First light with RASA8, ASI2600, and new obsy

[gorann]

9 minutes ago, tomato said:

Very impressive, I can feel another astro spend coming on...

Thanks! Yes, that is what happened to me.... Have a look at what Damien can do with his RASA:

https://www.astrobin.com/users/Damien.Cannane/

[ollypenrice]

1 hour ago, gorann said:

To see how much dust I can get out of the data I have, I merged the 90 minutes of gain 100 data (used in the previous version) with the 70 minutes of gain 0 I collected the same night, so totally 160 min. I then also did not crop it. Now I think I have caught the full extension of the galaxy dust except a tiny bit at the very left edge. If I frame it carefully and have another go at M31 with the RASA I could get it all in, but then there are so many other interesting objects to aim at.....

Still quite happy with how deep I could go with less than 3 hours of data and I found a bit more details in the core.

Yup, you're getting the upturned end on the left. Very good and more than very good for the exposure time.

Olly

[Sunshine]

Spectacular!

[gorann]

2 hours ago, Sunshine said:

Spectacular!

Thanks Sunshine!

[Datalord]

6 hours ago, gorann said:

Still quite happy with how deep I could go with less than 3 hours of data and I found a bit more details in the core.

 

Beautiful. My RASA is getting very little showtime because I'm too lazy to fight the light pollution, but you are really giving me the urge to spin it up.

[gorann]

2 hours ago, Datalord said:

Beautiful. My RASA is getting very little showtime because I'm too lazy to fight the light pollution, but you are really giving me the urge to spin it up.

Thanks, spin it up!

[clarkpm4242]

Now that is very pleasing!

I have exactly the same scope/camera combination awaiting first light 

Cheers

Paul

[gorann]

10 minutes ago, clarkpm4242 said:

Now that is very pleasing!

I have exactly the same scope/camera combination awaiting first light 

Cheers

Paul

I hope my first light made you even more excited Paul. This combo seems like a good match. Good luck with the weather, here it is a bit off right now. Look farward to see your first light!

[tomato]

Just pushed the button on a RASA 8 from FLO and they have stock.😊Going to couple this with @Tomatobro’s Atik Horizon OSC to see if I can make my M31 mosaic project redundant. In theory it can ride on the Mesu to make a triple rig but the proof of the pudding...

[gorann]

2 hours ago, tomato said:

Just pushed the button on a RASA 8 from FLO and they have stock.😊Going to couple this with @Tomatobro’s Atik Horizon OSC to see if I can make my M31 mosaic project redundant. In theory it can ride on the Mesu to make a triple rig but the proof of the pudding...

Honoured to have inspired your purchase! After all it is virtually the fastest wide field scope you can get and I am now doubting that it is behind the Tak Epsilons in image quality, but it is defenitvely well behind in price. And, in my short experience and from what I have read about it, collimation is never an issue with the RASA (spot on from factory) while it is a big issue with the Epsilons. And you do not have to deal with star spikes if you organize your camera cables in a circle. Drawback is that you cannot use a filter wheel but need a filter slider (Baader makes a dedicated one) if you go mono.

I would not consider putting it as a third scope on your dual Esprit rig on the Mesu. Sounds extremely complicated and you would rarely want to image the same objects. If you have an NEQ6 class mount lying around, put it on that with a tripod until you build an obsy for it (like I did). If you do not have an extra mount, you may want to invest in one. Maybe even an HEQ5 could swing it.

The very best of luck and CS!

PS. The Atik Horizon (=ASI1600MC) should be ideal for RASA8's proven image circle, I am pushing it with my ASI2600MC.

Edited August 20, 2020 by gorann

[tomato]

Thanks Goran, yes a Tak Epsilon was beyond my budget, and your wonderful M31 had a lot to do with my decision! @Tomatobro has a NEQ6 available, but I have been known to set up the dual rig from a bare mount in half a day, so I’ll change the scopes out if necessary. I still have a 100 mm APO so I could have widefield and close in dual rig combinations, I should be kept busy.☺️

 

[gorann]

1 minute ago, tomato said:

Thanks Goran, yes a Tak Epsilon was beyond my budget, and your wonderful M31 had a lot to do with my decision! @Tomatobro has a NEQ6 available, but I have been known to set up the dual rig from a bare mount in half a day, so I’ll change the scopes out if necessary. I still have a 100 mm APO so I could have widefield and close in dual rig combinations, I should be kept busy.☺️

 

You have some exciting projects to deal with when the sky clears! Good luck again and I am eagerly waiting to see the results.

[Adam J]

On 17/08/2020 at 23:15, gorann said:

I have been at the lookout for a wide field scope (what some people call astrographs) and this spring I came across a nearly unused RASA8, and after 6 months waiting time, due to the virus situation, I finally received an ASI2600MC - an APS-C sized cooled OSC with relatively small pixels (3.76 µm) that kind of fit the 400 mm FL of the RASA8 (ca 2 "/pix sampling). As I allready had my two obsies filled up with other scopes I decided to spend the summer building a third obsy for the RASA to put on my long-time retired NEQ6, my first mount bought in 2014 when I started my AP adventure, but having been laying in a closet for the last five years, beeing replaced by an EQ8 and a Mesu in my other obsies.

Wow, I did not think that the RASA 8 was spec'd to cover an APS-C sensor.

To quote celestron:

"Unlike the larger RASAs, the 8" model is not suitable for use with DSLR cameras. Instead it has been optimised for use with cameras that have sensors with a diagonal size ~22mm, which gives an image circle of 3.15°. This makes it an excellent choice for use with today's highly popular CMOS deep sky cameras, such as the ASI183 & ASI1600 series from ZWO. Starlight Xpress' compact CCD cameras also work very well. And whilst ~22mm diagonal is optimal the RASA 8 can also be used with larger sensors up to 32mm diagonal, including the APS-C sized sensors used in many mirrorless cameras, though some compromise must be expected at the image periphery. Celestron advise camera bodies should be less than ~100mm / 4" in diameter."

Did you have to crop that at all as it does not seem like you have had to make too many compromises with the APS-C sensor.

Adam

 

 

Edited August 20, 2020 by Adam J

[gorann]

Yes Adam, I read that too so I expected some edge problems with the 28 mm diagonal of the ASI2600 (even if 32 mm is more than APS-C). However, I found that vignetting is really minimal and no problem, but star shapes are a bit elongated at the edges but I fixed most of that in processing. Since it was not equal in all corners I think it could be related to minor tilt since the tolerances for tilt are extremely small at f/2. Right now I do not feel it is worth the work of trying to deal with it even if the ASI2600 has tilt adjustment. A DSLR is of course not possible at all to use since backfocus is only 29 mm.

 

EDIT: To answer you question, in the second image posted I did not crop and only a minimal crop in the first.

Edited August 20, 2020 by gorann

[tooth_dr]

1 hour ago, gorann said:

I am now doubting that it is behind the Tak Epsilons in image quality

Dont be using my image quality as reference 😂  

[gorann]

1 minute ago, tooth_dr said:

Dont be using my image quality as reference 😂  

It was excellent Adam, so why not. But how knows what seeing conditions contribute. Did you measure your SQM. I think mine was 21.1 that night (still a bit bright up here).

[tooth_dr]

14 minutes ago, gorann said:

It was excellent Adam, so why not. But how knows what seeing conditions contribute. Did you measure your SQM. I think mine was 21.1 that night (still a bit bright up here).

I have an SQM, has it 12 months ago and still sitting in the box, haven’t worked out how to set it up.

I would love to see you process my epsilon m31 data though to see how it compares  

 

[gorann]

Not sure what SQM you have. Mine is hand held and only have one button. I could give your data a go although I dont think there was anything wrong at all with your processing. Your Epsilon of course win in corrected image circle - 44 mm.

[tooth_dr]

4 minutes ago, gorann said:

Not sure what SQM you have. Mine is hand held and only have one button. I could give your data a go although I dont think there was anything wrong at all with your processing. Your Epsilon of course win in corrected image circle - 44 mm.

Thanks Göran. I’ll hoke out the SQM and start a new thread 👍🏼 It’s one that plugs into an Ethernet port and needs configured on the network. 

[Fegato]

Just came across this thread, thank-you...  

I'm a bit fed up endlessly fiddling with my Hyperstar in the freezing cold desperately trying to get "pinpoint star images" as promised. I didn't realise the RASA8 could take an ASI2600, the central obstruction is wider than I thought. I also hadn't twigged that the additional weight of the RASA over the 8 Edge HD was relatively small, so my CEM40 will carry it fine. 

Apart from the expenditure, I'll probably have to wait months too, but I'm sorely tempted. 

[gorann]

28 minutes ago, Fegato said:

Just came across this thread, thank-you...  

I'm a bit fed up endlessly fiddling with my Hyperstar in the freezing cold desperately trying to get "pinpoint star images" as promised. I didn't realise the RASA8 could take an ASI2600, the central obstruction is wider than I thought. I also hadn't twigged that the additional weight of the RASA over the 8 Edge HD was relatively small, so my CEM40 will carry it fine. 

Apart from the expenditure, I'll probably have to wait months too, but I'm sorely tempted. 

Hi Fegato! Yes I would have thought that the weight of an EdgeHD8 with Hyperstar would be about the same and the RASA 8. Good luck with it! You find my RASA8 images on my Astrobin (URL below). I see that both Astroshop.de and TS have the scope in stock.....