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Old October 5th, 2008, 03:44 PM   #1
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Help please regarding focal lengths

Hi,
I am a seasoned photographer, but a total beginning videographer. And I'm struggling to make sense of the focal lengths of video camera lenses.

If someone could point me either to a good online source or give me a quick guide how to calculate them , I'd appreciate it.

I want to make sure that the next camera I'll buy can take decent wide angle shots, and if it doesn't have a wide wide angle , to check if I can put adapters on it!

Thanks,
Petra.
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Old October 5th, 2008, 03:52 PM   #2
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Hi Petra,

If by "calculate" focal length you mean to determine their equivalent field-of-view in 35mm still photo terms, there is good news and bad news. The bad news is that the conversion factor for such equivalency values will change almost from model to model because it is determined by the size of the image sensor, and there are several different image sensor sizes being used among all of the various camcorder models.

The good news is that these 35mm equivalency values are almost always worked out ahead of time by the manufacturer, and stated in the specifications section of their marketing materials and operating manuals.

So, all you need to do is download the brochures or manuals for whatever camcorder models you're interested in, and check the specifications section of that brochure. Hope this helps,
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Old October 5th, 2008, 03:55 PM   #3
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thanks Chris,

I thought something like the bad news,

well, back into the depths of the internet, I need to compare what I've got with what I want to get ;-)

PS: if the specs state a filter diameter, can I assume that I could put a wide angle converter over it?
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Old October 5th, 2008, 04:03 PM   #4
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Ok,

my little one, point and shoot, has a wider angle!!

Next question: I've seen wide angle adapter lenses, for around $30, any brands to look out for, or avoid?

Ta.
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Old October 5th, 2008, 04:10 PM   #5
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I would be very leery of the optical quality in a such a super-cheap adapter. You get what you pay for in this business. I'm proud to say that Century / Schneider Optics sponsors this site; you can't go wrong with them. And yes they have wide-angle adapters for pretty much every filter thread size. It's pretty much a non-issue... wide-angle is recognized as a necessity, so it's available for practically every camcorder you can think of.
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Old October 5th, 2008, 04:25 PM   #6
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Hi Petra,

I would add a bit to Chris's comments and second Century / Schneider Optics for the wide angle lens adapter. Their quality is tops in the industry, and you won't be disappointed.

Unless you do particular work, nature comes to mind, a telephoto attachment is likely something you won't use much. Some event folks who do weddings do use them at the back of their churches and such for close ups. But what I really wanted to suggest that if your camera has a "digital zoom" switch, and most do, I'd suggest that you leave it on the 'off' position and leave it off.

Digital zooms use a portion of the imager to make the picture and throw away valuable pixels in the process. You just don't want that.

Good luck, and happy shooting.

Mike
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Old October 5th, 2008, 04:57 PM   #7
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Thanks Guys,

just had a look at what Schneider offers, and to be perfectly frank, I can't afford to buy these here in New Zealand :-(

If it's ok, could I post a link to our local auction site where one is offered, and get your opinion?

It is intended for a Canon HF10, and for live band shoots.
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Old October 5th, 2008, 05:06 PM   #8
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Century -usually- makes great optics. And Schneider has a great reputation for view camera and enlarger lenses. Probably the best there is.

But there is a recent incident in which WA adapters designed for the EX1 was recalled due to some pretty bad distortion problems. Do a search of this site and others for details.

For the EX1 it turns out Sony makes a very good WA adapter, and the price was competitive with what Century produced (and recalled). So careful shopping is always a good idea when purchasing accessories. Unfortunately that means reading reviews -- and that means that someone has to be the first guinea pig! :-)
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Old October 6th, 2008, 12:52 AM   #9
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Quote:
Originally Posted by Petra Alsbach View Post
just had a look at what Schneider offers, and to be perfectly frank, I can't afford to buy these here in New Zealand :-(

If it's ok, could I post a link to our local auction site where one is offered, and get your opinion?

It is intended for a Canon HF10, and for live band shoots.
Petra,

There is one other possibility. It is pretty well known that a lens best performing area is the central portion of the lens diameter. Your camera has a 37mm filter thread so a 37-52mm stepup ring will allow you to use 52mm accessories (just a tad bigger than the front of your lens barrel) and a 52mm wide angle converter will have your camcorder "seeing" through the central portions of it.

I have the HF100 (same camera as the HF10 without the internal memory) and the Digital Concepts 0.45x wide converter I paid around $39 for gives astounding results. With the camcorder hooked up to a 42" LCD 1080p TV I cannot tell any difference in detail and sharpness on the same scene shot with and without the converter.

One thing to keep in mind is that very few converters will allow you to zoom through and use the telephoto end. Mine works extremely well at the wide angle end (and that's what I bought it for) but does not do well once much past the mid range of the zoom.

Your mileage might vary but at that price it wouldn't be total disaster if it didn't work out.

Sample vids:

Digital Concepts 0.45x wide angle used on Canon HV20 for whole film due to having to work close in on a slippery hillside.
Vision Quest on Vimeo

Same converter on Canon HF100 used for in vehicle only. Both driver and through windshield.
Deer Watch on Vimeo
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Old October 6th, 2008, 07:28 AM   #10
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Bruce's films show what can be done shooting through a wide-converter when there's not the slightest trace of any straight lines to give the game away. Generally the more powerful the converter (0.45x is more powerful that 0.8x) the more barrel distortion you'll have to accept, where any straight lines that don't pass through the centre of the frame bow outwards. Looks goofy inside buildings, but out in the wilds or under water all is well.

And although Bruce says he cannot tell any difference in detail and sharpness on the same scene shot with and without the converter, he'll have to accept more flare - it's the law of the land. Wide-angle lenses are notoriously difficult to hood effectively, especially in any run 'n' gun shoot.

tom.
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Old October 6th, 2008, 12:53 PM   #11
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Thanks,

As I'm intending to use it in a live club situation, straight lines or flare are not my greatest worry, in fact I'd make that a feature!

I had considered getting a bigger one, will have a look what our local photoshop, which "caters" for the semi-professionals in the area , has on offer.

I'm hoping to get as extreme a wide angle as possible; I find , for now, it makes the shows a lot more dynamic ( punk and rock performances ;-), especially if it's a beginner band and they are not too comfortable on a stage yet!

BtW, if anybody out there has any samples in this particular area, I'd love to see their work.
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Old October 6th, 2008, 01:21 PM   #12
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And great footage btw!

Just had a look at the deer footage, lovely!
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