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Dear Mirrorless Camera Makers: Please Bring Back the Frame Line Selector


Have you ever used a Leica M Camera? If so, you may know of the little front mounted lever that displays bright frame lines in the viewfinder to show the field of view for lenses of different focal lengths?

This feature has been very useful to photographers over the decades. I propose to you that a bright-line feature could be implemented into the firmware for your mirrorless interchangeable lens cameras.

Here is how I think it should work:

Initially, the user goes to a menu item: “Prime Lens Library”. Let us say that the user has just purchased an 85mm lens. They select that lens from a list and add it to the library. Then they might also add a 50mm lens. And let us presume the camera has already registered a 35mm lens. Also, even though he or she does not presently own one, a 135mm lens is added to the lens listing.

Now. Suppose the photographer is using the 35mm prime lens, which the camera recognizes.

He or she realizes the 35mm lens is too short a focal length for the scene. The photographer presses the button assigned to the “Lens Selector” function. A bright-line appears in the viewfinder showing the field of view for a 50mm lens, and a “50mm” identifier appears in the lower right corner of the viewfinder image. Another press of the button, and now the identifier changes to 85mm and a new bright line frame shows the field of view for an 85mm lens.

The next press of the button brings up the frame for the 135mm lens, and a smaller bright line frame shows the field of view for that lens, even though the photographer does not yet actually own that lens.

The photographer changes the lens from the 35mm lens to the 50mm lens. The camera recognizes the change. While using this lens or she again presses the assigned “ Lens Selector” and the image in the viewfinder now shows a bright line frame for the 85mm lens, and, with another button push, the 135mm lens.

If the user is using a zoom lens, the framed images could cycle through all the prime lenses registered in the camera that are longer than the present zoom focal length.

Leica frame lines, as seen in the Leica M10 manual.

Adding this software feature would be extremely useful for any photographer using prime lines, especially landscape and scenic photographers. Also, it could be added to existing cameras through a firmware update. Doing so would certainly give owners a warm and fuzzy feeling.

Viewfinder lens selectors have been of various designs have been around since the dawn of interchangeable lens cameras, both still and cine/video. This implementation would be very welcome and very useful. It would also help sell prime lenses!

About the author: Bob Locher is a retired veteran amateur photographer who spent many years in the photography hardware business. The opinions expressed in this article are solely those of the author. Locher has written over 50 magazine articles as well as two books. You can find more of his work and writing on his website.

Image credits: Header frame line images via MIR Image Library/Leica