Time for a question about infrared

Discussion in 'Photography Beginners' Forum' started by shorty6049, Apr 13, 2007.

  1. shorty6049

    shorty6049 TPF Noob!

    Joined:
    Mar 8, 2007
    Messages:
    1,906
    Likes Received:
    1
    Location:
    Minnesota
    Can others edit my Photos:
    Photos OK to edit
    So i have been trying my hand at IR photography lately, and i've heard of this problem as well as experienced it. When taking photos, i usually use a fairly long exposure. i usually end up getting a slightly over-exposed area in the center of the frame. A lot of people attribute this to the lens you use. I dont know if i believe that or not, i was wondering though, could this be from light getting in the back of the camera through the viewfinder that i forgot to cover?
     
  2. bytch_mynickname

    bytch_mynickname TPF Noob!

    Joined:
    Jun 4, 2006
    Messages:
    303
    Likes Received:
    0
    What lens are you using?

    When I use my kit lens, I get some lens flare in the center but if I use my 50mm, I don't have that problem.
     
  3. shorty6049

    shorty6049 TPF Noob!

    Joined:
    Mar 8, 2007
    Messages:
    1,906
    Likes Received:
    1
    Location:
    Minnesota
    Can others edit my Photos:
    Photos OK to edit
    i'm using the kit lens, but i've also tried the 50mm and i think i had the same problem, The problem i have, is that i dont want to be buying multiple filters or step-rings. I was just wondering if having the cover off the viewfinder would contribute to it, because i never really thought about it until the other day. I'd try it but my friend borrowed my camera till tomorrow, so maybe i'll try it when i get it back
     
  4. fightheheathens

    fightheheathens TPF Noob!

    Joined:
    Aug 1, 2005
    Messages:
    1,011
    Likes Received:
    3
    Location:
    Berkeley
    Can others edit my Photos:
    Photos NOT OK to edit
    This is a problem anytime you shoot IR. IR is a different wave lenght then the light we see, hence the focus shift when shooting B&W IR.
    Basically lenses are not optimized to shoot IR and tend to get hot spots in the center. This has to do with the way the glass bends the light/focuses it near the edge of lens. Its sort of the same principle as to why a lens is sharper all over stopped down then when wide open. Ive seen the problem on every lens i have ever used to shoot IR though on some its less then others...on my 50mm pentax it was only noticable if the shot was incorrectly exposed or you looked at it a really long time...

    there is nothing you can do short of stopping down some, finding a lens specifically for IR use (good luck) and just trying different lenses.

    i hope this helps
     
  5. Digital Matt

    Digital Matt alter ego: Analog Matt

    Joined:
    Jan 30, 2004
    Messages:
    5,346
    Likes Received:
    65
    Location:
    Santa Barbara, CA
    Can others edit my Photos:
    Photos NOT OK to edit
    I'm a Canon user, so I can't tell what you lenses to use, but I can tell you that it is definitely from the lens. I use the Canon 50mm f/1.8 and there is absolutely no hotspot. There are several lenses that work well, and many that don't. It's a lot of trial and error. You can probably find info via Google as to what lenses will work well.
     

Share This Page

Search tags for this page

over exposed center in infra red long exposure