Beginning Astrophotograhy Questions

[Kowspot]

Hey all,

Been lurking on here for a while so this is my first post I have had an Orion SkyQuest XT8 Dobsonian for visual use for the past couple months and am in love with it! However I have been wanting to combine my two hobbys for a while now (photography and astronomy!) I know that dobsonians are pretty terrible for astrophotography so I was hoping you guys could help me out, since I am a college student I am on a budget.

Currently I am considering either the OMNI XLT 102mm Refractor or the OMNI XLT 120mm Refractor from Celestron. I was planning on the XLT 150mm reflector tube but I heard it has problems focusing with prime-focus DSLR (cant bring camera in close enough to focus). My main questions are:

1) With the XLT 102 or 120mm: Are these scope suitable for Long-exposure DSO Imaging? I would like to take pictures of Andromeda and other nebulas in our galaxy. My fear is that I will have the same problem with my dobsonian (cant bring the image to focus). Would I need to purchase a new focuser or would the stock one work? I plan on using my 2" Prime Focus adapter from Orion:http://www.telescope.com/2-Prime-Focus-Camera-Adapter/p/5269.uts?keyword=prime%20focus with my Canon EOS Rebel T3.

2) The OMNI XLT CG-4 mount, it has a 20lb limit and the scope is 9-12lbs. Along with my DSLR (Canon EOS Rebel T3) will the mount be acceptable? I was also planning on equipping the mount with a dual-axis motor and guidescope/autoguider. It will be under 20lbs but just don't know if thats "under-enough" for stability. I would like to take long exposure DSO shots.

3) The Dual-Axis motor from Celestron: Motor Drive, DA for CG-4 mounts Telescope (item #93522) / Omni XLT Series Telescopes / Telescopes / Products / Celestron.com has a port on the side. I don't remember the name but it essentially looks like an ethernet port. Is this port so you can plug in a go-to system or an autoguider? I am intrested in hooking an autoguider up to it.

Thanks again and I look forward to your responses!

[Cornelius Varley]

I think the quoted payload of 20lb is bit excessive, the equivalent Skywatcher EQ3-2/ Orion Astroview is rated for about 12lbs which is realistic. For astrophotography you need a mount that has a payload capacity of about twice the expected payload (telescope/camera etc). You may want to look at the CG5/EQ5/Skyview mount instead.

The dual axis drives don't have an autoguider ST4 port but you can add one by following these instructions EQ handset mods. You will also need an autoguider.

Peter

[Kowspot]

Hm I though the CG-4 was equivalent to the skyview pro? According to Celestron (What are the payload weights of Celestron mounts?) the cg-4 has a 20lb weight limit. I have seen that it is practically identical to the Orion Skyview Pro mount. Both are 20lbs, 1.75in steel legs, etc.. I know there was an old model of the CG-4 that was like the Skywatcher (spindly legs, etc..). So even with this do you think it wouldn't work?

I don't plan on having a ton of accessories. Just the drives and the camera. The guide scope is a possibility but won't be for a looooong time.

[Cornelius Varley]

The Celestron CG4 is the same as the Skywatcher EQ3-2 / Orion Astroview (I know because I have one). The Orion Skyview Pro / Skywatcher EQ5 are the same mount and are similar to the Celestron CG5 which is supposed to have better bearings and larger diameter tripod legs than the other two.

Peter

[Kowspot]

Ah I see. So after some more research I checked out the CG-5 like you recommended from Celestron. It has a 35lb payload and has an autoguider port! and motors etc... Would you recommend this mount with high quality refractor for AP? If so what kind of refractor would you recommend? I know for AP large mount + smaller scope is better.

[Cornelius Varley]

I would probably choose something like an ED80 refractor and guide with an OAG or finder guider.

Peter