QHY5L-II and OAG

[astrosathya]

Hi everyone,

I would like to use my QHY5L-II with my OAG. However, it seems like even at 2x Binning its not able to see stars. I've used Dark library, but no use even then

Any help will be appreciated.

[Dr_Ju_ju]

is it able to focus on any stars ??

[Davey-T]

What scope are you using it on ?

Dave

[astrosathya]

29 minutes ago, Dr_Ju_ju said:

is it able to focus on any stars ??

yes, only when I point the scope at a star rich FoV like a cluster or a huge nebula etc. I also use the same camera as a finderguider most times.

[astrosathya]

27 minutes ago, Davey-T said:

What scope are you using it on ?

Dave

GSO RC6 1350 FL.

[michael8554]

Hi Sathya

You need to set up a planetarium with Field of View frames like this:

 

Then you can plan how you frame your target so that some guide stars are in the guidecam FOV.

This shows two positions for the prism, the one on the long side of the main camera could be moved in to touch the edge of frame.

Michael

[astrosathya]

5 hours ago, michael8554 said:

Hi Sathya

You need to set up a planetarium with Field of View frames like this:

 

Then you can plan how you frame your target so that some guide stars are in the guidecam FOV.

This shows two positions for the prism, the one on the long side of the main camera could be moved in to touch the edge of frame.

Michael

That's a Brilliant idea Michael. I never thought about it maybe because the filter wheel of my camera is offset (plus heavy) and may affect the balance of the scope. But I will try this. By the way, I use stellatium to check FoV of my main camera, but please may I know what software have you taken the screenshot from?

[RyanParle]

8 hours ago, astrosathya said:

That's a Brilliant idea Michael. I never thought about it maybe because the filter wheel of my camera is offset (plus heavy) and may affect the balance of the scope. But I will try this. By the way, I use stellatium to check FoV of my main camera, but please may I know what software have you taken the screenshot from?

That looks like "The Sky 6" to me

[michael8554]

Found this online:

"Stellarium has this feature: Under the Oculars Plug-in, under the Sensors tab in Stellarium, you can specify the parameters for an off-axis guider. See https://photographingspace.com/stellarium-fov/ ."

 

10 hours ago, astrosathya said:

That's a Brilliant idea Michael. I never thought about it maybe because the filter wheel of my camera is offset (plus heavy) and may affect the balance of the scope.

I don't see how the planetarium impacts on scope balance...?

Michael

[RyanParle]

3 hours ago, michael8554 said:

Found this online:

"Stellarium has this feature: Under the Oculars Plug-in, under the Sensors tab in Stellarium, you can specify the parameters for an off-axis guider. See https://photographingspace.com/stellarium-fov/ ."

 

I don't see how the planetarium impacts on scope balance...?

Michael

I think @astrosathya was saying he was concerned that rotating his camera / oag might upset the balance of the scope. 

[astrosathya]

On 18/05/2020 at 00:44, RyanParle said:

I think @astrosathya was saying he was concerned that rotating his camera / oag might upset the balance of the scope. 

this is correct, because of the filter wheel.

[SimM]

On 17/05/2020 at 00:25, michael8554 said:

 

Then you can plan how you frame your target so that some guide stars are in the guidecam FOV.

You can use this two ways:

1. Establish how high your prism is above the main sensor (using plate solving);

2. See if your OAG is compatible e.g. with your Reducer.

Question: can you align the two sensors together? The prism has a bigger dimensions than most guide camera sensors. Some clearance has to be provided so that off-axis light e.g. from a Reducer is not to be cut-off (vignette) the main image. Like a cone of light F/4 or F/10, how much this affects the main sensor is also a function of how much back focus (BF) is behind the prism.

In the example shown, this shows two sensors. The prism on an OAG is usually square and bigger than the guide camera sensor. At 50mm (typically) in front of the guide camera, the prism appears at least 50% wider. So if the sensor was aligned as shown, the “shadow” of the prism  would be much bigger even before you consider how it looks off-axis.

In the diagram, if both sensors were rotated 90 degrees, would that represent what the guide camera sees with a minimally acceptable separation from the main sensor?

Simon

Edited June 2, 2020 by SimM