Lens Recommendations for Lunar Pics

So, thanks to all the great info (and pics) in this forums, I am looking to try my hand at astrophotography. I am looking at two areas: lunar and wide field. I'll tackle wide field in another post, for now I have a couple of basic question about lenses for lunar shots. My current gear is listing in my signature, so I won't repeat it here.

I guess I need a little more reach than my 70-200mm + 1.4C TC can offer, so I was looking at some other options:

• Canon EF 300mm f/4L IS USM
  
• Canon EF 70-300mm f/4-5.6L IS USM UD
  
• Canon EF 100-400mm f/4.5-5.6L IS USM
  

I probably would get the last one (100-400) since you already have the 70-200. Your 70-200 + TC gets you 280mm, so you wouldn't be getting a real increase in focal length w/ the 70-300 (only 20mm). Also, the 70-300 is a bit on the softer side @ the long end.

Which TC do you have? The canon one? If so, I don't think the 70-300 will work w/ that TC. If you have a different brand, then maybe. So that's another reason to get the 100-400--it will work w/ the TC (plus you'll get 560mm max).

Another option, if you plan on using it only for lunar shots, is to go the ebay route. Seriously. I bought an old vivitar manual focus 400mm f/6.3 (T-mount I think, but it came w/ a nikon adapter, which I then adapted to EOS mount) for around $100 or something. I've taken some nice shots w/ it...and although I initially only bought it for moon shots, I've used it on the mountains too when it's rainy/cloudy. Got some nice shots w/ that. But I never take it anywhere though...just stays at home.

You can even buy a telescope like this C90 @ amazon for less than the price of any of those lenses. Again, probably only really useful for lunar stuff, and maybe birding on a bright day. Because of the lens design, you'll probably get that odd dount bokeh.

If you're planning on only using the lens for lunar, consider the telescope. It'll get you a LOT of detail, and you probably wouldn't have to crop very much out of your pics. You do have to get adapters to hook up your DSLR to the telescope though, so look into that, if that's what you want. I don't think you'll spend more than $50 in adapters though, but just look into it and add it to the total price before deciding.

If you want to get another lens to complement the ones you have, then I'd say go for the 100-400. It's a pretty nice telephoto and covers a lot of range. You may want to try it first since it's a pump action zoom though.

Either way, I think 400mm is fine for lunar shots (to get started anyway). If you're not that satisfied w/ 300mm, you probably wouldn't be much more satisfied unless you make a larger leap focal length-wise.

also, welcome to the forum!

The Moon is very, very small in the sky. If you want to fill the frame then you need around 1500mm on your 7D. This is an uncropped image taken at 840mm.

Thanks folks for the advice--I got locked into the whole lens thing and did not even think about other options--I'll check our the C90 and I think my wife has a Meade telescope gathering dust somewhere. The good news is I can take the saved money and add it to my tracking mount fund.

Just a thought. If you don't have a lot of cash to throw around and only want to use the lens primarily for the Moon, you may want to look to ebay and see if you may be able to pick up a 500 or 600mm mirror lens. You may also need to get a EF adapter to fit your canon camera. They are usually F/8 manual focus lenses, but should be fine for the moon or for stationary bird pictures.

Thx--I'll go check eBay this evening....

Omar