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simonclivehughe
04-19-2005, 08:09
I'm thinking of picking up the CV 21mm lens for my R-D1. I already have the 35mm viewfinder from my 35mm Ultron lens and I'm wondering if anyone out there can compare its' field of view versus the 21mm D type viewfinder.

I'm used to "thinking inside the box" when using my 75mm, so I don't mind "fudging" a bit. Obviously, if I don't have to spend an additional $175 for the viewfinder, I'd rather not!

Jim Watts
04-19-2005, 08:35
Simon,
21mm on the R-D1 = 32mm equivalent. Its normally regarded that the safety margin with most viewfinders is x0.85, but there are individual differences. Your 35mm finder will therefore have a field of view of 35/0.85 = 41.18mm (lens) at infinity, so will crop too much. 32/41.18 = 77.7% coverage or a x0.77 safety factor.

A 28mm finder in theory should just about do 28/0.85 = 32.9mm (lens) at infinity. This = 32/32.9 = 97.3% coverage or x0.97 safety factor. But individual lens/finder differences, changes in focal length as you get closer, parallax and personal preference on cropping will affect this. See my thread: http://www.rangefinderforum.com/forums/showthread.php?t=5586
for more discusion on this. I'm considering a 28mm or a 21D but like you I'm looking for more practical experience. Most people who have the 21D seem happy but I think I would prefer a tighter smaller safety margin as long as I don't lose any image area.

pfogle
04-19-2005, 09:48
Jim - a question about the safety margin...

I'm pretty sure that the old Canon lit used to specify it was 85% coverage by area so that would mean, you take the square root to get about 92% linear, so 35 vf gives a view of 35/.92=38mm. I may be wrong, anyone know?

My experience with the 21D (never used the 28) is that it's pretty slack, and I find it hard to get a confident feel for the exact frame edges. It's a combination of framelines to loose, distortion, and the changing visibility of the frame as the eye pupil moves around in the eyepiece (if you see what I mean).

I'd certainly be interested to look at the 28, but I don't really want to spend any more either!

Phil

vincenzo
04-19-2005, 10:03
Also bearing in mind that the VC 21 D is plastic and rather over-sized in comparison to the small unobtrusive metal VC 35 finder.

Sukiari
04-19-2005, 11:53
I usually use the 35mm frame lines with the 21mm lens. The lines themselves are dead on rule of thirds guide lines with the 21mm lens, and the ability to keep both eyes open and use the rangefinder at the same time makes this method better than using an external finder in my opinion. I have good framing accuracy with this method.

Jim Watts
04-20-2005, 00:30
Jim - a question about the safety margin...

I'm pretty sure that the old Canon lit used to specify it was 85% coverage by area so that would mean, you take the square root to get about 92% linear, so 35 vf gives a view of 35/.92=38mm. I may be wrong, anyone know?

My experience with the 21D (never used the 28) is that it's pretty slack, and I find it hard to get a confident feel for the exact frame edges. It's a combination of framelines to loose, distortion, and the changing visibility of the frame as the eye pupil moves around in the eyepiece (if you see what I mean).

I'd certainly be interested to look at the 28, but I don't really want to spend any more either!

Phil
Phil,
You are of course correct about the calculation if it is by area and not linear. This may be the one of the reasons for the difference in of coverage in finders of nominally the same focal length. My gut feeling (without carrying out any measurements) is that Cosina Voigtlander use a linear interpretation where I think Leitz use area. I see much less "waste" using my M4 framelines on film than I do with the R-D1's on the sensor. I think this is conjecture is also supported by my trials of the VC 40mm Nokton using the R-D1's 35mm framelines. 40mm x 0.85 = 34mm so you should see a very slight crop on the final image, which I do. It is so slight that I find this a very usable combination. (must try to get another loan of the lens ;) )

Thanks for your comments on the 21D finder. I was very interested in your findings and it bears out exactly my experiences with the VC 25mm Skopar and finder on my M4. So I think for me the VC 28mm finder for the 21mm Avenon may be the best bet. I'm just a bit worried that parallax error may prove too much without a safety margin when close in. Do you find the 21D nearer to your original vision close-up? I'll just have to get a trial in the next few days. This finder is more readily available than the 21D.

I have been trying the VC 25mm finder since getting the 21mm lens but this is waaaay too slack for me.

Jim Watts
04-20-2005, 01:51
I had forgotten in the above that David Kieltyka thinks the 40mm Summicron-C an exact match for the R-D1 35mm framelines and that the VC Nokton may be closer to 42mm. Just goes to show that we should treat all values as nominal and go for practical trial if possible.

pfogle
04-20-2005, 01:53
Jim,

I think, with finders, like the lenses themselves, you just have to go with what feels right. I had the 40mm Nokton, didn't like it (can't even really say why, just felt wrong), changed to the 35 pancake; didn't like that, now I'm using the 35/1.7, which I like a lot. In the 21, I used the Cv 21, now I've just got the Avenon from Mike Tokue, and I like that more, even though it's probably not quite as sharp. I'm using the 21D finder, but don't take it too seriously. I'm not sure that another finder would be worth it for me, but if I was getting one again, I would definitely check out the 28 finder. For me it's as much 'do I want to stick my eye up to this thing' as much as 'is this showing an accurate frame'.

By the way, I think you're right about the different VF standards - the R-D1 is definitely looser than the Leicas or the non-pro Canon SLRs.

cheers
Phil

simonclivehughe
04-20-2005, 07:33
Well, the proof is in the pudding... I picked up a great used 21mm (sans finder) and it seems to work just fine with the CV 35mm finder that I had. If anything, I notice that on the LCD I actually get a tad more than I see in the finder, and it seems to be at the bottom of the frame. But the bottom line is that it's very workable!