Ready to try Astrophotography

[Jaypat75 (Jason)]

Hi Everyone,

First big post....so go easy on me

After doing numerous Star Trails and single shot astrophotography, I'm ready to step into the realm of AP using either a tracker or existing equipment.

My camera gear consists of a Canon 7D, 15-85mm f/3.5-5.6, Mark 1 Canon 50mm f/1.8 and Sigma 70-200mm f/2.8 APO DG Macro. I am also in possession of a cheap telescope(Aldi Nat Geo type) that has a EQ1 Mount. Mounting my DSLR to this telescope is nigh on impossible!

My question to the more experienced photogs out there is: Can I use the existing equipment (retro-fit the EQ1 mount with a motor drive and attachment for my DSLR) to achieve decent results? I'm interested in doing both Wide field and Deep Space Objects. Or are trackers the way to go? I am working to a budget so that will need to be kept in mind. I've looked at the three most portable star trackers ie Vixen Polarie, iOptron Skytracker Pro (and Skyguider) and the Star Adventurer Skywatcher and I'm none the wiser for which one would be best suited to my needs if the retro-fit option isn't ideally suited. I hear that counter weighting those trackers are helpful, so if the retro-fit option isn't viable I was thinking of cannibalizing the counter weight off the telescope to help out (if it fits of course )

Not aiming to get award winning photos, but just the reward of capturing something different in the night sky.

Looking forward to your responses!

[doppler (Rick)]

Hi Jason and welcome. We all have to start somewhere and this is a great place to ask lots of questions. There are plenty of us here that have to make do with tight budgets, but still come up with reasonable results. I'll start with the first one yes you can easily fit a RA drive to your EQ1 mount and use it to take wide field long exposures with a DSLR. There are plenty of of deep space objects large enough to capture with a telephoto lens with a bit of tracking. This one is cheap and simply attaches in place of the RA slow motion control.

http://www.ozscopes.com.au/skywatche...eq1-mount.html

There are various adapters available to fit cameras to mounts. The only problem with astrophotography is that the more you spend on equipment the easier it gets.

Rick

[sil (Steve)]

Jason, welcome. For a start you can do pretty decent astrophotography with what you have right now, just camera + lens + camera tripod is fine. You can compensate via processing technique. EG tracking gives you long exposure times without stars trailing, fomr regular tripod you can find the longest exposure time before the stars start trailing, then take a lot of photos in that position at that exposure then align and stack the images in eg DeepSkyStacker to bring out fainter structures and reduce noise. You can take video from a locked off tripod of planets drifting across the frame, then use PIPP to recenter each frame (basically aligning) then give that to autostakkert to process a planetary shot. ALL free software btw. All depend on what you want to capture, if you understand the limitations of your equipment etc and what the gear actually does for an astrophoto, then you can find alternatives to fill in gaps in the mean time until you can afford the bigger better mount etc.

A motorised tracking mount, you do the same but you get to take longer exposures for each shot. Then you ditch the dslr and grab an imaging camera (basically just a sensor in a box and record frames/video to your laptop for aligning and processing. A lot of time i spent on the computer whatever way you go, I suggest you start practicing with what you have.

[Jaypat75 (Jason)]

So using the advice of playing with what I have, I trialed using my 50mm f/1.8 lens and shot for a nice easy target...the Crux. For practice purposes I tried 30 x 6secs and shot 6 dark frames. ISO 3200 @ F/2.2. Stacked in DSS and some processing in LR afterwards. Will probably aim for f/2.8 next time and maybe bring the ISO down a notch or two. Comments and advice welcome.

https://farm5.staticflickr.com/4324/...57b95731_c.jpgAutosave_resize by Jason Paterson, on Flickr

[raymo]

You've made a start. You're stars are still elongated, so I'd try 4 secs
instead of 6. With such short exposures you can leave your ISO at 3200,
and even experiment with 6400. I'd leave the lens at F2.2, in fact I would come back to f/2, you need all the light you can get. Using f/2.8
will reduce the amount of detail you will collect, which has already been reduced by doing 4secs instead of 6. You can, if you wish, leave the noise reduction enabled, and let the camera take the darks for you. It would be a pain with long exposures, but fine for you. It would be easier to start with a wider lens; even a really cheap one would be fine for now.
raymo

[rally]

A good first start

Did your image stacking include derotation ?
Some packages do this automatically and some dont.

Otherwise I think the elongation is more likely to be lens distortion, field curvature.
Its more radial than anything else.
Even focus might have some contribution depending on your lens.
Stopping down the lens might help with this problem but reduces light on the faint non point source light objects.

However 4 secs without an equatorial mount will give you approx 4x15 arc secs = 60 arc secs of field rotation

The SCP is just off to the bottom left of the image which if field rotation was the problem should mean all stars would be progressively more elongated about the SCP the further to the top right of the image you get - yet the elongation is predominantly at the periphery of the image in all directions
Acrux and Mimosa in the centre are generally round.

Your image scale is probably around 18 arc secs per pixel so without doing the horrible maths for being so close to the pole, any field rotation elongation cannot be greater than 60 arc secs or 4 pixels, and is probably unlikely to be more than a few pixels given your proximity to the pole.

Maybe try to improve the colour using some white balance processing and or curves adjustment.

But its all one step at a time - before you've completed all the steps you'll probably find a year or so has passed ! It just takes time and practice.

Keep it up.

Rally

[sil (Steve)]

good start, as i sugggested before. take a series of test shots only dropping the exposure time down a notch each time. Sounds boring and time consuming but you only need to ever do it once for the camera/lens combo.

Camera lenses are never at their sharpest at their fastest aperture setting, so after you find the optimal exposure length, go take another set of test shots, this time keep exposure time identical and change aperature only from widest to around f8. You should notice the stars sharpen up somewhere in this range or at least be less distorted. Then you will have two good setting to rely on with that camera and lens.

A lot of astrophotography is boring trial and error stuff. We all appreciate the enthusiasm to see a good pic and when you're sitting outside in the cold you can be easily rushed into looking for shortcuts. But its up to you if you're serious and disciplined enough to put in the effort, it pays off in the long run.