Help! Night shots w/ Rebel XTi.

Discussion in 'Digital Photography' started by jwt, Jul 21, 2007.

  1. jwt macrumors 6502

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    #1
    I'm having trouble taking night shots with my new Rebel XTi/18-55. Under the automatic portion of the wheel, using landscape, no flash, and night portrait, the exposure times are long and I can't avoid camera shake. In addition, the photograph ends up being much brighter than the actual conditions. I've been playing with the advanced portion of the wheel, adjusting shutter speed and ISO, and I'm getting close, but even with the ISO maxed at 1600 the exposure time is still too long, resulting in camera shake. I'm willing to put the time in to learning how to take these shots, but the thing I don't understand is that my point and shoot Powershot A70, set to full auto with the flash disabled gets it right the first time with a fast shutter speed and no camera shake. I don't understand how a camera with a much smaller lens and aperture can take better pictures in low light. I need helpful suggestions, please.
     
  2. JHacker macrumors 6502

    JHacker

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    #2
    First, you should be using a tripod for these shots.

    Second, if the lighting IS actually enough for a night shot that would get you a shutter of at least 1/60, you're going to need a lens with an aperture of f/1.8 or f/1.4. Even with this, you probably won't get a fast enough shutter and will still need a tripod.
     
  3. Kamera RAWr macrumors 65816

    Kamera RAWr

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    #3
    Why not use a tripod. If you're shooting with a camera like a Rebel, meaning more than just a P&S, you should be able to afford a tripod. You'll get sharper results with it no matter how high your ISO is with hand held shots. :)
     
  4. adrianblaine macrumors 65816

    adrianblaine

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    #4
    They're right. The only thing that can help significantly is a tripod. I've used tops of trash cans, and cars as well. Find anything steady to set it on.

    A good rule of thumb for hand-holding shots is to never get the shutter speed below your focal length. It's a little more complicated with a digital rebel because you have to multiply by 1.7... for example:

    if you are shooting at 18mm (x1.7)=30.5

    this means you most likely won't be able to hold a steady shot for anything less than 1/30
     
  5. swiftaw macrumors 603

    swiftaw

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    #5
    I presume you mean more than (longer than) 1/30
     
  6. adrianblaine macrumors 65816

    adrianblaine

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    #6
    You are correct.

    It's probably a bad habit I learned a long time ago....
     
  7. seenew macrumors 68000

    seenew

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    #7
    In addition, you might want to purchase a cable release. You shake the camera more than you might think when you hit the shutter button.
    http://www.amazon.com/Adorama-Digital-Remote-Release-Cable/dp/B000F5PKRS/

    I also found that when I used the IR remote for long exposures at night, there was significant pink splotching in the top and right side of the photos, presumably from the infrared light emitted or received from the camera. Particularly noticeable when shooting longer than 30s. The cable release fixed that.
     
  8. ChrisBrightwell macrumors 68020

    ChrisBrightwell

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    #8
  9. jwt thread starter macrumors 6502

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    #9
    I guess I was wrong about the comparison of aperture sizes. It turns out my powershot has a aperture of f/2.8. That explains why it does better in low light. Since my Rebel's 18-55 lens has a max aperture of f/3.5, that means I need a (3.5/2.8)^2 = 1.56 longer longer exposure time, right? So if the powershot requires 1/8 to take a picture, the 18-55 needs 1/8*1.56 ~ 1/5.

    Also, you guys are talking about exposure times of fractions of a second. My Rebel is taking anywhere from 2-10 seconds in dim indoor lighting, using the automatic settings. That just doesn't seem right to me.
     
  10. Doylem macrumors 68040

    Doylem

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    #10
    New lens?!? Nah... All you need is a tripod and cable release. Then you can go with the lowest ISO, for the best definition... and choose whatever aperture/shutter speed combination you want. 30secs at f22? No problem...

    I shoot a lot of pix after the sun's gone down, but while there's still a bit of colour in the sky. The camera's easily fooled in these rather extreme lighting conditions. So I use a tripod, take a couple of test shots, review the shots, adjust the exposure... till I get what I want.

    Without a tripod, you're always compromising. With a tripod, you're in charge...
     

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  11. ChrisBrightwell macrumors 68020

    ChrisBrightwell

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    #11
    With a 25-second exposure at f/13 (according to the EXIF data on that attached shot), you're at the whim of every single thing in that frame to stay still and/or not shine a light in your face.

    With an aperture value of f/1.8, you could use roughly 1/4th of that time (a 6-second exposure) and, by adusting to ISO 400 or ISO 800 from ISO 100, you almost have a shot that you can hand-hold pretty easily. ISO 1600 at f/1.8 gives you a shot that you can hand-hold.

    There are times when a super-narrow aperture (say, f/22) and a tripod make sense, but there are other times when being able to hand-hold an f/1.8 lens makes more sense.

    Besides ... for $75, what do you have to lose?
     
  12. Doylem macrumors 68040

    Doylem

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    #12
    Yes, a long exposure can be 'interrupted' by lights, cars, etc. Sometimes these are effects are wanted, sometimes not. But with a tripod I'm still in control of the result... even if the solution to the problem of extraneous goings-on is merely to take another shot.

    And, yes, you can push up the ISO, widen the aperture and lower the shutter speed to what can be hand-held. But I rather like the slight inconvenience factor of a tripod, 'cos it makes me put a bit more thought into each picture. Each to theit own, I guess... :)
     
  13. ChrisBrightwell macrumors 68020

    ChrisBrightwell

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    #13
    I totally understand that and, to an extent, agree. My point, however, was this: There are some shots (dare I say, a vast majority of the night-time shots I take) that are simply impossible with anything other than my 50/1.8 or a similar lens.

    In fact, I've had the 50/1.8 struggle enough with dragging shutters that I've contemplated selling it for a 50/1.4 or something similar.

    Different styles of photography, obviously, but a tripod and shutter release aren't a one-size-fits-all solution. That's all I'm saying.
     
  14. Doylem macrumors 68040

    Doylem

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  15. adrianblaine macrumors 65816

    adrianblaine

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    #15
    If you are hand holding in low light, then you are going to have to switch away from automatic mode. Sometimes you just have to override it.

    Put the camera in Tv mode and scroll the wheel until you get to 1/30 of a second. The camera will then choose an aperture (and if it is dark, it will open it all the way up). If the picture turns out too dark, try other ISO settings. If it still looks like crap, then you are either going to have to get a different lens or use a tripod for what you want to do.

    Just remember, if you shoot at 1/30, you are going to have to be zoomed all the way out. The further you zoom in, the faster the shutter speed will need to be.
     
  16. form macrumors regular

    form

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    #16
    I almost always use Manual mode. Set the lens to its widest, 18mm (reduces the effect of camera shake), set to minimum aperture, f/3.5, set to ISO1600, set your shutter speed to what the metering system thinks is adequate, brace yourself against a solid object, and use burst mode to increase your chances. Alternately, if the subject is close, use the popup flash. If this isn't enough, set your camera on a solid object or a tripod.

    If you don't want to use a tripod, get a faster lens or a more powerful flash. The 50mm f/1.8 gathers plenty of light (8x more than your kit lens), but when wide open, its contrast is low.

    There is a reason the kit lens is inexpensive; it doesn't make everything easy.
     
  17. arogge macrumors 65816

    arogge

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    #17
    The camera is probably metering off of the dark background. You need to use spot metering.
     
  18. jwt thread starter macrumors 6502

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    #18
    I know I'm a novice, but isn't the calculation for this, (3.5/1.8)^2 = 3.7, not 8? Please correct me if I'm wrong. I'm eager to learn.
     
  19. seenew macrumors 68000

    seenew

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    #19
    3.5 opening one (full)stop to 2.8 = 2x light
    3.5 opening two (full)stops to 2.2 = 4x light
    3.5 opening three (full)stops to 1.8 = 8x light

    it's squared with each full stop. I hate half stops. They're the devil.
    and I hate hate hate the one-third stop system on the Rebels. f/3.5 sucks.

    easy to remember, each full stop change will either double or half the amount of light reaching the film or sensor.

    f/0.5, f/0.7, f/1, f/1.4, f/2, f/2.8, f/4 f/5.6, f/8, f/11, f/16, f/22, f/32, f/45, f/64, f/90, f/128.
    (in order from open to closed) it is near impossible to find lenses in the extremes of both ends (ie f/1 or f/128). Kubrick did use f/0.7 in filming a scene lit by candles in Barry Lyndon.
     
  20. miloblithe macrumors 68020

    miloblithe

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    #20
    f/3.5 to f/2.8 is 2/3 of a stop. F/2.8 to 2.0 is one stop. F/2.0 to f/1.8 is 1/3 of a stop. The total is 2 stops, so 4x.
     
  21. seenew macrumors 68000

    seenew

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    #21
    :D I said I hated 1/3 stops
     
  22. miloblithe macrumors 68020

    miloblithe

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    #22
    How do you feel about half stops? Or are you a full-stop kind of guy? :)
     
  23. seenew macrumors 68000

    seenew

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    #23
    give me my full stops, and I can manage much better. I had a professor once who went on for over an hour when someone showed him their camera had 1/3 stop increments. Haha.
     
  24. jeffzoom91 macrumors regular

    jeffzoom91

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    #24
    I had this problem too

    Except it was in Alaska, so I needed a quick fix, because my laptop (Linux craptop) was not doing well at the time, so couldn't ask anyone.

    1) Shoot RAW (you'll thank me later)
    2)get tripod, or other stable surface
    3) if you can't get a cable release, put it in self portrait mode and wait.
    4) put it in program, and lower the EV (AV+/- button on your camera) down up to 1 full stop down.
    5)When you get home, review the shots on a calibrated display, and move the EX slider in your raw processor in either direction to suit you, and do custom "click" white balance.

    That's how I did it, it was so annoying, I did not want my night shot to look like broad daylight. $1k on camera, cards, and batt (lenes were hand-me-downs from my dad) and I can't take a sunset, MY FRAKING PHONE can do that. Needless to say, I was a little angry.

    Just keep trying, and btw, automatic is useless for everything except total noobs. Use program at the least.
     
  25. form macrumors regular

    form

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    #25
    My error, it's 4x. f/1.8 is one stop faster than f/2.5, which is one stop faster than f/3.5.
     

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