fast glass question

Discussion in 'General Shop Talk' started by kellylindseyphotography, May 6, 2008.

  1. kellylindseyphotography

    kellylindseyphotography TPF Noob!

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    I've been looking at my next investment which will be a new lens, probably the 2.8 one. I have some questions that have probably been asked a zillion times but for the life of me can't find what I need to know while doing a search on it...

    2.8 and 1.8 are wonderful if your shooting macro and low light.. but how often do you REALLY go that low? Especially if you are shooting a moving subject and not using a tripod? (think: toddlers) With the razor thin depth of field, will this lens be to my advantage?

    If not, what lens should I go for? Right now, I just shoot with the kit lens. It goes to 3.5 but I never go that far open.
     
  2. Big Mike

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

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    Actually, when shooting macro, you usually want to use a smaller aperture (higher number), in order to get a deeper DOF...because being so close will usually make it thin.

    A 'fast' lens (large max aperture) is good because it allows you to get a faster shutter speed than a slower lens. So if you are shooting a fast moving subject...you probably want to freeze the movement and you need a faster shutter speed to do that.

    F2.8 lenses don't usually have 'razor thin' DOF...so it's not usually a worry about getting your subject in focus. The shutter speed is usually a bigger concern, and that's where 'fast' lenses can help.

    Large apertures also give you the option to have a shallow DOF. You don't have to take advantage of that, if you shoot with smaller apertures...but at least you have the option.

    Lastly, a larger max aperture will let more light into the lens when you are looking through the viewfinder....so it's a brighter image and AF might work better. Actually, some cameras have special AF sensors that are only useful with F2.8 or faster lenses.
     
  3. JIP

    JIP No longer a newbie, moving up!

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    A lens being a faster lens or having a 2.8 or 1.8 max aperture has nothing to do with the aperture you are going to use. Generally the maximum aperture is going to be a measure of he overall quality of a lens. If a lens is a 2.8 lens the glass is going to be larger and usually of a better quality and it will be made to more exacting standards and to boot all the other things the other people mentioned will be there to.
     
  4. kellylindseyphotography

    kellylindseyphotography TPF Noob!

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    Thank you both very much, you answered my question exactly!
     
  5. That One Guy

    That One Guy TPF Noob!

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    a good lens that is very sharp, great in low light and an upgrade from the kit is the 50mm f1.8. while not a zoom, it is a great lens to have. honestly i don't miss the zoom function when using that lens. it sells for around $85 i think.
     
  6. That One Guy

    That One Guy TPF Noob!

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    one more thing. after you use that lens^^, next stop is the L series and believe me once you use an L you won't want anything else.
     
  7. ukreal1

    ukreal1 TPF Noob!

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    I love my 50mm 1.8, I couldn't afford the extra $200 for the 1.4 but I am fie with mine, ust did a model shoot the other day and very happy with the results...
     

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