How does the half-press-shutterbutton on cameras work? - Page 1
Forum section: electronics / projects

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: December 10, 2022, 03:00:45 pm
content: For those who have no idea what I'm talking about:Many highend digital cameras have a default behavior where pressing the shutter button halfway activates the auto-focus and exposure mechanisms, pressing it fully activates the actual shutter and takes a picture. There are usually tactile responses to both of these positions, the shutter button has almost no resistance up to the halfway point, then you feel like you hit a significant increase of resistance (activates auto-focus), then you feel a stop when the button is depressed (activates shutter).How is this done electromechanically?

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: December 10, 2022, 03:14:12 pm
content: AFAIK it's two concentric switches with different actuating forces under the same button.

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 10, 2022, 03:19:14 pm
content: Yup just 2 switches, one on top of the other, the rest is mechanical design and manufacturing...

author: TimFox
author_rank: Super Contributor
timestamp: December 10, 2022, 05:20:59 pm
content: If you connect the external control switch for those functions, it is often a slide mechanism with a button, connected through a small TRS "stereo headphone" plug.

author: Someone
author_rank: Super Contributor
timestamp: December 10, 2022, 10:31:11 pm
content: There are switch parts specifically made for this application, Panasonic "double action" with the first action have a much lighter activation force than the second.

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: December 10, 2022, 10:54:54 pm
content: As complicated such a switch design must be, it's not as hard as explaining to a elderly parent with a far too complicated pro-sumer Pentax the subtilty of setting the focus and then squeezing the shutter not just slamming it.

author: TimFox
author_rank: Super Contributor
timestamp: December 10, 2022, 10:56:08 pm
content: On any camera, one should squeeze the shutter release so as not to shake the camera.

author: magic
author_rank: Super Contributor
timestamp: December 11, 2022, 09:12:28 am
content: Olympus can be set not to release the shutter in AF modes until focus is acquiredNot 100% sure what happens if you press and release the button before it manages to focus, prolly nothing.

author: ledtester
author_rank: Super Contributor
timestamp: December 11, 2022, 09:40:54 am
content: I was just looking this up a day ago...In this video at about 0:15 you can see a teardown of a Panasonic remote shutter release:Arduino Panasonic remote shutter release (DMW-RSL1 disassembly) -- Hirudinhttps://youtu.be/DNj48nwUjxk?t=15sBasically there is a sandwich of three metal strips. Press down halfway and you connect the top and middle strips; press all the way and all three are connected.For pinout info on different cameras see:https://www.doc-diy.net/photo/remote_pinout/Most cameras use a resistor network to distinguish between a half-press and full press.Update: Look on aliexpress/ebay for cheap clones of these devices.

author: magic
author_rank: Super Contributor
timestamp: December 11, 2022, 10:08:40 am
content: That's how the cheap remotes are made and their tactile feedback is pretty poor.The buttons on cameras are much nicer, clearly made differently. Besides, if you open a camera, you will see those switches are tiny.

author: dkonigs
author_rank: Regular Contributor
timestamp: December 12, 2022, 04:32:28 am
content: Quote from: Ed.Kloonk on December 10, 2022, 10:54:54 pmAnd yet this mechanism in cameras is over 30 years old. We've been having to explain it to people for a very long time.

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 12, 2022, 01:20:47 pm
content: Same as trying explaining 1+1=2, you cant stop people from get born to this world. Same reason why camera or oscilloscope sale will never end like forever..

author: bson
author_rank: Unknown
timestamp: December 12, 2022, 11:55:16 pm
content: Quote from: dkonigs on December 12, 2022, 04:32:28 amAnd it greatly predates autofocus and microcontrollers. Initially it was used to turn on the light meter circuit and needle...