Fast prime lens question

Discussion in 'Photography Beginners' Forum' started by Lazy Photographer, Aug 15, 2009.

  1. Lazy Photographer

    Lazy Photographer TPF Noob!

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    Through following the forum and other resources I've been hearing a lot about prime lenses. Many seem to be fans of the 50mm F1.8 primes. So here's my question (don't laugh, I'm new):

    I've heard that a low F stop such as 1.8 will give you a very shallow depth of field. If that's the case, doesn't that really limit your use of those prime lenses fixed at 1.8? Or am I totally missing something here?
     
  2. Josh66

    Josh66 Been spending a lot of time on here!

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    It's not fixed at 1.8, that's just the maximum.
     
  3. Lazy Photographer

    Lazy Photographer TPF Noob!

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    Well that sure changes the picture (excuse the pun). I'm used to seeing lens specs list aperture range from max. to min., so I assumed the primes were fixed, since they don't list the min. Thanks for clearing that up.
     
    Last edited: Aug 15, 2009
  4. Plato

    Plato TPF Noob!

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    As you've already been told, it's not fixed. That's the maximum. However, when you do shoot wide open, it allows you to keep the subject in focus with the background blurred. The subject really pops out.

    Here are some snapshots that will give you an idea of what I'm talking about. Roughly 1/3 of the shots were taken with 50mm f/1.4 or 85mm f/1.8 wide open.
     
  5. Josh66

    Josh66 Been spending a lot of time on here!

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    The reason primes only have one number listed is because they don't zoom.

    Some zooms have a constant maximum aperture throughout the range... Many have two listed though.

    When you see two maximum apertures listed, the first one is for the wide end of the lens, the second one is for the long end.
     
  6. Lazy Photographer

    Lazy Photographer TPF Noob!

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    Thanks. Checked out the photos. Nice work.
     
  7. Lazy Photographer

    Lazy Photographer TPF Noob!

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    Thanks. I think I've got it now. One other thing: Why are folks so hot on the 50mm? I mean, that's not very wide, is it? Isn't that somewhere in the range of 75mm after the crop factor is considered? I would think something like a 20mm would make more sense, no? Of course, I realize there's likely hundreds of dollars difference between the two sizes, but is that the only reason, because they're relatively inexpensive for a fast lens?
     
  8. Plato

    Plato TPF Noob!

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    The sunrise is really beautiful. Do you have to get up early to take shots like that? ;)
     
  9. Samanax

    Samanax TPF Noob!

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    The 50 f/1.8 is inexpensive and you can use it for low light situations, when you want a shallow DOF (to isolate the main subject from the background) and it's also used as a portrait lens by some. It's just a nice focal length to have.
     
  10. Lazy Photographer

    Lazy Photographer TPF Noob!

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    I assume you're talking about the photo I posted on my blog. Yeah, that was indeed EARLY. Got up for a piss around 5 and next thing I know I'm in my car heading for the hydro corridor. It was dark when I started. Took like 200 shots over the course of an hour. It was fun. You can check out the four photos I originally posted that morning here. Thanks, by the way.
     
  11. Lazy Photographer

    Lazy Photographer TPF Noob!

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    Yeah, I guess. I usually like wide angle stuff so for me it would probably not be wide enough. Something fast that zooms would be nice, like 20mm-60mm. I got a feeling it don't come cheap.
     
  12. TUX424

    TUX424 TPF Noob!

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    For that you are looking at a 24-70 f/2.8, they range from $600-$1700.
     

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