Lunar imaging issues - have I got the basics wrong somewhere?

[Fraser G]

Hi, I am a total beginner and am just starting out in astrophotography. I've got the basic equipment - Celestron LCM114, a new to me Canon 650D and a variety of lenses. I have the telescope connected to PC via Wifi, and the camera connected for live viewing on the PC via USB cable (with 2 good quality USB extension cables, does that affect anything?). I'm not experienced with a DSLR either, just started learning how to use it. I took some images of the moon yesterday evening - not full dark - and they are not half as pin-sharp as I would like. I'm probably struggling with a variety of issues so any guidance would be wonderful, thanks! 

I have done my best to collimate the scope, using a laser collimator. The image of the secondary mirror centre spot properly aligns on the target dial, but there is a lot of "splash" around dial - does this suggest more work is needed here?

When taking images (the scope was not tracking as I didn't have long and there wasn't time to align it), I used a variety of ISOs and shutter speeds to test different settings (seeing as I have the most basic grip on my DSLR I am bumbling about a lot). However despite spending a while trying to get the focus spot on, and using different camera settings, on even the best images I am getting a lot of rainbow colours around the edges of craters, as well as fairly blurry edges. I've added a picture so you can see what I am on about.

What are the key things I need to focus on (ha!) to improve things? Many thanks in advance, and sorry if I'm posting in the wrong place. 

IMG_0039.CR2

[Fraser G]

Oh dear, I wish I'd taken a good look on this forum before I bought that LCM114 a few years ago. "Bit of a turd" seems to be a consensus view

Am I wasting my time with it?

[ONIKKINEN]

Had to look the scope up, but seems like the scope is a repackaged and remarketed powerseeker 114, which is one of the worst value scopes money can buy (for a lot of people). The powerseeker name is so radioactive it seems Celestron in their deviousness has come up with alternative naming schemes for it...

[vlaiv]

Something is quite strange with that image.

Despite it maybe not being the best scope out there - I'm certain that it can produce better images of the moon.

How exactly did you setup your scope and camera to take the image. There are several ways this can be done:

1. Telescope + eyepiece + some sort of adapter to attach the camera + camera with lens

2. Telescope + eyepiece + some sort of adapter + camera without the lens

3. Telescope + barlow lens + camera without the lens (adapter is simple T2 ring in this case)

4. Telescope + camera without any additional optics (again just T2 ring)

Fourth way is the best as it places the least additional optics between the telescope and camera - and telescope itself acts as a giant lens for camera. Problem is that with this model - you probably can't reach the focus that way - which is why most people go with option 3. Barlow lens pushes focus point further out - and you can reach the focus that way. Additional benefit is that it makes Lunar image larger.

If you can, set it up like that for lunar shots.

Then it is down to optimizing your conditions.

- Use very short exposure length with higher ISO setting. Ideally - you want exposure to be something like few milliseconds (use manual settings for your camera).

- Wait for moon to be high up in the sky. Lower it is - more susceptible it is too seeing disturbances

- Wait for scope to properly cool to ambient temperature.

- don't aim over larger objects that accumulate heat during the day - like houses or roads or parking lots or even big bodies of water - lakes, ponds, swamps. Ideally, you want to have a field or forest on the ground in direction where you aim your scope.

Even if you take all precautions - sometimes atmosphere just want play ball and seeing will be poor. You won't be able to get good image in such conditions.

As far as color issues - that is due to some optics element - like eyepiece or camera lens. Not sure what you have been using - that is why I asked about configuration.

[Steve Ward]

10 minutes ago, vlaiv said:

10 minutes ago, vlaiv said:

As far as color issues - that is due to some optics element - like eyepiece or camera lens. Not sure what you have been using - that is why I asked about configuration.

I'm pretty sure that's a Bird-Jones design with a built in Barlow giving the nasty CA . A  renamed Powerseeker 114eq.

 

[vlaiv]

3 minutes ago, Steve Ward said:

I'm pretty sure that's a Bird-Jones design with a built in Barlow giving the nasty CA . A  renamed Powerseeker 114eq.

Oh, right.

I thought it was simple 114/500 newtonian.

[Fraser G]

Thanks, everyone; @vlaiv, I am using option (2) - I tried (4) but couldn't get any focus and don't have any extension tubes, which I have heard may be needed.

Thanks for the other tips, I'll try them next time I get a chance. The moon's getting higher at the moment so hopefully a few more nights and I'll get a better environment for round #2! 

[vlaiv]

3 hours ago, Fraser G said:

Thanks, everyone; @vlaiv, I am using option (2) - I tried (4) but couldn't get any focus and don't have any extension tubes, which I have heard may be needed.

In that case - it might be a better option to try #1.

Use your low power eyepiece instead of high power EP - it is probably going to be better corrected.

[Fraser G]

Thanks again, Vlaiv. Not sure how I can try option 1 - need to check into this to see how to attach with the lens (another adapter I guess). 

Although I am now thinking of looking for a better scope (OTA) and attaching it to my existing goto mount - limited funds mean a new scope and mount are out of reach, but maybe I could afford just the scope... 

I will be joining a local astro society soon, so looking at things realistically - I will take what equipment I have to the next meeting and see what the members have to say/advise on. I might just stick with what I've got - poor as I suppose it's turned out to be - and learn from them while saving for something worthwhile.

Really appreciate the responses.  

Edited May 27, 2023 by Fraser G