SP 50mm framelines

[abenner]

So I just got an SP and love it. Not quite as easy to focus as my M4-P, but the finder is plenty bright and like the isolated 50mm framelines.

The question I have is, is there a purpose to the way that the 50mm framelines look? In other words, the lines aren't just four corners or equal appearing lines, but rather the edges of the lines appear to be cut at an angle and the upper line looks different than the lower line. Forgive my crude description, but I'm not looking through the finder right now.

I'm sure someone with some knowledge of the SP knows what I'm talking about and can educate me a little. Thanks in advance.

 

[furcafe]

While I'm not a Nikon RF expert, my understanding of how most projected framelines work is that they are just lines cut in a mask, see this thread:

http://www.rangefinderforum.com/forums/showthread.php?t=48868

So, my theory is that the shape & size of the various cuts are necessary to make it possible for the SP to display the different framelines together, which is different from the Leica M series cameras that only show framelines either 1 @ a time or in pairs. See jlw's post (#9) in the thread above.

So I just got an SP and love it. Not quite as easy to focus as my M4-P, but the finder is plenty bright and like the isolated 50mm framelines.

The question I have is, is there a purpose to the way that the 50mm framelines look? In other words, the lines aren't just four corners or equal appearing lines, but rather the edges of the lines appear to be cut at an angle and the upper line looks different than the lower line. Forgive my crude description, but I'm not looking through the finder right now.

I'm sure someone with some knowledge of the SP knows what I'm talking about and can educate me a little. Thanks in advance.

 

[abenner]

Well, I get what folks are saying but that's not quite what I was asking; again, difficult to describe what I'm talking about. So, a picture is always worth a thousand words... In this photo I pulled from the SP manual, you can see what I'm talking about. The manual doesn't mention why the framelines look the way they do, so that probably means there's no rhyme or reason to it, but I guess they just look different to me so I figured there must be a purpose.

 

[VinceC]

I had one of these apart about 20 years ago to replace a hair-sized spring that made the framelines display correctly.

If you look at the diagram below, the different framelines are held together by thin strips of foil, much thinner than paper, like overlapping leaves. If you change the framelines from 50 to 85 to 105 to 135, you can sort of see how the shapes of the 50 frameline shifts a little as the slats and stripes move around. You can also clearly see the evidence of the diagonal strips that hold it all together.

 

[Highway 61]

The masks slides with an angle of 45° to come into position and to get out of it, this explains that the edges of the lines in the finder aren't cut at a 90° angle but at a 45° one, and that the lines of the upper right part of the frame are the opposite twins of the lines of the lower left part of the frame.

If you look at the 85, 105 and 135 framelines, you will notice the same thing.

To sum-up : the symmetry axle, alongside which the framelines slip, crosses the composing frame diagonally, not horizontally.

When my SP hasn't been used for a while, or if it's cold, it takes a while for the 135mm framelines to display (which they do with no problem) when I directly switch from 50 to 135. It might be a stiff lubricant issue but I for sure won't get into the mechanism - works for me.

 

[VinceC]

And, of course, the reason they slide at a 45 degree angle is because that's the direction of parallax ... the finder is 45 degrees from the center of the lens.

 

[Highway 61]

And, of course, the reason they slide at a 45 degree angle is because that's the direction of parallax ... the finder is 45 degrees from the center of the lens.

Forgot about this - of course. 🙂

 

[abenner]

I knew there was a reason! Interesting. Thanks for educating me. Never fails to find plenty of smart people around here.

 

[splitimageview]

Bottom line: I'm a big fan of the SP viewfinder. Having a separate 28/35 finder allows the 50+ finder to be 1:1, instead of reducing the magnification to cram in all the frames.

 

[VinceC]

Ditto on that. The Nikkor short telephotos are excellent, and the SP finder means there's no compromizing. You can get the most out of each lens. Reduced image viewfinders are a difficult compromise because they make the images from 50mm and longer lenses so small.