These Lenses are WHAT focal length if they were 35mm??? at DVinfo.net

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Old April 18th, 2005, 03:23 AM   #1
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These Lenses are WHAT focal length if they were 35mm???

OK, so break it down for us all..

What are the millimeters for these cameras if they were 35mm cameras?

1. JVC HD10U (???mm to ???mm)
2. SONY FX1/Z1 (???mm to ???mm)
3. JVCHD100 w/stock lens (???mm to ???mm)
4. JVCHD100 w/optional wide (???mm to ???mm)

and while we're at it....

5. Panasonic DVX100a (???mm to ???mm)
6. Canon XL1s w/stock lens (???mm to ???mm)
7. Canon XL2 w/stock lens (???mm to ???mm)
8. Canon XL1s/XL2 w/optional wide (???mm to ???mm)
9. Sony PD150/170 (???mm to ???mm)
10. Sony VX2000/2100 (???mm to ???mm)

and if you know....

9. Panasonic HVX200 (???mm to ???mm)

Can someone break it down once and for all, in one single post?? It would help a million people!

- Shannon W. Rawls
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Old April 18th, 2005, 04:18 AM   #2
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The answer to all your questions is the same:

7.2x.

Every camera you listed is a 1/3" camera, so take the existing focal length and multiply by 7.2, and that's the approximate equivalent focal length as mounted on a 35mm still camera.

Example: DVX is 4.5 to 45mm. 35mm equivalent = 32.5 to 325mm.
Others I know off the top of my head:
VX2000/2100/PD150/PD170: 6mm to 72mm, 35mm equiv = 43mm to 518mm
Z1/FX1: 4.5mm to 54mm, 35mm equiv = 32.5 to 389mm
HVX200: 4.5mm to 58.5mm, 35mm equiv = 32.5 to 420mm.
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Old April 18th, 2005, 11:22 AM   #3
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This one was a surprise to me when I learned it, but it's relevant if anyone is looking to duplicate the look of a feature 35mm...

The magnification factor for 1/3" to 35mm cine is 4.4x.
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Old April 18th, 2005, 11:31 AM   #4
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A great article on digital depth of field, by Bob Atkins.
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Old April 18th, 2005, 11:55 AM   #5
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Hmm... OK, this one's for Charles and Barry, I guess:

Charles: I see what you're saying here, due to the smaller frame of a cine 35mm camera (as opposed to an SLR or Vista camera), the magnification factor for a given lens is less - sounds right to me.

However, we still talk about a 50mm (cine) being a "standard" FOV lens, do we not (although I appreciate the point that 40mm is actually more regularly used which would fit in with what you're saying).

So what's going on here?? Are we all just using short-hand for cine lenses (just thinking here - on 16mm a 25mm lens is regarded as standard view as well, isn't it) that doesn't *quite* fit the truth? I've never noticed a tele effect from a 50mm on a 35mm cine camera, but then I wasn't really looking...

Surely the Z1 doesn't have the equivalent of a 20-240mm lens??? That'd be astounding!

Am I just being stupid, once again?! ;)
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Old April 18th, 2005, 12:59 PM   #6
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Quote:
Originally Posted by Dominic Jones

Surely the Z1 doesn't have the equivalent of a 20-240mm lens??? That'd be astounding!

Am I just being stupid, once again?! ;)
No, you're pretty much right. In terms of a 35mm movie camera, the Z1's lens is equivalent to about 20 to 240, yes.
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Old April 19th, 2005, 02:08 AM   #7
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The idea of a "standard" lens is 1:1, which I always took as being able to open one eye and seeing an object the exact same size as it appears in the other eye (in the viewfinder). However, this depends on the viewfinder optics to some extent.

I too find the 40mm to feel more like "normal", or human vision; that or the 35mm. But I think a true POV can depend on the emotion of the scene. There's no reason that a 25mm or a 100mm can't sell a POV in certain circumstances.
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Old April 19th, 2005, 05:29 AM   #8
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The notion of 35mm equivalance put out by the camcorder industry is one of the biggest lies out there. What they are accurately referring to (although not specifically saying so) is the similarity on field of view, FOV, as defined by a formula given at this link

http://kmp.bdimitrov.de/technology/fov.html

thus a 50mm lens on a 6mm image chip is proportionally similar to a 360mm lens on a 43.2mm image chip - but only from the point of view of FOV.

the 360mm lens on the 35mm still camera will have a pronounced telephoto effect giving a flatter image (dreamy, far away look, isometric) and will have DOF properties which far exceed the 50mm lens. Try this at home folks!

In short the only thing that is equivalent in all aspects to a 360mm lens is another one
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Old April 20th, 2005, 04:02 PM   #9
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Quote:
Originally Posted by Barry Green
No, you're pretty much right. In terms of a 35mm movie camera, the Z1's lens is equivalent to about 20 to 240, yes.
Wow, I'm impressed. That's a fantastic bottom end on focal length - much better than the 150/170's...

Charles:
Agree entirely re: different length lenses for POV. We shoot a lot of interactive training content at the moment (which is largely if not totally POV), and have shot on some lenses getting on for 100mm equiv, for sure - a lot of it is in the framing, imho - especially if the bg isn't too important/relevant/busy.

John - no lens will have the same DOF as 35mm on any 1/3" or 1/2" CCD camera. However, the rule still holds in so much that the proportional difference in DOF between a 50mm lens on a 1/3" camera and a 10mm, say, lens on 1/3" camera is the same as it would be on the equivalent lengths to 35mm - it's just that the DOF on the video camera will be much wider (proportionally) across the whole spectrum.

It's a bit harsh to call it "lying", imo. There's no way to simulate 35mm DOF other than with a 35mm size gate or CCD - which of course is where equipment like the P+S adaptor comes in... But yeah, you're dead right - they are really talking about equivalent FOV.
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