Apeture/Shutter Speed combos?

Hi Guys,

Looking to get a DSLR soon so am learning the features of my Panasonic FZ7

I have a question on aperture and shutter speed combinations.


Last night was experimenting and found that (dont quote me on numbers or values here just being theoretical)

F8 and 2.5 secs willl produce a shot
F2.8 and 1/30th sec will produce same exposure,

I assume if i go midway between the 2 then i could get same shot again

I understand that on f8 the tiny hole lets in less light hence shutter open longer, and with the hole made bigger more light so less time.

Obviously the f2.8 is easier to use handheld due to the shutter being open for less time but if using a tripod what will be the difference between these two settings??

If i upped the iso to 200 from 80 would i then be able to drop the shuuter time on the f8 due to the 'film' being more sensitive to light??


Thanks for any help to a new guy on the bandwagon

Regards

Lee

[lmaolmao]

ok, im new to this, but the way i see it, each stop of aperture lets in 1/2 or 2x the amount of light depending on if its opening or closing.

same with shutter speed. so the amount of light into the camera may be the same for the 2 settings.

BUT, a large aperture (small number?) lets in light from less than optimum angles, reducing your depth of field (the results with changing aperture i find really appealing).

so, if im correct (and im probably not), your shots will have the same exposure, but you will have different depths of field.

on iso, i think your right , increase iso -> increase sensitivity, so faster shutter speeds.

[Cadire]

I posted this link somewhere else (that I can't seem to find any more!), but it's a nice little simulator to play with this kind of stuff.

http://www.photonhead.com/simcam/

Enjoy

[onefivenine]

You're both correct.

ISO, Shutter Speed, and Aperture are inter-related.
Changing one will affect the others, and as you say, increasing the ISO sensitivity will allow you to use a faster shutter speed - good for avoiding camera shake or freezing motion.

Most cameras tend to suffer from noise once you increase beyond a certain ISO value. That's something to watch out for.

[petrolhead]

These links may help

[FONT=Arial]Apature (F number) - [/FONT][FONT=Arial]http://en.wikipedia.org/wiki/F-number[/FONT]

[FONT=Arial]Shutter Speed - [/FONT][FONT=Arial]http://en.wikipedia.org/wiki/Shutter_speed[/FONT]

[FONT=Arial]Film Speed (ISO) - [/FONT][FONT=Arial]http://en.wikipedia.org/wiki/Film_speed[/FONT]

[FONT=Arial]There is also a usefull test - [/FONT][FONT=Arial]http://www.silverlight.co.uk/tests/f_stopc.htm[/FONT]

[senu]

Sorry if this is a repeat of any info above: just skip it if it all sounds familiar

Aperture / Shutter speeds also have a 3rd variable : film speed (or in the case of digital,) ISO

Relating to exposure. And has been stated above: In film higher speed leads to grain , and in digital, noise

If you put the Camera in program AE ( I don't know if the FZ7 calls it that), turning the "wheel " will give you different combinations to get optimal exposure. bigger apertures ( lower f nos) need more critically focusing, and lower shutter speeds need steadier hands ( or a tripod once OIS is unable to cope)
Another experiment to try would be on the same scene to use aperture priority and see what shutter speed the camera selects, Use Shutter priority and see which apertures the camera selects: then use manual and select them independently: using 1 or 2 ISO values. Then review the results

You'll find them instructive: . A lot of the time the cameras on Program Mode do a good job but for creative photography it helps to know what effect adjusting one or other will have