Lens and flash swaps: In all of my Nikon camera manuals it says, when attaching or detaching a lens, to “Turn the camera off.” Same with the flashes, “Turn both flash and camera off.”...

DaveC Loc: Illinois

In all of my Nikon camera manuals it says, when attaching or detaching a lens, to “Turn the camera off.” Same with the flashes, “Turn both flash and camera off.” I try to do this but often forget. For years. I’ve never had a problem. Has anyone? What could be the consequences? Does Canon and other makes specify this?

Longshadow Loc: Audubon, PA, United States

It may cause a problem, it may not, but the propensity to do so is there.
The lens and flash are peripherals to the camera processor, much as printers & scanners are to a computer. The processors (if on) are always talking to the peripherals.
Sometimes it may cause a "hiccup" when simply unplugged. (Ergo problems with unplugging memory chips as opposed to "ejecting" them.)
Not sure about Canon's recommendation yet, but I always turn my camera off when changing lenses, but I make sure the flash is off before I remove it.

Old Timer Loc: Greenfield, In.

Any time you work work with any thing that is electrical you should turn of appliance. Such as changing batteries in a car. The flow of current can short and cause a spark and do damage. That is the reason most manuals tell you to disconnect power before servicing.

LarryFitz Loc: Beacon NY

Any time connecting and disconnecting any electrical/electronic equipment it is a good idea to have both items powered down. Small little electronic pulses can and do occur. An individual pulse will cause the device to have a problem. But, if poked in the ribs enough times it will start to hurt.

Many devices do power down automatically.

gvarner Loc: Central Oregon Coast

I forget once in a while too, never had a problem. But I do try to remember to turn them off, just in case. I could imagine that tripping the shutter while mounting a lens or a flash that was already on could be a big problem.

Kmgw9v Loc: Miami, Florida

DaveC wrote:

In all of my Nikon camera manuals it says, when attaching or detaching a lens, to “Turn the camera off.” Same with the flashes, “Turn both flash and camera off.” I try to do this but often forget. For years. I’ve never had a problem. Has anyone? What could be the consequences? Does Canon and other makes specify this?

Cannot argue with "all" of the manuals; but it is not something I think about much.

ejones0310 Loc: Tulsa, OK

DaveC wrote:

In all of my Nikon camera manuals it says, when attaching or detaching a lens, to “Turn the camera off.” Same with the flashes, “Turn both flash and camera off.” I try to do this but often forget. For years. I’ve never had a problem. Has anyone? What could be the consequences? Does Canon and other makes specify this?

From page 48 of my Canon 80D manual, "When attaching or detaching a lens, set the camera's power switch to <OFF>."

It is best practice to power off any electronic device when removing a component that is connected electrically to the device. Breaking the electrical connection can cause transients that can damage semiconductor components. Powering the unit off will power down those circuits.

rgrenaderphoto Loc: Hollywood, CA

There is a reason it is recommended.

tcthome Loc: NJ

DaveC wrote:

In all of my Nikon camera manuals it says, when attaching or detaching a lens, to “Turn the camera off.” Same with the flashes, “Turn both flash and camera off.” I try to do this but often forget. For years. I’ve never had a problem. Has anyone? What could be the consequences? Does Canon and other makes specify this?

Like said here, # 1 reason is electrical. Lens contacts, flash contacts.

# 2 probably not a problem but could cause a software disruption. Why take a chance , if you remember , turn it off.

BebuLamar

I would turn the camera off although there were times that I forgot.

PAZ Loc: Glen Ridge NJ

In the heat of the battle anything can happen, including popping out the SD card while the camera's on. Stuff happens, just have your recovery software ready if needed. Cameras and cards are more reliable than ever but if you have two card slots, set one for raw and one for jpeg, one time, last year I had the raw card fail and couldn't even recover them but I had the jpegs as backup.....Phew!

PAZ Loc: Glen Ridge NJ

In the heat of the battle anything can happen, including popping out the SD card while the camera's on. Stuff happens, just have your recovery software ready if needed. Cameras and cards are more reliable than ever but if you have two card slots, set one for raw and one for jpeg, one time, last year I had the raw card fail and couldn't even recover them but I had the jpegs as backup.....Phew!

RWR Loc: La Mesa, CA

It’s always wise to turn off a flash when attaching or removing, but for lenses I think it’s only recommended for those with the glitzy gold decoration on the mount.

speters Loc: Grangeville/Idaho

DaveC wrote:

In all of my Nikon camera manuals it says, when attaching or detaching a lens, to “Turn the camera off.” Same with the flashes, “Turn both flash and camera off.” I try to do this but often forget. For years. I’ve never had a problem. Has anyone? What could be the consequences? Does Canon and other makes specify this?

Yep, that is the same across all camera brands, one is to turn if off, when ever removing or adding an accessory that has a electronic connection, as memo cards, remotes, flashes, lenses etc. If you have done otherwise for years without any promblems just says, that you've been lucky so far, as the chances of damaging your camera and/or the devices are increased multifold!

jerryc41 Loc: Catskill Mts of NY

DaveC wrote:

In all of my Nikon camera manuals it says, when attaching or detaching a lens, to “Turn the camera off.” Same with the flashes, “Turn both flash and camera off.” I try to do this but often forget. For years. I’ve never had a problem. Has anyone? What could be the consequences? Does Canon and other makes specify this?

That seems to be a universal instruction - "unplug, disconnect, turn off." I try to do that, but I've often forgotten, and everything still works.