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Comment by minot | Hacker News Reader

> mirrorless camera (with clean HDMI out)

sorry if this is a stupid question but I don't have much experience with cameras and recently learned that cameras have a limited lifespan when it comes to the shutter (the thing that opens and closes to let in light). It is apparently enough of a concern that people ask for this count when buying used.

So my question is: does a video in this HDMI out mode count as just one click? how does this work? Also can you completely avoid using a battery with a power line adapter?

I tried using an old Nexus 4 as a live streaming camera a while back but after a few weeks the battery bulged and the gorgeous glass back shattered.

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does a video in this HDMI out mode count as just one click?

Effectively zero clicks:

Aside from rotary shutter options available on a few high-end (>$50,000) digital cinema camera models, video exposure time is controlled by sensor electronics; all other mechanical shutter mechanisms I'm aware of remain open when capturing video (for any combination of recording, HDMI out, in-camera LCD live view, or electronic viewfinder display).

Pedantically, I suppose you can count one click for a normally closed (DSLR) shutter and zero clicks for a normally open (mirrorless) shutter, though I have no idea if DSLR firmware actually bothers to do this.

I'd also guess that simply opening and eventually closing the shutter causes less wear and tear than a typical <<1 second still photo exposure.

Also can you completely avoid using a battery with a power line adapter?

Generally, yes; in cases where battery-free DC input is not otherwise available, inexpensive "dummy battery" adapters are typically available that pass power through the camera's battery contacts from an external source.

Check adapter compatibility before buying a camera, however; make sure that a compatible dummy adapter (a) exists, (b) doesn't physically interfere with camera operation (buttons, tripod mount, etc.) and (c) attaches without a significant risk of damage to the camera (e.g., if you plan to use the camera in anything other than a totally stationary position, you probably want to ensure the battery compartment door can be closed, removed, or otherwise secured when the dummy battery is connected).

> does a video in this HDMI out mode count as just one click

A mirrorless camera's shutter is only used during taking photos (and some cameras, like the Sony A7S2 which I own, can also run in "shutterless" aka silent mode, at a slight expense in picture quality). It will not be impacted at all if the camera is used exclusively for video.

> Also can you completely avoid using a battery with a power line adapter?

Not with Sony Alphas, they will drain the battery even if hooked up to a powerful USB charger. Get a "dummy battery" for your camera.

> I tried using an old Nexus 4 as a live streaming camera a while back but after a few weeks the battery bulged and the gorgeous glass back shattered.

I hope you got rid of the phone or at least took out the battery, when it bulges it's having internal issues and now is a fire / explosion risk. You probably used a cheap power supply that has lots of high frequency ripple.

On many mirrorless cameras the shutter is open by default (even when the camera is closed), so not even one shutter "count" on this type of usage (the shutter is only used when taking a photo, and not even then if in silent mode is used). Shutter lifespans are in the tens of thousands to hundred of thousands normally. It's good to know the value when buying used (because you don't know what you are buying, some cameras have such a high burst rate that you can reach hundred of thousands in hours if you keep the button pressed).

For many cameras you can find a power line adapter that replaces the actual battery and connects to power (Canon cameras cannot charge their batteries in-camera so this is a must for them).

I don't think modern cameras are going to open/close the shutter continuously. That would cause a lot of noise while filming, and they usually record sound too. They rather use "electronic shutter" while filming, which is just another name for ignoring some exposure time. So it would count as one click, or maybe less.

> can you completely avoid using a battery with a power line adapter?

This is going to depend on the particular camera. I just tested a mirrorless camera, doesn't work without a battery, and doesn't use the DC power while on.

The shutter count is just a good estimate for how much the camera has been used.

Using the camera for video doesn't really have much impact compared to photography since the shutter is just kept open

In all cameras that have a video mode, the mechanical shutter does not activate on every frame. The exception is some video cameras that use a rotating mechanical shutter, but those do not have a limited number of clicks.

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