Teleconverter advice needed

[Jonathan Betz]

I am interested in purchasing a teleconverter for my Sony HDRFX1, and am curious if anyone has had experience using cheap teleconverters like this Bower 72mm 2x:

http://cgi.ebay.com/72mm-2-0X-Teleconverte...93%3A1|294%3A50

or this more expensive Raynox 72mm 1.8x:

http://raynox.co.jp/english/video/hdp9000ex/index.htm

Specifically, I would like to know what specific problems may occur when using a cheap teleconverter other than the obvious consequences of teleconverters (vignetting and increased camera shake). What quality issues are involved with using cheap teleconverters? Advice from someone who has used one would be great. I want to know what my footage will look like with a cheap converter and whether it will still be worth it. I am going to use it for filming shots to go in a showreel on Vimeo, so although I will be filming in 1080p, I will only (or primarily) be showing the footage in 720p flash on Vimeo. I need higher magnification, but probably can't afford an expensive converter.

Any help would be greatly appreciated.

[Chris Sanderson]

My experience with these things - all of which degrade the image somewhat - is that, as with most optics, you get what you pay for...
Go for the manufacturer's extenders/adapters if possible and from someplace you can return it without charge if you hate it  

[Jonathan Betz]

Can you elaborate on what exactly "degrading quality" means? What will my HD footage look like? Will it be blurry? dark? unsaturated? something else? I have seen Youtube videos that looked pretty good using teleconverters, but they are obviously low quality web videos. I want to post this video in 720p flash on Vimeo, and so I am wondering if a relatively cheap teleconverter will be worth it for this application (I am trying to update my wildlife showreel and need more magnification on the cheap). I know cheap teleconverters, or teleconverters in general, are not an ideal solution. i just need to know if it will still be worth it given the (specific) downsides. Thanks

[Chris Sanderson]

I cannot be specific since I am completely unfamiliar with the products you have linked to.

That being said here are some things that I would look for in testing the adapter: more than one stop loss of speed, loss of acuity (aka fuzziness) overall and/or in the corners, chromatic aberration in high contrast fine detail (branches against sky), vignetting, poor out-of-focus backgrounds (bokeh), colour shifting, no lens hood. Likely this is not an exhaustive list but it's a start... Good luck!

Chris S

[Jonathan Betz]

Thanks. I didn't expect that anyone would have used my exact setup. I was just wondering about the types of problems I might face. You provided exactly the type of advice I was looking for. I think I will take a chance on a teleconverter and I'll post my findings when I do.