EOS 70D : Slow shutter speed when LCD screen turned on

[talk2sachinj]

Hi !
Need your help. I am beginner & I have new 70D camera. When LCD panel turned off, the shutter speed is quite fast. When I turn on LCD Panel, the shutter speed automatically slows down & sounds annoying. The pictures are same in both cases. Also, the high speed continuous photo shoot, the shutter speed slows down when the LCD panel is turned on. Please help me to fix this. 

[hsbn]

I think it is not the shutter speed but the auto focus. Change to different focus mode for LV to see what fit your style.

[talk2sachinj]

Hi

Thanks for reply. I tried different focus modes in LV. But it is still slower shutter. Please find two quick video's on attached link. Appreciate your help. 

https://www.dropbox.com/sh/hplr7nm5j1l6baa/AAD1WTK6vFN1OuIleH1v9Cy5a

Regards,

Sachin

[talk2sachinj]

Please turn on your computer speakers so that you can hear the difference in shutter speed. 

This happens in Auto, Manual & other modes on dial.

Thanks !

[MikeSowsun · Accepted solution]

There is nothing wrong with your camera.  It is working as it should when using LiveView.  

There are two different types of Auto Focus:

1) Normally with a Film SLR or Digital SLR, you look through the optical viewfinder and view your scene through the lens of the camera.  Behind the lens a mirror reflects the image up into the optical viewfinder. When using the viewfinder the camera uses "Phase Detection" Auto Focus. With PD AF the image passes through a transparent part of the mirror to PD AF sensors below the mirror.  When you half press the shutter button the AF operates and when you fully press the shutter button the mirror flips up out of the way to allow the image to reach the image sensor behind the now open shutter curtain. While the mirror is flipped up, you can not see anything through the optical viewfinder.  This all takes place very quickly and makes a fair bit of noise from the action of the mirror flipping back and forth and the shutter curtain opening and closing. 

2) When using LiveView on a DSLR, the rear LCD image displays the image. In order to for this to happen the mirror must be flipped up and the shutter curtain must be fully open.  The optical viewfinder becomes useless and the only way to see anything is by looking at the rear LCD screen. Auto Focus is no longer done with Phase Detection sensors below the mirror and now used  Contrast Detection Auto Focus is used by reading the focus right off the image sensor.  This type of AF is slower than PD AF.  

The difference in sound is only because the mirror is already flipped up as soon as you press the LiveView button and all you hear is the sound of the shutter curtain clsoing and then opening up again so you can once again see the image on the LCD screen  . The actual shutter opening and closing speed is exactly the same. 

Here is more info on how Phase Detection AF works:

Phase Detection AF

Here is the description of each number shown in the above illustration:

1. Ray of light
2. Main/Reflex Mirror
3. Secondary Mirror, also known as “Sub-Mirror”
4. Camera Shutter and Image Sensor
5. Eccentric pin (1.5mm hex) for adjusting the Main Mirror
6. Eccentric pin (1.5mm hex) for adjusting the Secondary Mirror
7. Phase Detect Sensor (AF Sensor)
8. Pentaprism
9. Viewfinder

[talk2sachinj]

Hello Mike,

Thanks a lot for detailed explanation. I have big relief that the camera is working normal. 

Regards,

Sachin

[MikeSowsun]

Glad to help.