Embarrassing, on a $2500 camera

Discussion in 'Digital Cameras' started by RichA, Mar 10, 2014.

  1. RichA

    RichA Guest

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  2. RichA

    Bowser Guest

    Bowser, Mar 10, 2014
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  3. RichA

    Alan Browne Guest

    Over the years I've collected some pretty good Minolta/Sony glass. I
    think I'd need an adaptor to use it on the A7, however.

    I do need to add an 85mm f/1.4 to the collection too.

    No hurry here, though.
    Alan Browne, Mar 10, 2014
  4. RichA

    Alfred Molon Guest

    Alfred Molon, Mar 10, 2014
  5. RichA

    Me Guest

    "Light leak present in upper right and left side. 30 seconds, f/2.8, ISO
    25600. Exposure made within 3 inches of 60W incandescent bulb."

    That's kind of extreme testing IMO - it wouldn't surprise me if many
    other cameras would leak some light when using such a test.
    Me, Mar 10, 2014
  6. RichA

    PeterN Guest

    Reminds me of that old story where a woman picks up a chicken in a
    butcher shop: sniffs under its legs and wings; hands it back to the
    butcher saying: "this chicken stinks." The butcher says: "lady could
    you pass a test like that?"
    PeterN, Mar 10, 2014
  7. Try this with any SLR camera: place a light source really close to the
    viewfinder and make a long exposure. Light gets in. This is why the
    better SLRs all have shutters for the viewfinders. You'll find that
    less expensive SLRs also include a little rubber widget that is
    intended to go over the finder during long exposures as well.
    Oregonian Haruspex, Mar 10, 2014
  8. RichA

    Alfred Molon Guest

    Not a problem if the DSLR has an EVF.
    Alfred Molon, Mar 11, 2014
  9. RichA

    Sandman Guest

    The A7 has an EVF, so light leak from the finder is not a problem there.
    The light leak is from the mount. Many people tested without a lens, and
    just the cap on, and still got leaks.

    No SLR should leak light this way.
    Sandman, Mar 11, 2014
  10. RichA

    RichA Guest

    Some of the Zeiss-Sony lenses are decent though.
    RichA, Mar 11, 2014
  11. RichA

    Bowser Guest

    Yes. Both of them. That takes the total native lens count to three.

    Bowser, Mar 11, 2014
  12. ALL SLRs leak light through the finder. I'm not sure about the mount,
    but he took a very long exposure at a very high ISO setting in order to
    get his Sony to exhibit this leak. I wonder if anybody else has tried
    a similar trick on any other SLRs - maybe they all have this problem!

    We can't tell that they don't leak from the fact that this one does anyway.
    Oregonian Haruspex, Mar 11, 2014
  13. It's not really an SLR if it has an EVF though. The R stands for
    Reflex (archaic form of reflected) and without a mirror directing the
    light to an optical viewfinder a camera can not be said to be an SLR.
    Oregonian Haruspex, Mar 11, 2014
  14. RichA

    Peter Irwin Guest

    That depends on how good the seals are around the mirror when it
    is in the up position. If well designed, it really shouldn't leak
    at all. (Although it doesn't leak much since it needed a super high
    ISO setting.) The purpose of the viewfinder shutter or cover is not
    to prevent light from reaching the film chamber, but to prevent
    stray light from reaching the light meter when using autoexposure
    with the eye away from the finder.

    Peter Irwin, Mar 12, 2014
  15. This sounds reasonable, but I also know that many mirrors have a
    partially transparent portion these days to feed the exposure meter,
    and it is conceivable that light could leak through this portion.
    Oregonian Haruspex, Mar 12, 2014
  16. RichA

    Sandman Guest

    I wasn't talking about light leaking from the finder above. The Sony A7 has
    an EVF, so light leak can't possibly come from the finder, the light leak
    comes from the mount - no SLR should leak light from the mount.
    That's who you test light leaks.
    They don't. People use SLR's to take very long exposures all the time
    without light leaks problems.

    (Disclaimer: Obviously there have been other SLR with light leak problems
    from the mount, but no SLR *should* leak this way)
    Of course not.
    Sandman, Mar 12, 2014
  17. RichA

    Me Guest

    There's a secondary fully silvered meter behind the "window" on the main
    semi-silvered mirror, which directs light down to the AF sensors.
    This closes / folds against the main mirror when the mirror is up.
    To clarify what Peter Irwin says above, auto metering is not determined
    while the mirror is up, but stray light can enter the eyepiece and throw
    out metering measurement before the shutter is pressed.
    In most cases, it's not an issue at all - as your eye is over the
    viewfinder, but if using auto metering on a tripod with remote shutter
    release (or delay) etc, then it can be a problem (easily solved).
    Me, Mar 12, 2014
  18. Of course they do, but for example, it might be tough to detect if you
    are shooting at ISO 100 with a 1/100th shutter speed even if there is a
    leak. This test was obviously extreme, and it makes me wonder if this
    issue could be present on other interchangeable-lens cameras when
    subjected to such a test.
    Oregonian Haruspex, Mar 12, 2014
  19. RichA

    Sandman Guest

    Guess how people DID find out that the A7 leaks? Yes, you got it - by
    actually shooting with high ISO in long exposures. You know, people do
    that. And that's how they find out. That's how we know that few SLR's have
    this problem, because people actually use them to shoot long exposures
    No. The test wasn't extreme, nor should any SLR be suspectibel to it.
    Sandman, Mar 12, 2014
  20. RichA

    PAS Guest

    One can argue that the test is extreme and yes, other cameras are
    susceptible to it
    PAS, Mar 12, 2014
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