Advice(and Shoutiness) requested, please.

[Andrew_Campbell (Andrew)]

Greetings, folks. I have been astrophotographing with DSLR's and Canon L lenses for a bit now, and am seriously looking at jumping into the world of scope based gudied astrophotography. So, I have a few queries, if you will lend me your wisdom, please.

The mount I have been looking at is the Skywatcher EQ6-Pro with the Synscan controller (although I am happy to, and confident with geeking out with EQMod and a laptop for the controls). For the roughly $1,800.00 price, is there better out there that will do the job, or is it pretty much the lower tier serious mount for AP?

There are three OTA's that I have been looking at (or at least classes of ota's).
1- Cassegrain based (an RC tube) http://www.bintel.com.au/Telescopes/...oductview.aspx
2- Reflector type: http://www.bintel.com.au/Telescopes/...oductview.aspx
3- Refractor, basically an ED80 APO from wherever.

The three OTA's are roughly in the same price bracket and I have Canon 350D, 7D and 5DMKIII to choose from (and am happy to rip off the IR plate from the 350D) What would your advice be as to the tech type (Cass, Refl, Refr) to go for firstly. I have it in my (often twisted) mind to get either the RC or the Reflector for deepsky stuff with a decent APO which I would use as a guide scope when I was doing tiny faint stuff, and then use the APO as my main when doing widefield photos (and either guide from another source, or forget guiding and rely on the mount to guide for the required time accurately enough) The RC is appealing as it is lightweight and *should* be more thermally efficient and require less messing around.

Ok, that's it for now, although I have dozens more questions that will follow; enough to test the most patient souls

Cheers,

Andrew in Perth.

[rogerco (Roger)]

Its pretty standard advice to go for the ED80. Don't forget you will need a guide scope and camera (allow another $600).

The shorter focal length makes it easier to get started with setup and guiding. As you will see mentioned elsewhere, thinking in terms of a permanent pier to save on setup time is also a consideration.

Good luck.

[Andrew_Campbell (Andrew)]

Cheers. That leads to my next question:

Is there a resource that will show me what I can capture at a given focal length? I've been looking, but can't seem to find what I'm looking for. Sort of a "At 1500mm Focal Length, this is your field of view for THESE DSO, here they are at 2000, here they are at 500" etc.

[rogerco (Roger)]

Yep there is, I think some of the planetarium programs will allow you to define a view. Can't quite find it at the moment.

[CJ (Chris)]

Stellarium has it in configuration, plugins, oculars.

[OzEclipse (Joe Cali)]

Originally Posted by Andrew_Campbell

Cheers. That leads to my next question:

Is there a resource that will show me what I can capture at a given focal length? I've been looking, but can't seem to find what I'm looking for. Sort of a "At 1500mm Focal Length, this is your field of view for THESE DSO, here they are at 2000, here they are at 500" etc.

Starry night Pro Plus(SNPP) has a camera field function. Pro plus is the most expensive version - full price $250USD but they sometimes have end of version promotions around this time of year - I purchased my version of pro plus January 2 years ago for USD$99.

I am not sure if the cheaper versions of starry night have this field of view function for eyepieces and cameras. SNPP uses stitched photographic images of the sky for a photorealistic view. Attached is a screen shot of the function display. I have selected to display the DSLR field around eta carina with 3 different lenses.

I think Stellarium is free so you might want to try that first.

You can of course calculate it yourself using the image size formula

angular size(degrees) = I(mm) x 57.3 ÷ f(mm)

where
I is image size (in this case the dimensions of the DSLR sensor)
f is the focal length of the lens or telescope

There are online lists of the angular size of deep sky objects
http://en.wikipedia.org/wiki/User:Ia...y_angular_size

Best of luck

Joe

[rmuhlack (Richard)]

Originally Posted by Andrew_Campbell

Cheers. That leads to my next question:

Is there a resource that will show me what I can capture at a given focal length? I've been looking, but can't seem to find what I'm looking for. Sort of a "At 1500mm Focal Length, this is your field of view for THESE DSO, here they are at 2000, here they are at 500" etc.

CCDCalc is what you are after - its a simple freeware program where you select telescope and camera from a drop down list and then you can browse through the collection of images to see what the field of view is with different targets and telescope/camera combinations. You can also add you own scopes and cameras to the lists as well (all you need are FL, f-ratio, pixel size and ccd dimensions)

http://newastro.com/book_new/camera_app.php

re mounts, I would suggest a HEQ5 or NEQ6 as a minimum. Both are great mounts for the price, with the main difference being the max weight that each can comfortably carry. Both good options, so it really depends on what scopes you want to use in the future. The actual NEQ6 mount itself is quite a bit heavier than the HEQ5, so that might also be a consideration if you have to carry your gear a long way to set up.

[mithrandir (Andrew)]

Originally Posted by Andrew_Campbell

Cheers. That leads to my next question:

Is there a resource that will show me what I can capture at a given focal length? I've been looking, but can't seem to find what I'm looking for. Sort of a "At 1500mm Focal Length, this is your field of view for THESE DSO, here they are at 2000, here they are at 500" etc.

People have mentioned CCDCalc - exactly what you want for the purpose - and with the extra image library you might even be able to preview the targets you want to image.
Every planetarium program I have lets you define and overlay a FOV. Stellarium is probably the most configurable. CdC, C2A, Hallo Northern Sky are a bit less flexible but require less grunt from the PC and graphics card.
Rotating the FOV to match the desired framing is probably the hardest part.

[Andrew_Campbell (Andrew)]

Thanks gents, that's exactly what I was looking for. I bought the NEQ6 mount, and am working out the best way forward as far as scopes goes. I was going to just get a guidescope (the 'Awesome' Orion pack) and piggyback my Canon DSLR on that while I investigated OTA's, but it seems harder than it has to be, given I would eventually be getting a scope to hang the camera off.
I'm wondering whether to get a basic ED80 or whether to fork out for something higher end (like a Stellarvue or Williams Optics).
My intent is not really observational, but it would be nice to have the option if it was available, which gets messier if I get a AP specific tube