av and tv stop guide

[stigmundfreud]

been a long time since I used stop guides as I've become lazy but anyone got a link to chart which shows each f stop and lets you see how many stops are betwen them, same for tv too ta

[jon-]

Too lazy to google too?

http://en.wikipedia.org/wiki/F-number

1/3rd scale down the page.

ETA: http://en.wikipedia.org/wiki/F-number#Typical_one-...

Tv is just half or double.

Edited by jon- on Friday 23 October 16:44

[stigmundfreud]

Cheers, now for the old "what lens gives as close a view to the human eye"

[jon-]

50mm on 1.6 crop, 85mm on full frame (i don't actually know, I'm guessing. For all I know it could be a 10mm, but then you'd probably be a fly with that field of view.) :P

[Pete Baraka]

... and these days you can change your 'film' speed on the fly, so an ISO / stops reference chart can be useful too.

Pete

[jon-]

Pete Baraka said:

... and these days you can change your 'film' speed on the fly, so an ISO / stops reference chart can be useful too.

Pete

ISO follows the same trend as shutter speed, double it per stop so 100,200,400,800,1600 etc.

The brilliance of digital is we don't need to know all this as the camera works it out for us in semi auto, we just need to know where we want the exposure to be (Ev adjustments) and what creative style we want (DoF, motion blur etc)

[Pete Baraka]

OK I know they're an 'idiot guide' but sometimes they can be useful. I made these -



Pete

[Major Bloodnok]

stigmundfreud said:

Cheers, now for the old "what lens gives as close a view to the human eye"

One with a focal length about the same as the diagonal of the sensor/negative: 50mm on 135, 35mm on APS/C sensors, 80mm (ish - depending on exact format) on 120.

[Major Bloodnok]

BTW: doubling/halving the f number is a two-stop change (so f/2 to f/4 reduces the amount of light by a factor of four). Doubling/halving the shutter speed is a one-stop change (1/30 to 1/60 halves the amount of light).

[tim-b]

Major Bloodnok said:

BTW: doubling/halving the f number is a two-stop change (so f/2 to f/4 reduces the amount of light by a factor of four). Doubling/halving the shutter speed is a one-stop change (1/30 to 1/60 halves the amount of light).

Yep, so in terms of f numbers, 1 stop is multiplying (or dividing) by √2 - about 1.4ish.

[Major Bloodnok]

tim-b said:

Major Bloodnok said:

BTW: doubling/halving the f number is a two-stop change (so f/2 to f/4 reduces the amount of light by a factor of four). Doubling/halving the shutter speed is a one-stop change (1/30 to 1/60 halves the amount of light).

Yep, so in terms of f numbers, 1 stop is multiplying (or dividing) by √2 - about 1.4ish.

Indeed. Hence the sequence: 1, 1.4, 2, 2.8, 4, 5.6, 8 ...

[prelude4ws]

If you have an iPhone or an iPod Touch there are a couple of handy apps for this sort of thing, Photobuddy and Photocalc, which have exposure calculators as well as DoF and flash guides even sun and moon times for best light!

[LukeBird]

prelude4ws said:

If you have an iPhone or an iPod Touch there are a couple of handy apps for this sort of thing, Photobuddy and Photocalc, which have exposure calculators as well as DoF and flash guides even sun and moon times for best light!

Oooh may have to look those out!

Thanks!