Users of older Leica cameras will remember the complicated procedures required for flash usage in the film era. There were quite a few of the screw-mount Leica bodies that started life with no synchronisation and had it added later with marvellous attachments that clamped onto shutter speed dials and then closed contacts with spring levers and rotating arms. Users could dial in all sorts of delay times and I'll bet nearly every one was wrong...
In the M -series times the M3's and M2's were initially fitted with quick-connect sockets that did not match anybody else's cords...and we all went out and bought extra connectors to convert either the flash or the camera to shoot. We all then promptly lost them and had to buy more, but that is another story.
At last, in the digital era, the M series and other Leica cameras that have hot shoes on the top have been the recipients of new electronic flashes that have TTL contacts and simplified control mechanisms. If you flash, you can get that synching feeling easily...*
Here is one of the latest. The SF 40.
I am not suggesting treason for Leicaphiles if I point out that the shape of the flash and the controls are remarkably similar to those of the Nissin i40 series of flashes. They are made to fit Nikon, Canon, Micro 4/3, Sony, and Fujifilm cameras and now it would appear that Leica have decided that they will also be of benefit.
These are terrifically capable flashes and allow easy control of output power in TTL and manual modes. They command or slave and also provide that little bit of constant front light for video work.
The really nice thing about them when you use them on smaller cameras is the fact that they are a small size in themselves and have concentrated the weight of the batteries low down in the body. You are not waving a big bulky mass on the hot shoe.
Note that they have the internal zoom facilities that take advantage of maximum light for a particular focal length.
And they have the red dot...
* The older readers will now think of a Bovril ad for the rest of the week...