Does this look collimated

[Starman1115]

Hiya guys as the title says does this look collimated ? its my Skywatcher 150p iv just processed an image of m42 i took a few months back. It doesent look like we will be getting out anytime soon in the uk the weather is poop so thought id give my equipment a going over. Here is the image i took of M42 and a image through the collimation cap. 

[Ricochet]

I can't see enough reflections in your collimation cap picture to tell if it is correctly collimated or not but looking at the diffraction patterns around your stars I can immediately see that you need to baffle the edge of your primary mirror. The picture below shows the test baffle I made for mine (sorry, forgot to take a photo of the final baffle) on top of the mirror clips but other people have made narrower ones that sit under the mirror clips on the face of the mirror. To add the baffle requires taking the primary out so the telescope will require recollimation afterwards. My Bresser scope has small washers between the mirror clip and mirror cell. I don't know if the Skywatchers do as well but I would advise that each time you remove a screw you put a cocktail stick down into the hole to prevent any washers going walkabout. 

[happy-kat]

Is there some tilt, or something,  as well as the three wide defractions are not symmetrical?

[Sunshine]

Do the same photography with a de focused star at high power, nebula will not give you good indication of collimation and the shot through the cap will only give idea of a decent collimation to start with. Star test will be the end all of test.

achieve as close to this as you can and you’ll be fine 

[Pete Presland]

+1 for the star test, try to check mine every time I go out.

[Ricochet]

19 minutes ago, happy-kat said:

Is there some tilt, or something,  as well as the three wide defractions are not symmetrical?

As it is a 150p I suspect that the focuser draw tube is racked in far enough to intrude into the light path, hence the larger gap in the edge scatter diffraction. 

[Starman1115]

43 minutes ago, Ricochet said:

I can't see enough reflections in your collimation cap picture to tell if it is correctly collimated or not but looking at the diffraction patterns around your stars I can immediately see that you need to baffle the edge of your primary mirror. The picture below shows the test baffle I made for mine (sorry, forgot to take a photo of the final baffle) on top of the mirror clips but other people have made narrower ones that sit under the mirror clips on the face of the mirror. To add the baffle requires taking the primary out so the telescope will require recollimation afterwards. My Bresser scope has small washers between the mirror clip and mirror cell. I don't know if the Skywatchers do as well but I would advise that each time you remove a screw you put a cocktail stick down into the hole to prevent any washers going walkabout. 

Hiya , Im a complete begginner to the hobby and the thought of removing my primary is a little daunting.

[Starman1115]

42 minutes ago, happy-kat said:

Is there some tilt, or something,  as well as the three wide defractions are not symmetrical?

Hiya, Im really not sure im a complete begginer as i say so i dont know whats going on.

[Starman1115]

41 minutes ago, Sunshine said:

Do the same photography with a de focused star at high power, nebula will not give you good indication of collimation and the shot through the cap will only give idea of a decent collimation to start with. Star test will be the end all of test.

achieve as close to this as you can and you’ll be fine 

 

Hiya, This seems like a good place to start thank you. That is when we get some clear skys :-(

[Starman1115]

24 minutes ago, Ricochet said:

As it is a 150p I suspect that the focuser draw tube is racked in far enough to intrude into the light path, hence the larger gap in the edge scatter diffraction. 

Hiya, just had a look inside and the tube sticks through about an inch. Is it normal for it to stick through that much ?

[Ricochet]

35 minutes ago, Starman1115 said:

Hiya, just had a look inside and the tube sticks through about an inch. Is it normal for it to stick through that much ?

It just depends on where the point of focus is. With an eyepiece it probably doesn't stick through that much but a dslr needs more infocus. I'm not sure it's making much of a difference to your pictures other than blocking part of the edge that is scattering light around each star so I wouldn't really sorry about it unless one of the imagers have a good reason to make an alteration. 

[alacant]

Hi. Do you have a coma corrector? There is -I think- astigmatism.  The reflection is not correct for your telescope. It may help if you centred the secondary both in the tube and in the focuser first and then tweaked the primary using a star. Make sure it remains dead centre of the field of view. HTH.

[Sunshine]

Ignore the primary at first, look through your cap at the secondary, even though the secondary is oval in shape, it should look round as you look through the cap and that round appearing secondary should be fairly well centred within the edges of the focus tube itself. if that looks ok then now concentrate on the image of the primary within the secondary mirror, you should be able to see the mirror clips and the entire edge around the primary reflected in the secondary, then rack your focuser tube all the way in and out, keep an eye on the primary as you do this, the edges of the primary should remain visible while focussing in and out all the way. This means that the secondary is pointing at your primary which is what you want because it means the light your primary gathers is all going to make it to your secondary, id say enough with the secondary at that point.

 Is there a marked centre on your primary? like a small sticker? if so, that little marker is what you want to put smack in middle of the tiny dot you're seeing in the centre of the secondary which is actually the reflection of the underside of your cap, that tiny dot is where your eye is looking through.

your final adjustments will be the primary, loosen the primary lock screws/knobs and begin turning the adjustment screws/knobs one at a time quarter turns and watch how that little sticker is moving relative to the little dot smack in the centre of the secondary, if it moves away then reverse the turn, try other knobs and inch it closer to the target. Once centred you can be pretty sure the light path it pretty well aligned, the star test will reveal any misalignment in which case you'll ONLY NEED TO ADJUST THE PRIMARY!! do not!! mess with the secondary in the dark of night because you'll guaranteed be back to square one!

very important, collimation can be like a virus that infects your enjoyment, use the tips of everyone here and if you follow then you won't be far off, look through the scope, if objects like the moon and planets impress you and come to sharp focus with detail then STOP THERE, don't be consumed with collimation because its a battle you'll never win, every scope has inherent design flaws and imperfection which collimation will never correct. And, atmospheric conditions often wreak havoc with attempts to star test a scope, have a look, if you're blown away by what you see after you've done your best to collimate then you've won!!