Focusing a 90mm 2.0 with R3A?

H

Hephaestus

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Hi all, I need to call on the RFF gurus once again!

The problem is this: I almost exclusively shoot a 90mm lens indoors, so I’m usually shooting at f 2.8 or less. I’m thinking the R3A might be a great camera for me, on account of the life-size viewfinder. However, I’ve heard that the base-length of the finder is relatively short and it has trouble focusing fast lenses. Is there much truth in this?

To summarize:
-Would you be comfortable regularly focusing a 90mm 2.0 wide open on an R3A?

-Is there a different camera that might be more suited without moving to a 0.85 Leica?

Thanks very much and happy nearly New-Years.
-Ryan
 
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Not very comfortable esp. for large prints at f/2.

And you could try the Leica M3 which has 0.95 magnification. (Sorry, but this is life.)
 
A finder magnifier could make things easier, IF the metering display can still be seen.

I'd be more concerned with finder blockage by the lens barrel.
 
Thanks for the help!

I was afraid there might be problems! A built-in light meter is important to me, so I suppose I'll have to save my pennies for a few months and try for a 0.85 Leica. I shouldn't feel so upset about that, but the money is a stretch and I hate spending that much money on my walk around / beater camera that just gets tossed in my bag wherever I go.

Anyway, thanks for the advice!

Good light!
-Ryan
 
another related question:

Isn't focusing a 90mm at f2 pretty much the same as focusing a 50mm at 1.5? The DOF is probably just as shallow.
 
Hephaestus said:
Thanks for the help!

I was afraid there might be problems! A built-in light meter is important to me, so I suppose I'll have to save my pennies for a few months and try for a 0.85 Leica.
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Actually, I wasn't saying the metering display couldn't be seen with a magnifier like the one from Megaperls. I'm simply not sure one way or another. :eek:

I think you should handle the Leica 0.85 body before making a deicision. Even at this magnification, the 90mm framelines are still too small for my taste, especially with the huge missing corners. Of course you could get a magnifier for it as well, and there won't be a finder blockage problem because the viewfinder window is much further away from the lens mount than the R3A's.
 
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Mazurka said:
Of course not. The Apo-Lanthar's maximum aperture should tell you something. :p

More at http://imx.nl/photosite/leica/technics/rfaccuracy.html
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Mazurka,

The effective base length of the R3A/R3M cameras is 37mm, almost the same as a Leica with 0.58x finder (40.17mm base length). A 0.58x Leica is able to focus a 1.8/85mm Canon lens. Therefore, the R3A/R3M has no problem to handle a 2.0/90mm, even if the R2A/R2M cannot focus accurately anything faster than the 3.5/90mm Apo-Lanthar, due to its shorter rangefinder base length (25.16mm).

I can confirm that my R3M is indeed able to focus accurately a 90mm Summicron. And the 1:1 finder is very nice with a short tele. After you get used to it, aiming the camera with both eyes open is a huge advantage.

Cheers,

Abbazz
 
Abbazz said:
The effective base length of the R3A/R3M cameras is 37mm, almost the same as a Leica with 0.58x finder (40.17mm base length). A 0.58x Leica is able to focus a 1.8/85mm Canon lens. Therefore, the R3A/R3M has no problem to handle a 2.0/90mm, even if the R2A/R2M cannot focus accurately anything faster than the 3.5/90mm Apo-Lanthar, due to its shorter rangefinder base length (25.16mm).

I can confirm that my R3M is indeed able to focus accurately a 90mm Summicron.Abbazz
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37 is 92.1% of 40.17. Humans share more DNA with the chimpanzee than that. But somehow I don't think you'd believe we are "almost the same as" a chimp. :p

The ability to focus is vastly different from repeatable accuracy or ease. I can focus anything with just a helicoid and a proper distance scale and don't even need a rangefinder. How much accuracy I can repeatedly achieve is another matter, obviously.

Keep in mind that there are a lots of links in the chain of the RF system (including lens, body, RF AND operator vision/skill), each with its own tolerance. The shorter the rangefinder base, the better-adjusted the whole system needs to be. Those people who had their Konica RF cameras adjusted to Leica specs know this only too well.

Need more numbers and don't want to read Puts' page? At the minimum focussed distance of 1 metre, the 90AA has a depth of field from 0.993 to 1.007 metres, i.e. plus and minus 0.7% from 1 metre, or a mere 1.4 cm in total.

OTOH, I do agree that a longer-base rangefinder is not a must if you never or rarely shoot a 90/2 lens fully open at close range.
 
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Abbazz said:
Mazurka,

The effective base length of the R3A/R3M cameras is 37mm, almost the same as a Leica with 0.58x finder (40.17mm base length). A 0.58x Leica is able to focus a 1.8/85mm Canon lens. Therefore, the R3A/R3M has no problem to handle a 2.0/90mm, even if the R2A/R2M cannot focus accurately anything faster than the 3.5/90mm Apo-Lanthar, due to its shorter rangefinder base length (25.16mm).

I can confirm that my R3M is indeed able to focus accurately a 90mm Summicron. And the 1:1 finder is very nice with a short tele. After you get used to it, aiming the camera with both eyes open is a huge advantage.

Cheers,

Abbazz
Click to expand...

I agree with Mazurka on this one. The Leica .58x viewfinder is designed for maximum effectiveness with wide angle lenses, not with 85 & 90 mm lenses. Use it with those lenses at f/1.8 and f/2 at your own risk. And the Bessa 1.0x viewfinder is even short of that.

The 37 mm effective base length of the Bessa viewfinder is achieved by the increased magnification. IMO, the mechanical advantage of a longer base line such as the Leica is always preferable to the same effective base length achieved by increased magnification. If for no other reason, the longer base line is more effective because of its ability to minimze the effect of any slight misalignment of the rangefinder. However, it is the ability of the longer base line to make fine adjustments in focus that are required with such shallow depth of field at these focal lengths at or near maximum aperture that makes the leica a superior instrument. Add increased magnification to a viewfinder with the Leica's base line & it becomes an instrument capable of even greater precision. However, increased magnification with the short base line of a Bessa & you still have a short base line, less capable of fine adjustments in focusing.
 
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