Star Adventurer

[Starman john]

Hi folks I’ve taken my first step into asrtophotgraphy, I’ve bough a skywatcher star adventurer and will be using a canon 1300d with a 18-55 and 75-300 lenses. Looking at trying to capture M45 and M42 for my first attempt, any advice with iso and exposure time and how many shots I will need to take will be greatly appreciated.

[Mr niall]

I used that exact setup for a while! I managed to get 60sec at 300mm with a good polar alignment.

Generally speaking though you should be aiming for at least 90 to 120 secs to start picking up dust lanes on M45; M42 I've never actually imaged but I think (others may need to verify this) is that you want to take two separate sets of exposures - one as long as possible, and another of reasonably short (15 to 20 secs) to fill in the inevitably blown out core that you get from a long exposure times.

General advice for anything is aim for at least an hour of data if possible.

ISO - I find ISO 1600 still very low on noise, but unless conditions are really good I don't often use it as light pollution around my house totally obliterates anything above 60 secs more often than not so I generally use 800. But, as with all these things; you just have to play and find what works for you.

[Davey-T]

Hi John and welcome to SGL, there's a long running thread on imaging with the Star Adventurer.

Length of exposure with 18 / 55 lens will probably be limited by local light pollution if you have any and exposures with 300mm limited by mechanical performance of the mount.

I use ISO 800 / 1600  and can do 90 secs with Canon 300mm f/4 which may be a bit lighter than the 300 zoom but 60 secs should be achievable, and as many subs as you can get.

Pleiades should be doable on quite short exposures.

As with all mass produced stuff some Star Adventurers perform better than others, if yours can't achieve these times, especially if you get eggy stars it's worth checking that it's rotating at the correct sidereal speed.

Dave

[pipnina]

Generally longer exposure times are better in theory. In practice with DSLRs however you may find there is a balance to be struck as longer exposures can exacerbate the dark current in the sensor (purple glow caused by heat) and DSLRs often do not have the same dynamic range as the cooled CMOS chips - stars become saturated quicker.

I find 30 seconds is a good balance for my D3200, 60 if my target is faint and the tracking is up to it.

I also have the Star Adventurer, a very good piece of kit. Be aware to try and balance the weights (i.e. if clutch is undone, the camera will not flip upside down under own weight) if you have the kit for it, it will help you get longer exposures.

Good luck and have fun

[SteveNickolls]

Hi and thanks for posting,

You have just bought a great piece of kit which used within its limits will do you proud. As Davey-T notes depending on the light pollution where you live will place a glass ceiling on how long you can expect to expose for. You might want to try this out at your imaging site to know how good or bad the light pollution is and its affects on your imaging, at least for OSC-http://www.pbase.com/samirkharusi/image/37608572

There's a lot been said about which ISO to use but if you are in the situation where light pollution is a pain I would advise you to experiment on the ISO used and see what you prefer to use-there's no golden rule especially where light pollution rules. A higher ISO won't capture anymore detail in your images but it will make them brighter albeit at the cost of dynamic range. I've experimented with 1600, 800, 400, and 200; the benefit from using a lower ISO is you will be able to expose for longer. 

The ability to take longer exposures with the Star Adventurer (SA) depends on a few factors such as your own experience and ability to polar align the mount and not subsequently knock it when later adding, adjusting, moving and tightening  and loosening the optics to the mount (all done at night and possibly in the numbing cold). Individual mounts vary and the design of the SA places a limit to the weight and length of optics you can realistically use. The longer the focal length of your lenses the shorter the individual exposure you can expect to take without star trailing. My own experience, for what it is worth has shown that 180 seconds are achievable with a 300mm lens, and 900 seconds and more with a 135mm lens. I routinely expose for 300 seconds at ISO 400 and f/2 using a Samyang 135mm lens which is a great lens to buy sometime. If you can download the SkyWatcher Mini App you can use the polar clock utility to get accurate polar alignments. You can get a distinct advantage by ending the polar alignment routine when Polaris is on a main division (10, 20, 30 etc minutes) or at the midway point (5, 15, 25 etc minutes). If you can get or make something like this-https://www.darkframeoptics.com/product/polarite-right-angled-polar scope it will help take the pain out of polar aligning. It has a x2 magnification to allow really accurate judgments when polar aligning. I think practically there is a sensible limit to how long you want to take on each exposure. I have reduced my exposure times from 900 to 300 seconds after following the advice gleaned from tests which you can find in articles here-http://www.stark-labs.com/craig/articles/articles.html now a plane or cloud passing overhead only spoils a 5 minute exposure and not a 15 minute one. ? If you take really long light frames you will have to endure taking equally long dark frames, not ideal at the end of a long session with work possibly the following morning.

As for how many exposures to take, that really depends on the object but if you can achieve 2 hours of total exposures your image ought to be fine but some faint objects will need much more exposure. 

This is a lot to absorb I know and the best I can say is- you have a great mount in the SA, go experiment with the lenses you have and enjoy the time learning. Don't forget to post your images though. ?

Best Regards,
Steve