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Old 02-10-2008, 04:12 PM
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dugnsuz (Doug)
to baldly go...

dugnsuz is offline
Join Date: Aug 2005
Location: Hahndorf, South Australia
Posts: 4,200
Originally Posted by Quark View Post
Greetings All,
Just seeking some advice on the suitability of the Canon EF 70-300mm F4-5.6 IS USM Lens for astro photography. I have noted some very nice wide field images on the IIS forums that have been taken with the higher quality and expensive L series Lens's.

I recently purchased a Canon 450D with a EF S 17-85mm IS USM Lens. At this stage I don't intend modifying the 450D. It will be used prime focus on a 16" F4.5 Newt and I want to see how that turns out before considering any mods.

I was thinking about the 70-300 for general use and wondered if anyone on IIS had used it piggyback for Astro work.

Hi Trevor,
I haven't used the 70-300mm but I did some widefield stuff with the 17-85mm lens.
Below is a link to a pic of the Large Magellanic Cloud done with the 17-85mm @ 85mm...

Wasn't too impressed with the colour and resolution from this lens, camera was unmodded at the time.

Compare this with the same object taken with a 70-200mm f4L lens at 70mm...

Camera was modded so unfair comparison perhaps, but resolution and colour correction of non H alpha stuff is still obviously better I reckon.
I think you would get similar performance to the 17-85mm with the 70-300mm lens but that's not based on first hand knowledge/experience though.
The 70-200mm f4L is probably the most cost effective entry into the L series of lenses. I got mine 2nd hand for $650 and I love it.
I'm sure you wouldn't regret purchasing it for day or night work.
Good luck
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