Quote Originally Posted by Mewael View Post
Are you Leica LTM users (IIIf/IIIc/etc.) comfortable using your Leica's without an auxillary viewfinder?
Yes, very much. I have used a II, IIIc and IIIf for a few years now, and have no parallax or framing issues.

I can recommend the SBOOI - the Leitz 50mm external finder - it's nice and bright, and 1:1 so you can use it with both eyes open all day long.

I have a Rollei 35 and a Kodak Retina but I can't focus accurately enough with the former and the later isn't that ergonomic.
If it makes you feel any better, I've found the Rollei 35 frame lines not all that accurate. At least not for the original version (no idea about later models.) I have a Retina Ia and the viewfinder leaves much to be desired. Fortunately it has an accessory shoe, so if you have a 50mm finder you can just slip it in and use that instead.