First light for 6" StellaLyra RC - Bubble Nebula

[fireballxl5]

Here's the first light image from my Christmas present, a StellaLyra 6" f/9 Ritchey-Chrétien Telescope, capturing NGC7635 the Bubble nebula in Cassiopeia. More info on Wiki...https://en.wikipedia.org/wiki/NGC_7635

Subs captured over New Year's Day (4 off) and 5th Jan (remaining 58). Setup needs tweaking as there seems to be some tilt causing elongation of stars in the far left of the field (largely cropped out here) and stars are OOF away from the centre. Hopefully I don't need a flattener but this also needs investigating. I think that this also impacted guiding as stars in the field of the OAG were particularly poor. Seeing didn't seem to be so great on either night and this will also be a factor. Maybe I should just stick to using refractors lol, but this combo provides an image scale of 0.71"/pix in a light-weight package that I can pick-up and move in and out of the house with ease. It should be usable for smaller galaxy and PN imaging, so worth persevering with.

Scope: StellaLyra 6" f/9 RC

Camera: ASI071MCPro

Filter: IDAS D2

Mount: RST135E

Guidecam: ASI462MC

Subs: 62x180s

CS, Andy

[geeklee]

Great first light Andy.  Very nice star field and plenty of detail in the Bubble.  I haven't dusted off my RC6 yet for this year.

[fireballxl5]

11 hours ago, geeklee said:

Great first light Andy.  Very nice star field and plenty of detail in the Bubble.  I haven't dusted off my RC6 yet for this year.

Thanks🙂

I've mentioned the suspected tilt but I'm also unhappy with the star shapes.  Guiding wasn't consistent owing to intermittent cloud and very elongated stars in the OAG, with the guide star being lost many times.

I'm now wondering which upgrades are standard or needed with your typical RC6 when imaging with an ASP-C sensor🤔

Focuser,  tilt plate,  flattener? 

Any advice appreciated,.

CS, Andy

[iantaylor2uk]

You can adjust the tilt on the 071 MC Pro camera if you need to.

[geeklee]

50 minutes ago, fireballxl5 said:

I'm now wondering which upgrades are standard or needed with your typical RC6 when imaging with an ASP-C sensor🤔

I'm typically imaging with a smaller sensor Andy so not sure what would optimise an APS-C size version.  On my StellaLyra RC6, I have the Baader Diamond Steeltrack focuser upgrade and have a reducer too (not used this yet)

[fireballxl5]

1 hour ago, iantaylor2uk said:

You can adjust the tilt on the 071 MC Pro camera if you need to.

Yes that's true but I use the camera with other scopes and lenses so would prefer not to 🙃

Edited January 10, 2022 by fireballxl5
typo

[jjosefsen]

I think you need a flattener for APS-C sized sensors, but not tried a sensor that size myself, so that is just 2nd hand info.

[iantaylor2uk]

There's some discussion of flatteners that work for these telescopes at: https://www.cloudynights.com/topic/560592-rc-field-flattener/

It seems as if you may need one for the RC6 with an APS-C sized camera sensor (which was a surprise to me as I thought one of the selling points of these scopes was that they were "coma free, chromatic aberration free and spherical aberration free optics" - according to the advertising blurb)

[fireballxl5]

2 hours ago, iantaylor2uk said:

There's some discussion of flatteners that work for these telescopes at: https://www.cloudynights.com/topic/560592-rc-field-flattener/

Thanks @iantaylor2uk, useful read.

After reading one user note that their '6" RC + APS sensor looked absolutely awful without some kind of corrective optics' it makes me appreciate how satisfied I am with this first light image! 🙃

[Len1257]

I think a tilt plate might be a less expensive first option! I would be over the moon (!) if that was my first image from a new scope. Got an RC8 in my sights.

I did notice the extra diffraction spikes around the bright stars? Are they caused by the scope design like the edges of the primary mirror in a Newtonian?

[fireballxl5]

3 hours ago, Len1257 said:

I would be over the moon (!) if that was my first image from a new scope.

Thanks @Len1257🙂

3 hours ago, Len1257 said:

I did notice the extra diffraction spikes around the bright stars? Are they caused by the scope design like the edges of the primary mirror in a Newtonian?

I'm not expert but I think they show that the edges of the field are out of focus when compared with the centre of the field (where focus was set). This is the main reason for the need of a flattener when using an APS-C sized sensor. In fact FLO have confirmed that a fours thirds sensor is best suited for use with the RC6.

Here's a crop of the target that I feel makes the most out of the image.

[teoria_del_big_bang]

On 10/01/2022 at 08:47, geeklee said:

I'm typically imaging with a smaller sensor Andy so not sure what would optimise an APS-C size version.  On my StellaLyra RC6, I have the Baader Diamond Steeltrack focuser upgrade and have a reducer too (not used this yet)

What focuser and adapter did you fit ?
I was looking at  Baader SteelTrack Diamond RT for Refractors , which doesn't sound right as it is for refractors but looks to me that it is the only one that Baader make an adapter to M90 x 1 for, Baader SteelTrack Diamond RT Adapter (M90x1) for Refractors & GSO RC scopes

I was worried about the long adjustment on this focusser and how much the inner part of the focusser would travel into the scope when fully retracted.
The SCT version sounds a better option but cant find a suitable adapter.

Steve

[geeklee]

17 minutes ago, teoria_del_big_bang said:

What focuser and adapter did you fit ?

You're right on all counts Steve!  I purchased the following which I think is the same as your links above.  I also got the related ClickLock clamp.

On my RC6 I have the extension tubes on natively and with these, the focuser is fine and doesn't impact the scope.  If you were to remove too many extension rings then you'd have a problem as you mention.  Here is mine from last year - I think I'm missing one extension ring but can't be sure!

@Adreneline has the 0.75x reducer alongside the BDS with no issues.

 

Edited March 3, 2022 by geeklee

[teoria_del_big_bang]

18 minutes ago, geeklee said:

You're right on all counts Steve!  I purchased the following which I think is the same as your links above.  I also got the related ClickLock clamp

Many thanks for that.
Sorry for all the questions but is it easy to rotate this focusser (I guess on the dovetail) to get better framing ? sort of like a manual rotator.
I just thought the stock focuser (albeit pretty poor) was easy to do this with the screw lock collar so just wondered if you could do the same by maybe loosening a lock screw on the dovetail, rotating and locking the grub screw again.

Steve

[Adreneline]

6 minutes ago, teoria_del_big_bang said:

is it easy to rotate this focusser

Sorry to jump in but in my experience it is not easy to rotate the focuser without loosening about eight tiny screws - you can see them in the photo below.

The much easier solution is to use a Baader Click-Lock.

This is my arrangement:

I chose not hang the EAF on the focuser spindle - I'd rather use a belt drive. I also find it easier if the EAF is on top as it gives plenty of clearance for the ASIair and TP-Link wifi extender.

HTH

Adrian

 

[teoria_del_big_bang]

1 minute ago, Adreneline said:

Sorry to jump in but in my experience it is not easy to rotate the focuser without loosening about eight tiny screws - you can see them in the photo below.

The much easier solution is to use a Baader Click-Lock.

This is my arrangement:

I chose not hang the EAF on the focuser spindle - I'd rather use a belt drive. I also find it easier if the EAF is on top as it gives plenty of clearance for the ASIair and TP-Link wifi extender.

HTH

Adrian

 

Oh of course it would, feel a bit silly now, of course that's a far better option.

Steve

[Clarkey]

22 hours ago, teoria_del_big_bang said:

Oh of course it would, feel a bit silly now, of course that's a far better option

Fwiw you can rotate the focuser which reduces the risk of introducing tilt. I put this on my RC8. Very good upgrade.

[johninderby]

Simple solution with the Steeltrack is to replace one of the grub screws in the M90 adaptor with a thumbscrew. Then easy to rotate by loosening the thumbscrew. Some people don’t seem to be aware you can do this.

[dweller25]

On 11/01/2022 at 13:41, fireballxl5 said:

Thanks @Len1257🙂

I'm not expert but I think they show that the edges of the field are out of focus when compared with the centre of the field (where focus was set). This is the main reason for the need of a flattener when using an APS-C sized sensor. In fact FLO have confirmed that a fours thirds sensor is best suited for use with the RC6.

Here's a crop of the target that I feel makes the most out of the image.

Looks awesome to me 👍