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-   Canon XH Series HDV Camcorders (https://www.dvinfo.net/forum/canon-xh-series-hdv-camcorders/)
-   -   XH A1 Zoom Number vs 35mm Equivalent Focal Length (https://www.dvinfo.net/forum/canon-xh-series-hdv-camcorders/81683-xh-a1-zoom-number-vs-35mm-equivalent-focal-length.html)

Michael Wisniewski January 28th, 2008 03:58 AM
FWIW worth, I spent the evening with a digital SLR mounted above the XH A1, comparing different focal lengths. Everything between 35mm and 135mm matched very closely with the EXIF data - including the FOV. So I'm inclined to use the numbers from the EXIF data to calculate the 35mm equivalent.

Chris Hurd January 28th, 2008 09:19 AM
Well I'm still at a loss as to why there's so much disparity between the EXIF data and the F.O.V. test... but...

*If* we accept the EXIF data as valid, then here's a *rough* 35mm equivalency scale for commonly used focal lengths (except I know I'm missing a few of the more common 35mm focal lengths -- what are they?):

Code:
Z00        32.5mm
Z02        34mm
Z06        36mm
Z10        38mm
Z12        40mm
Z19        45mm
Z25        50mm
Z29        55mm
Z34        60mm       
Z40        70mm
Z46        80mm
Z50        90mm
Z54        100mm
Z60        120mm
Z64        135mm
Z65        140mm
Z70        165mm
Z75        200mm
Z80        240mm
Z85        300mm       
Z90        380mm
Z91    400mm
Z95        500mm
Z99        650mm

Cal Bickford February 1st, 2008 03:28 PM
common 35mm focal lengths
 
I've used Chris's method and a multiplication factor of 7.2222222 to determine some of the more common focal lengths as they relate to Z#s. Hope this is helpful to you all...

To get as uniform a reading as possible, I set the zoom speed to 1 and gently tapped the zoom button until the Z# changed thus taking the reading from the very start of the zoom value as opposed to midway through (that is, you can actually zoom through Z5 a little bit before it changes to Z6 etc.)

all the values are usually accurate within a couple of tenths of a milimeter though at the upper end of the range (180mm and 300mm) they are within 2mm.


32.5mm=z0
35mm=z5
40mm=z12
50mm=z24
65mm=z37
75mm=z43
85mm=z48
100mm=z54
135mm=z64
150mm=z67
180mm=z72
300mm=z85

Cal Bickford February 1st, 2008 06:39 PM
whoops! just noticed that my post is pretty much a repeat of your last one chris. Didn't mean to steal your thunder lol but I guess I over looked that last post. Anyways, seems like our numbers are pretty similar.

Chris Hurd February 1st, 2008 10:06 PM
It's all good Cal. Reassures me that we're coming up with the same numbers.

Nic MacDonald August 27th, 2009 08:12 AM
Chris, Cal, this is brilliant, thanks for working this out. I think in 35mm focal lengths and tend to be quite organised (read: pedantic) about what lens length is used for what shots so it's always irritated me not really knowing what focal length I was shooting at, even roughly. I'm printing a list of 35mm equivalents and sticking it to the back of my camcorder.

Nic


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