EBL & 1:1 Viewfinder + Lens Choices?

H guys,

I have a new-to-me Voigtlander R3m. It came with a 40mm Nokton Classic lens that I don't love for various reasons, so I've been looking for a 50mm lens. I've more or less set my sights on the newer 50mm f1.2 Nokton Aspherical lens, which by all accounts is a great lens at a great price point.

 

Looking at B&H's site for this lens, I thought I'd ask if anyone could compare the Nokton 50 f1.2 to the Zeiss ZM Planar f2? Got 3 answers so far I think one of which actually addressed the question of comparison BUT one answerer posted this:

 

"I'm going to say the main issue is going to be focusing accuracy. The 1:1 viewfinder is excellent for a 50mm lens, but the actual rangefinder effective base length (EBL) is only 75% as long as a Leica's (most common) .72x finder with an EBL of 49.3mm. While a great lens, focusing may be hit or miss with the f1.2 on that particular camera."

 

To which I say, "huh?" & "what?"

 

Can anyone clarify this for me, please?

 

Effective Base Length?

What's that exactly?

How does EBL affect a camera viewfinder's relationship with a lens?

 

Is this one minuscule & deeply nuanced factor, or a for real issue that should definitely be addressed when choosing a 50mm lens for this R3m Rangefinder camera with its 1:1 viewfinder?

 

Thanks in advance!

Tom

An internet search has turned up this article on explanation of EBL

https://www.35mmc.com/24/01/2015/quick-guide-rangefinders-effective-base-length-ebl/

It looks like you found the answer, but in short longer rangefinder base length (distance between two windows) and/or greater magnification mean a more accurate rangefinder.

 

I can't say if the f1.2 will be hard to focus on the R3m, never having owned either, but the Bessa is at a disadvantage compared to Leica/Contax/Nikon.

 

That said, it was presumably designed with the Nokton in mind...

 

Maybe the question is not so much if the camera can focus the lens, but if you can.

 

What were the issues with the 40mm? If any of them were focus related, be wary, the 50mm will be harder.

I find the 40mm a bit too wide for my liking. AND the focus ring is tight up against the body of the camera. Which makes it a bit fiddly to get a solid hold on for focusing.

Quoting Cameraquest

• Keeping the same 37mm rangefinder base length as R/R2, the R3M's increased magnification to 1:1 means an EBL or Effective Base Length of 37 mm. That is less than the Leica M .58 finder at 40.16 mm, but it is a substantial improvement over the R/R2/R2A/R2M at 25.16 mm. For more info on Rangefinders, Viewfinders, and Effective Base Length see RF/VF.
  
• Rangefinder Base length of 37mm: This translates to an effective rangefinder base length of 37mm for the 1.0x magnification R3A, and 25.6 mm(37mm x .68 magnification) for the R2A. In other words, the R3A's rangefinder is 74% as long as the standard .72 Leica M finder, while the R2A's rangefinder is 51% as long as the standard .72 Leica M finder with EBL of 49.32.
  

I'd be extremely(!) concerned about that when shopping for insanely fast glass. I believe my 90/2 worked on M4-P even better on M3 and it does feel pretty lost i.e. not practically focusable on a 0.68 VF of an early digital, most likely due to lack of EBL.

Yes sure others seem to occasionally manage their extremely fast glass. I have no clue if they take their kit for a CLA one or two times per year, how much better their eyes might be and so on.

I might be willing to someday try a 35/1.4, otherwise I'll stick to 50/2 & 90/4. An optimist might set the benchmark for 0.68x Leica finders to 90/2.8 & 50/1.4. I feel way too lazy, to lug lens speed that I am no way confident to use wide open around.

I find the 40mm a bit too wide for my liking. AND the focus ring is tight up against the body of the camera.

I'm no fan of solitary 40mm lenses either (I tried it on an old fixed lens RF, for a roll or 3) but I'd make a bigger step than replacing a 40 with a 50mm. TBH: I don't like 50mm very much on FF. Its fine on 1.33 or even 1.6 crop.

Why not follow the original CL concept and scoop up an inexpensive 90/4 to go with what you already have?

Did you take wide open shots with your f1.4 and feel your sharp & precisely focused results still drowning in DOF? If not: Why care? Lens speed you don't need is just a spine breaker and money dump on Rangefinders. It really takes a TTL focusing system to make unused lens speed nice to have.

Thanks for the differing perspective.

Well as somebody said already, somewhere: "rent a lens and see how you like it".

Might just give that a try.

Yes, it is more difficult to hit exact focus at wide apertures with a shorter rangefinder base length. At narrower apertures one is often covered by the depth of field compensating for minor focus errors, but wide open one has to rely much more on their own visual acuity as well as the images coinciding in the rangefinder. The base distance in the rangefinder is the key here. As the base distance increases so does the potential for accurate focus. Leica took advantage of this is several models by having an increased base distance. The article cited above does a good job in laymans terms of explaining why effective base length is important.

I use a lot of fast glass- using a short-throw fast lens on a narrow-base RF is challenging. Too bad long-throw lenses are "not the fashion". Much easier to focus a long-throw Canon 85/1.5 on my M9 than it is some of the newer lenses.

 

7Artisans 75/1.25, Wide-Open by fiftyonepointsix, on Flickr

 

7Artisans 75/1.25, Wide-Open by fiftyonepointsix, on Flickr

 

7artisans 75/1.2, wide-open on the M9.

 

 

Practice helps.

RF specific side note on lens "loveability": #Viewfinder blocking. IDK how annoying that will be with the Nokton.

Sure if you need(!) speed desperately, it is worth working around that, but a next wealth leading to a not VF blocking slower lens's purchase "ordinary use in mind", would look "normal" to me...

Practice helps.

True. But is that the way to go in the 2020s on film? 30 years ago 35mm was the spray & pray medium at hand. Now I'd want more keepers.

I've never been one for "spray and pray", have used RF cameras for over 50 years- since I was 11 years old.

So easy, an 11 year old can use them. Why do people think this is hard? You bring two images together, press a button.

I use a lot of fast glass- using a short-throw fast lens on a narrow-base RF is challenging. Too bad long-throw lenses are "not the fashion". Much easier to focus a long-throw Canon 85/1.5 on my M9 than it is some of the newer lenses.

 

7Artisans 75/1.25, Wide-Open by fiftyonepointsix, on Flickr

 

7Artisans 75/1.25, Wide-Open by fiftyonepointsix, on Flickr

 

7artisans 75/1.2, wide-open on the M9.

 

 

Practice helps.

Good shots Brian. The 7 artisans lens does you proud.