13 replies to this topic

[ChazS]

I am totally new to this. I purchased a Celestron Advanced VX 9.25in Schmidt-Cassegrain Telescope 12046. I had a bad AVX to start with (power socket broke inside housing). They replaced with a new one. In the few weeks I have learned how to level, balance and set up the scope properly. I can use the hand held controller or CPWI program with wifi to find planets or stars. So now that I can find stars and planets I have another issue.  I have black round dot in the center of every planet or star I look at. Also I thought planets like Jupiter would have color, but all I see is white round planet with a black round dot. I know this has to be something I have not set up correctly as it is happening with every planet or star we view. I appreciate any suggestion as I stated before I am totally new to this. This is a learning experience for me and my son and we have enjoyed everything to this point. 

[siriusandthepup]

Sounds like you are out of focus. That is what shows the black dot in the center. That is the shadow of the secondary mirror. It disappears in focus. You won't see anything out of focus. Try getting into focus on the Moon.

Edited by siriusandthepup, 27 January 2023 - 09:16 AM.

[Hikescdnrckys]

Agree with Sirius, you are out focus. Turn the focus knob on the scope in one direction, and you will notice the black dot getting bigger and bigger. We call this the donut. Is the donut pretty much in the center of the white light or off to one side? If in the center that is good, it means the scope's optics are at least roughly aligned (or collimated) and you will see sharp images with lots of detail. If not, the scope needs collimation and there are lots of good posts here and on YouTube on how to collimate.

 

Now turn the focus knob in the other direction and the black dot should get smaller and smaller until it disappears, which means you are in focus. If you keep turning in that same direction the black dot reappears and starts to get bigger again, you are once more out of focus. As Sirius says, start with the moon first, then move back to Jupiter. You should see at least some yellowish bands across Jupiter when in focus. 

 

Welcome to a fantastic hobby!

[Minuam]

I am totally new to this. I purchased a Celestron Advanced VX 9.25in Schmidt-Cassegrain Telescope 12046. I had a bad AVX to start with (power socket broke inside housing). They replaced with a new one. In the few weeks I have learned how to level, balance and set up the scope properly. I can use the hand held controller or CPWI program with wifi to find planets or stars. So now that I can find stars and planets I have another issue.  I have black round dot in the center of every planet or star I look at. Also I thought planets like Jupiter would have color, but all I see is white round planet with a black round dot. I know this has to be something I have not set up correctly as it is happening with every planet or star we view. I appreciate any suggestion as I stated before I am totally new to this. This is a learning experience for me and my son and we have enjoyed everything to this point. 

Welcome
Few days ago, when I looked at the Jupiter, I could not see the equatorial belts even though Jupiter was high at the meridian.
This is partly due to the fact that the observing is being done in winter and scope has not achieved the thermal equilibrium.
When I de-focused the star, I could see ants crawling all over the de-focused star.
It took 4 hours for the scope to get thermal equilibrium and then I could see trapezium clearly but the Jupiter was gone by then.
My 5” SLT took 4 hours so your scope might take even longer to achieve thermal equilibrium.
Next time, when you do observing, look at a bright star and de-focus all the way

and if you see ants crawling within concentric circles of the star then you have to wait for the observing.
You can also leave your scope outside as well much in advance for temperature equilibrium.
Good Luck

[ChazS]

Wow, thanks everyone for the quick replies. I appreciate it. I will try to focus tonight and see what happens. I am pretty sure I focused all the way and the dot just stayed there. Also if I am not centered on the star the dot is not either so it must be the center of the scope. Thanks again for all the help. I will let you all know if I am successful. I will start searching on collimation as well. 

[JOEinCO]

....I will start searching on collimation as well. 

 

Don't touch the collimation yet. It helps A LOT to have a good bit of experience with the scope before messing with the collimation. Patience is rewarded.  

 

Where are you located, generally speaking?

[rhetfield]

Wow, thanks everyone for the quick replies. I appreciate it. I will try to focus tonight and see what happens. I am pretty sure I focused all the way and the dot just stayed there. Also if I am not centered on the star the dot is not either so it must be the center of the scope. Thanks again for all the help. I will let you all know if I am successful. I will start searching on collimation as well. 

Does that scope have an extension tube or 90 degree diagonal.  If you are focused all the way in and the focus is still off, then you need to make sure the extension tube or 90 degree diagonal are installed.

 

Extension tubes exist on some scopes so that a camera can be installed - the camera needs the extension tube or diagonal removed to focus.  The eyepiece needs it in there to focus.  Also, some people will buy a better quality 90 degree diagonal than what often comes with a scope.

[vtornado]

I agree with focus issues.  The easiest thing to focus on is something terrestrial, because it doesn't move. Try during the daytime.  Water towers, far away tree tops, radio masts

are all good targets.  The farther away the better.  Use your lowest power eyepiece.

Once you have it sharp, wait until night, and use the same eyepiece.  Infinity

focus should be close to terrestrial focus.  If you use Jupiter, if the white spot

is getting larger you are going the wrong way.  The focus spot is the smallest image.

 

During terrestrial is the best time to align your finder with the main scope too.

 

This is an SCT no extension tubes are needed.  The SCT has a large range

of focus.  This is wonderful for attachments such as cameras and bino viewers,

where newts can struggle.

Edited by vtornado, 27 January 2023 - 11:04 AM.

[ChazS]

Don't touch the collimation yet. It helps A LOT to have a good bit of experience with the scope before messing with the collimation. Patience is rewarded.  

 

Where are you located, generally speaking?

Okay, I am on the York River in VA. I used a channel marker about 1/4 mile away to get the spotter scope aligned. I will try to find something further away and use 90 degree diagonal and lowest powered eyepiece to focus. So I have 25mm in the scope currently, will swap out to the 32mm correct? The higher "mm" number the lower the power of the eyepiece? Sorry still learning. 

 

Updated, I have done the above and image is clear in the scope. I think most were correct because it took a lot more turns to focus than I know I would have done at night.  Hopefully tonight we will be able to finally see some stars. I really do appreciate everyone's help, 

Edited by ChazS, 27 January 2023 - 03:38 PM.

[MinT]

Okay, I am on the York River in VA. I used a channel marker about 1/4 mile away to get the spotter scope aligned. I will try to find something further away and use 90 degree diagonal and lowest powered eyepiece to focus. So I have 25mm in the scope currently, will swap out to the 32mm correct? The higher "mm" number the lower the power of the eyepiece? Sorry still learning. I appreciate everyone's help

Your scope has a 2350mm focal length, so if you want to figure out magnifications, divide that number by your eyepiece focal length.  

 

So for example, your 25mm eyepiece gives you 2350/25 = 94x magnification, and your 32mm eyepiece gives 2350/32 = 73x magnification.  

 

A Barlow would change the scope's focal length, so if you have one of those, that's another way to change magnification.  

[aeajr]

Okay, I am on the York River in VA. I used a channel marker about 1/4 mile away to get the spotter scope aligned. I will try to find something further away and use 90 degree diagonal and lowest powered eyepiece to focus. So I have 25mm in the scope currently, will swap out to the 32mm correct? The higher "mm" number the lower the power of the eyepiece? Sorry still learning. I appreciate everyone's help

Welcome to the wonderful world of astronomy with lots and lots of things to learn.

 

The higher the number on the eyepiece the lower the power.  Best to start with your lowest power eyepiece, just so you can see more sky.  Once you have your target in view you can go to higher powers.  

 

I agree with others, that you sound like you are out of focus.   Stars should be pinpoints.   If you are looking at Jupiter, the image will get smaller and smaller as you focus until it comes into focus.  The moons of Jupiter will be visible and will be small and bright pinpoints that are brighter and a little larger than the surrounding stars.   

 

Jupiter at low power will be small at 73X and even 93X.  Eventually you will want eyepieces to take you to higher magnifications.  Your scope should be able to hit 175X easily on planets and most nights I would expect you can exceed 200X on planets on most nights.  Atmospheric conditions will be the limiting factor.  You should be able to hit or exceed 250X on the Moon. 

 

A 15 mm eyepiece will hit 156X

A 10 mm eyepiece will give you 235X

 

Which eyepieces?  Depends on your budget.  An eyepiece can cost $30 or it could cost $300+.  So consider your budget as you plan to add eyepieces. The article below may be helpful.

 

 

 

Understanding Telescope Eyepieces- There are recommendations, based on budget,

but the meat of the article is about understanding the considerations and specifications to know when selecting eyepieces.
https://telescopicwa...cope-eyepieces/

 

Understanding and using a Barlow Lens
https://telescopicwa...ens-and-how-to/

[GGK]

Okay, I am on the York River in VA. I used a channel marker about 1/4 mile away to get the spotter scope aligned. I will try to find something further away and use 90 degree diagonal and lowest powered eyepiece to focus. So I have 25mm in the scope currently, will swap out to the 32mm correct? The higher "mm" number the lower the power of the eyepiece? Sorry still learning. 

 

Updated, I have done the above and image is clear in the scope. I think most were correct because it took a lot more turns to focus than I know I would have done at night.  Hopefully tonight we will be able to finally see some stars. I really do appreciate everyone's help, 

Welcome to the hobby and to Cloudy Nights.

 

Close Focus - minimum distance to target that will reach focus - is around 60 feet on the C9.25 with the stock diagonal, so you should be able to focus on the marker 1/4 mile away with the diagonal installed.  It might take some patience to get the marker into the view because even with the 32mm Plossl (your widest field eyepiece right now), the true field of view, or TFoV, is about 0.66^o.  

 

Close focus is fully clockwise on the focus knob and infinity focus is fully counterclockwise.  It takes about 30 turns to get from one end to the other.  So if you focus on the mile market during the day, then take the scope out at night, you will be turning counterclockwise as you approach focus on a star.

 

It's a good check to verify you have the full focus turning range.  Sometimes a lump of grease makes it feel like you're at the end when you aren't.  The ends are hard stops.

 

Final comment right now is to always end the focusing action by turning the focus knob counterclockwise so the focuser is pushing the primary mirror up against gravity.  This prevents focus shift while observing.

 

All of this will be in your manual too.

 

Gary

[siriusandthepup]

Just a note on eyepieces. Your telescope is an F/10.

 

That's good! That means that it will perform extremely well with the simplest of eyepieces. Keep that in mind when you look to add to your eyepiece collection.

 

A simple and inexpensive Plossl will do a great job for you. Save your money for later for the exotic eyepieces. Don't get sucked into all the hype. Yeah I love the exotics too, but I've been doing it 60 years. I appreciate the basic eyepieces used in the right scopes. Don't even think of buying an expensive eyepiece during your first year.

[ChazS]

Well it worked great. My son and I were able to see Jupiter and its moons, Mars, and the Moon last night. Thanks to all for your help and suggestions.