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About electronic front curtain shutters

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mhohner View Drop Down
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Posts: 1724 		Post Options Post Options   Quote mhohner Quote  Post ReplyReply Direct Link To This Post Topic: About electronic front curtain shutters
    Posted: 19 September 2011 at 20:54
Here's my little piece about electronic front curtain shutters.
Sony/Minolta F.A.Q., bodies, lenses, flashes.
 



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sdm9465 View Drop Down
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Posts: 1180 		Post Options Post Options   Quote sdm9465 Quote  Post ReplyReply Direct Link To This Post Posted: 19 September 2011 at 21:04
Thanks for the well written article. I'm curious why the option for mechanical first curtain is still present. Are there also disadvantages to the electronic first curtain shutter?
Steve

www.pbase.com/smeredith
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mhohner View Drop Down
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Posts: 1724 		Post Options Post Options   Quote mhohner Quote  Post ReplyReply Direct Link To This Post Posted: 19 September 2011 at 21:15
I'm not sure why the mechanical front curtain is still there.
Sony/Minolta F.A.Q., bodies, lenses, flashes.
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dca1213 View Drop Down
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Posts: 3780 		Post Options Post Options   Quote dca1213 Quote  Post ReplyReply Direct Link To This Post Posted: 19 September 2011 at 21:34
Great article, it confirms my concerns regarding the A33 and A55 shutters having to do twice the work of non live view shutters with secondary sensors. I felt that was a design flaw given that the same shutter used in a non SLT would only provide half of the service life on those first generation SLT's.

Good work!
Dennis
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Peekayoh View Drop Down
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Posts: 3166 		Post Options Post Options   Quote Peekayoh Quote  Post ReplyReply Direct Link To This Post Posted: 19 September 2011 at 21:43
I read somewhere that the Electronic shutter was heavier on the battery. Hence the choice.
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bartman View Drop Down
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Posts: 957 		Post Options Post Options   Quote bartman Quote  Post ReplyReply Direct Link To This Post Posted: 19 September 2011 at 21:45
Tnx! You increased my knowledge. I like to know how things work.
 



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mhohner View Drop Down
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Posts: 1724 		Post Options Post Options   Quote mhohner Quote  Post ReplyReply Direct Link To This Post Posted: 20 September 2011 at 15:13
I've updated above posting today.
Sony/Minolta F.A.Q., bodies, lenses, flashes.
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Peekayoh View Drop Down
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Posts: 3166 		Post Options Post Options   Quote Peekayoh Quote  Post ReplyReply Direct Link To This Post Posted: 20 September 2011 at 16:37
That's a bit of a disappointment for those of us with lots of Minolta.
I'll inquire into that with Sony.
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mhohner View Drop Down
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Posts: 1724 		Post Options Post Options   Quote mhohner Quote  Post ReplyReply Direct Link To This Post Posted: 20 September 2011 at 21:15
I thought about the last point a bit more. The following is speculation, or an informed guess, if you will:

I think they meant A-mount lenses adapted to NEX cameras. Maybe the aperture of A-mount lenses closes slightly slower than the aperture of E-mount lenses. After all, the aperture mechanism of A-mount lenses and E-mount lenses is different. With a mechanical front curtain, this does not matter, as the aperture can be closed while also the shutter closes. But with the electronic front curtain, exposure begins while the aperture may still be closing, so you get uneven exposure as described (the parts of the image that are exposed first are slightly brighter).

If this is the case this will be a non-issue with A-mount cameras. There the camera will know the aperture reaction time and will delay exposure accordingly when using the electronic front curtain.
Sony/Minolta F.A.Q., bodies, lenses, flashes.
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mhohner View Drop Down
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Posts: 1724 		Post Options Post Options   Quote mhohner Quote  Post ReplyReply Direct Link To This Post Posted: 28 September 2011 at 18:31
There's another update.
Sony/Minolta F.A.Q., bodies, lenses, flashes.
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Peekayoh View Drop Down
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Posts: 3166 		Post Options Post Options   Quote Peekayoh Quote  Post ReplyReply Direct Link To This Post Posted: 28 September 2011 at 19:05
This is the explanation I had from Sony....

3rd party lenses may be affected, or lenses that have had a lot of use over several years.

If the exposure begins whilst the aperture mechanism is still closing than the bokeh effect may be spoilt. Essentially, you could have selected F16 at 300mm, and then see that the bokeh is distorted as the aperture irises were still traveling between F5.6 and F16 for the first part of the exposure
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Posts: 14428 		Post Options Post Options   Quote sybersitizen Quote  Post ReplyReply Direct Link To This Post Posted: 03 October 2011 at 07:42
Here's a dpreview thread with some strange results being attributed to the electronic shutter...

"The a77 manual states that images can vary in brightness and even be partially bright and partially dark when using KONICA MINOLTA lenses with electronic first curtain shutter enabled and a fast shutter speed.

This isn't the whole story. This can also happen with non-Minolta lenses.

I can confirm it happens with both the SONY 70-300 G and the Sigma "BIGMA" 50-500.

It does not happen with any shorter focal length Sony lenses.

The problem is solved by turning the Electronic first curtain shutter to OFF in the menu."


Examples:

http://www.flickr.com/photos/25561955@N03/6203053479/
http://www.flickr.com/photos/25561955@N03/6203058025/
TheSyberSite
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Adrian Harris View Drop Down
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Posts: 292 		Post Options Post Options   Quote Adrian Harris Quote  Post ReplyReply Direct Link To This Post Posted: 03 October 2011 at 10:17
Why this whole situation is absolutely crazy...

With totally electronic viewing cameras - IE. Live view LCD and EVF., there is no need for the lenses to lag at all. They should permanently be at the selected F setting. - as the electronics can brighten the image for the photographer, which also provides true WYSIWYG as regards DOF. Perfect.

Its only older cameras with OVF that need the lens open - because otherwise the viewfinder image would be to dark for the photographer.

So this should never have been an issue for the A77 and its electronic first curtain !

Any thoughts?
Adrian

www.t1000.co.uk
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vitor View Drop Down
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Posts: 1966 		Post Options Post Options   Quote vitor Quote  Post ReplyReply Direct Link To This Post Posted: 03 October 2011 at 12:17
Originally posted by Adrian Harris Adrian Harris wrote:

Why this whole situation is absolutely crazy...

With totally electronic viewing cameras - IE. Live view LCD and EVF., there is no need for the lenses to lag at all. They should permanently be at the selected F setting. - as the electronics can brighten the image for the photographer, which also provides true WYSIWYG as regards DOF. Perfect.

Its only older cameras with OVF that need the lens open - because otherwise the viewfinder image would be to dark for the photographer.

So this should never have been an issue for the A77 and its electronic first curtain !

Any thoughts?


There is a limitation with the AF system where it will struggle if using the lens in step down mode. That's why the AF mechanism wont focus with lenses with apertures lower then f/8 (not sure if won't fail before that)
vitorfonseca.com
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