Can't achieve focus with FLO's Sky-Watcher 9x50 Finder & ZWO ASI120MM-Mini Bundle

[Samibotss]

Hello There!

I'm reaching out to you all regarding a recent acquisition of an Auto-guiding bundle, which includes a Sky-Watcher 9x50 Finder scope & ZWO Asi 120MM with C adapter.

The problem is, I can't seem to achieve focus on the (I think?) standard configuration. I'm looking to try my hand at guiding purely with the camera at first (no EQMod/ EQDirect), but since the stars look blown out, so PHD2 can't lock down and track anything. I've included images of both what I see in PHD2, and how my camera is attached to the finderscope.

I'm just wondering, if I need to buy an extension or if I'm missing something in the way it's setup.

 

Any input is appreciated

- Sami N.

.

[Cornelius Varley]

Is this straight out of the box or have you attempted to change the focus by adjusting the front element of the finder ?

[GoldTop57]

Also is there a 1.25" extender included that you can screw into the front of the camera so it can sit further out of the scope?

[Samibotss]

1 hour ago, Cornelius Varley said:

Is this straight out of the box or have you attempted to change the focus by adjusting the front element of the finder ?

I have tried to adjust the front element, but there is little travel between the minimum and maximum positions. I'll retry tonight to see if I can get it to focus that way.

 

58 minutes ago, GoldTop57 said:

Also is there a 1.25" extender included that you can screw into the front of the camera so it can sit further out of the scope?

I have screwed an included extender already, although it is quite small ( you can see the separation between the camera's black ring and the extender on the photos)

[Clarkey]

I have used the C adaptor with the SW finder and 120 mini and it is fine. I did have to wind the focused right to the end of its travel, but it did work.

[Samibotss]

2 hours ago, Clarkey said:

I have used the C adaptor with the SW finder and 120 mini and it is fine. I did have to wind the focused right to the end of its travel, but it did work.

ok I see, thanks for the insight I'll try and reajust it

 

[Samibotss]

Well, I've completely pushed the focuser, and I think I've managed to fix the focusing issue. However, despite PHD2 finding a star, it doesn't seem to be guiding much. the crosshair is still brown, and since I'm guiding only with the camera, I can't do much in the of calibration. I can hear the mount seemingly trying to reajust when I turn on guiding, but I cant seem to push my exposure times beyond what I normally can achieve.

 

 

[michael8554]

The info in your screen grab is limited.

Despite a 3 second exposure, Signal to Noise SNR is only 4.0, the yellow figure in the toolbar indicates it's of concern to PHD2.

If you move the blue slider to the left the display would show the stars better.

And if you displayed the Star Profile (Tools - Star Profile) we could maybe tell if that's a hot pixel or not.

(Though you are using the PHD2 Darks)

"Cal" on the toolbar is red, indicating either that the Calibration failed, or maybe you haven't tried yet - you did press the green button to make PHD2 Cal, and then guide ?

Post your PHD2 GuideLog, such as it is, so we can check your settings.

Michael

[Samibotss]

On 14/08/2021 at 11:26, michael8554 said:

The info in your screen grab is limited.

Despite a 3 second exposure, Signal to Noise SNR is only 4.0, the yellow figure in the toolbar indicates it's of concern to PHD2.

If you move the blue slider to the left the display would show the stars better.

And if you displayed the Star Profile (Tools - Star Profile) we could maybe tell if that's a hot pixel or not.

(Though you are using the PHD2 Darks)

"Cal" on the toolbar is red, indicating either that the Calibration failed, or maybe you haven't tried yet - you did press the green button to make PHD2 Cal, and then guide ?

Post your PHD2 GuideLog, such as it is, so we can check your settings.

Michael

So, I've went out again last night, and despite having ajusted the focuser all the way, the stars still look blown out. I've tried doing the calibration by pressing the green button, but it doesn't seem to calibrate much.

Again, guiding on such blown out stars doesn't seem to be working out too well for me, I'm getting worse results than with no guiding

Archive.zip

I've attached my PHD2 logs above.

[michael8554]

Without even looking at your GuideLog, I know realise the huge blob in your Saturday image is not a globular cluster, but an out-of-focus star, and what I thought were the stars are hot pixels.

So you have not "fixed the problem", the focus is still way out.

Take off the guidecam and focus the sun onto a flat surface.

Roughly measure from the back of the scope to that point.

That's where the ZWO sensor has to be located, it's 8.5mm inside the front of the camera with no adapters mounted,

Michael

 

Edited August 16, 2021 by michael8554

[Samibotss]

1 hour ago, michael8554 said:

Without even looking at your GuideLog, I know realise the huge blob in your Saturday image is not a globular cluster, but an out-of-focus star, and what I thought were the stars are hot pixels.

So you have not "fixed the problem", the focus is still way out.

Take off the guidecam and focus the sun onto a flat surface.

Roughly measure from the back of the scope to that point.

That's where the ZWO sensor has to be located, it's 8.5mm inside the front of the camera with no adapters mounted,

Michael

 

I see. I'll try that and see what I get.

[Budgie1]

If you've screwed the front element in as far as it will go and you still can't get focus then you may have to try removing the front element locking ring.

Unscrew the front element and the locking ring, then screw just the front element back on to the finder. This will give you more thread and allow you to get the camera sensor and front element closer together. I had to do this on the same setup, but using the Celestron version of the 9x50. It does mean you can't lock the focus on the finder but it didn't seem to move that much when I was using it like this.

When you find focus, the stars will be pin point, you're still out of focus in that last PHD screen shot.

 

[Samibotss]

1 hour ago, Budgie1 said:

If you've screwed the front element in as far as it will go and you still can't get focus then you may have to try removing the front element locking ring.

Unscrew the front element and the locking ring, then screw just the front element back on to the finder. This will give you more thread and allow you to get the camera sensor and front element closer together. I had to do this on the same setup, but using the Celestron version of the 9x50. It does mean you can't lock the focus on the finder but it didn't seem to move that much when I was using it like this.

When you find focus, the stars will be pin point, you're still out of focus in that last PHD screen shot.

 

I'll definitely try this as well!

[jacko61]

According to the FLO website, your finderscope needs 18mm backfocus from the metal tube. As Michael stated above, the ASI120mm mini has 8.5mm from the sensor to the front of the fixed black ring so you need to add 9.5mm to that to get the correct backfocus. I also noticed a comment from one person on the FLo site that they had to remove the focus lock ring which was also mentioned above..

Sky-Watcher 9x50 Finderscope | First Light Optics

graeme

 

[Mctoot]

I use the ASI120mm with the stock finder scope that came with my 200P-DS. I have tried to measure from the back of the scope (tricky while trying to hold my phone with the other hand!). In this case the C- adapter is not completely flush with the back of the scope - I estimate its around one turn in.  I have not had remove the locking ring at the front of the scope to achieve focus . You can see from the EKOS guiding image that my stars are OK in the ASI120mm - I just managed to screenshot as the clouds rolled in - sorry (happy to provide a better shot when I next get out) Anyway - I hope this is useful/helps! 

 

[Samibotss]

On 23/08/2021 at 09:22, Mctoot said:

I use the ASI120mm with the stock finder scope that came with my 200P-DS. I have tried to measure from the back of the scope (tricky while trying to hold my phone with the other hand!). In this case the C- adapter is not completely flush with the back of the scope - I estimate its around one turn in.  I have not had remove the locking ring at the front of the scope to achieve focus . You can see from the EKOS guiding image that my stars are OK in the ASI120mm - I just managed to screenshot as the clouds rolled in - sorry (happy to provide a better shot when I next get out) Anyway - I hope this is useful/helps! 

 

 

On 17/08/2021 at 13:01, jacko61 said:

According to the FLO website, your finderscope needs 18mm backfocus from the metal tube. As Michael stated above, the ASI120mm mini has 8.5mm from the sensor to the front of the fixed black ring so you need to add 9.5mm to that to get the correct backfocus. I also noticed a comment from one person on the FLo site that they had to remove the focus lock ring which was also mentioned above..

Sky-Watcher 9x50 Finderscope | First Light Optics

graeme

 

 

On 16/08/2021 at 21:18, michael8554 said:

Without even looking at your GuideLog, I know realise the huge blob in your Saturday image is not a globular cluster, but an out-of-focus star, and what I thought were the stars are hot pixels.

So you have not "fixed the problem", the focus is still way out.

Take off the guidecam and focus the sun onto a flat surface.

Roughly measure from the back of the scope to that point.

That's where the ZWO sensor has to be located, it's 8.5mm inside the front of the camera with no adapters mounted,

Michael

 

Thank you all for the useful feedback

I've finally gotten clear skies & time to test it out, and indeed, I had to remove the locking ring. Ended up with sharp, pinpoint stars!

Guiding results are still abysmal, but I'm guessing it's because I'm missing a calibration to tell PHD2 where the scope is pointing, and I'm guiding on camera.

I'm gonna try EQMod Ascom guiding, to let PHD2 control the mount directly. I'm wondering if this will eliminate the need for a calibration, or the need for a recurring calibration?

[michael8554]

14 hours ago, Samibotss said:

I'm gonna try EQMod Ascom guiding, to let PHD2 control the mount directly. I'm wondering if this will eliminate the need for a calibration, or the need for a recurring calibration?

Pretty basic PHD2 questions, sounds like you've not read any of the PHD2 Help and How To guides available via the PHD2 Help menu.

Such as

https://openphdguiding.org/phd2-best-practices/

Also if you start using EQMOD, don't get caught out by the default ASCOM PulseGuide Setting of 0.1, up that to 0.5 or more:

 

[Samibotss]

10 minutes ago, michael8554 said:

Pretty basic PHD2 questions, sounds like you've not read any of the PHD2 Help and How To guides available via the PHD2 Help menu.

Such as

https://openphdguiding.org/phd2-best-practices/

Also if you start using EQMOD, don't get caught out by the default ASCOM PulseGuide Setting of 0.1, up that to 0.5 or more:

 

Indeed I have not, but I will now