Voigtlander Bessa RF mystery push button on top???

[chuck_t]

<p>I have the same black Bessa RF (rangefinder) with separate focusing and viewing window. I can't figure it out what is the top button is for? It seems that there is a spring under.<br>

I also wonder is there any chance of light leak from the red window on the back when I reel to the next frame??</p><div></div>

[Dustin McAmera]

<p>Does that button not let the front unfold?</p>

[john_liberty]

<p>Not sure what the button is for. Yes, there is indeed a chance of fogging the film when you open the red window, so do it in the shade and you'll be fine. Just turn your back to the sun. Great camera!</p>

[h._p.]

As Peter says, the button is the front release. On mine, it's counterpoised by a pretty strong spring that yanks the front out quite smartly.

[Argenticien]

<p>I think you'll find that it's not the front release (which is a similar-looking button in analogous location on the bottom). This "button" on the top is actually not a button at all. It is a post that you rotate 90 degrees to put in place the 6x4.5 mask in the viewfinder window. On mine, this post has a few ridges across its top. To turn it, one either sticks a fingernail between ridges or just kind of presses down to make enough friction with a fingertip. It's rather fiddly. (And in my case, useless, because I haven't got the 6x4.5 mask that counts,<em> i.e.</em> , the one for the film gate.)</p>

[j.p._dahl_n]

<p>David van Hemel is correct. You turn it to swing the viewfinder mask in place. I use my RF-Bessa for 6x4,5 at the moment, loaded with Tri-X.<br>

The button for opening the camera is on the bottom.</p>