Canon Lens-is it ED Glass ??

[FOOTPRINT]

Hi All,
Wonder if anyone knows if the Canon EOS300D and 350D Lenses are made from ED glass, I ask because pictures taken of the Milky-Way by myself and the recent ones posted by- garyh- seem to have quite good colour resolution, (colours in focus) which normal glass camera lenses dont, when used for astrophotography, ED camera lenses cost a heap (looked on E-Bay at prices), Ill post one of my pictures also as an example, appreciate any imput here on the subject.

cheers....Jim

[RB]

Jim, so which lenses are we talking about?

Cheers mate.

Also what's the details of the milky way shot?

[Garyh]

Hi Jim,
Don`t know about the ED glass, the 2 canon lenses I have are polycarbonate, no glass in them at all, I don`t know about the top end stuff APO lenses but?..
Cheers Gary

[Octane]

Jim,

As far as I'm aware, only the L-series of Canon EF lenses are made with fluorite which I believe is an ED-type glass.

I use my EF 50mm F/1.4 (non-L-series) lens for most of my widefield images. There is a lot of chromatic aberration when the lens is wide open; I mainly image at F/2.5 and there is a little aberration, especially around the edges. Gary imaged at F/2.8 (with the same lens) which I believe would have helped in lowering the aberration.

In general, the L-series lenses (those with the red stripe around the front of the barrel) are two or three (and more) times the cost of the standard EF series of lenses.

Regards,
Humayun

[avandonk]

All the Canon super telephoto lenses (300mm and up) use one fluorite element and two ED (Canon calls it UD) glass elements as well as the usual optical glasses. All the L lenses have either or both an ED element (or two) and aspheric elements depending on focal length and or zoom.
For instance the 135mm F2L has two ED (UD) elements.
The take home message is you get what you pay for.

If you shine a green laser pointer into a lens with a fluorite element there is no scatter from the fluorite element unlike the glass elements. It is almost as if it is not there.

More info here
http://www.usa.canon.com/consumer/controller?act=ProductCatIndexAct&fcategoryid=153

Bert

[RB]

Bert is absolutely right that's what makes the 300mm f/2.8 lens (and up) so special, they really are in a class of there own.
The only other L series lens which has one fluorite element is the EF 100-400mm IS telephoto.

The rest of the L series, as stated, use UD lenses which minimise but not completely eliminate CA dispersion.

[tornado33]

Yes, as Bert, myself and anyone else who have had the honour of using a flourite lens has found, its almost magical in its ability to provide sharp, chromatic abberation free images to the edges at insanely wide aperatures, literally outperforming slower non flourite lenses that have been further stopped down.
Scott

[FOOTPRINT]

Hi All,
Im a bit late responding to all the replies, better late than never, First I should have been a bit more detailed in my query, I did of course mean the Canon Lenses as supplied with the Camera (EOS300D or EOS350D), as the related picture was taken through same.

Andrew- the Pix. I posted was 4 x 6 Min. at ISO800, DF removed-Canon EFS 18-55mm Lens , at 18 mm, -EOS300D (modded) guided LX200/10"-MX7C-Astroart- processed with IP.

Thanks for the comparisons on ED/UD glass upmarket lenses to the supplied Camera Lenses, I must agree, one gets what one pays for (hopefully).

While we are on the subject, any ideas on "Mirror" type Camera Lenses, I believe they have a lens in the light path also, wonder if this would upset the colour collimation as it is very close to the image sensor element ???

cheers.................Jim