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Thread started 06 Nov 2006 (Monday) 18:31
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How come, focus and f/stop issue

 
90blackcrx
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Nov 06, 2006 18:31 |  #1

How come, when I focuses on the white car the backround car is also clear ? Used an f stop of about 3.5

IMAGE: http://i3.photobucket.com/albums/y72/90blackcrx/IMG_2816.jpg

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bolantej
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Nov 06, 2006 18:38 |  #2

with a wide angle lens you get more depth of field, meaning your image will have more areas that are sharp. park that car in a feild or something and use a longer focal length and you'll get the blurred BG I think you're after.




  
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90blackcrx
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Nov 06, 2006 18:39 |  #3

Also I just noticed, my pictures seem grainy. Is this normally when shooting under low light ?

http://i3.photobucket.​com …lackcrx/IMG_281​6large.jpg (external link)

So is the car in focus, because the white car is pretty much the same depth of view ?


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90blackcrx
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Nov 06, 2006 18:55 as a reply to  @ 90blackcrx's post |  #4

See this picture looked blurry , the white car but once it was resized smaller it seemed fine. Could that be from my monitor screen causing the grainy ?

IMAGE: http://i3.photobucket.com/albums/y72/90blackcrx/IMG_2809.jpg

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crn3371
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Nov 06, 2006 18:55 |  #5

The exif info for your shot says f7.1, which is why you have a large dof. It's grainy because you shot at 1600 iso.




  
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90blackcrx
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Nov 06, 2006 18:59 as a reply to  @ crn3371's post |  #6

DAMMIT, thank you my iso keeps resetting to 1600, why.


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SD929
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Nov 06, 2006 19:00 |  #7

90blackcrx wrote in post #2226590 (external link)
See this picture looked blurry , the white car but once it was resized smaller it seemed fine. Could that be from my monitor screen causing the grainy ?
QUOTED IMAGE


Is that a b18C1 or a c5 in that pic, either way nice motor, remember racin is for the strip! :-)


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basroil
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Nov 06, 2006 19:07 |  #8

i think you should try to learn more about your camera though trial and error, as well as research on how the camera works. knowing your equipment and how to use it is important... and don't fret using high ISO, as long as you do it properly, it can be managable even in terrible lighting (overexpose by half a stop and you get cleaner pics at iso 1600 than at iso800 without the overexposure, or worse yet, half stop underexposure). don't get too many speeding tickets, they'll keep stealing money from your camera fund


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90blackcrx
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Nov 06, 2006 19:07 |  #9

SD929 wrote in post #2226611 (external link)
Is that a b18C1 or a c5 in that pic, either way nice motor, remember racin is for the strip! :-)

Not a c5, had one in a few months back though

IMAGE: http://i3.photobucket.com/albums/y72/90blackcrx/IMG_2817.jpg

3.5 f/stop, focus was at 18.0mm

I think its because my focal length, I forgot about that. Also the engine is a customers car. If I would of zoomed in, would the car in the back be more blurry ?

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unix04
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Nov 06, 2006 20:00 |  #10

^ well, keep in mind as you zoom, your lens' opening will get smaller...sorta negating the effect of longer focal length...

if you wanna play with DOF, buy yourself a 50/1.8. it's about $70! :)


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90blackcrx
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Nov 06, 2006 22:53 |  #11

unix04 wrote in post #2226838 (external link)
^ well, keep in mind as you zoom, your lens' opening will get smaller...sorta negating the effect of longer focal length...

if you wanna play with DOF, buy yourself a 50/1.8. it's about $70! :)

Yeah I know. I was not trying to get longer focal length, rather trying to get the back blurry. So would zooming in changed this?


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unix04
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Nov 07, 2006 02:10 |  #12

90blackcrx wrote in post #2227756 (external link)
Yeah I know. I was not trying to get longer focal length, rather trying to get the back blurry. So would zooming in changed this?

as a quick note... longer focal lengths and wider maximum apertures will decrease depth of field, which will give you the blur that you're looking for.

that said... zooming in would mean increasing your focal length. and when you increase your focal length, your lens' aperture will get narrower. (you'll go from 3.5 on the wide end to 5.6 on the long end). as a result, using a longer focal length wont get you the depth of field you need to blur the background.

i hope that sounds more clear to you now...


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How come, focus and f/stop issue
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