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Sony HVR-Z7 / HVR-S270
Handheld and shoulder mount versions of this Sony 3-CMOS HDV camcorder.


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Old December 4th, 2007, 09:14 AM   #1
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crop factor with SLr lenses?

havent found any info on this but will the z7's ability to mount slr lenses be plagued by crop factor just like the Eos adapter on the XL1?
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Old December 4th, 2007, 09:31 AM   #2
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yes. It is listed in the PDF manual. Also read the post below which discusses image flip, and we also touched on this. It basically becomes a telephoto adapter when using the SLR lenses.
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Old December 4th, 2007, 01:01 PM   #3
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Where is the pdf manual?
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Old December 4th, 2007, 04:49 PM   #4
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Having an interest in telephoto lenses but no experience with SLR lenses on video cameras, are these SLR lenses expected to provide a high quality (telephoto) image? i.e., does the 'crop factor' degrade the image?
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Old December 4th, 2007, 05:33 PM   #5
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In theory if the slr lense is of high quality (canon fixed L series) then the resulting quality should be fine. The crop factor actually helps as the "sweet spot" on most lenses is toward the center.
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Old December 4th, 2007, 07:38 PM   #6
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yes. It is listed in the PDF manual. Also read the post below which discusses image flip, and we also touched on this. It basically becomes a telephoto adapter when using the SLR lenses.
Where can we find the PDF manual for the camera... thanks
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Old December 4th, 2007, 08:46 PM   #7
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http://www.sonybiz.net/res/attachmen...3315642481.pdf
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Old December 4th, 2007, 09:13 PM   #8
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That is not a manual for the camera that is the preliminary brochure for the new HDV products. That admittedly contains some interesting information.

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Old December 4th, 2007, 09:43 PM   #9
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Reading the brochure, it spells out the crop factor of using Alpha lenses.
7x. So your 50 mm "normal" lens will yield the perspective of a 350 mm lens.

If you are doing nature videography, it could be just the ticket.
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Old December 5th, 2007, 06:05 AM   #10
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Could be interesting putting my Canon 300mm on there...

that'd be 2100mm with the x7 and if the ole multiplyer on it also
a wopping 4200mm... I could see to Mars with this camera
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Old December 5th, 2007, 09:14 AM   #11
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Could be interesting putting my Canon 300mm on there...

that'd be 2100mm with the x7 and if the ole multiplyer on it also
a wopping 4200mm... I could see to Mars with this camera
Actually, I believe the 7x crop factor is for lenses designed for Sony's Digital-Alpha APS-C cameras, which use a 24x15mm sensor. If you're using a 35mm SLR lens, you should get a bit larger crop factor. If my math is right, I'm thinking it might be closer to 10.5x.

I've been looking for a crop factor chart that includes 35mm SLR lenses, but can't seem to find one.
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Old January 15th, 2008, 02:38 PM   #12
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My understanding is that manufactures of DSLR still use the true focal length, not the equivalent focal length for the new sensor sizes. This is at least the way Olympus does it, along with Nikon. So using some legacy glass should result in no greater or lesser multiplier than using a lens designed for the Sony alpha series(I haven't read up much on the alpha series). And just as Jack Davis said the best area of glass on lenses is in the center. Also DSLR lenses are designed for upwards of 8megapixles and higher resolutions, older lenses from my reading didn't have quite as nice glass but should be fine for 1920x1080 which only comes out to a little more than 2 megapixles.
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Old January 15th, 2008, 03:36 PM   #13
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Where can we find the PDF manual for the camera... thanks
The manual doesnt appear to have been released yet.

This seems standard procedure for Sony cams : no PDF manual until model is officially released.
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Old January 15th, 2008, 05:48 PM   #14
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I am pretty excited about this camera. I would be going for the EX1 if it wasn't for the fact that every so often I do an extended shoot where I go through several tapes a day for a week or more Most of the rest of the time a card or two is more than enough.
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Old January 18th, 2008, 10:54 PM   #15
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Focal Length Multipliers

Quote:
Originally Posted by Brian Standing View Post
Actually, I believe the 7x crop factor is for lenses designed for Sony's Digital-Alpha APS-C cameras, which use a 24x15mm sensor. If you're using a 35mm SLR lens, you should get a bit larger crop factor. If my math is right, I'm thinking it might be closer to 10.5x.

I've been looking for a crop factor chart that includes 35mm SLR lenses, but can't seem to find one.
And you won't. People can build tables for it, but it would confuse people more.

First of all, any lens, be it a DSLR or a 35mm film or a Medium format lens, if it says there 50mm. It is 50mm. There are no conversions or multiplier in effect.

The conversion comes into play only when you use a different size sensor or film. But a 50mm is a 50mm regardless of sensor size or film size. The reason is simple. It is really 50mm when you measure it. No ifs. No buts.

What changes is the FOV or Field of view. The smaller sensor has a narrower FOV because the image formed by the 50mm is bigger than the sensor or capture media. It sees only part of the entire image circle, hence you have the crop.

If you now print this, or project it to your screen or monitor, in effect, it is like zooming into the image that is captured. All that pixel is concentrated only on that part that is captured by the sensor whose size is smaller than the image circle projected by the lens.

This is where the confusion really starts. To approximate or give the actual image captured we now start putting conversion factors to show the equivalent of the lens as captured by the film or sensor. Normally, the smaller sensor has an effect of zooming in or magnifying the image. So we apply a "multiplier" or a conversion to the image captured. The common reference is the 35mm film as this is the most common. Thank goodness for that because if the basis is a 6x6 or some other format, it will add to the confusion.

Now, most calculations are based on the 35mm film size/format. So, to simplify things these conversions are done using that as the basis. So for a Canon 40d or 400d, with a 1.6x crop factor, a 50mm has a field of view (FOV) of 80mm (1.6 x 50mm). If it were a larger film or sensor, that 50mm would probably be a wide angle lens instead in terms of FOV.

What is incorrect to say is that the 50mm becomes an 80mm lens. Or to ask why not label it an 80mm to prevent confusion. The reason is it is not a 50mm lens. It is a 50mm. That "mm" isn't a hypothetical measure.

With video cameras, because the sensors are smaller by a large degree, it is not uncommon to use smaller lenses (e.g. 3mm - 5mm to 60mm). As you can see, they use "mm." It's because it is the proper measurement. Now, when they want to convert it to the equivalent 35mm FOV, then you use the multiplier to get the equivalent FOV. To some it is 7x. The smaller the sensor, the larger the multiplier.

It's nice to see a 20x or 30x zoom. And this is easy to do with tiny 1/6" sensors. But notice how most 1/3" sensors are limited to 10x or 12x. Going past these may involve compromises in image quality in the long end, or an increase in max aperture on the long end.

In any case, most video cameras have small sensors that even if the lenses were designed for crop cameras, such as the tamron Di-II lenses, their image circle will still fit into the much smaller video sensor. Not so sure about the alpha lenses. Regardless, the multiplication factor will still be the same if we are comparing it a 35mm sensor, even if its image circle is smaller. 50mm is 50mm.

Well, until the time by which video sensors are affordable as to make them as big 35mm sized sensors, that's the only time we have to worry if a dslr lens will "fit" into these video cameras and their attachments. In any case, expect to see a lowering of zoom range due to image quality compromises.
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