Aperature Size and shutter Speed

[The PIT]

Okay you'll get a warning about Camera shake but l overheard one expert saying that he wanted a focal length of 2.8 so he could use a very fast shutter speed.
So wondered what is the general rule of thumb for this is??

[spadnos]

That's probably an aperture of f2.8 (not focal length)

The "total exposure" of a frame is (related by) shutter speed * film ISO * aperture^2.

That's why either (for example) going from f2 to f2.8 OR going from 1/500 to 1/250 OR going from ISO 200 to ISO 400 is one stop more exposure.

When shooting a fast moving object, you may decide that a certain shutter speed is needed (one wedding photographer once said "All Professionals shoot at 1/125" - when most of our customers were using 1/250 or faster ). The output medium or sensor may determint the ISO. Digital sensors have a specific ISO range, and if you need high resolution, that means low ISO for film.

The only variable left is aperture. (or adding lots of light, which isn't always practical)

- Steve

[The PIT]

Yup it was aperture size I was on about. Most cameras come with a min iso of 200 unless you spend a bit of dosh. 400 is too noisy unless again you spend a lot of dosh. So you're limited too iso of 200.
So what shutter speed woould you recommond with say a aperture of 2.8 and the other extreme 8.

[spadnos]

It depends on what you're shooting, how much light you have, and what depth of field you want. (I should have had light level in that equation before)

Unfortunately, although I know quite a bit about the math/science of photography, I need an automatic camera or a lightmeter to be able to take a well exposed picture.

(I don't focus very quickly, either)

- Steve

[gt40]

The bigger the aperature the lens, the better - you can always stop it down if need be. These lenses are obviously more expensive, but give you the most versatility.The camera will always be able to give you a larger f value (smaller aperature) but is limited by the f-value of the lens.
Smaller f-stop - higer shutter speed, lower depth of field.
it all depends on the effect you want.
For sports pictures, you will want to freeze the action, so a fast shutter speed is essential - a smaller f-value lens will be required.
For scenery, you will want a larger depth of field (more objects will appear in focus) so a larger f-value would be beneficial.

[The PIT]

Most of the time I'm shooting landscapes and scenery. So I'm looking at an aperature of 8 on my own camera. However life ain't simple and as you said theres light to take account off and since I'm taking scenery it blows around a bit close to camera.
What I've been doing lately, when the camera has been saying hand shake, is going down to say 6.x or lower getting the higher shutter speed allowing for light and that seems better.

[az]

Does your camera allow shifting? (Shifting means changing aperture size and exposure time at the same time, retaining the same exposure (like going from 1/125 at F2.8 to 1/250 at F2, or vice versa)). If it does support shifting, try it out, it'll help you grasp the concept a little better (I still have to stop and think when I'm thinking of aperture sizes and their effects on exposure and depth of field)

Oh, and exposure bracketing can also be very helpful

BTW, when you fear camera shake, press the camera to your eye, and fire the shutter in the pause between exhaling and inhaling. Serial exposures also help lots, there will almost always be one image that's less blurred than the rest.

AZ

[The PIT]

Come on it's a fujifilm s7000. Looking quickly through the book nothing is mentioned so take it as a no.
The camera tels me when shake is likely and the git is normally right despite how I steady myself.

[spadnos]

Set the camera in P mode instead of A, and you can do the adjustments az mentioned. Just spin the wheel, and the exposure will remain constant but with different shutter speed / aperture combinations.

- Steve

[gt40]

General rule to remember - any shutter speed less than 1/60 is prone to shake, even from the action of pressing the shutter button.

[VJ]

As a side note, to eliminate shake when using a tripod, the selftimer can be helpfull...
(press the button, and a couple of seconds later, the picture is taken: no need to even touch the camera then)


Jörg

[VJ]

Another thing I have been wondering: in lenses with variable aperture (e.g. a 24-85 mm f/2.8-4), how does the aperture vary with the focal length ?

Is it lineair ?
(Actually, it doesn't always look lineair, judging by some lenses... but what is it then ? Does the exposure formula (shutterspeed/aperture/iso) play a part ?)

Jörg

[Greebe]

@VJ, normally the f# increases at the lower end of the zoom range. It's not linear, more of a step if anything. this is one of the issues telephotos have when dealing with extremely wide field of view (for the respective zoom range).

@Jon, I doubt there is a general rule (I've never read of any other than, 1/60th and less being prone to user induced blur), Generally depends on how steady your hand is... a cup of coffee (or Tea) and it'll be 1/60th or more. I've actually taken some pic that were blur free @1/10th sec... impressed myself to say the least, but you can't depend on it consitantly. The jitters are not good when taking pics, well unless you're one of the fancy artsy fartsy types

Here are some rules of thumb on stop motion...

http://www.tpub.com/content/photography/14209/css/14209_93.htm

The most basic and neccessary to know rule of thumb for proper exposures is the 'Sunny f/16 Rule'.. here are a few links to explain that...

http://www.tpub.com/content/photography/14209/css/14209_97.htmctually

Reading this in it's entirity would give you a much better grasp of what setting will have X net effect. I grewup with a father who served in the military as a photographer and had film cameras in my blood from very early on. Altho these don't have the same attraction as years past, 99% of all apply to digital camera photography today.

Basic...

http://www.tpub.com/content/photography/14209/

Advanced

http://www.tpub.com/content/photography/14208/

[VJ]

Originally posted by Greebe
@Jon, I doubt there is a general rule (I've never read of any other than, 1/60th and less being prone to user induced blur)

In analog photography, there is a rule of thumb that suggests keeping the shutterspeed under 1/focal length. So when you are shooting with a 200mm lens , the shutterspeed should be < 1/200.
However, for digital, this changes slightly. While there isn't a concensus over the reason, it appears that digital cameras are more prone to camerashake (e.g. a D1x is more prone to shake then an F5). Some people blame the fov-multiplier, others bring into accout the grain of the film .
I'm not sure what happens when moving to digital cameras with smaller sensors, also because the cameras are different to hold.

For what it is worth, it is only a rule of thumb: I have shot sharp images at 1/10 and 85mm. (I have read the respiration technique as suggested by Az before, and it does help)


Jörg

[Greebe]

I'd believe the fov multiplier long before believing it's the grain issue. The same could be pondered with using high speed film, but has been disproven over and over again

The respiration technique has been used by pro's for ~100 years now... only being relearnt by newcomers of photography.

BTW guess I was really doing good @ 300mm fl