Looking to get into planetary imaging

[scitmon]

As the title says, I'm thinking of getting into planetary/lunar imaging.  I have a severely underused Skymax 180 which I want to use, and I'm wondering if anyone can recommend any resource to get me started? Or perhaps answer some questions:

- what is best to capture videos to?  an onboard minipc or the asair? or just use a laptop? Which software is best?

- Is an autofocuser worth the money or can I get good focus manually?

- do I capture in EQ or AZ mode?

[vlaiv]

11 minutes ago, scitmon said:

what is best to capture videos to?  an onboard minipc or the asair? or just use a laptop? Which software is best?

Laptop with SSD and SharpCap

12 minutes ago, scitmon said:

- Is an autofocuser worth the money or can I get good focus manually?

No, it is not worth the money, use manual focus (and learn how to focus while looking at live stream on your laptop)

12 minutes ago, scitmon said:

do I capture in EQ or AZ mode?

Makes no difference - use one that is easier for you / feels more comfortable.

[scitmon]

Thanks for the responses @vlaiv

I was also wondering what the limiting factor tends to be when adding more focal length such as a barlow... I presume its the seeing conditions?  If so am I likely to be pushing it too far with 5400mm FL?  

[vlaiv]

1 minute ago, scitmon said:

Thanks for the responses @vlaiv

I was also wondering what the limiting factor tends to be when adding more focal length such as a barlow... I presume its the seeing conditions?  If so am I likely to be pushing it too far with 5400mm FL?  

No, seeing is for all intents and purposes "ignored" when doing lucky imaging. This is under assumption we are talking about lucky planetary imaging (which only makes sense).

What determines best focal length is pixel size. In fact - not focal length but F/ratio. You want to be between x4 and x5 pixel size in micrometers with your F/ratio.

Say you have 3.75um pixel size, then F/ratio to aim for is  4* 3.75 = 15, so F/15 and 5 * 3.75 = 18.75 so F/18.75

 

[scitmon]

Ok... so am I better off trying to match a camera to my scope, or matching my F Ratio to the best camera?

For example ZWO say their best planetary camera is a the 678MC with a pixel size of 2μm, am I better using this with a reducer? or x2 bin? 

Or go for something like ASI662MC which is a much closer match at 2.9μm?

Edited August 22, 2023 by scitmon

[vlaiv]

5 minutes ago, scitmon said:

Ok... so am I better off trying to match a camera to my scope, or matching my F Ratio to the best camera?

For example ZWO say their best planetary camera is a the 678MC with a pixel size of 2μm, am I better using this with a reducer? or x2 bin? 

Or go for something like ASI662MC which is a much closer match at 2.9μm?

If you are yet to get the camera - it's better to go with camera that will match your current scope.

You don't want to go overly small with your pixels to avoid binning. Binning is ok when doing solar or lunar (in particular if you do Ha, in which case - above x4-x5 rule changes to x3 rule as it uses longer wavelength of light with less resolution) because you have enough signal to swamp the read noise in short exposure.

Read noise is dominant factor in lucky imaging. You want to freeze the seeing - which means very short exposures - like 5ms or there about. In such short exposure planets don't give too much light (unlike Moon and the Sun) so read noise becomes an issue. For this reason you want low read noise camera and you want to avoid binning (as it increases read noise with CMOS sensors).

[scitmon]

the 662 looks like the leading candidate then, thank you for the advice!

[scitmon]

So I had my first planetary imaging run on the 24th and here is my result: https://www.astrobin.com/ed1uex/ 

I am pretty pleased with the result and a few things occurred to me on reflection:

• Getting the target in the fov was a big challenge.  I was hoping I could attempt plate solving but quickly realised that was a non starter with the skymax's very narrow fov.  My finder wasn't aligned so I had to rely on polar aligning, slewing to target and then doing a spiral search.  This was still not straight forward, and it just took time and perseverance to get it.  Other than aligning the finder in daytime before hand, any one have any tips with this?
• I did 10ms exposures for 90 seconds, based on a youtube video guide I was following, I defo want to try even shorter next time.  Any recommendations on settings welcome.
• I encountered a meridian limits mid session and could not find any options to flip with stellerium and/or EQMOD, I ended up disabling limits, is there any danger in doing this other than cable tangling?
• Will there be any benefit in using my 2x barlow next time?

 

Edited December 4, 2023 by scitmon

[bosun21]

I use a flip mirror in my 150 Maksutov which along with an accurately set finder makes placing the planet on the sensor easy enough. I use 5 - 7ms and a relatively small ROI to provide the highest possible frame rate which is around 200 FPS with an Asi585MC. I tried a 2x barlow and found that I received better results without it. 4-5 x pixel size for me came to f15 and the 150 is f12 which is much closer than using a barlow which would be f24. I myself have never had to do a meridian flip while capturing (at least not yet). Great first planetary image 👍.

Edited December 4, 2023 by bosun21

[Pete Presland]

15 hours ago, scitmon said:

 

Getting the target in the fov was a big challenge.  I was hoping I could attempt plate solving but quickly realised that was a non starter with the skymax's very narrow fov.  My finder wasn't aligned so I had to rely on polar aligning, slewing to target and then doing a spiral search.  This was still not straight forward, and it just took time and perseverance to get it.  Other than aligning the finder in daytime before hand, any one have any tips with this?

 

Once you have the finder aligned , use a long FL eyepiece to centre the planet.

Have the exposure setting very high, when you put the camera in to the telescope and you should see a large out of focus disc as you insert the camera.

You can then adjust position as required. The more you practice the easier it gets. Aligning the finder scope is an essential part of the scope set up, whatever you are doing.

10ms should be fine as long as the seeing is not too bad. It might be referred to as lucky imaging, but there is nothing lucky about planetary imaging.

 

[PeterCPC]

A Flip mirror is worth it's weight in gold. So much easier.

[PeterC65]

You could add a low cost camera to your finder and use this for plate solving.