Aperture question

I recently purchased a used 28-70 f/2.8. I was shooting deer last weekend, and granted it was getting dark out, all the pictures came out blurry. I can't post the pictures right now. My question is this, the deer was at about 40 yards, Is there a maximum range my 2.8 aperture can reach out to? Should I have been using an aperture closer to 8 or 9 since the deer were further away?

f2.8 is exactly what you would need.. you need to post a picture either with EXIF in or post the EXIF as well.. only when we see the picture and your shutter speed etc can we tell whats going on

Maximum reach has nothing to do with apeture. What was your shutter speed? That's gonna be the cause of the blurriness.

no it would not make any diffrence to the shot .
Rob.

i get the feeling your thinking dept of field at f8 /f9 would help -it would not help at 40yds as even at f2.8 you have aprox 75ft dof .
Rob.

Thanks guys. I will need to go look at what the shutter speed was at

GyRob- So your saying if the deer were over 75 ft that 2.8 would not be the right aperture?

I'm not sure if "right aperture" is the best way to look at it. All apertures can be right depending on what kind of shot you want.

Now if you have low light 2.8 may be the only aperture that will give you the shutter speed you need.

First off, there are 400mm lenses with f/2.8 apertures-- the difference between a short lens and a long lens at f/2.8 is the amount of focus depth in the image (this being the amount of front to back distance that is sharp). The longer the lens, the smaller the depth at the same aperture.

I suspect the problem you were having was that not only did you have motion blur but the deer didn't make up enough of the frame for the camera to focus well-- did they even come close to filling the frame?

cherokee01 wrote in post #4584020
GyRob- So your saying if the deer were over 75 ft that 2.8 would not be the right aperture?

I think your misunderstanding what changing the aperture actually does.. It controls the amount of light getting through the lens, and allows you to control depth of field. DoF is affected greatly by distance, but thats very different from saying you have to shoot x aperture to get a shot from y feet away. different apertures don't have different "reaches" in the way you asked in you original post.

maybe read up on some camera basics to get a better understanding?

Shutter speed is key. BTW, what ISO setting did you have your camera set to?

I remember the deer did not make up the scene. ISO was 400 to 800. Shutter speed was 1/30th.

TopGear-I know the basics, but I was just confused if Feet from "target" had any role in what aperture you should use.

Thanks everyone for your help. I also went back and read the "Going Manual" guide to get a better understanding.

Your shutter speed was too slow at 1/30. You're most likely seeing motion blur.

cherokee01 wrote in post #4584020
Thanks guys. I will need to go look at what the shutter speed was at

GyRob- So your saying if the deer were over 75 ft that 2.8 would not be the right aperture?

its a bit more complex than that as DOF changes with each lens and apeture and distance.
F2.8 would be the RIGHT apeture but so would f4 - f5.6 and f8 etc .
you need to understand the basic's by reading up on exsposure /apeture/ and shutter speed / and how ISO comes into it as it affect's all of the above .
I know it may seem very conplecated and confusing at the moment but reading about it will help .
it's just not posible to exsplain it here in a forum .
a tip on shutter speed -if your hand holding the camera with a 200mm lens aim for around 1/400sec -with a 100mm aim for 1/200sec so if you had a zoom lens such as your 24/70 and it was at 60mm set around 1/25sec alway's try to double the the lenth of the lens when you set your shutter speed this will help avoid camera shake.
Rob.

You can get a better understanding of what aperture and shutter speed will let you accomplish by checking out this Canon website. It explains it all...

http://web.canon.jp/im​aging/enjoydslr/index.​html