What Lens...?

[simondodd]

So I'm thinking for travelling it will be easier to just take a camera, small tracking mount and a zoom lens...

My question is what sort of focal length can I 'get away with' for doing deep sky objects?

I already have the standard 55-200 Nikon kit lens but I will need something with a bigger focal length for getting galaxies etc...

Any tips on what lenses I should be looking at? I know its a 'how long is a piece of string' sort of question but it would be nice to have some options from people in the know

Is the wide aperture as important when using a tracking mount or can I get away with a smaller aperture when using a tracking mount?

Will a 600mm lens be long enough for most of the Messier objects or should I be looking at closer to 800/1000mm lenses?

Any advice would be greatly appreciated as I have paychecks burning holes in my pockets haha

Thanks in advance!

[DorsetBlue]

Use the following:

http://www.skyatnightmagazine.com/field-view-calculator

Replace telescope with "Camera Lens"

[happy-kat]

Have  you identified the actual objects you want to image?

[simondodd]

I would like to capture all the Messier objects but just starting out with a few of the easier ones at first...

[simondodd]

Thats a really handy calculator! Thanks for that!

[Davey-T]

You can enter camera / lens combinations into Stellarium to check FOV.

A large lens will need a substantial mount.

Dave

[happy-kat]

They are different sizes hence make a list then see what works in the calculator link above. Also fast lens that can be used wide open is good. Not all lenses make great astro lenses, prime lens is better generally I think. Going on poste I see on here 135mm or 200mm sizes used, not great long zoom lenses.

[Nova2000]

Big lenses are heavy to be used on a tracker. 

From my experience. 

They should be balanced. So you can use them easier. With my tracker I get 30sec shots with a 500mm lense. 

Many galaxies are small and require a good mount. 

 

[Knight of Clear Skies]

Wide angle lenses are good for capturing shots of the Milky Way, while lenses between 50mm and 200mm are a good place to start capturing DSOs. Some are surprisingly big, for example here's our two nearest large neighbours taken with a 50mm lens.

The Messier list isn't necessarily the best place to start for len imaging, it's missing some large and fairly bright targets.

[simondodd]

WOW!!! Thats an epic pic! Especially for a 50mm! May have to try my 200mm on Andromeda and see what I can get