Advice for beginner AP

[Enterprise]

Hi guys many of you have probably seen me b4, lurking around with my ninja orange tube 6SE. So far it has served me well, but i think im ready for the next step!

Portability of the Nexstar 6SE is a good thing, my whole setup can be stored in a max-airline-handcarry luggage plus tripod. Which i know a GEM setup surely cannot do such a thing.

Looking into GEM and was recommended SXD, mainly because i wanted an AP ready mount, which can also be used for larger aperture cats for observing, am i correct on this?

Having experienced alot of newtonians and cats, im relatively new to using refractors (having always been given the "more aperture the better" argument), which kind of refractors will allow me to take AP of large DSO like nebula and do i need a seperate one for taking smaller DSO like galaxies and globular clusters?

For example, using my 6SE setup and APS-C DSLR, orion nebula fills up almost the whole frame, is too large to image pleiades, fits 3/4 of the moon in its frame and nicely engulfs the core of omega centauri. What would be the equivalent in terms of refractors and does focal length matter?

Cheers for the start of an amazing hobby!

[weixing]

Hi,
The focal length of the scope and sensor size determine the Field of View that the image will cover.

IMHO, since you are just starting to learn AP, instead of spending more $$, my suggestion is to use your current equipment to learn AP. Once you had some experience in AP, you'll know exactly what you need and can get the right equipment. So instead of getting a new scope for AP, get a focal reducer for your C6SE... it's a lot cheaper.

Anyway, for a start, use your camera lens to image those very large object. The rest of the object, you can use your C6SE with focal reducer to image them.

Just my S$0.02.

Have a nice day.

[Gary]

Hey Jay. There's one copy of Introduction to Digital Astrophotography by Robert Reeves in the library. You can place an online reservation for $1.55 and have them deliver the book to your nearest library for your collection.

Or you can just buy the book:
http://www.willbell.com/DigitaAstrophoto/Default.htm

In the above link, you can read the table of content, preface, index and chapter 1 online (pdf) and decide if this book is suitable for you.

By the time you are halfway through reading this book, NEAF 2011 will be here and you can apply your newly acquired AP knowledge to refine your buying decisions base on existing or *gasp* upcoming products!
http://www.rocklandastronomy.com/NEAF/index.html

Another issue to think about is AP motivation and morale when deciding what AP equipment to buy. Try to ask yourself the following question:

- In Singapore, how much time/patience do I have or am willing to commit to set up and tear down for AP? Do I need a semi-permanent/permanent set up at home to react to the sky condition quickly?

- Am I willing and have the time to travel overseas regularly to search for better skies to capture more quality images?

I agree with Weixing to start with something relatively simple with your current equipment and get your feet wet in deep sky AP before making a big budget AP setup purchase. Nothing beats real life experience when it comes to learning. For example, XXX kg seems to be portable for me in theory until I start lugging it and my back starts firing some pain signals to my brain it is not.

Research online the best deepsky and lunar planetary your 6SE is capable of doing with DSLR and webcam and try to achieve that.

In the process of matching those quality, you will find your answers to the 2 questions posed above.

[kochu]

Hi Enterprise,

If you want to know what you can get with what scope

Try this program

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

Kochu/21-3-11

[cloud_cover]

I'm not an expert by any means but I concur with Weixing that the cheapest way to start may be to get a focal reducer and stick it into the C6SE.
Having said that, I'm not sure if the visual back is a 2" or 1.25" opening. If its 1.25" you may have vignetting issues with the relatively larger chip of the DSLR.
Why not try some planetary shots first? They don't require long exposures that deep sky objects do and you will benefit from that very long focal length (1500mm) of the 6SE.
Regarding your question on whether you need 2 refractors for different objects: not really. You can start with a smaller and faster refractor (such as the AT-66 quadruplet) for widefield and use your 6SE for smaller objects but its probably best to use a lower focal length and start by taking wider and brighter objects. This is less technically demanding than trying to image the dimmest, smallest DSO out there as it greatly reduces an errors of tracking Do bear in mind as you are using a DSLR a field flattener is probably needed for most telescopes (unless they are quad designs - those incorporate a flattener as the 4th lens)

[timatworksg]

Your Nexstar 6SE is a very capable scope for AP. As all have mentioned, start with what you have. AP can be bad for the health...haha! From late nights of frustration if one is expecting great results straight off!

Your APS-C DSLR is capable. Experiment with it and have fun. Don't worry of the large targets not filling the view. Pleides is very wide and so will be Lagoon and Eta Carina nebulas. But you could get some interesting shots if the core close up with some framing and being different. Don't compare or try to imitate what you see from HQ imagery.

Some experimenting, trying and knowing how it all works with some framing of key areas...can make for some fantastic shots!

As for refractors...the bigger the lens the more it cost. A Large Refractor can still get a wide FOV if coupled with a Large CCD cam. But this comes at a hefty price!

Test shots on M42, Omega Centauri, various brighter Open Clusters so you have a gauge on how your combination gives you results. Try to image when targets are around 30degrees up away from most LP.

Lastly have fun! Keep at it and you never know what your gonna get!!

[orly_andico]

isn't something missing from this discussion? the nexstar 6 is an alt-az fork. thus, field rotation.

the Meade Envisage software can do software field derotation. The catch is.. it's for Meade scopes. And the software field derotation only works if you keep the exposures short, real short (15 seconds probably maximum).

You'll need a wedge. The (discontinued) nexstar wedge only goes down to 25 degrees. Better go with a wooden wedge like this one from Covington's web site.

http://www.covingtoninnovations.com/astro/woodenwedge/

the other issue (yet again) is that the nexstar scopes are one-arm forks, am not sure if that fork is strong enough to track precisely if you lay it on its side.

my suggestion... find an f3.3 focal reducer, and use a Meade DSI or a webcam. The field of view will be extremely tiny (small chip) but the f3.3 will allow you to take usable images even at the short exposures needed if you're alt-az mounted.

[Enterprise]

Thanks for contributing to this discussion everyone!

Weixing: Iv been taking some pictures using prime focus already! So far only shutter speeds of 10s or less produce good image, anything more i can see trailing. Maybe it has to do that the gears and alignment are not good enough to be accurate? (not using GPS)

Kochu and Gary: Thanks for your resources! More things to read when im free at work hehe!

Timat: Will try what you have suggested for now

Orly: Thanks for pointing it out. In fact thats the main concern that i have to want to change to something equatorial. The fork also is not very strong as my DSLR is quite heavy, will try and show some results once i buy a cheap reducer.

Cheers all! Clear skies ahead for earth day

[orly_andico]

the 10-second limit is due to field rotation. pretty sure of that.. (since you're alt-az, there's no such thing as imprecise polar alignment!)

i think the nexstar 6 can be de-forked then put it on an equatorial mount. even a small one like a vixen polaris or CG-3/CG-4 could carry it very comfortably. these types of mounts are cheap and easy to carry around.

beware of "planning for a big mount for the future." that big mount will weigh you down. i just got my CGEM and can't get over how heavy the darn thing is.

[Gary]

@Enterprise: You are welcome. Yeah. So many books and magazines, so little time.

@Orly: C9.25 + 2" crayford + binoviewer on CGEM. Dude, time to update your blog and show us some nice photos of this combo!