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A77 multiple shutter count per image

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Miranda F View Drop Down
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Post Options Post Options   Quote Miranda F Quote  Post ReplyReply Direct Link To This Post Topic: A77 multiple shutter count per image
    Posted: 14 February 2021 at 21:27
Originally posted by gigo gigo wrote:


The cause is that extra light enters through the gap between the two curtains, so it is affected by the position of the principal point of the lens. If the position of the principal point is known, the exposure unevenness caused by the angle at which the light enters differs depending on the position of the frame can be corrected.
Of course, a lens whose principal point position is unknown cannot be corrected.

Due to the principle of occurrence, this problem becomes more pronounced with lenses with short focal lengths and large apertures. There is no problem with lenses with medium telephoto or higher and lenses with F2.8 or higher.

Aaah! I see! A brilliantly clear explanation, thanks.
What a pity Mark Galer couldn't given that simple explanation his tiresomely-wordy video.
Miranda F & Sensorex, Sony A7Rii, A58, Nex-6, Dynax 4, 5, 60, 500si/600si/700si/800si, various Sony & Minolta lenses, several Tamrons, lots of MF primes and *far* too many old film cameras ...
 



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Post Options Post Options   Quote gigo Quote  Post ReplyReply Direct Link To This Post Posted: 14 February 2021 at 16:46
It is often more useful to know the cause than to list the phenomena.

The so-called EFSC problem occurs because the front and rear curtains of the focal plane shutter are not on the same plane. It also occurs with mechanical shutters, but it is not noticeable because the distance between both curtains is close enough.
With a pure electronic shutter, it is possible to achieve the ideal state of completely the same plane, so it does not occur at all.

The cause is that extra light enters through the gap between the two curtains, so it is affected by the position of the principal point of the lens. If the position of the principal point is known, the exposure unevenness caused by the angle at which the light enters differs depending on the position of the frame can be corrected.
Of course, a lens whose principal point position is unknown cannot be corrected.

Due to the principle of occurrence, this problem becomes more pronounced with lenses with short focal lengths and large apertures. There is no problem with lenses with medium telephoto or higher and lenses with F2.8 or higher.

The ratio of influence depends on the ratio of the gap between the exposure slot and the front and back of the curtain, so it depends on the camera.
The faster the curtain speed, the wider the slot width at the same shutter speed, so the ratio with the gap front and back the curtain becomes smaller and the effect becomes smaller.

The problem with EFSC involves many parameters. In general, the explanation such as "this will happen" is very inaccurate.

EDIT:
There is no electronic front curtain setting menu in 7C. A combination of the two,

Pure electronic shutter.

Electronic front curtain + mechanical rear curtain.

only.

If there is no mechanical front curtain, the electronic front curtain and the mechanical rear curtain can be brought closer to each other.

Edited by gigo - 14 February 2021 at 20:06
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Post Options Post Options   Quote addy landzaat Quote  Post ReplyReply Direct Link To This Post Posted: 14 February 2021 at 15:33
All you want to know about Electronic Front Curtain Shutter by Mark Galer: Switch it off or leave it on.
Why not follow me on Instagram? @Addy_101
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Post Options Post Options   Quote gigo Quote  Post ReplyReply Direct Link To This Post Posted: 13 February 2021 at 18:21
If you search for the keyword "hvl-mt24am EFCS", you'll find that many forums (including dyxum here) have reported this issue many times.
The report is fragmented and the conditions are not well understood.
In my case, I have faced this problem with 99II + MFC-1000 + Ring flash + 3x-1x Macro.
In addition to EFCS off, there was also a report that it was solved by the second curtain synchronization.
Apparently MFC-1000 doesn't like EFCS.
Can anyone try with 7C that can't turn off EFCS?
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Post Options Post Options   Quote sybersitizen Quote  Post ReplyReply Direct Link To This Post Posted: 13 February 2021 at 17:52
^ Odd. I don't have that problem with my 5600HS(D) flashes used on my A77. At normal sync speeds, TTL results are the same with EFCS on or off, and the 5600HS(D) was introduced in 2000, a year before the Minolta macro flashes.

The only issue I've encountered is potential banding when HSS is used with EFCS, but the macro flashes don't support HSS.
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Post Options Post Options   Quote amrep Quote  Post ReplyReply Direct Link To This Post Posted: 13 February 2021 at 17:10
Because otherwise the TTL preflash metering (witch is *the* important feature of this flash) will not work. When EFCS is on it will just fire almost like manual, turn EFCS off and suddenly the exposure is perfect. This is my experience, but there are also similar reports:
https://www.talkemount.com/threads/a7-with-minolta-macro-twin-flash-2400.16199/#post-122590

Iím not sure there is a physical limitation behind this, it might be just a compatibility problem. The Minolta macro flash controller (year 2000) predates any Sony camera with a first curtain shutter by a margin.

I should also say that I havenít tried the Sony unit, Iím just guessing/inferring it works the same as the very similar Minolta unit.
 



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Post Options Post Options   Quote sybersitizen Quote  Post ReplyReply Direct Link To This Post Posted: 13 February 2021 at 16:02
Originally posted by amrep amrep wrote:

EFCS sould be turned off when using the Minolta MFC-1000 or the similar Sony MT24AM flash controller.

Why?
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Post Options Post Options   Quote amrep Quote  Post ReplyReply Direct Link To This Post Posted: 13 February 2021 at 09:28
EFCS sould be turned off when using the Minolta MFC-1000 or the similar Sony MT24AM flash controller.
For non-macro flash work it is often not necessary to turn off EFCS.
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Post Options Post Options   Quote sybersitizen Quote  Post ReplyReply Direct Link To This Post Posted: 13 February 2021 at 05:38
Originally posted by stiuskr stiuskr wrote:

For me [EFCS is] always off unless I'm shooting from a tripod

Why does a tripod make a difference for you?

or macro shots which is usually with flash

So you're saying you do use it with flash?

and it should always be off when doing flash work.

Or you're saying you don't use it with flash?

There should be no problem using EFCS with normal flash at normal sync speeds.
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Post Options Post Options   Quote SnowFella Quote  Post ReplyReply Direct Link To This Post Posted: 13 February 2021 at 03:49
With the A77 I almost always kept the EFCS on, only a few limited situations when it could have an effect on images.
1: Any HSS flash shooting can, likely will, cause banding.
2: High shutter speeds. Least mine started underexposing at high shutter speeds. In extreme situation could also introduce banding even under natural light.
3: Fast lenses shot wide open. EFCS can affect how bokeh in foreground or background is rendered.
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Post Options Post Options   Quote stiuskr Quote  Post ReplyReply Direct Link To This Post Posted: 12 February 2021 at 23:49
Originally posted by samfieldhouse samfieldhouse wrote:

Originally posted by addy landzaat addy landzaat wrote:

Enjoy it - it seems a lot of people recently got a "new to them" A77


Ha yes, me too. I've just been reading up on electronic first curtains to try and understand under what conditions I should switch it off.


For me it's always off unless I'm shooting from a tripod or macro shots which is usually with flash and it should always be off when doing flash work.
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Post Options Post Options   Quote samfieldhouse Quote  Post ReplyReply Direct Link To This Post Posted: 12 February 2021 at 14:29
Originally posted by addy landzaat addy landzaat wrote:

Enjoy it - it seems a lot of people recently got a "new to them" A77


Ha yes, me too. I've just been reading up on electronic first curtains to try and understand under what conditions I should switch it off.
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Costas View Drop Down
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Post Options Post Options   Quote Costas Quote  Post ReplyReply Direct Link To This Post Posted: 11 February 2021 at 08:55
Yeh, the 18-250 is not in the same league as the 16-50.

8000i : a700 : a77II Minolta - 24 2.8, 100 2.8 Macro RS, 100 2.8 Macro D, 500 Reflex, Sony - 35 1.8 SAM, 16-50 2.8 SSM, 70-400G, 18-250 DT
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Post Options Post Options   Quote Murman Quote  Post ReplyReply Direct Link To This Post Posted: 10 February 2021 at 18:31
With a constant f1.4. While your are wishing - go all the way.
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