A Few Questions

Discussion in 'Photography Beginners' Forum' started by AdamBomb, Nov 26, 2008.

  1. AdamBomb

    AdamBomb TPF Noob!

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    Hey Guys, I've been out shooting quite a bit lately, and I'm kinda confused about some things. I'm trying to get 100% comfortable with Full Manual.

    1. I was out behind my work and snapped a shot of this box, and I couldnt get the background to go OOF. What do I need to do different? I was going for a pretty drastic DOF, Which I didnt get.

    1/500 f4.5

    [​IMG]




    2. Why did the Plants turn out like this? Too Slow of a shutter speed?

    1/25 f25 ISO200

    [​IMG]




    3. Would you do anything different to this one? Focus more towards the middle?

    1/200 F4.5 ISO200

    [​IMG]
     
  2. William Petruzzo

    William Petruzzo TPF Noob!

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    1. The depth of field is affected by your aperture. At f/4.5 you're not going to get things really dramatically out of focus. Unless they're much earlier in your focal range. At the distance you shot the box, you will probably need something more like f/1.8 or f/1.4, but even then, it won't be dramatically out of focus.

    2. I actually can't really see a problem with the plants. But, 1/25 is probably too slow, if you see a bit of motion blur up close, that's you're problem.

    3. I would have focused closer to the middle. But that's not a rule. It's actually not a bad picture.

    Keep up the good work.
     
  3. bigtwinky

    bigtwinky No longer a newbie, moving up!

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    What distance were you from the box / what focal lenght were you using on your lens?

    There are 3 things that will affect the DOP

    1- distance between you and the subject. The greater the distance, the fuzzier it will be (so using 50mm focal lenght or backing up and using a 125mm will net a difference)

    2- distance between the subject and the background. The greater the distance, the fuzzier the background.

    3- the apeture setting. The wider the apeture, the fuzzier the background. 4.5 isn't huge. You would probably see a difference if you shoot at 1.8 or 2.8


    For the out of focus flowers, a rule that was told to me by a teacher is that to avoid camera shake, make sure your shutter speed is at least 1 over your focal lenght. So if you are shooting with a 50mm focal lenght, your shutter speed should be at least 1/50 (or the closest equivalent). If you are shooting with an 18-200mm zoom lens, you should keep the shutter speed at at least the longest focal lenght, so that would be 1/200.

    At 1/25, that does seem kinda slow. You are aiming for a good depth of field at f25, so everything would be in focus. The smaller the apeture (or higher f#), the slower the shutter speed. You can try dialing that down to an f16 or so, which should help with the shutter speed. Or, when doing landscapes, use a tripod with a remote shutter or the camera's timer.


    For the logs, I think the DOP is ok. You could chose to focus on the middle and not have the foreground in focus, thats personal taste. I don't like the stuff on the ground personally. Maybe a tighter crop or only having logs with no ground? I dunno. Composition is something I need lots of work on myself.


    **disclaimer... I am a photo noob. I am learning alot, but some stuff may be a bit off. If anything is, please correct me.
     
  4. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    DOF is controlled by a few things. First is the lens aperture, a bigger aperture will give you a smaller DOF. You were at F4.5, which is probably the max or close to it for your lens...so that was right. Part of the trouble is that F4.5 really isn't all that large of an aperture. F2.8 or F1.8 etc would really help here, which is one reason why people shell out for lenses with large max apertures.

    Secondly, the focal length also controls DOF. The longer the lens, the more shallow the DOF can be. It looks like you may have been at a wider focal length. So try zooming out.

    Also, the distance to the subject will control the DOF. The closer you are to your subject, the shallower the DOF. And of course, the farther away the background (or foreground) is, the more out of focus it will be. In your shot, you can see that it gets more out of focus as you go down the street.


    Turn out like what? They aren't totally sharp, is that what you mean? If you were hand holding the camera, then yes, the slow shutter speed probably contributed. Even if you were on a tripod, the wind may have moved the plants during the exposure. Also, there will be some distortion when you use an extremely small aperture like that.

    That's a personal call, do whatever you think works best. Better yet, try it several different ways and then choose the best one when you get back to your computer. I like it way you have it, with the sharpest parts as the closest...and letting it run out of focus as it moves away from us.
     
  5. AdamBomb

    AdamBomb TPF Noob!

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    Thanks for the Replies. Yes, this kit lens only goes up to 3.5. So to get a deeper DOF, I should try keeping the focal lengths at a minimum (18 mm for my lens) and F/3.5?


    Focal Lengths:

    1. 40 mm

    2. 40 mm

    3. 38 mm
     
  6. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    That's only at the wide end of the zoom. When you zoom out, the max will drop to F5.6.

    Not quite. A deeper DOF means more area in focus (the opposite of what you were going for in #1)...which you can get by using a wider focal length...but using a large aperture like F3.5 will give you a shallower DOF. So if you want the background to be out of focus (Shallow DOF) then use a large aperture (small F number). If you want a deep DOF, then use a small aperture (large F number). The focal length should be secondary to aperture when controlling DOF.

    Your camera probably has a DOF preview button...which allows you to see through the lens with the aperture stopped down to it's set value.
     
  7. AdamBomb

    AdamBomb TPF Noob!

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    Oops, I meant deeper like, "Drastic." :lol:
     
  8. AdamBomb

    AdamBomb TPF Noob!

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    So, It must be the my lens' capabilities, I Took this one at 18mm, F3.5, ISO200, and 1/1000. Still Not getting the Shallow DOF that I want! Time for a Nifty 50?

    [​IMG]
     
  9. AdamBomb

    AdamBomb TPF Noob!

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    Anyone?
     
  10. OldClicker

    OldClicker TPF Noob!

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    Set it on Aperture Priority set at the lowest f-stop. Set the ISO to get a usable shutter speed (i.e. 1/125 sec or less if hand held). Use the lens at 105mm. Stand at the minimum focus distance of the lens and focus on one of those spots of fungus on the bark on the side of the tree with the background as far away as possible. - TF
     
  11. Harmony

    Harmony TPF Noob!

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    Yes! Yes! Go for the fifty!
     
  12. Jim Stafford

    Jim Stafford TPF Noob!

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    Like Old Klicker said, use the zoom, you can get the hort depth of feild you want by getting to the long end of your zoom. Get away from the 18mm and get out to the 105mm
     

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