subject was not correctly exposed in the wider shots. Only if you are exposing the original image without specific concern for the subject you are zooming in on later should your exposure change, but that is because you are entirely changing the subject, not just because you happen to be zooming.

Try this test. Take a wide shot centered on a subject. Then zoom in the same subject without changing exposure at all and take another shot. Load both pictures on your PC, crop the wide shot to the exact same size as the narrow shot and compare them. They should have the same exposure.
 
Yes, would seem to be a result of using evaluative metering rather than spot as shouldn't happen with spot assuming the subject "spotted" remains the same.
 
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