Anyone having this problem with the Sony A7? black area of image.

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Blackubuntu
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Anyone having this problem with the Sony A7? black area of image.
2 months ago

Playing around with my Minolta MD Legacy glass the last couple of days and I am noticing part of the image is blacked out. It happened with my 500mm vivitar tele and a 100-300mm Minolta MD zoom lens.

I had the camera set with the e-front curtain shutter on. I changed this to off and it exposes the images like I expect.

blacked out part of the image.

e-curtain turned off.

is there something I am missing?

Sony Alpha 7
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verybiglebowski
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Re: Anyone having this problem with the Sony A7? black area of image.
In reply to Blackubuntu, 2 months ago

Blackubuntu wrote:

Playing around with my Minolta MD Legacy glass the last couple of days and I am noticing part of the image is blacked out. It happened with my 500mm vivitar tele and a 100-300mm Minolta MD zoom lens.

I had the camera set with the e-front curtain shutter on. I changed this to off and it exposes the images like I expect.

blacked out part of the image.

e-curtain turned off.

is there something I am missing?

At 1/6000s EFC might be too slow. Try it at slower speed and see if it happen. Above 1/500s, there is no reason to use EFC anyway. You might experience similar problems with HiSpeed flash photography.

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SQLGuy
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Re: Anyone having this problem with the Sony A7? black area of image.
In reply to Blackubuntu, 2 months ago

I have not had that problem with any of my lenses, but that does (sort of) fit the warning in the NEX-7 manual:

"When a Minolta/Konica Minolta lens is used, set this item to [Off]. If you set this item to [On], the correct exposure will not be set or the image brightness will be uneven."

I still have no idea why this should happen, though. The original theory was that EFCS might fire too fast for the iris to be reset for shooting in an A-mount lens; but that's obviously not what is happening here.

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Graham Best
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Re: Anyone having this problem with the Sony A7? black area of image.
In reply to Blackubuntu, 2 months ago

I don't know why one would want to photograph a static scene at 1/6000 ISO 1250, but as you've discovered, there's a price to pay. Obviously, your image is dark on the left, as you were holding the camera in portrait mode with the top of the frame left

This earlier thread describes the cause.

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Blackubuntu
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Re: Anyone having this problem with the Sony A7? black area of image.
In reply to Graham Best, 2 months ago

That explains it. In testing the long tele's I cranked up the ISO and not paying attention to the shutter speed.

I live in western Washington state and not used to this bright stuff called sunshine here. Again, I am screwing around with a bunch of legacy glass, trying to find that nirvana of sharp that I am always seeking.

Thanks,

Jess

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Brian_Smith
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Re: Anyone having this problem with the Sony A7? black area of image.
In reply to Blackubuntu, 2 months ago

As the manual says, certain telephoto lenses are not compatible with electronic front curtain shutter.

You have found one of them.

You need to turn off EFC shutter with that lens.

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Blackubuntu
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Re: Anyone having this problem with the Sony A7? black area of image.
In reply to Brian_Smith, 2 months ago

The lenses are manual focus MD glass with an adapter.  One of the posters above ID'd the problem as too fast of a shutter speed due to the ISO being cranked up.

Thanks,

Jess

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Brian_Smith
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Re: Anyone having this problem with the Sony A7? black area of image.
In reply to Blackubuntu, 2 months ago

Blackubuntu wrote:

The lenses are manual focus MD glass with an adapter. One of the posters above ID'd the problem as too fast of a shutter speed due to the ISO being cranked up.

Yes, it only happens with certain telephoto legacy lenses at higher shutter speeds. You have found one of them.

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SQLGuy
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Re: Anyone having this problem with the Sony A7? black area of image.
In reply to Brian_Smith, 2 months ago

But that still doesn't make any sense. A manual lens isn't a lens at all as far as the body is concerned - it's just a spot of light hitting the sensor.

What about if the OP removes the lens and just shoots without a lens at the same ISO and shutter speed, with EFCS on? My bet is that he's still going to see that shadow.

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Brian_Smith
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Re: Anyone having this problem with the Sony A7? black area of image.
In reply to SQLGuy, 2 months ago

SQLGuy wrote:

But that still doesn't make any sense. A manual lens isn't a lens at all as far as the body is concerned - it's just a spot of light hitting the sensor.

What about if the OP removes the lens and just shoots without a lens at the same ISO and shutter speed, with EFCS on? My bet is that he's still going to see that shadow.

Page 266 of the Sony A7 User Help Guide notes:

"When a lens made by another manufacturer (including a Minolta/Konica-Minolta lens) is used, set this item to [Off]. If you set this function to [On], the correct exposure will not be set or the image brightness will be uneven."

Granted, they could explain "brightness will be uneven" a bit better - but it refers to edge darkening as shown in the example.

The same page also notes:

"When you shoot at high shutter speeds with a large diameter lens attached, the ghosting of a blurred area may occur, depending on the subject or shooting conditions. In such cases, set this function to [Off]."

I don't see ghosting in his example, but either way the solution is the same. Turn off EFC.

I've only heard of EFC incompatibility mentioned with telephoto legacy lenses - but it may not be limited to long glass.

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SQLGuy
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Re: Anyone having this problem with the Sony A7? black area of image.
In reply to Brian_Smith, 2 months ago

Brian_Smith wrote:

SQLGuy wrote:

But that still doesn't make any sense. A manual lens isn't a lens at all as far as the body is concerned - it's just a spot of light hitting the sensor.

What about if the OP removes the lens and just shoots without a lens at the same ISO and shutter speed, with EFCS on? My bet is that he's still going to see that shadow.

Page 266 of the Sony A7 User Help Guide notes:

"When a lens made by another manufacturer (including a Minolta/Konica-Minolta lens) is used, set this item to [Off]. If you set this function to [On], the correct exposure will not be set or the image brightness will be uneven."

Granted, they could explain "brightness will be uneven" a bit better - but it refers to edge darkening as shown in the example.

The same page also notes:

"When you shoot at high shutter speeds with a large diameter lens attached, the ghosting of a blurred area may occur, depending on the subject or shooting conditions. In such cases, set this function to [Off]."

I don't see ghosting in his example, but either way the solution is the same. Turn off EFC.

I've only heard of EFC incompatibility mentioned with telephoto legacy lenses - but it may not be limited to long glass.

Yes. I had already posted more or less that same first line from the NEX-7 manual. But, as I mentioned a couple of months ago in the other thread that was linked, I don't think they are talking about the shutter curtain causing the issue - I think they are saying that the camera won't always get the aperture set to the selected value before starting the exposure. If the iris is closing while the shutter is firing, that will result in "uneven" brightness.

My theory is that some of these cameras have a bit of error in the synch between their physical and electronic shutters that becomes noticeable at high shutter speeds. I am not that fond of this theory, but it's the only thing I can think of that explains this behavior.

If you have another theory, I would be very interested to hear it.

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sybersitizen
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Re: Anyone having this problem with the Sony A7? black area of image.
In reply to SQLGuy, 2 months ago

SQLGuy wrote:

... But, as I mentioned a couple of months ago in the other thread that was linked, I don't think they are talking about the shutter curtain causing the issue - I think they are saying that the camera won't always get the aperture set to the selected value before starting the exposure. If the iris is closing while the shutter is firing, that will result in "uneven" brightness.

That doesn't help explain the phenomenon, because it would result in overexposure of the part of the frame that gets exposed first - and because of the upward-moving shutter, that's the bottom of the camera (which, because of the inverted image created by the lens, ends up being the top part of the photo in normal landscape orientation). But the result we see is the opposite effect: underexposure.

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SQLGuy
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Re: Anyone having this problem with the Sony A7? black area of image.
In reply to sybersitizen, 2 months ago

sybersitizen wrote:

SQLGuy wrote:

... But, as I mentioned a couple of months ago in the other thread that was linked, I don't think they are talking about the shutter curtain causing the issue - I think they are saying that the camera won't always get the aperture set to the selected value before starting the exposure. If the iris is closing while the shutter is firing, that will result in "uneven" brightness.

That doesn't help explain the phenomenon, because it would result in overexposure of the part of the frame that gets exposed first - and because of the upward-moving shutter, that's the bottom of the camera (which, because of the inverted image created by the lens, ends up being the top part of the photo in normal landscape orientation). But the result we see is the opposite effect: underexposure.

Yes. I know. That's what I was saying: that the line from the manual does not suggest the behavior the OP is seeing.

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verybiglebowski
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Re: Anyone having this problem with the Sony A7? black area of image.
In reply to SQLGuy, 2 months ago

SQLGuy wrote:

sybersitizen wrote:

SQLGuy wrote:

... But, as I mentioned a couple of months ago in the other thread that was linked, I don't think they are talking about the shutter curtain causing the issue - I think they are saying that the camera won't always get the aperture set to the selected value before starting the exposure. If the iris is closing while the shutter is firing, that will result in "uneven" brightness.

That doesn't help explain the phenomenon, because it would result in overexposure of the part of the frame that gets exposed first - and because of the upward-moving shutter, that's the bottom of the camera (which, because of the inverted image created by the lens, ends up being the top part of the photo in normal landscape orientation). But the result we see is the opposite effect: underexposure.

Yes. I know. That's what I was saying: that the line from the manual does not suggest the behavior the OP is seeing.

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A7 with kit lens and a number of legacy lenses (mostly Canon FD); A3000 converted to IR.

This phenomenon has nothing to do with legacy, telephoto or WA lens. It is related to high shutter speed. Electronic first curtain has to discharge sensor pixels (switch them off) before they are switched back on, in order  to start the exposure and prior to mechanical shutter that follows closely (at high shutter speeds) will end exposure.

This process of discharging pixels is not instanious, it takes row by row pixel discharging. Idea is, that pixel draining itself (that starts the exposure right afterward) copy the speed of mechanical shutter.

But at a higher shutter speed, EFC can't finish discharging pixels before the shutter starts to close, in order to end the exposure.. Thus part of the image (where mechanical shutter close before exposure even started, or where it started too late) remain darker (unproperly exposed).

Please note that this explanation is extreamy simplified, but I hope you got the idea.

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SQLGuy
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Re: Anyone having this problem with the Sony A7? black area of image.
In reply to verybiglebowski, 1 month ago

Remember that one shutter "chases" the other at high shutter speeds. The electronic shutter starts exposure, line-by-line, at the same speed as the mechanical shutter will traverse the sensor... the result being a strip of exposure between the two shutters that sweeps across the sensor and exposes all of it equally. This actually seems to be an issue where, in some cameras, the speed of the mechanical shutter doesn't match the speed of the electronic shutter. Maybe Sony or Copal was inconsistent in the specifications of the shutters they supplied.

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