what does a telextender do? at DVinfo.net

Hagop Matossian · August 27th, 2002, 11:24 AM

what does a telextender do?

multiply the amount by which you can zoom?

B. Moore · August 27th, 2002, 03:19 PM

Hi,
what ever the value of the extender is, is what you times the lens. i.e. the stock 16X 5.5mm-88mmIS XL-1 lens with a 1.6 extender is close to 1000m ( in35mm equivalence) If you were talking just plain 35mm lenses a 50mm lens with a 2 x extender wwould be 100mm.

Bruce

Jeff Donald · August 27th, 2002, 04:24 PM

Bruce is correct. The math works out like this: 5.5mm-88mm zoom multiplied by 1.6 gives us a 8.8mm-140.8mm zoom lens. The 35mm film equivalant can be obtained by multplying those result by 7.2 (63mm-1014mm). This yields a magnification of a little over 20x at maximum zoom (1014 divided by 50). But, like all things in photography and video, the gain comes at a price. You will loose a little over 1 stop of light. A 2x extender losses 2 stops of light.

Jeff

Hagop Matossian · August 28th, 2002, 12:17 PM

cheers guys

B. Moore · August 28th, 2002, 07:49 PM

Thank you Jeff,
you put it much more elloquently and informative thanI. I was not sure about the exact f/stop loss,but I thought he'd figure that part out.

Thanks again

August 27th, 2002, 11:24 AM	#1
Hagop Matossian Woodyfang Join Date: Jun 2002 Location: London/Nicosia Posts: 125	what does a telextender do? what does a telextender do? multiply the amount by which you can zoom? __________________ 10 films online http://www.undeadarmy.org STOP PRESS!! http://www.honeyweasel.com STOP PRESS!! Lighting Cameraman / Director / Producer / Music Producer / DJ / Web Designer / Visualist / Media Student / IT Tutor / Digital Artist W00dy See, W00dy d00...

August 28th, 2002, 12:17 PM	#4
Hagop Matossian Woodyfang Join Date: Jun 2002 Location: London/Nicosia Posts: 125	cheers guys __________________ 10 films online http://www.undeadarmy.org STOP PRESS!! http://www.honeyweasel.com STOP PRESS!! Lighting Cameraman / Director / Producer / Music Producer / DJ / Web Designer / Visualist / Media Student / IT Tutor / Digital Artist W00dy See, W00dy d00...

August 27th, 2002, 03:19 PM	#2
B. Moore Major Player Join Date: Sep 2001 Location: Glendale, AZ Posts: 181	Hi, what ever the value of the extender is, is what you times the lens. i.e. the stock 16X 5.5mm-88mmIS XL-1 lens with a 1.6 extender is close to 1000m ( in35mm equivalence) If you were talking just plain 35mm lenses a 50mm lens with a 2 x extender wwould be 100mm. Bruce

August 27th, 2002, 04:24 PM	#3
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	Bruce is correct. The math works out like this: 5.5mm-88mm zoom multiplied by 1.6 gives us a 8.8mm-140.8mm zoom lens. The 35mm film equivalant can be obtained by multplying those result by 7.2 (63mm-1014mm). This yields a magnification of a little over 20x at maximum zoom (1014 divided by 50). But, like all things in photography and video, the gain comes at a price. You will loose a little over 1 stop of light. A 2x extender losses 2 stops of light. Jeff

August 28th, 2002, 07:49 PM	#5
B. Moore Major Player Join Date: Sep 2001 Location: Glendale, AZ Posts: 181	Thank you Jeff, you put it much more elloquently and informative thanI. I was not sure about the exact f/stop loss,but I thought he'd figure that part out. Thanks again