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Dual-Beam Focusing?


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#1 Chris Rowe

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Posted 11 September 2009 - 03:40 AM

Hello, first post and sorry if this has been covered elsewhere, I've looked all over and can't really find what I'm looking for. I recently acquired a Nizo 148 Spezial and have been non-stop thinking about proper focusing. I do not believe this camera has split-image as its specs just say dual-beam. I have searched for anything related to this but can't find info regarding Super 8. Looking through the lens I can't see the red or blue outlines of split-image and this system just doesn't seem to be that common which is probably why there isn't much info about it.

If anyone could point me in the right direction that would be very much appreciated. I'm also not sure if having automatic exposure would lead to varying brightness and darkness throughout certain shots. I want everything to be as smooth as possible with basically a constant exposure so I'll probably just have to use manual settings.

Thanks in advance
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#2 Richard Tuohy

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Posted 11 September 2009 - 07:07 PM

Hello, first post and sorry if this has been covered elsewhere, I've looked all over and can't really find what I'm looking for. I recently acquired a Nizo 148 Spezial and have been non-stop thinking about proper focusing. I do not believe this camera has split-image as its specs just say dual-beam. I have searched for anything related to this but can't find info regarding Super 8. Looking through the lens I can't see the red or blue outlines of split-image and this system just doesn't seem to be that common which is probably why there isn't much info about it.

If anyone could point me in the right direction that would be very much appreciated. I'm also not sure if having automatic exposure would lead to varying brightness and darkness throughout certain shots. I want everything to be as smooth as possible with basically a constant exposure so I'll probably just have to use manual settings.

Thanks in advance

Hi there Cris,
I haven't heard of 'dual beam focusing'. I would have assumed it meant the range-finder type of focusing aid with the colour defraction you describe. As you say, the range-finder focusing aid system was very rare on super 8 cameras. Some Bell and Howell models (in fact made by Chinon or Sankyo I believe) have this type of focusing aid. Otherwise I would have assumed it meant 'split image' focusing aid - the type with the circle in the middle divided by a horizontal (or sometimes vertical or even diagonal) line. Is there any kind of circle visable in the centre of the viewfinder image?
As for exposure, what you say is correct, though some light meters are less 'reactive' than others. Often times too a camera designed for mercury batteries which is being used with lithium batteries (not recommended by the way) will show hyper reactive light meter fluctuations. Yes, use the internal meter for the exposure, then set the camera to manual.
cheers,
richard
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#3 Chris Rowe

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Posted 12 September 2009 - 05:48 AM

Hi there Cris,
I haven't heard of 'dual beam focusing'. I would have assumed it meant the range-finder type of focusing aid with the colour defraction you describe. As you say, the range-finder focusing aid system was very rare on super 8 cameras. Some Bell and Howell models (in fact made by Chinon or Sankyo I believe) have this type of focusing aid. Otherwise I would have assumed it meant 'split image' focusing aid - the type with the circle in the middle divided by a horizontal (or sometimes vertical or even diagonal) line. Is there any kind of circle visable in the centre of the viewfinder image?
As for exposure, what you say is correct, though some light meters are less 'reactive' than others. Often times too a camera designed for mercury batteries which is being used with lithium batteries (not recommended by the way) will show hyper reactive light meter fluctuations. Yes, use the internal meter for the exposure, then set the camera to manual.
cheers,
richard



Hi Richard thanks for the response. That's good about the meter issue, and also my meter is powered by the AAs so maybe it won't be hyper reactive if I do leave it in auto like the ones that require the photo cells. As for the focusing I was actually thinking at first Dual-beam was another name for split-image but I do not see the circle in the center of the viewfinder or anything really. If I type it in to google I get what appear to be unrelated scientific topics. I think I'm just going to go for it and try to set things as best as I can and see what happens. If I set the focus all the way back will I get clear pictures for far away subjects like distance views?
Thank you,
Chris
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#4 Jim Carlile

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Posted 21 September 2009 - 01:51 AM

"Dichroic" is the name for the blue-red images that come togther at the focus point, but that's not what the 148 uses.

This Nizo lacks a center-circle split image, so what you do is just focus until the double image in the viewfinder comes together. It's a rangefinder, just not with the split image circle. The later 148 macro has split image focus, as do the bigger models.

Only dichroics are the underrated, more expensive Chinons, which were badged as Bell and Howell and the Beaulieu 1000 series. Maybe a few other brands-- it never caught on, harder to use in lowlight, but effective in general.
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