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300mm + 2x Converter =?

Fri Dec 20, 2002 6:43 am

Hello everyone,

When you put a 2x converter on any lense does it double it? For example would a 300mm + 2x Converter = 600mm?

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Matt
CRJ-700 FO
 
wietse
Posts: 3630
Joined: Thu Oct 18, 2001 12:49 am

RE: 300mm + 2x Converter =?

Fri Dec 20, 2002 6:56 am

Yes...

but it also doubles your apperture (makes it less light sensitive)

So a 75-300mm F4-5.6 lens becomes a 150-600mm F8-11.2 lens... wouldnt want that... Smile

Wietse
Wietse de Graaf
 
mirage
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RE: 300mm + 2x Converter =?

Fri Dec 20, 2002 7:04 am

This one was at 600mm, using a Canon 75-300 4.5-5.6 and a Canon 2x teleconverter.


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Luis
 
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clickhappy
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RE: 300mm + 2x Converter =?

Fri Dec 20, 2002 7:27 am

and of course, with the Focal Length Multiplier Factor of a DSLR you can add x1.5 for a D100, x1.6 for a D60, and x1.5 for a S2.
 
ckw
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Joined: Fri Aug 27, 2010 12:26 am

RE: 300mm + 2x Converter =?

Fri Dec 20, 2002 9:51 am

DSLRs have a CROP factor, not a focal length factor ... there is a big difference. The crop factor of a DSLR is exactly the same as enlarging the central portion of a 35mm - it does not decrease the depth of field or add the optical compression effect of a true focal length multiplier (such as a teleconvertor) - a picture taken with a 400mm on a DSLR (with a crop factor bringing it up to 600mm) is not the same as a shot taken with a 600mm on a 35mm.

Cheers,

Colin
Colin K. Work, Pixstel
 
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clickhappy
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RE: 300mm + 2x Converter =?

Fri Dec 20, 2002 10:17 am

 
photopilot
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Joined: Mon Jul 15, 2002 11:16 am

RE: 300mm + 2x Converter =?

Fri Dec 20, 2002 1:34 pm

One slight correction of what Wietse says.

A tele-converter does not "double" the aperature of a lens. It adds effective f:stops. A 2x converter adds 2 f:stops to the exposure. Therefore a 75-300mm F4-5.6 lens becomes a 150-600mm F8-f:11 lens... not 11.2

A 3x converter generally adds 3 f:stops. eg. a 2.8 lens will become an f:8 lens.

Each converter comes with an exposure compensation value written down somewhere in the instructions. At least it should, though with through-the-lens metering this generallly isn't a problem. It is only us guys that use a hand-held incident meter that have to take this into account.

One other thing. Converters tend to break down in quality most noticeable at the frame corners first. With the "crop" factor of DSLR's, this doesn't affect you as soon. Another benefit to DSLR's.

Hope this helps.

Steve
 
jwenting
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Joined: Mon Apr 23, 2001 10:12 pm

RE: 300mm + 2x Converter =?

Sat Dec 21, 2002 1:44 am

Correct Steve. DOF stays the same too (so you get f/8 with the DOF you'd get at f/4 when selecting f/4, but the amount of light needed doubles.
I wish I were flying
 
ckw
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RE: 300mm + 2x Converter =?

Sat Dec 21, 2002 1:58 am

Another thing which stays the same is the minimum focusing distance - this can be a real boon if you're into insect or flower photography. My 300mm has a so called "macro" capability, which is OK - but stick a 2x convertor on it, and I've got both a much more powerful macro capability PLUS the ability to work at a comfortable distance from the subject ... and, because I could be a meter or more from my subject, I can easily use fill-in flash if necessary.

Cheers,

Colin
Colin K. Work, Pixstel
 
lugonza_2001
Posts: 310
Joined: Tue Oct 30, 2001 4:31 am

RE: 300mm + 2x Converter =?

Tue Dec 24, 2002 4:54 pm

One important thing, i believe that when you use a convertor, you lose the auto-focus capability.

Best regards

Luis

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