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Crop factor for regular 8mm


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#1 Patrick Cooper

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Posted 31 May 2011 - 08:42 AM

Seeing as that the size of the regular 8mm frame is almost half of that of super 8, is there close to a 2x crop factor when comparing lens focal lengths and angles of view to super 8? For example, if you had a regular 8mm camera that has a 30mm lens, would the angle of view of that 30mm prime be close to that of a 60mm in super 8?
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#2 Brian Drysdale

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Posted 31 May 2011 - 09:22 AM

Regular 8mm is larger than you think, its frame is 4.5mm wide and Super 8 is 5.79mm, I guess that would be approx 1.3, to get near x 2 you'd nearly be shooting on standard 16.
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#3 Patrick Cooper

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Posted 31 May 2011 - 10:38 AM

Yea, it's been a while since Ive viewed any regular 8mm film. Strange that a lot of sources claim that the super 8 frame is 50% larger than regular 8mm when that is not really the case.
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#4 kevin jackman

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Posted 31 May 2011 - 10:56 AM

Ive done the math a few times and it is a few hairs over 50% compared to the 8mm frame. ut it math it's all relative, going from super8 down, the frame is about 33% bigger. It depends on your perspective. So 50% from 8mm up and 33% from super8 going down.
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#5 David Mullen ASC

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Posted 31 May 2011 - 11:07 AM

http://en.wikipedia...._and_super8.png

Brian is correct, the conversion factor is 1.3X.
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#6 Martin Baumgarten

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Posted 31 May 2011 - 07:24 PM

The hype that Super 8mm is 50% larger than Regular 8mm is just that...hype. It was based mainly on projection cropping since they are less severe on the Super 8mm projectors...well..the better ones. The 8mm projection gate cropping standard was based on the one used for 16mm, and applied to the smaller frame, it was harsher than it needed to be. Later higher end projectors for Regular 8mm didn't crop as severely. Many enthusiasts even filed out their projector gates to a more 'normal' perspective.

Thus, focal lengths for both formats aren't all that dissimilar. The "normal" focal length for Regular 8mm is 12.5mm and for Super 8mm it's 15mm. Although many Regular 8mm camera lenses for normal are 13mm. Remember, the 'normal' standard has more to do with perspective, in maintaining that relative to all gauges. What's really usable for normal, is relative of course. I think most of us prefer a wider angle than what is set as normal focal length. That being said, the basic prime lens builtin to virtually all beam-splitter Super 8mm cameras if you were to remove the front zoom standard is 15mm. And the same goes for those later model Regular 8mm cameras that had zoom lenses, but with a 12.5mm or 13mm prime lens in there. [Normal 8mm, Double 8mm, Standard 8mm etc, with apologies for those outside of the USA since it's common for us to refer to the old bootlace as Regular 8mm].

Anyhow, this gives you a reference starting point, and the other posting stating that Super 8mm was 1.3x larger is on the mark, so I would use that to compute relative focal lengths, to get the same image magnification compared to the Super 8mm counterpart and vice-versa.

Hope my two cents here helps.
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#7 Patrick Cooper

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Posted 31 May 2011 - 08:46 PM

Thanks all. Very informative. Now I can get a greater sense of the sort of field of view that one can get on the commonly available regular 8mm cameras and lens combinations. Although I haven't had an extensive look at all the equipment options out there, I am surprised that manufacturers didn't put longer focal length lenses on these cameras, unlike super 8. On super 8, there is some pretty impressive telephoto power on some cameras for people like myself who enjoy filming subjects like wildlife (60 and 70mm etc at the tele end of the zoom.) With regular 8mm, they could have taken more advantage of the small frame and put some decent focal lengths on there to attain similar or even greater magnifications. Yet what I am seeing on regular 8mm zooms is very conservative at the telephoto end - 30mm etc which would be equivalent to about 40mm in super 8 - not too bad but nothing really spectacular. Though thus far, I haven't checked out what sort of primes are available in regular 8mm.

Edited by Patrick Cooper, 31 May 2011 - 08:51 PM.

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#8 Dom Jaeger

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Posted 01 June 2011 - 03:29 AM

Yes 36mm or 38mm (or 1 1/2") were usually the telephoto primes or converters supplied with early Regular 8 cameras. Most of the fixed zoom models that started to appear in the early 60's followed that trend, going up to between 30 and 40mm.

There were some longer primes made in D mount, or the various other 8mm camera mounts around, by companies like Som Berthiot, Wollensak, Kern, Rodenstock and Kodak (and likely others), usually 50mm (or 2") and 75mm ( 3"), but going as long as 150mm ( 6"). They seem hard to find, though.

Angenieux and Schneider also made longer, interchangeable zooms, such as 8-48 or 6.5-52. The longest zoom I've heard of is an Angenieux 12-120 for the French-made Ercsam Camex.
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