How to focus my Celestron NexStar 6se

[Ned]

I’m struggling to focus my Celestron NexStar 6se. I tried to focus on the moon; it was a misty night and a full moon and all I could see was a white blur no matter where a turned the focus nob. Any tips on how to get it focusing properly? Am I doing it wrong or was it just a bad night for it?

[Stu]

19 minutes ago, Ned said:

I’m struggling to focus my Celestron NexStar 6se. I tried to focus on the moon; it was a misty night and a full moon and all I could see was a white blur no matter where a turned the focus nob. Any tips on how to get it focusing properly? Am I doing it wrong or was it just a bad night for it?

Even on a bad night you will see plenty of detail on the Moon. Some basic questions….. what eyepiece were you using? Start off with the lower power (likely 25mm) to get the target centred and in focus.

Are you sure you were on target?  Particularly on a misty might, the view will get pretty bright even with the Moon out of the field of view. My guess is that you didn’t actually get the Moon in the view, so worth checking your finder is aligned accurately.

[Ned]

Thanks for your help. We tried again on a less misty night and we were on target and our eyepiece is 25mm. We still couldn’t get any focus though. Any more suggestions would be appreciated.

 

[Stu]

Just now, Ned said:

Thanks for your help. We tried again on a less misty night and we were on target and our eyepiece is 25mm. We still couldn’t get any focus though. Any more suggestions would be appreciated.

 

Can you post a picture of the setup in case anything looks awry. Have you tried in daytime on a distant object?

[Ned]

No we have not tried in the daytime we have only tried at night and are having some difficulty. Here is a photo of it (it isn’t the greatest photo it was dark when we took

[Kimboman]

Hi to focus this telescope go right through one way until it will not go any further, then turn the focus the opposite way  and you will then notice the telescope start to focus .

This is due to the  focus goes through approx 30 odd turns to come to focus.

set your finder up in daylight an a distant tv Ariel or lamp standard then you should be ok

[Ned]

Hi thanks for your help. We have gone all the way there and back again and it’s isn’t focusing. Should I turn it all the way clockwise or anti clockwise first or does it matter? And how slow do I need to go?

[Peter_D]

I would make sure the front corrector plate had not dewed up - you don't have a  dew shield. This will happen pretty quickly in the winter, especially if the scope is being brought out from a warm house. SCTs are prone to this.

I use a proper dew shield. You can get one that fits the 6SE specifically. You can also make a homemade one using foam. You can also get heated dew straps.

HTH

PS Also check eyepieces and diagonal for dew. If any glass surface have dewed up, you will get a foggy view.

If it is dew, don't wipe if off. Leave your scope to dry in a cool place. Leave caps off front and back.

 

Edited December 21, 2021 by Peter_D

[Starwatcher2001]

I'd recommend you try during the daytime as Stu mentioned (makes it easier to see what you're doing, it's easier to find something to see, and you're less likely to have dew problems). Don't try focusing on something at the bottom of the garden though (unless you've got several acres), try rooftops and chimneys a 1/2 mile away or so. (Telescopes by design aren't designed to focus on close things).

Do take it from one end of the focuser to the other, it's a surprisingly long, long way.

If that doesn't work, loosen the eyepiece and move it outwards, even out of the holder, whilst looking through it. It can be tricky to keep it aligned but you might find a place it will focus. If that's the case, you may need an extension tube. But I'd be surprised if that's the case.

You could also try without the diagonal (just put the eyepiece in the tube). But again, I'd be surprised. From your photograph it looks like you've got it set up correctly.

 

Edited December 21, 2021 by Starwatcher2001
trypo

[Mick H]

To add what others have said, turn the focus knob slowly as you will easily miss if you go to fast.

[powerlord]

Yup don't try at night until you've done during day at something far away. When you get that working, count how many turns from full clockwise in it is. And note down. I don't know if your celestron needs an extension or not with visual, maybe others do, but if in daylight all way in and out still not bringing to focus, chances are maybe needs extension?

[RT65CB-SWL]

Hi @Ned and welcome to SGL. 

As others have said, the focus knob takes a lot of turns. 

One thing that no one seems to have suggested is, did it come from a warm room in the house? ...and how long did you leave it before viewing?

I give mine between 30-60 minutes, visual back pointing up to the sky. This allows any heat in the tube to escape, if it has been stored in the house, (or vehicle if attending a star party), and to acclimatise to the outside temperature before putting in an eyepiece.

When finished and everything indoors, setup indoors and leave caps off everything, (including eyepieces and accessories in a dish/draining rack), and corrector plate/secondary mirror at an angle pointing towards the floor, allowing any condensation/dew to run off; while I rest and sleep. Then pack away when I know everything is dry. 

[Cosmic Geoff]

A dew shield for a SCT should be regarded as standard equipment - not an accessory.

I have found that the easiest way to get a totally out of focus SCT into focus is to aim it at a really bright near-point light source, e.g. Jupiter or Sirius. You should see a grey donut.  Just wind the focus knob in the direction that makes the donut smaller and ultimately reduces it to a point of light (or small disk, in the case of a bright planet).

[bosun21]

I’m betting on the dew problem as when I take my 127 out into the cold from the warm house i let it cool down. However the body of my scope is wet with dew making a dew shield paramount. I find reaching focus is relatively easy, especially on the moon. Due to this i would look elsewhere.