First light with my Edge HD 11" Hyperstar v4

[gorann]

Finally!

Here is the story. Back in August 2020 I bought a second hand RASA 8 (for about 1000 GBP) although I heard many doubted the RASA, but that was primarily from experience with Hyperstar set ups. Luckily it needed no collimation and I was thrown away by the deep images it produced. It made me somewhat of a RASA pioneer here at SGL and I think I inspired a few, even including @ollypenrice to invest in a RASA. I liked it so much that I invested in a second one to get a dual-RASA8 rig that I have now been running for a while on a Mesu 200 Mk I. Lately I have noticed that more and more people go for a RASA 11, especially since Celestron in version 2 had fixed the mirror flop / focusing problems. Although my dual RASA 8 rig has the same light grasp as a RASA 11, I envied the possibility for easy filter changes that comes with the longer back focus of the RASA 11.

Last summer I noticed a Starizona Hyperstar v.4 for Celestron Edge HD 11" for sale second hand in the UK for a very reasonable price (500 GBP).  Since I have long had an Edge 11 that I rarely use (after I got a Meade 14" ACF) I now saw the possibility to almost get a RASA 11 and with the same possibilities for a filter slider. So I bought the Hyperstar and as the seller refused to send it outside the UK I had it mailed to a friend in the UK that I would in any case see at a meeting that summer (= no VAT😁).

While I am at a dark site in rural Sweden (SQM sometimes 21.6) I have realized that seeing is rarely good enough for using a scope like the 14" Meade with 3.5 m focal length. I had the 14" residing on an EQ8 in an obsy next to my RASA 8 obsy, so it had to give away for the Edge 11 with Hyperstar. This was back in November and it was freezing cold (down to -25°C some nights), so I really could not find the stamina to start using the Hyperstar as I was convinced I would need to spend hours trying to get it collimated. So until now I devoted the clear nights to my RASA 8 rig. The second problem was that I am really no fan of the Synscan hand controller that came with the EQ8 and I started looking into a way of controlling it the same way I do with my Mesu, which is with Cartes du Ciel. That would alleviate much nocturnal confusion for me. I solved the problem by getting a SW USB dongle to connect to the hand controller port on the mount, and installing the Green Swamp Server software (that I read is better than old EQMOD) on a Laptop. So last night I finally could find no excuse for not trying to get the Edge 11 with Hyperstar working. It was clear and mild (+5°C) and a lot of moon so not much valuable imaging time would be wasted.

Two hours later I was very happy! After a bit of fiddling with the computer I could easily control the mount with Cartes du Ciel. But even better, my fist image showed much better star shapes than I dreaded even at the corners of the APS-C chip of the QHY 268MM I attached to the setup. OK, they are a bit eggy but nothing that BlurXT2 would not fix. So, for the time being at least I will not touch the collimation screws on the Hyperstar. Since I already had a Baader UFC filter slider I did not by the rather expensive Starizona one (which comes with a dedicated adapter to get the right back focus), so I was a bit unsure if I had managed to get the back focus right (it is supposed to be within a fraction of a mm). But obviously I did not mess that up too much.

So here is my fist light from last night. 8 x 10s of Capella (no guiding, no calibration frames). I did not spend much effort focusing so I expect I could get the stars a bit tighter. I see two artifacts from reflections but I assume they will not be present as long as I do not aim at the brightest stars in the sky, and I have no intentions of doing that. The images are just lightly stretched in PS. The first one before BlurXT2 and the second one after BlurXT2 with stars good enough for me.

Cheers, Göran

Edited March 23 by gorann

[ollypenrice]

That looks very promising.

Olly

[gorann]

20 minutes ago, ollypenrice said:

That looks very promising.

Olly

Thanks Olly!

Feels like I just got a RASA 11 for 500 pounds!

[ollypenrice]

2 minutes ago, gorann said:

Thanks Olly!

Feels like I just got a RASA 11 for 500 pounds!

How well will it hold focus, do you think?

Olly

[Elp]

I'm sure you'll enjoy it. I just leave the HS flush (closed) and image away. It's more difficult the larger the sensor but I use it simply for taking in the good stuff. For stars I've got a refractor.

[gorann]

2 minutes ago, Elp said:

I'm sure you'll enjoy it. I just leave the HS flush (closed) and image away. It's more difficult the larger the sensor but I use it simply for taking in the good stuff. For stars I've got a refractor.

Thanks Elp! Yes, I know someone using a full frame sensor with it (https://www.astrobin.com/users/equinoxx/) but I will not go there. My first targets will probably be faint SNR and PN candidates.

[gorann]

10 minutes ago, ollypenrice said:

How well will it hold focus, do you think?

Olly

Good question. Unfortunately, to find out I will have to wait until clouds disappear and it looks like it will take a while. Frustrating!

[Elp]

You could try on a far off object during the day and meridian flip it a few times. I don't refocus mine, but it's a much smaller scope.

[gorann]

14 hours ago, Elp said:

You could try on a far off object during the day and meridian flip it a few times. I don't refocus mine, but it's a much smaller scope.

I think I just wait until the next clear night and take it from there. If I need to refocus now and then I will just do it and I always do it after a flip. The need for refocus will of course depend on how steady the temperature is and I will use the mirror locks between focusing, but that will not allow autofocus (which I in any case never used). What has surprised me and other RASA users is how good they maintain focus, so I hope my Hyperstar set up will behave similarly.

Is the smaller scope you talk about a Hyperstar?

[Elp]

44 minutes ago, gorann said:

Is the smaller scope you talk about a Hyperstar?

Mines a C6 with a HS lens. With SCTs I thought it was more to do with mirror flop due to changes of movement/orientation of the scope rather than temperature fluctuations which affect focus.

[gorann]

1 hour ago, Elp said:

Mines a C6 with a HS lens. With SCTs I thought it was more to do with mirror flop due to changes of movement/orientation of the scope rather than temperature fluctuations which affect focus.

It is a bit of both. Mirror flop is no problem if I remember to tighten the mirror lock screws after focusing. With regard to temperature my RASA8 can take about 3°C without losing focus but more than that will start affecting focus. My guess is that the whole steel tube expands / contracts. With an ordinary SCT at f/10 (so more focus depth), temperature will probably have less effect.

[gorann]

By the way, for the autumn I was thinking of the possibility of making side-by-side dual mount of this, I just love doubling the data, by putting an Esprit 100 next to it. I think the EQ8 should be able to handle this (it handled my 40 kg Meade 14" just fine) and the field of view are virtually the same for these scopes (540 mm for Hyperstar and 550 mm for Esprit). I could then collect RGB with an AIS2600MC on the Esprit and NB with the big fellow. I got all the stuff just need to put it together. But for now it will only be the Hyperstar.