Apeture Rule Of Thumb

[Photoman65]

I am new to Photography and would like to know the rule of thump for apeture control in particularly low light conditions. Shooting in low light often result in many images becoming blurred. What are some techniques to resolve this problem with aperture control. Is shooting in 2.8 apeture good for low light vs 5.6. How does a 5.6 or 11 affect shooting in low light? Also, how is apeture control managed based on distance from subject. I can use an experts advice here.:cry:

[perfect_pixel]

Hi Photoman,

The larger your aperture (smaller number) the more light the lens lets through to the sensor. Conversely the smaller the aperture the less light is let through.

Your shutter speed determines how long the sensor is exposed to the light the lens is letting through.

In low light you therefore need either a large aperture or a slow shutter speed to ensure that the picture is not underexposed (i.e. too dark).

The aperture does not directly influence how far you are from the subject however the larger the aperture the smaller will be your depth-of-field (i.e. the range of objects at different distances from the focus point that are in focus). With a very large aperture of say 1.4/1.8 you will have a very small depth of field. If you close the aperture down to 5.6 this will give a greater range which is in focus.

The third thing to consider is your ISO speed. ISO is very basically how much detail is recorded. A high ISO speed will record less detail (higher 'noise') but allow you to use a faster shutter speed.

Best bet is to put your camera on Av mode and experiment with what aperture is suitable for whatever you are shooting. If you cannot hand hold at your fastest possible shutter speed then use a tripod.


Steve

[deadpass]

I know someone is going to recommend that you read "understanding exposure" I can't remember the author, but anyone else on here should. The smaller the aperature(or higher f/ number) the more light you'll need to expose the same shot if everything else is the same. Using a high ISO setting, with a larger aperature(lower f/ number) and as slower shutter speed will give you the ability to shoot in the lowest light situations possible without using a flash.

crap perfect pixel, ya beat me by less than a minute!

[perfect_pixel]

crap perfect pixel, ya beat me by less than a minute!


:p:p :lol:

[kevin_c]

I know someone is going to recommend that you read "understanding exposure" I can't remember the author, but anyone else on here should. The smaller the aperature(or higher f/ number) the more light you'll need to expose the same shot if everything else is the same. Using a high ISO setting, with a larger aperature(lower f/ number) and as slower shutter speed will give you the ability to shoot in the lowest light situations possible without using a flash.

crap perfect pixel, ya beat me by less than a minute!

'Understanding Exposure by Bryan Peterson' - just go to Amazon.com/co.uk etc. and search, you'll find it - Well worth the money IMO

[Photoman65]

Thanks for the details everyone. I'll try these techniques.

[Hermeto]

Try this two links:

http://www.canon.co.jp/Imaging/enjoydslr/p_2_006.html

http://www.canon.co.jp/Imaging/enjoydslr/p_2_007.html

[tekkie]

Hey guys another new guy, I got my Rebel XT camera a couple weeks ago and its my first DSLR so still trying to get the hang of things. I had a Canon G5 before this but I never really fooled around with the manual settings to much.

Hermeto thats a great link, I have read many things over the past few weeks and that link is a very "user friendly" version that I will be going back to :)

[slyone]

I too find myself shooting mostly low-light conditions, don't even bother with anything above 2.8 for those conditions. 2.8 or better/faster/lower f/#, might want to get the nifty-fifty which is a fixed length 50mm f/1.8 which is very cheap(inexpensive $75.00) to mess around with at first.

[perfect_pixel]

You could also look at a hotshoe flash speedlight/sigma etc. which would help...


Steve

[Bill Ng]

Your answer lies here ....

http://photography-on-the.net/forum/showthread.php?t=249006

Bill

[soileauj]

I found this on an earlier post:

http://www.morguefile.com

[Pekka]

I would like to give a simple view on this, how I see it:

The primary consideration when talking about aperture should artistic. You choose the aperture which combined with the focal lenght produces the required depth of field, a DoF that you need to get the look and subject separation/depth needed. Aperture is primarily a compositional element.

Do not choose aperture based on lens sharpness curve. Do not choose the aperture based on someone elses images. Do the choice of aperture for each image first and foremost based on what your image, your sense of composition, look and needs dictate. After that you may have to compromise with ISO and fight with shutter speeds (tripod, monopod, change aperture) but that is only by consequence.

Choice of aperture is very much tied to focal lenght. That is why those two should never be separated in discussions.

[strmrdr]

I would like to give a simple view on this, how I see it:

The primary consideration when talking about aperture should artistic. You choose the aperture which combined with the focal lenght produces the required depth of field, a DoF that you need to get the look and subject separation/depth needed. Aperture is primarily a compositional element.

Do not choose aperture based on lens sharpness curve. Do not choose the aperture based on someone elses images. Do the choice of aperture for each image first and foremost based on what your image, your sense of composition, look and needs dictate. After that you may have to compromise with ISO and fight with shutter speeds (tripod, monopod, change aperture) but that is only by consequence.

Choice of aperture is very much tied to focal lenght. That is why those two should never be separated in discussions.

Well said.
Chose the aperture based on focal lenth and how you want the shot to look then adjust everything else as needed to get the shot.

What I used to like to do is set the shutter speed to the min. acceptable for me in that situation (handheld, tripod, stop motion, whatever) then when I pick the aperture, I knew if it was going to work with a glance at the meter.
If its over exposed adjust the shutter up to bring it into the right combo.
If it was underexposed at that speed then with film I had no choice but to select another f-stop but with digital Id try a higher ISO first and if I couldn't get it with an acceptable ISO then id change the f-stop.

With digital my baseline would be the lowest ISO and the slowest shutter speed for the situation.
Where with film the ISO was fixed and the shutter speed at the slowest for that situation was my baseline.

With experence you will know where to set it for different situations and can change your baseline but by goint back to your basic baseline at first it gives you a clean starting point.

[strmrdr]

my min. shutter speeds. no IS no flash

Non moving object handheld 1/focal lenth is a good start I could hold 1/.75 x focal lenth back then usualy.

slow moving object (person walking) 1/focal lenth 1/125 min
fast moving object(person running) 1/focal lenth 1/250 min.