Collimation mirrors

[Mark68]

Hi,

I have a basic skywatcher heritage 100p. 

I recently bought this eye piece

https://www.ebay.co.uk/itm/SVBONY-8-24mm-1-25-Zoom-Eyepiece-Multi-Coated-Lens-Astronomy-Telescope-Parts-/283934574144?_trksid=p2349624.m46890.l49292

But it seems even when I look at the moon it hasn't improved on when I used the standard eye pieces that came with the scope. 

I have seen about collimation the mirrors, but haven't a clue what this is or if I need to do it with my telescope. Any advice is much appreciated.

 

Thanks

[johninderby]

Here’s. basic bit on colimation that’s worth a read and it does have info on collimating the Heritage 100p with photos.

http://www.waloszek.de/astro_collimation_e.php

Edited February 20, 2021 by johninderby

[Spile]

I suspect that collimation of your mirrors (if needed or possible on your I00P ) is not going to improve the view of the moon with your new eyepiece. 

Try comparing the trapezium in Orion and splitting Castor with both eyepieces.

 

 

Edited February 21, 2021 by Spile

[Ricochet]

6 hours ago, Spile said:

Collimation of your mirrors (if needed) is not going to improve the view of the moon with your new eyepiece.

Generally speaking, this is not true. Good collimation is vital for high quality planetary and lunar viewing. 

On 20/02/2021 at 10:04, Mark68 said:

I have seen about collimation the mirrors, but haven't a clue what this is or if I need to do it with my telescope. Any advice is much appreciated.

What other lenses and barlows do you have? Assuming that you don't have any collimation tools then the best thing for you to do is to point your telescope at Polaris. Choose an eyepiece that is approximately equal to your focal ratio, or an eyepiece-barlow combination to simulate one. For your F4 scope, you want a 4mm eyepiece or you could use an 8mm eyepiece and a 2X barlow. Precisely centre Polaris in the field of view and defocus the image enough to make the diffraction rings more obvious. From the in focus position you will probably move your focuser perhaps a millimetre or two out of focus. Check that all the rings are concentric inside and outside of focus. If they are your collimation is fine. If the rings are not concentric and the inner rings are all squashed to one side of the largest ring then the collimation is out. Carefully move the star around the field of view and see if when the star is off centre in a certain direction the circles become concentric. If this does work then you will probably want to look at buying a cheshire and centre spotting the primary, if this is not already done.

However, the focuser on your telescope is not particularly sturdy and the weight of a heavy eyepiece such as your new zoom could cause the focuser to sag, which will throw the collimation off. Check how the collimation looks with both your zoom+barlow, and your 10mm+barlow (if you have one) and compare the differences. Some people have shimmed the drawtube of this kind of focuser to reduce the amount of flex when extended. If you find this is a problem for you then you might also want to investigate this option.

Additionally, as your telescope is F4 you will have both a high level of coma from the telescope, and also your eyepieces will have their own aberrations due to the steep light cone entering them. If you do all your planetary observing with a 2X barlow in the focuser, then from the perspective of the eyepiece the light cone is a much shallower F8, and eyepiece aberrations will be greatly reduced.

[Spile]

2 hours ago, Ricochet said:

Generally speaking, this is not true. Good collimation is vital for high quality planetary and lunar viewing. 

My wording was not very helpful so I have edited the original. I was attempting to suggest that the OP looked for reasons other than collimation for reasons described in the above link.