F-STOPS EXPLAINED

Shooter · **Joined:** Thu Aug 14, 2008 3:50 am **Posts:** 49

Could you explain f-stops for me, from f32 all the way down to f1.4 inclusive of their equivalent shutter speeds? For example: f16 @ 1/250 is the same as (what). How do you work this out? Is there a formula?

Also, could you tell me how ISO works on digital cameras. What makes it more sensitive to light by changing the ISO numbers? And lastly,

Could you also explain (stopping-down or step down )and why is there a stop-down button on most cameras?

geofflaw · **Joined:** Sun Dec 23, 2007 8:03 am **Posts:** 1445

That's why I write tutorials.

http://www.geofflawrence.com/photography_tutorial_shutter_speeds_and_apertures.php#aperture

http://www.geofflawrence.com/photography_tutorial_ISO_film_speed.htm

Shooter · **Joined:** Thu Aug 14, 2008 3:50 am **Posts:** 49

Your tutorial only explains aperture and shutter speed, but not what I asked you in my last post.

Shooter · **Joined:** Thu Aug 14, 2008 3:50 am **Posts:** 49

Check out this web site: It gives an in-depth explanation on f-stops, shutter speeds and ISO, and their equivalents.

photonhead.com/simcam/filmspeed.php

geofflaw · **Joined:** Sun Dec 23, 2007 8:03 am **Posts:** 1445

I don't really understand what you want, apertures and f-stops are the same thing. Anyway I'm glad you've found something you like.

Shooter · **Joined:** Thu Aug 14, 2008 3:50 am **Posts:** 49

Geoff,

I hope you are not angry with me from what I said in my last post about F-stops. I only wanted to know if there was a formula in determining f-stops with shutter speed. For example, if I am shooting at f 16 with a shutter speed of 1/250 and I need to blur the background, what aperture or shutter speed should I use?

The photonhead simcam website that I posted was able to explain it to me in detail. If you go to that website and click on simcam, you can actually take shots with different apertures and shutter speed and you will see what the exposure will be like. From this I was able to understand f-stops fully.

You see I used to work in a darkroom and when I was processing film, I knew what overexposure and underexposure meant, but ever since buying myself a camera, I was a little confused with those two words, only to realize it was the reverse of the darkroom procedure. For example, when you overexpose a print in a darkroom, it comes out dark, but with a camera, the picture comes out bright, and that what was confusing me.

So please don't be angry with me from my last post. I am here to learn! Forgive me?

geofflaw · **Joined:** Sun Dec 23, 2007 8:03 am **Posts:** 1445

No problem, glad to hear you got it sorted out.

Shooter · **Joined:** Thu Aug 14, 2008 3:50 am **Posts:** 49

Is there a short formula one can use in working out aperture, shutter speed and ISO?

Keith201 · **Joined:** Wed May 02, 2012 6:17 am **Posts:** 5

You will probably find all the information you are looking for at

"The Ultimate Exposure Meter"

http://www.fredparker.com/ultexp1.htm

F-STOPS EXPLAINED

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