To 1.6X extender Users at DVinfo.net

Darren Kelly · November 25th, 2004, 04:27 PM

Hi guys,

I got this about a week ago, and have used it on 4-5 occasions. My maincomplaint with it is it seems to soften the image more than I would consider acceptable. I can also see the slight loss of light.

I'm just interested if this is comon to other users or do I have a lemon. I bought it on ebay, so I don't know I have a return ability.

thanks

DBK

Rob Lohman · November 26th, 2004, 03:12 AM

Could you post a frame from the video that looks too soft to your
eyes? I could imagine (don't know for sure) that you get some
light loss because the light has to travel to an additional optical
adaptor.

TingSern Wong · November 28th, 2004, 08:20 AM

I don't see any problems using Canon XL1.6 teleconvertor on the 20X Canon lens. The image is sharp ... If you want to see a snap shot (one frame) - pass me your email id - and I will send one or two pictures from my Canon XL2 to you. It is PAL however.

A. J. deLange · November 28th, 2004, 01:29 PM

I've used lots of tele extenders over the years and it doesn't seem to matter whether they come from Nikon or Bud's Tele Extender Works, they all soften the picture appreciably. IOW, some degree of softening is to be expected. The question is really as to what degree is acceptable to you. I don't use them any more because we're not exactly long on resolution in SD video to begin with. If you want sharp telephoto buy one of the adapters and use lenses made for SLR's.

Rick Bravo · November 28th, 2004, 02:43 PM

Anytime you add glass, especially in the form of an extender, you will lose some resolution. The loss shouldn't be so noticeable that the picture becomes distracting or unusable. If your picture has degraded that much, there may be a problem with your particular unit.

Any extender will be good for a 1 1/2 to 2 stop loss in light transmission, that's why extenders are not too user friendly in low light.

RB

Darren Kelly · November 28th, 2004, 03:12 PM

These are all things I am aware of when it comes to still photography, but never having a broadcast lens with a doubler on it, or using somethinglike this on a video camera, which has less resolution than a still picture, I was hopeful it wouldn't make as much of a difference.

On light...

I assumed the aperture would widen or open automatically to compensate

On Sharpness...

I didn't think it would be noticable on video due to the reduced resolution.
I've used both Sony and Century converters before infront of the lens with good success.

Am I making any sense?

DBK

TingSern Wong · November 28th, 2004, 08:33 PM

A simple thumb of rule is this -

1.5x - 1.6x teleconvertor will cause the prime lens aperature to be reduced by 1/fstop, while a 2X teleconvertor will push it to 2 stops less light.

Hence, using a lens of f/1.4 and putting a 1.6x teleconvertor in between - will reduce light reaching the CCD to f/2. Using a 2X teleconvertor will get that number down to f/2.8.

The lens aperature is fixed. It will not open any wider. The camera has to compensate for the reduced light, by using a slower shutter speed (assuming you are already using maximum opening for the lens).

As for reduced sharpness, it should not be that obvious - as I told you earlier. With or without teleconvertor, I can't see any degradation in the image recorded on my XL2 - using my 20X Canon lens.

What might cause your problem could be camera shake. 20X with a 1.6 teleconvertor multiplies the magnification to 32X - and unless you have a rock steady tripod placed on a rock steady platform, any shake will be magnified appropriately.

TS

November 25th, 2004, 04:27 PM	#1
Darren Kelly Major Player Join Date: Aug 2003 Location: Vancouver Posts: 351	To 1.6X extender Users Hi guys, I got this about a week ago, and have used it on 4-5 occasions. My maincomplaint with it is it seems to soften the image more than I would consider acceptable. I can also see the slight loss of light. I'm just interested if this is comon to other users or do I have a lemon. I bought it on ebay, so I don't know I have a return ability. thanks DBK __________________ Darren Kelly

November 26th, 2004, 03:12 AM	#2
Rob Lohman RED Code Chef Join Date: Oct 2001 Location: Holland Posts: 12,514	Could you post a frame from the video that looks too soft to your eyes? I could imagine (don't know for sure) that you get some light loss because the light has to travel to an additional optical adaptor. __________________ Rob Lohman, visuar@iname.com DV Info Wrangler & RED Code Chef Join the DV Challenge \| Lady X Search DVinfo.net for quick answers \| Buy from the best: DVinfo.net sponsors

November 28th, 2004, 02:43 PM	#5
Rick Bravo Major Player Join Date: Sep 2003 Location: Miami, FL Posts: 574	Anytime you add glass, especially in the form of an extender, you will lose some resolution. The loss shouldn't be so noticeable that the picture becomes distracting or unusable. If your picture has degraded that much, there may be a problem with your particular unit. Any extender will be good for a 1 1/2 to 2 stop loss in light transmission, that's why extenders are not too user friendly in low light. RB __________________ "The future ain't what it used to be." Yogi Berra. www.rbravo.com

November 28th, 2004, 03:12 PM	#6
Darren Kelly Major Player Join Date: Aug 2003 Location: Vancouver Posts: 351	These are all things I am aware of when it comes to still photography, but never having a broadcast lens with a doubler on it, or using somethinglike this on a video camera, which has less resolution than a still picture, I was hopeful it wouldn't make as much of a difference. On light... I assumed the aperture would widen or open automatically to compensate On Sharpness... I didn't think it would be noticable on video due to the reduced resolution. I've used both Sony and Century converters before infront of the lens with good success. Am I making any sense? DBK __________________ Darren Kelly

November 28th, 2004, 08:20 AM	#3
TingSern Wong Major Player Join Date: Jan 2004 Location: Singapore, Rep of SINGAPORE Posts: 749	I don't see any problems using Canon XL1.6 teleconvertor on the 20X Canon lens. The image is sharp ... If you want to see a snap shot (one frame) - pass me your email id - and I will send one or two pictures from my Canon XL2 to you. It is PAL however.

November 28th, 2004, 01:29 PM	#4
A. J. deLange Major Player Join Date: Jun 2004 Location: McLean, VA United States Posts: 749	I've used lots of tele extenders over the years and it doesn't seem to matter whether they come from Nikon or Bud's Tele Extender Works, they all soften the picture appreciably. IOW, some degree of softening is to be expected. The question is really as to what degree is acceptable to you. I don't use them any more because we're not exactly long on resolution in SD video to begin with. If you want sharp telephoto buy one of the adapters and use lenses made for SLR's.

November 28th, 2004, 08:33 PM	#7
TingSern Wong Major Player Join Date: Jan 2004 Location: Singapore, Rep of SINGAPORE Posts: 749	A simple thumb of rule is this - 1.5x - 1.6x teleconvertor will cause the prime lens aperature to be reduced by 1/fstop, while a 2X teleconvertor will push it to 2 stops less light. Hence, using a lens of f/1.4 and putting a 1.6x teleconvertor in between - will reduce light reaching the CCD to f/2. Using a 2X teleconvertor will get that number down to f/2.8. The lens aperature is fixed. It will not open any wider. The camera has to compensate for the reduced light, by using a slower shutter speed (assuming you are already using maximum opening for the lens). As for reduced sharpness, it should not be that obvious - as I told you earlier. With or without teleconvertor, I can't see any degradation in the image recorded on my XL2 - using my 20X Canon lens. What might cause your problem could be camera shake. 20X with a 1.6 teleconvertor multiplies the magnification to 32X - and unless you have a rock steady tripod placed on a rock steady platform, any shake will be magnified appropriately. TS