Lens hood half moon shadow?

Discussion in 'Digital Photography' started by dwd3885, Jun 3, 2009.

  1. dwd3885 macrumors 68020

    Joined:
    Dec 10, 2004
    #1
    I have a Sony A200 with Sal-1800 lens and sh0006 lens hood (both came with the lens kit).

    I am having a problem when I take a photo zoomed out all the way with the lens hood on and the flash, there is a half moon effect on the bottom center of the photos. I do not know why this is. When the flash is off it is fine, and when I zoom in a little bit it is fine, and when I take off the lens hood all is fine.

    Is this a problem with the flash (not going up as high as other cameras)? a problem with the lens hood (get a flower lens hood)?

    Any advice on how to deal with this. I mean, I could just zoom in a little bit and be OK, but I want to know if this is a problem everywhere.
     
  2. advan031 macrumors 6502

    Joined:
    Aug 16, 2008
    #2
    This is a common problem with on-board flash and a prominent petal lens hood.

    Your solution would be to buy a external speedlight/flash.
     
  3. dwd3885 thread starter macrumors 68020

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    Dec 10, 2004
    #3
  4. GT41 macrumors regular

    Joined:
    Apr 25, 2007
    Location:
    Ontario, Canada
    #4
    Remove the lens hood altogether when using the flash and you won't have this problem. Though if the lens is big and your flash doesn't pop up very high, even the lens can sometimes interfere with the light beam from the flash and cause shadowing at the bottom of the picture.

    :)
     
  5. leighonigar macrumors 6502a

    Joined:
    May 5, 2007
    #5
    Just think about what you are doing here. Draw a mental line between the flash and the bottom-most bit of the scene you're taking a picture of. If that line intersects the lens/hood then you will get a shadow. In some situations you can turn the camera upside down so the shadow will be on the ceiling or 'in the sky' where it doesn't matter. As the others have said, either take the hood off, use a different lens or a bigger (taller) flash. These things change the way this 'line of light' intersect the lens.
     
  6. dwd3885 thread starter macrumors 68020

    Joined:
    Dec 10, 2004
    #6
    I get it now. Have any of you seen the Sony a200 flash height and compared it to other camera's flash heights?
     
  7. dwd3885 thread starter macrumors 68020

    Joined:
    Dec 10, 2004
    #7
    So this is slightly off the original topic, but can I get a petal/flower lens hood for this lens? Even though the one Sony has is not a flower/petal hood?
     
  8. NightGeometry macrumors regular

    Joined:
    Apr 11, 2004
    #8
    I've not actually measured, but I don't think there is a lot in it (having used the pop up flash on a number of cameras.

    If you do a reasonable amount of flash photography, I'd suggest getting a flash unit. I use a HVLF42AM, which is pretty good (for my limited needs), there are units cheaper, try your local camera shop to see if they do a bottom of the range unit, Metz do a fairly cheap one (remember that Minolta developed their own hot shoe design, so an ISO hot shoe flash won't fit). You should be able to find cheaper flashes, but getting one just a bit better that you can use off camera is a lot more useful (and great fun to learn to use, too).

    You could always get a hot shoe adapter from eBay / hong kong, mine cost about £4, and use a cheap flash - but you have to be careful about voltages. I only use my adapter to fire a dirt cheap and very temperamental radio trigger.


    Again, go into your local camera store, especially if their is a second hand or specialist one anywhere near you. Take the lens, and ask them if they have anything that'll fit.

    I think a better flash would be the best solution, but if you can find a cheap second petal hood that fits, and you don't use the flash a lot, that is going to work out way cheaper.
     
  9. leighonigar macrumors 6502a

    Joined:
    May 5, 2007
    #9
    I have no idea where this idea of getting a petal hood came from, perhaps someone suggested it further up this thread. All I can says it - it will not help this problem, actually it might make it worse as the problem for the flash is how far the top of the hood sticks out

    - petal hoods exist mainly as a compromise hood for a zoom lens, but are always an improvement if pushed to the limit of length. Really you want a hood to be as long as possible and for a normal telephoto it can be quite long and block a lot of flare without being shaped like a 'flower' simply because the lens is only observing a small portion of the aperture of the hood. With wider angles you would want a hood which offers better flare protection than is possible with a flat-ended hood, and because the image formed on the sensor is rectangular we can block everything but that rectangle of image. If you put a petal hood on a lens and look into it from above with a bright sky above you you can see how there is a rectangle of light reflected on the front element, with a circular hood there would be a circle formed and the circle would pass through the corners of the rectangle - i.e. the area would be unnecessarily large and so more flare would result.

    The top and sides (barring the 'corners') of a petal hood will be longer than they would be with a normal hood and so they will block the flash more readily.

    Apologies if you know all this and it was an unrelated question. Bottom line - if you're shooting with the flash, take the hood off. If you still have a problem you need a bigger (taller) flash.
     
  10. bartelby macrumors Core

    Joined:
    Jun 16, 2004
    #10
    I have the same problem with my D70 and Sigma 18-55 (even without the hood I get a shadow). So I use the ghetto diffuser method.
    [​IMG]
     
  11. leighonigar macrumors 6502a

    Joined:
    May 5, 2007
    #11
    Certainly worth a try (if the OP doesn't get it - it's a split film canister). Of course, you may find you have too little power left to play with, but if it works it's low cost.
     
  12. bartelby macrumors Core

    Joined:
    Jun 16, 2004
    #12
    For me it works for close up stuff where the shadow causes the most problems.
     

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