DOF question...

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simple question, does my DOF get smaller the more I zoom?
 

Helen B

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If you stay in the same place, focus on the same object and keep the same aperture then yes. The longer the focal length, the smaller the depth of field (if focus distance, aperture and format are kept the same).

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Helen
 
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If you stay in the same place, focus on the same object and keep the same aperture then yes. The longer the focal length, the smaller the depth of field (if focus distance, aperture and format are kept the same).

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Helen

so not just my zoom, but my physical distance from the subject matters? of course understanding I'm using an open aperature f/2.2
 

Helen B

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so not just my zoom, but my physical distance from the subject matters? of course understanding I'm using an open aperature f/2.2

Yes, the greater the distance, the more depth of field. If you balance zoom and distance so that the object stays the same size in the viewfinder the depth of field stays the same for close objects.

As the object you are focusing on moves further away the more you tend to get greater depth of field with a wide angle lens than with a longer lens. In technical terms as you approach the hyperfocal distance of the wide angle lens, the wide angle has more depth of field.

What zoom lens do you have that has a constant aperture of f/2.2?

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Yes, the greater the distance, the more depth of field. If you balance zoom and distance so that the object stays the same size in the viewfinder the depth of field stays the same for close objects.

As the object you are focusing on moves further away the more you tend to get greater depth of field with a wide angle lens than with a longer lens. In technical terms as you approach the hyperfocal distance of the wide angle lens, the wide angle has more depth of field.

What zoom lens do you have that has a constant aperture of f/2.2?

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Helen

I don't, I'm just starting out with a prosumer camera. The lense in a 38mm to 380mm. The fstop actually starts at f/2.8 and just the slightest zoom it drops to f/3.2. I'm trying to get a picture of my cat where the DOF is very small ( and maybe I can't with this cam ), but I want a picture of him where his head is clear, but the better part of his body is blurred out....I'm guessing I sould stay back and zoom in on him?
 

ann

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with that lens you lose the 2.8 as you zoom out.
 

Big Mike

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Also, I'm guessing that your camera is one that has a very small sensor (like 99% of non SLR digital cameras). This makes it hard to get a shallow DOF.
 

jasonkt

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I was wondering about that, all I have to learn on is a P&S (still a second job away from my first DSLR) and while I can take photos I like, I can't recreate the sharp subject/blurry background effect well unless I'm shooting macro. At first I thought it was a lack of understanding the concepts on my part, but I'm beginning to realize it's probably my limited range of settings, is that correct? (fujifilm s5100)
 

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