70-200/2.8 w2X = diffusion

[Jay Todd]

While using a used EF 2X on my 70-200/2.8 I was suprised by the amount of diffusion surrounding highlights on the 10D images. The glass(es) were all clean, and there was no camera shake (tripod). I knew there would be a loss of image quality, but not like this.
Is this the norm?

[Scottes]

Post an example please? I don't have an answer but I am eventually planning a 2x TC for my 70-200.

[AJSJones]

"Halation

Halation appears as a slight blurring or spreading of light around an object in a photo. This is caused when light passes through the film emulsion, strikes the film base and is reflected back into the emulsion; taking a slightly different path."

I've heard of this sporadically and know of this term (definition above obviously for film but internal reflections could do this for a digital sensor too). Sometimes it's seen, sometimes not... Did you have a filter on the lens too? Light can sometimes reflect back out to the front and back in again off the filter and high contrast edges would be where you'd notice it. There was a recent thread somewhere about the Canon super teles having a meniscus lens as their front (mainly protective) element for just this reason (can't locate it right now).

If you google for halation you might be able to track down some useful information

Andy

[Ferdinand]

I shot these birds with my 70-200mm f/2.8L IS with EF 2x Mk.II. I think they are okay....

http://mcauslan.force137.com/gallery/10D/medium/20040328%20Shoreline%206.jpg

http://mcauslan.force137.com/gallery/10D/medium/20040328%20Shoreline3.jpg

http://mcauslan.force137.com/gallery/10D/medium/20040328%20Shoreline4.jpg

http://mcauslan.force137.com/gallery/10D/medium/20040327-011.jpg

Regards,
Ferdinand