50mm f1.8 - am I an idiot??

Discussion in 'Photography Beginners' Forum' started by nemophotos, Sep 21, 2009.

  1. nemophotos

    nemophotos TPF Noob!

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    I'm NOT a professional photographer - nor do I want to be - I just want to take good photos of my new baby.

    I borrowed my friends 50mm f1.8 lens the other day and when I shot with it - I was thinking - this isn't really much different than my 18-55mm lens.

    Then when I went back and looked at my photos - I noticed NOTHING was shot at f1.8 - and it hit me - was I supposed to manually crank the aperture? I assumed it would automatically set to f1.8 because I thought it was fixed... but now I'm guessing maybe not.

    So am I an idiot??? Did I just totally miss out on it? I may have to borrow it again so I can use it CORRECTLY.

    I'd love for someone to let me know if I was SUPPOSED to manually crank the aperture to f1.8 or if it was supposed to know.

    Sorry - i'm a total noob.
     
  2. Samanax

    Samanax TPF Noob!

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    What shooting mode were you using?

    If you want to use f/1.8 you have to either shoot in Av (aperture priority) or M (manual) and set the aperture value to f/1.8.

    If you're shooting on AUTO or P the camera will decide what exposure settings to use (aperture, shutter speed and ISO).

    What camera are you using?
     
  3. PhotoXopher

    PhotoXopher TPF Noob!

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    It doesn't default to f/1.8, necessarily. An f/1.8 lens has an maximum opening of f/1.8 but can go down to f/22 (for example) as well.
     
  4. jbylake

    jbylake Dodging the Men in Black Supporting Member

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    It would help greatly if you:
    Tell us what F/stop you were shooting
    What kind of camera
    Film or Digital (I'm assuming digital)
    If Auto mode film, or digital...what mode?

    No, you're not an idiot..I'd say that anyone on this site has either goofed, badly, at least once, or fibs alot.;)

    If digital, do you have a "photoshop" type of editing software?
    Sometimes you can salvage a poorly taken shot, if you're good with the software. I'm not that good with it, but I've seen others do miracles with it (photoshop, gimp, etc..).

    Hope it all works out ok...

    J.:mrgreen:
     
  5. nemophotos

    nemophotos TPF Noob!

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    Sorry - Yes, shooting digital with a canon digital rebel.
    Yes, I was shooting in manual
    And that makes sense about having to SET it to 1.8 - I think it was still "stuck" in 4.5 from the other lens I was using.

    And I'm not worried about salvaging the shots - they weren't bad - just not as blurry in the BG as I wanted. I was just playing around with it to see if it was what I wanted for a new lens. But now I'm ticked that I didn't get to test it out to it's full ability. guess I need to borrow it again hehe.

    Thanks all!!
     
  6. Big Mike

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

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    The F number in a lens's name is it's Maximum aperture...meaning that you have the option to use that aperture...but with most lenses, you can also use smaller apertures as well.

    In auto modes, the camera won't necessarily use the max aperture...not unless the light levels start to get low. One of the biggest advantages of lenses with a large max aperture, is that when the light does start to get low, you can use a larger aperture....which means that you can get a faster shutter speed...and a faster shutter speed will probably mean less motion blur in your images. That's why we call these 'fast' lenses.

    Of course, if you use Av or M modes, you can manually set the aperture value to what you want. In Av mode, the camera will automatically give you the shutter speed to match the aperture you have chosen, for the light that you are in.

    Even when shooting at F5.6, if you look closely, you should notice that your 50mm lens performs better than your 18-55mm lens. This is partially because the 50mm is a prime (non zoom) lens, so it's optics are very simple and thus can easily give you great results. Zoom lenses are more complicated, so the cheaper ones tend to be less than spectacular.
    Also, it's typical that most lenses don't perform their best at their maximum aperture. So at F5.6, the 50mm lens is about three stops down from it's maximum, which should put it right in the sweet spot. The 18-55mm lens (at 55mm) is right at it's max at F5.6, which is where it will be at it's worst.
     
  7. flyin-lowe

    flyin-lowe TPF Noob!

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    I am a noob as well and I just got a 50-mm 1.8. I had time to go out and shot about 15 shots with it real quick after I got it. From my very limited experience depending on what type of picture you plan on taking I don't think you would want it cranked down to 1.8 if you are doing just a protrait type shot and the lighting is decent. If you want a close up of the feet or hands or something you might. I set up a little statue on my deck rail and started at 1.8 and went up from there taking the same shot over and over going up one step at a time. I was a couple steps above 1.8 before those pics looked decent and the entire statue was in focus. Again it totally depends on what type of shot you are going for and the lighting.
     
  8. TJ K

    TJ K No longer a newbie, moving up!

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    It's fixed at 50mm not at f/1.8. You have to set that by either using manual or aperture priority mode. You can change the aperture on the 18-55 as well but it doesn't do it on its own unless you put it in auto mode.
     

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