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Old August 16th, 2006, 01:15 PM   #1
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Newby question

Sorry if this has been discussed before, but my search didn't supply any specific answers.

If I understand correctly - using a 35mm "non-glass" lens adapter, eg; just material with no optics - say Canon to Nikkor - will cause my focal length to increase 7.2 times, eg 100mm becomes a 720mm.

However, if I use, or build, a GG adapter, this increase in focal length does not occur? My 100mm stays 100mm and the only real issue to deal with is the various light loss depending on build or vendor?

Thanks in advance.
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Old August 16th, 2006, 07:34 PM   #2
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You mean using a Nikkor lens with a Canon XL-series body?
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Old August 16th, 2006, 07:48 PM   #3
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Yes, the magnification would stay the same with a 35mm adapter. Your video camera will only see what the lens sees at it's focal length. But that's using the video camera's current lens, unless you're using a relay adapter like the Letus XL model.
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Old August 16th, 2006, 09:52 PM   #4
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I think the operative term should be "apparent focal length" as the real focal length of a given lens does not change.

With the adaptor, the observed field of view does, depending upon how much area of the relayed image on the groundglass screen is seen by the video camera.

Apologies if this is being a bit pedantic.
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Old August 17th, 2006, 12:42 AM   #5
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To answer and ask:

Sam - Yes, use Nikkor lenses on a Canon XL H1;

Glenn - So the adapters such as the M2 attach to the front of the stock lens? Or in the case of the Letus, replace the stock lens by using a relay lens? One allows the (in my case) Nikkor lens to go in front of the stock lens and the other (the relay) allows the Nikkor to replace the stock lens?

But in either case, my 200mm telephoto Nikkor lens, stays a 200mm and doesn't become a 1600mm telephoto - correct?

Sorry, not usually this dense - just looking for a plain, easy to understand answer since I already spent some cash on something that isn't what I wanted.
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Old August 17th, 2006, 06:08 AM   #6
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Quote:
Originally Posted by Michael Fischler
But in either case, my 200mm telephoto Nikkor lens, stays a 200mm and doesn't become a 1600mm telephoto - correct?
as Bob said, You may call it apparent focal length. That doesn't mean that Your lens FL is changed but Your overall optical system. Because FL is definated using scale ratio = "how many times goes projection of object to real object". So in real You'll experience FL grow in most cases, see also my other post and thisone
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Old August 17th, 2006, 09:15 AM   #7
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Quote:
Originally Posted by Michael Fischler
But in either case, my 200mm telephoto Nikkor lens, stays a 200mm and doesn't become a 1600mm telephoto - correct?

Hehe, a simple 'yes' or 'no' is hard to get around here, isn't it? (sorry Frank)

Yes! Is the answer... a GG adapter is exactly what you're looking for.

If you have a canon XL and don't want to build it yourself, the Letus is everything you need. If you want to build your self and save some money, there are a lot of places to look to get started (I'm finishing/tweaking my own adapter now and am very excited with the results, email me if you want to DIY)
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Old August 17th, 2006, 10:29 AM   #8
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Quote:
Originally Posted by Michael Fischler
I already spent some cash on something that isn't what I wanted.
A few years back I didn't know enough about optics, and I bought an EF adapter for my XL1s thinking I could use my superwide EOS lens. Wrong. $400 down the drain (unless I want to use a telephoto in full manual mode).
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Old August 17th, 2006, 01:12 PM   #9
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Thanks Justin! The simple answer I was looking for!

And Frank - thanks for the referral to your other posts - good info!

Sam - my hit wasn't that high, but $260 still hurts - though it is nice to have some (now) super-telephoto's for nature/wildlife shots :-)
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