18 replies to this topic

[jamiejako]

 

A quick first attempt with my new Celestron Edge HD11 (0.7x).

 

Shot on ASI2600MC Duo mounted on the ZWO AM5N, photo of the rig added below.

 

Only 60 x 1min subs on Bin2, I started getting elongated stars after meridian flip - I assume because of mirror flop, so I stopped early.

 

Way too close to the payload limit at 18.5kg, but guiding was decent at around 0.7-0.9".

 

Stacked (drizzle 2x) and processed in Pixinsight.

 

I also added some minor quality of life improvements for my ASIAir:

 

1. The GLinet Slate 7 WiFi router which connects via LAN to the Air, and extends my home network. File transfer speeds have gone up from 5-8mbps to 30mbps, and I see images on my iPad almost immediately after shooting them.

 

2. A Samsung T7 SSD connected to the Air, didn't see any change in write speeds, but makes offloading files to my PC lightning fast at 500mbps, and don't have to bother with powering on the Air.

 

[pyrasanth]

A good first light.

 

The issues around mirror flop sadly will continue to be a concern. It makes everything a bit more difficult as locking the mirror makes automated focusing impossible.

 

When you get a bit more comfortable with your setup and your feeling financially able I would invest in the Optec SMFS. This will allow you to lock the primary mirror and focus using the secondary mirror which is fitted into a very precise (0.2 micrometer step) focusing motor controlled through ASCOM focusing plus its own software package if desired. This was a game changer for me on my C14- ultra fine focusing with a locked mirror- one less thing to worry about.

 

The mount, being close to capacity, may be a more important upgrade depending on budget- welcome to the Celestron SCT money pit!

Edited by pyrasanth, 29 April 2025 - 07:58 AM.

[lucutes]

Nice shot. Better than I did when I first got my C11HD.

 

A good first light.

 

The issues around mirror flop sadly will continue to be a concern. It makes everything a bit more difficult as locking the mirror makes automated focusing impossible.

 

When you get a bit more comfortable with your setup and your feeling financially able I would invest in the Optec SMFS. This will allow you to lock the primary mirror and focus using the secondary mirror which is fitted into a very precise (0.2 micrometer step) focusing motor controlled through ASCOM focusing plus its own software package if desired. This was a game changer for me on my C14- ultra fine focusing with a locked mirror- one less thing to worry about.

 

The mount, being close to capacity, may be a more important upgrade depending on budget- welcome to the Celestron SCT money pit!

To follow up. I like ASIAIR and I currently use the 174 on the V2-OAG. I only recently found out about this Optec device but that would make ASIair useless. Maybe I should get in the habit of refocusing with the EAF and then locking the mirror down. 

[jamiejako]

A good first light.

 

The issues around mirror flop sadly will continue to be a concern. It makes everything a bit more difficult as locking the mirror makes automated focusing impossible.

 

When you get a bit more comfortable with your setup and your feeling financially able I would invest in the Optec SMFS. This will allow you to lock the primary mirror and focus using the secondary mirror which is fitted into a very precise (0.2 micrometer step) focusing motor controlled through ASCOM focusing plus its own software package if desired. This was a game changer for me on my C14- ultra fine focusing with a locked mirror- one less thing to worry about.

 

The mount, being close to capacity, may be a more important upgrade depending on budget- welcome to the Celestron SCT money pit!

 

Thank you for your insights, both here and on my EAF issue post.

 

I will look into the Optec, but as lucutes said I do like the ease of using the ASIAir, and often take my rig when I go camping to lower Bortle sites. I saw cheaper external focusers like the Baader Steeltrack that go directly on the imaging train getting recommended in some threads, where the primary is locked after rough focus, and the EAF runs on the external focuser. I am planning to try this out as a first step.

 

I'm also looking at a new mount, the iOptron HAE69C is on the top of my list unless ZWO decides to launch the AM7.

[choward94002]

...

 

Only 60 x 1min subs on Bin2, I started getting elongated stars after meridian flip - I assume because of mirror flop, so I stopped early.

 

Way too close to the payload limit at 18.5kg, but guiding was decent at around 0.7-0.9".

 

...

 

 

Regarding the mirror flop, which happened at the meridian flip ... just don't do that

 

I have been using my rigs in an East only/ West only configuration for years (collimate inclined one direction, use green tape to indicate direction, image only in that direction) and it has solved a lot of problems ...

 

- Since there's nothing to cause the mirror to flop in the baffle tube, it doesn't ... use the focuser to lock it in one direction, done

- With no meridian flip, there are no cables to get wound up and so cable management is much, much easier

- With the tube not being shaken like a snow globe in the meridian flip, the flats are much more stable ... floating dust motes that have settled stay settled

- Since I'm not slewing the scope like an anti-aircraft turret doing the meridian flip, the drive motors have much less load on them and last much, much longer ... they really like a nice sedate 5'/sec slew, not a 10deg/sec slew

- Since the scope tube is spending all of it's time in one basic orientation, making limit switches is far easier ... I have four mercury switches inline to the driver motor power supply, if the tube goes more than 45deg away from zenith in dec or RA on the "good" side, more than 10deg away from zenith on the "bad" side the appropriate mercury switch disconnects the power and a runaway slew is stopped ... doesn't get more foolproof than that

- Since the imaging train isn't getting tossed around like a rag in the laundry machine, tilt errors are much less common and much easier to handle ... with a meridian flip when the imaging train is flopped around (think a mop handle in a paper towel tube) I would usually get tilt errors after a flip due to the imaging train being resettled and changing the weight characteristics (because with an OAG or filter wheel the weight distribution will change).  Keeping one orientation allows me to adjust the imaging train so that the offset weight is always "down", meaning once a tilt adjustment is made that's it

- I use a dew shield for the scopes, which extends about another 3ft beyond the end of the SCT, if there was a meridian flip that shield would need to clear the ground (or the pier, or something else) meaning I would need to make a pier 4ft off the ground for clearance, plus 2ft for the mount making servicing the scope a ladder affair ... without the meridian flip, the pier only needs to be high enough for the imaging train to have room, which for my gear is 1.5ft, plus 2ft for the mount means I can do servicing while comfortably standing

 

... just a thought ...

Edited by choward94002, 29 April 2025 - 11:24 AM.

[pyrasanth]

Thank you for your insights, both here and on my EAF issue post.

 

I will look into the Optec, but as lucutes said I do like the ease of using the ASIAir, and often take my rig when I go camping to lower Bortle sites. I saw cheaper external focusers like the Baader Steeltrack that go directly on the imaging train getting recommended in some threads, where the primary is locked after rough focus, and the EAF runs on the external focuser. I am planning to try this out as a first step.

 

I'm also looking at a new mount, the iOptron HAE69C is on the top of my list unless ZWO decides to launch the AM7.

There are certainly options- I suggested one of many. The other limitation to consider will be back focus-you need to be at 146 mm to your camera sensor, you have 5 mm either way to be optimal. There is a lot of head scratching & trying things out.

[Wjeremy 15]

I use a zwo eaf compatible short focuser in the imaging train and it works well. The key is the short focuser, unfortunately the GSO SCT focusers,which are good quality, are too long. I use a star trip from Ali Express which works great but with the tariffs not sure if that would still be a good price.

Setting the right backspace is straight forward. Just set the focuser at 91 mm length (same length as the Celestron t adapter), attach the image train with standard 55 mm backspace, and bring the system to focus with the native focuser knob. Lock the mirror then you can use the ear for fine focusing and it should be within a couple of mm of the 146 mm backspace.

Also, FYI I'm using the C11 edge on an AM5 mount with counterweight and it works fine.

[jamiejako]

I use a zwo eaf compatible short focuser in the imaging train and it works well. The key is the short focuser, unfortunately the GSO SCT focusers,which are good quality, are too long. I use a star trip from Ali Express which works great but with the tariffs not sure if that would still be a good price.

Setting the right backspace is straight forward. Just set the focuser at 91 mm length (same length as the Celestron t adapter), attach the image train with standard 55 mm backspace, and bring the system to focus with the native focuser knob. Lock the mirror then you can use the ear for fine focusing and it should be within a couple of mm of the 146 mm backspace.

Also, FYI I'm using the C11 edge on an AM5 mount with counterweight and it works fine.

 

Awesome, good to know it works! Just to check, is this the Star Trip? 

 

https://a.aliexpress.com/_oCaa05r

 

A few questions since you have it:

 

- The description mentions it is 40mm with 35mm travel. Do you add spacers for the remaining 16mm (or more since there needs to be travel) to hit 91mm before the image train?

- Do you need any adapters to attach the EAF?

- How do you deal with filters changing the focus? When you change the filter, do you unlock the mirror, refocus, and lock again? 

[Wjeremy 15]

Exactly that focuser. It's handy because they make bases for it to use with SCT, Newtonian and other scope types. Just make sure you get the SCT base, fits the C11 out of the box.

1. The base adds extra spacing of something like 45 mm, so the total focuser length ends up being 85-88 mm. I just rack out the focuser the extra 3-5 mm to get 91 mm and lock it, add the imaging train and then bring the system to focus with the C11 focuser knob. Then you should be at the correct backspace.

2. No that focuser is eaf compatible

3. Use autofocus with eaf. The mirrors stay locked and the C11 focuser stays put. It only adjusts the inline focuser.

[miahal]

With EAF, just make sure the setting to refocus after the flip is on. Problem solved!

[jamiejako]

With EAF, just make sure the setting to refocus after the flip is on. Problem solved!

 

I do have it turned on, but I was getting elongated stars after the EAF routine finished. I have all of the EAF settings to run auto AF turned on - every 1h, every 1° temp change, before new target, before new filter, and after meridian flip. I believe the process of the flip introduces tilt in the primary mirror since it is left unlocked for the EAF. In the interim I think I will try locking the mirror before the flip to see if it improves anything, and also try the external focuser approach.

[lucutes]

Exactly that focuser. It's handy because they make bases for it to use with SCT, Newtonian and other scope types. Just make sure you get the SCT base, fits the C11 out of the box.

1. The base adds extra spacing of something like 45 mm, so the total focuser length ends up being 85-88 mm. I just rack out the focuser the extra 3-5 mm to get 91 mm and lock it, add the imaging train and then bring the system to focus with the C11 focuser knob. Then you should be at the correct backspace.

2. No that focuser is eaf compatible

3. Use autofocus with eaf. The mirrors stay locked and the C11 focuser stays put. It only adjusts the inline focuser.

There was two versions I saw for SCTs. One had a bigger thread for full frame cameras and the other for SCT. Can I still use my Celestron OAG? Do you have a picture of this in action?

https://www.aliexpre...4409529951.html

[miahal]

I do have it turned on, but I was getting elongated stars after the EAF routine finished. I have all of the EAF settings to run auto AF turned on - every 1h, every 1° temp change, before new target, before new filter, and after meridian flip. I believe the process of the flip introduces tilt in the primary mirror since it is left unlocked for the EAF. In the interim I think I will try locking the mirror before the flip to see if it improves anything, and also try the external focuser approach.

It looks like ioptron has released a new focuser. Looks promising, I am planning ot use it myself.

 

https://www.highpoin...h-2-visual-back

[Wjeremy 15]

lucutes, on 04 May 2025 - 11:38 AM, said:

There was two versions I saw for SCTs. One had a bigger thread for full frame cameras and the other for SCT. Can I still use my Celestron OAG? Do you have a picture of this in action?
https://www.aliexpre...4409529951.html

I forget which thread size I have, I think it might be the 54 mm. I would pull it off my imaging train and look but I'm in between capture sessions and I want to use the same flats for both, sorry.

See image attached. I use an imaging train with a standard 55 mm backspace. In my case it includes a zwo oagl off axis guider and filter wheel. With a Star Trip focuser and SCT base, the focuser needs to be racked out three more millimeters to reach the 146 mm suggested back focus for the C11 Edge HD.

Whether or not you can use a Celestron oag depends on what else is in your imaging train. You have 55 mm to use up.

Attached Thumbnails

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[jamiejako]

I use an imaging train with a standard 55 mm backspace. In my case it includes a zwo oagl off axis guider and filter wheel. With a Star Trip focuser and SCT base, the focuser needs to be racked out three more millimeters to reach the 146 mm suggested back focus for the C11 Edge HD.

Whether or not you can use a Celestron oag depends on what else is in your imaging train. You have 55 mm to use up.

 

Does the StarTrip have a rotator? If not, since there is no backspace left to add a rotator, do you not do multi-night sessions of the same target?

 

The Baader Steeltrack seems to have a built-in rotator. 

[Wjeremy 15]

Does the StarTrip have a rotator? If not, since there is no backspace left to add a rotator, do you not do multi-night sessions of the same target?

The Baader Steeltrack seems to have a built-in rotator.

No rotator. Image train attachment is with three compression screws so you can rotate manually.

I do multiple nights on the same target. Usually I leave everything attached between sessions, but if I were adding data to an old acquisition for example I would just rotate it manually to get the same framing.

Edited by Wjeremy 15, 06 May 2025 - 02:01 AM.

[lucutes]

It looks like ioptron has released a new focuser. Looks promising, I am planning ot use it myself.

 

https://www.highpoin...h-2-visual-back

Does that work with ASIAIR?

[jamiejako]

Adding an update to this thread since I got multiple inputs on focusing and tilt:

From digging through old threads and talking to other C11 owners, I got an excellent piece of advice to solve for tilt: finish focusing counter-clockwise.

This is also mentioned in the Celestron user manual: 
 

 

 

Critical focusing is best accomplished when the focusing knob is turned in such a manner that the mirror moves against the pull of gravity. In doing so, any mirror shift is minimized. For astronomical observing, both visually and photographically, this is done by turning the focus knob counterclockwise.

 

I ran a few tests on M3 last night:

1. Before (elongated stars):

 

This is right after finishing the EAF routine after the scope slewed to M3. I left the mirror locks unlocked for the AF to run. My EAF routine was finishing counter-clockwise, but I was still seeing elongated stars.

 

2. After (round stars):

 

At this point, I ran 2 coarse steps up and 2 back down to force finish counter-clockwise - I heard the cling sound as I was doing this - which I assume made the mirror settle. I ran another AF routine for good measure, and suddenly got nice and round stars.

 

3. Final M3 image:

 

This is 60 x 120s subs, with the first half before meridian flip right after I got the image from above. After the flip, I saw the elongated stars came back, so I repeated the same routine to finish counter-clockwise and the rest of my subs were good.

----

 

I will probably get an external focuser like the Baader Steeltrack to mitigate this issue, but I have atleast found a reliable way to solve for tilt now. I also think finishing focus counter-clockwise would still apply for getting rough focus when using an external focuser too.

[astroian]

Another focusing option for you: the TCF-LEO low profile focuser from Optec. I use it on my HD11: it works a treat.

Cheers,
Ian