Hey, recently I started a project making an intervelometer for my dslr. I decided that I would use the external shutter release pin. Here's the diagram:
In this I have to bridge those wires automatically with an arduino. I know that I can use relay or other mechanical methods but I don't want it to be noisy. So could someone please help me with this.
Thanks.
The only method to do it independently from the curcuit is using a relay.
You also can use a transistor (mosfet) or optocoupler in some cases, but it depend on parameters of switched signal.
how do i use a transistor
google "mosfet key mode"
i cant understand that. I am just a beginner
Just google this:
Mosfet Key Mode Beginner Tutorial
You should get something you understand
Okay, I have checked out a video but thing is that the camera and the microcontroller don't have a common ground.
A reed relay would be a good choice.
They are tiny and don't make any noise.
The one shown in the link can be driven diretly from an UNO pin
https://www.digikey.com/en/products/detail/comus-international/3570-1331-053/7497099
In that case, check if there is a ground pin on the audio-jack looking thing in the picture in the first post, and if so you should be able to use that as a common ground
If you don't want to get too deep into the electronics part however, and want to keep it as simple as possible, then what @jim-p put would be the best solution. Just make sure to check the current rating of the reed relay.
Could u pls make ur point more clear as i am very new.
You said that you knew that you could use a relay, so what don't you understand?
First, decide: Do you want to use the MOSFET method or the Reed Relay method?
I am sorry. I was talking about the mosfet. And I did like the reed relay method. But I just wanna know about the mosfet method
All right. You will have to test your device and see if there is a ground pin on the interface you are using to control it.
In this, If I had to guess, the ground pin would be the leftmost one. Test that and see if it's right. If so, you can use it as common ground.
Shouldn't I ground the microcontroller to the leftmost pin. As I would be using batteries to power the microcontroller.
What did your camera cost?
Is it cheap enough so that you can buy several to experiment in case you burn-up one?
It you want to learn about MOSFET this is a place to read
https://wolles-elektronikkiste.de/en/the-mosfet-as-switch
Something about optocouplers:
https://www.electronics-tutorials.ws/blog/optocoupler.html
Finally - as already stated here by several experienced members - the solution depends on the electrical situation on the side which you want to switch. Without some (basic) knowledge in electronics and measurement with a volt- and amperemeter you might quickly "brick" something expensive ... The smell of boiling electronic parts or burning printed circuit board tracks is paving the way of experience ... 
Potential free switches are the least risk but still any intervention does include risks. No risk, no pain (but also less fun) ...
Good luck and take care!
ec2021
No its not cheap. Its a dslr. Thats the reason why I ask so much questions😂
Then use the reed relay. If you don'r do the MOSFET circuit right, then godbye dslr
Yeah ur right. But about octocouplers, are they a good option