Which setup is best for imaging?

[jermng]

My camera will be a QHY2

Is it your setup or your friends?

The C8 will be a 400mm scope with 8" aperture. Isn't this sound very cool since the weather here is not always encouraging. Short exposure can pickup many details if compare to the slow f/10 setup.

You still gotta consider the mount. Although the FL becomes shorter, the weight of the larger scope (not forgetting the photographic equipment) can be double (or more) that of a smaller refractor. With a lighter scope you get to use a smaller mount which saves you ALOT of weight and money.

You could of course get a big mount for your small scope and even then it'll e easier to image with the small scope.

Also, people (me at least), don't normally image BOTH planets and DSOs seriously on the same night exept maybe to test equipmet. Just pick one kind and bring out the equipment you need. Dont bring too much equipment into the field and not use half of them. If your ob site is your backyard, it'll just be a matter of swapping OTAs. on one mount.

That's what I'm doing now - small 480mm scope for DSO imaging and a slightly larger 8" SCT for planetary.

and BTW, both work together very well if just for visual use too.

[Robin Lee]

Actually 2 persons are involved as I'm interested in this field too.

Anyway, thanks for you guys' advice!

I will advise him to go to the 80mm ED + HEQ5. I will still do planetary photography since the limitation of my mount. Star cluster is my another target.

[weixing]

Hi,
My S$0.02 on HyperStar solution:
1) HyperStar solution seem more suitable for observatory rather than in the field as connecting a camera on the corrector plate need to be very careful, so is something you don't want to do it in the field. Also, a camera mounted on the corrector plate with connecting wires need to be handle with care. A knock on the camera or entangle with the wires might damage your corrector plate... this do happen in the field especially in the dark.

2) It's common for the primary mirror of SCT to flop a bit when SCT is moving (such as pointing to a new direction) or mirror shift during focusing. At such "fast" f-ratio, this might cause the collimation to off easily and you might need to collimate the scope very offen.

3) Since you need to use the "shoot and trial" method to collimate the scope, you must prepare yourself to spend more time doing collimation especially collimate such "fast" scope is not easy.

By the way, unless you are quite experience in astrophotography, a simpler setup might be is a good way to start. As you gain more experience, you'll know the do's and don'ts and the precaution need to be taken... there are lot's things waiting to happen that can spoils your astrophotography session and mood especially on complicated systems with lot's of wires.... and they do happen. So experience is really very important.

Good luck and have a nice day.

[Robin Lee]

Hmm.. so the golden rule is to keep everything simple and get started. Do I get it?

[mymoon]

Hmm.. so the golden rule is to keep everything simple and get started. Do I get it?

If your friend has got a canon DSLR and 50mm f1.8 lens (f1.4 better) a camera tripod and a ballhead and this article will get him going

http://www.pbase.com/samirkharusi/beginners

with this he will learn about taking light frames, dark, flat, bias and registering them, stacking and processing and finishing off with Photoshop. Also he will learn to use the various programmes like Image Plus or deepskystaker and most importantly he will get gratifying results


He will not be complicated with the learning curve of setting mounts, alignment, drift, collimation and even focus.


If he found that AP is his cup of tea, maybe his next step will be

http://www.samirkharusi.net/skymemo.html and

a canon 400mm f5.6 and a hutech 40D and produce images like this

http://www.pbase.com/image/88717819/original


or he can be ambitious and go for the canon 500 mm f/4 L IS lens
where at f/4 the image of Comet Holmes is the sum of 36 one-second exposures at ISO 1600 from a stationary tripod

http://www.clarkvision.com/galleries/ga ... -c800.html


Like Remus said to me your set up depends on how long and how deep you want to go into AP.

my 2 sen



cheers

[Meng Lee]

To summarise:

1) Start with focal length less than 400mm if you are not autoguiding.
2) Only load the mount to about at most 60% of it stated loading capacity
3) learn drift alignment properly
4) Learn collimation of C8 properly
5) For planetary, a larger scope will always do better than a smaller scope, regardless of APO whatsoever.

[universe24]

Look for a good tracking mount system at first, then only look an imaging optic.
No single optic system can do all type of astrophotography.

[MooEy]

somehow i went to look at the hyperstar website. somehow misleading. film is very much slower than today's dslr/ccd chips, and does not have the kind of resolution of today's ccd. comparing film to ccd is already wrong.

the hyperstar at roughly f/2 is somewhere 2-3 stops faster than a typical flattened/reduced refractor which is usually ard f/4.8 to f/6. that makes the hyperstar only at best 8x faster.

given that most exposure does not take any longer than 10min on today's ccd, it's not really that big an improvement as compared to the days of film. a decent mount can prolly track 1min or so without guiding, a really gd mount can take prolly 2min. do consider if u really need that kind of speed.

~MooEy~

[rcj]

Hi Kim Miau,

with regards to the Hyperstar option which I have considered in the past before, it comes to attention that the construction of the Hyperstar kits are more for Celestron SCTs rather than Meade equivalents. Another subtle point that most would overlook is shooting at fast focal ratios have its restrictions as well - you need dark skies. Otherwise very soon, the fast fr system will soak up light pollution 'noise' as well, and your skyfog limit is quite short. Thus this is based on the assumption that you have access to frequent dark skies location, otherwise the Hyperstar option might not be so viable, except for really short exposures (again, compromising how deep should one go for certain DSOs). There are successful images taken in this combi with QHY's CCD cameras no doubt, but what happens when one would like to try tri-colour imaging with the use of filter wheels? Or will you be happy with imaging in just hydrogen-alpha for instance?
No matter what focal length one is imaging in, you NEED to drift align, whether it is imaging with a 28mm camera lens or a 3000mm f.l. telescope. You may image in alt-az but there will be field rotation (which needs to be taken care of). Perhaps your choice was based on the fact that you have an existing meade SCT? My suggestion would be to use the SCT for planetary imaging, and like what others have mentioned, another refractor on a GEM for wide field imaging for a start. We all have to start somewhere, but it would be wise to learn how to walk first (and make mistakes) then fly and soar to your peril. Refractors are cheap nowadays. Get the fabled Orion 80ED and with a decent cheap DSLR (modified), you are good to go for many DSOs. Of course, you may want to consider autoguiding, which adds another guidescope (say Borg 50, etc) and also ensure your mount supports autoguiding.

[Robin Lee]

What a helpful community~ Hehe

Remus, you're right, my choice is really based on my current scope since I wish I can save more since I don't have the ability to earn money yet. Perhaps, I should keep doing planetary imaging until I get my salary for a deep sky imaging equipment.

Alright, I'll advise my friend and convince myself to get a 80ED + HEQ-5 to plunge into the deep pocket burning hole, the dso astrophotography. Do you guys suggest a CG-5? I heard that it's noisy. I can get a Synta 80ED at RMB4500 but I don't have that money.

Do you mind that I take this thread as a reference for my new article - Hyperstar or not?