Telescope recommendations

[Barath deena]

Hello there, am a newbie with regards to astro photography. as a university student am constrained financially but my obsession with astrophotography for over a year has pushed me and I have bought a Canon 700d (which will get a full spectrum mod soon) and SW star adventurer 2i pro. I've played around with it for nearly 2 months now. Am able to to get just under or over 2 minute subs with a 300mm lens after weeks of understanding how to polar align it properly in the southern hemisphere.(I live in Melbourne now). Am looking to buy a telescope that is under 3kg and over 400mm that would fit my budget of max 1000$ inc focal reducer/field flattener but lesser is better.

Some of the options under consideration are; 

SW evostar 72ed (also, does anyone here have experience with evolux ?)

 

Svbony sv48 90mm

https://www.ebay.com.au/itm/SVBONY-SV48-Telescope-Astronomy-2-F-5-5-90mm-Refractor-OTA-Double-Speed-Focuser-/273921570267?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l6249&mkrid=705-154756-20017-0

 

SVBONY SV503 Telescope 80ED F7 Telescope OTA Focal Length 560mm for Exceptional Viewing and Astrophotography https://www.amazon.com.au/dp/B085NTQL2C/ref=cm_sw_r_apan_glt_fabc_YEP7S9BSVZ6W0C6S65PZ

 

Astro tech AT72EDII 

https://www.astronomics.com/astro-tech-at72edii-refractor-ota-fpl-53-f-6.html

 

Let me know your recommendations. And tips. Cheers.

 

 

 

[Icesheet]

Of the three you’ve listed the AstroTech is the best option by far. The first is an achromat which is generally not suitable for astrophotography. The second is an ED doublet but has a lower quality ED glass than the AstroTech plus the weight and focal length will be too much for the Star Adventurer IMO. 

However, when you add the 0.8x reducer/ Flattener then you’re back at 344mm FL with the AstroTech so not much more reach than your lens (what lens btw?). Also, the more you push the Star Adventurer in FL the shorter your unguided subs will be which will then likely require an extra investment to get an auto guiding set up.

 

If you really want to start imaging at a longer FL then I would seriously consider upgrading your mount first. Not as exciting as a new scope I know but it’s the sensible way to go I think. If you must have a new scope then the AstroTech should be a nice upgrade from your lens but consider factoring in auto guiding if you can.

 

[AstroMuni]

On 24/10/2021 at 11:48, Icesheet said:

If you really want to start imaging at a longer FL then I would seriously consider upgrading your mount first. Not as exciting as a new scope I know but it’s the sensible way to go I think.

I would second this.

Having a good mount is essential in this journey to AP. (A go-to mount is not essential but gives you additional abilities in terms of control via laptop.) I would say Guiding is the next step and investment.

Edited October 25, 2021 by AstroMuni

[rickwayne]

Unfortunately the usual deep-sky road really is steep and rocky without a good mount, and good mounts are just expensive by the nature of the beast -- it's extremely difficult to build something with sub-arcsecond mechanical precision that will carry kilograms of load without expensive tooling and expensive materials. Toss in the small production runs, and you've a recipe for high prices. 

Once you get beyond camera-lens focal lengths, you're invariably talking something heavier, requiring a more robust mount to carry it precisely, and larger, with a higher moment of inertia, requiring more powerful motors to move it precisely, as well as the added magnification which makes any tiny error apparent.

Do people manage it? Yes, and they're rock stars. Or they image for 20 hours and throw out 80% of their frames (sort of a lucky-imaging-writ-large strategy).

I would not presume to tell you what you want to do. But I would advise you that too much scope for the mount is a hallowed old cliche of new astrophotographers. There are a lot of 300mm targets in the sky; I certainly haven't run out in the three years since I got my Stellarvue. If you're getting consistent two-minute exposures at 300mm, you've got the keys to a great deal of the kingdom. Narrowband read noise would present a challenge, to be sure, but I bet you could pull off even that.

[Bridgehouse]

If you're looking for under 3kg then I presume that's because you want to keep it on the existing mount? Don't forget you'll want to factor in the weight of any mount rings, extension tubes, filter holders, camera etc. and the tube is longer than a normal camera and lens so weight isn't the only factor. Then, you get onto guiding - you'll want to take longer subs, won't you?

Ultimately this means mount upgrade. Probably more than you first thought as well if you want an appreciable difference from where you are now. I'm just getting back into things again after a long break. I started looking at cheaper options and eventually got so frustrated that I totally reset my budget and decided to buy a bit at a time as I could afford it. 

I managed to find a really mint used Televue NP101is - a scope I'd always wanted - and that blew any budget out the water before even starting. Then, with the mount, I worked out how long it would take to get the next chunk of budget together and ordered a Losmandy GM811G. I'm already into silly money and I don't even have a camera yet. 

Now, you don't have to go to the extremes I've gone to, but I'd say upping the mount and looking at EQ5Pro/EQ6 territory is a good start. Once there, you'll have much better options in terms of scope weight - refractors are generally heavy (just the glass alone can be and the tube needs to be really stiff to keep everything in check).