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Improving a Skywatcher 150P / EQ3 - what order? :)


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Hi guys,

So I've got my 150p - had it out a couple of times, and while I'm very pleased with it, I obviously want to get the most I can out of it.

For reference, it's a 6" 750mm F5 newt.

My current issues are mainly:

* Sharpness of images - especially near the outer 1/3rd of the eyepieces - is this a result of the cheap supplied eyepieces or not so good collimation ?

* Focussing of images - things never look 'tack sharp' - not sure again if this is due to the EPs or collimation. A dual speed focuser would be nice but the low profile skywatcher one doesn't fit the 6" so we're into £300 quid moonlight territory - not something I want to contemplate just yet.. :icon_scratch:

* Magnification - I can get 75x with the supplied 10mm eyepiece but find myself using the supplied barlow quite a bit.

* Image wobble - the mount isn't the best - I have the legs partially extended. People have suggested plonking a house brick in the accessory tray or similar.

I plan to obtain the following pieces in order to hopefully tweak the scope a little and get the most out of it:

* A cheshire collimator

* An orion twistlock 2" to 1.5" EP adaptor (no point in getting nice EPs if I'm screwing metal bolts into them.. )

* A WO 6mm SPL or A WO 4mm UWAN EP - possibly both in time.

Any advice on the above would be gratefully received - not least which EP would be best for both planetary and some DSO observations - or if I'm jumping the gun buying more EPs so soon

Cheers :)

Edited by Nermal
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The eyepieces supplied will not be great, but it depends on what you can afford and what is available to you. There seems to copies of eyepieces around that if accurate copies are good value, problem is you have to spend your money to find out.

Should be able to get 150x magnification, basically the same as the diameter (in mm). If the eyepieces are not great then neither will the barlow be. Two poor bits of optics will give a very poor image.

Now to upset the reflector fraternity. Generally reflectors will give a "softer" image then a refractor. So "tack sharp" may not be realistic. Some reflectors will be sharp but there is probably a price difference to make you wince. Good optics means MONEY. Skywatchers are mass produced after all and suffer from the consequences. Also F/5 means it has to be more accurate and any inaccurancies will be magnified by the laws of reflection.

Image wobble is magnified by the scope magnification and it sounds as if you are looking for more magnification. So you will get more wobble as you up the magnification.

WO eyepieces have a good reputation and will be an improvement over the ones supplied, I am getting the SWAN's. Only suggestion I have here is to buy the cheaper one first. Less outlay if you don't like them. Think that SCS Astro do range of planetery eyepieces that may be worth looking at.

Won't say what to buy, it is your money so you spend it.

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To take your issues one at a time:

* Sharpness of images - especially near the outer 1/3rd of the eyepieces - is this a result of the cheap supplied eyepieces or not so good collimation ?

Most probably cheap eyepieces being used in a fast scope. At F/5 your scope is fast and more demanding on eyepieces with the results that you see. Cure = get some better quality eyepieces.

* Focussing of images - things never look 'tack sharp' - not sure again if this is due to the EPs or collimation. A dual speed focuser would be nice but the low profile skywatcher one doesn't fit the 6" so we're into £300 quid moonlight territory - not something I want to contemplate just yet.. :icon_scratch:

This sounds like collimation. Get a cheshire eyepiece and read Astro Baby's guide to collimation. No need for a new focusser.

* Magnification - I can get 75x with the supplied 10mm eyepiece but find myself using the supplied barlow quite a bit.

Your scope should be able to handle 200x reasonably comforably but you will need a 3.7mm eyepiece to get that. Alternatively you could get a decent 7mm and a better (than the one supplied) 2x barlow lens.

* Image wobble - the mount isn't the best - I have the legs partially extended. People have suggested plonking a house brick in the accessory tray or similar.

Make sure all the nuts and bolts on the mount are tight. Adding some weight to the centre of the tripod (sand bag on a rope ?) will help as well. If your tripod legs are aluminum then upgrade to ther steel leg tripods - the EQ5 one fits the EQ3-2 mount.

* I plan to obtain the following pieces in order to hopefully tweak the scope a little and get the most out of it:

* A cheshire collimator - good idea !

* An orion twistlock 2" to 1.5" EP adaptor (no point in getting nice EPs if I'm screwing metal bolts into them.. ) - or a cheaper compression ring adaptor at half the cost.

* A WO 6mm SPL or A WO 4mm UWAN EP - possibly both in time. - consider the TS Planetary HR's for £35-£50 each. The UWAN's are superb though ......

Hope that helps :)

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Thanks for the great replies guys - really helpful :)

If I were to save for a UWAN would I be better off getting just the 4mm or the 7mm and a barlow ?

I'll probably get the 6mm SPL (or look into the TS Planetary HRs) to start as this is within my price range already.

Can anyone recommend a compression ring adaptor - I've heard of people using WO ones but can't seem to find a stockist online.

Thanks again :icon_scratch:

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good quality eyepieces like those already mentioned will be a big improvement. consider buying second hand off this forum.

if you feel you will stay in the hobby then invest in good quality eyepieces as you can always keeps these if you sell a scope for eg a bigger aperture.

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I have the same scope and collimating it and buying some better eye pieces made a huge difference.

I also have a electronic focuser which helps with 'wobble'

Good to know - a cheshire, compression ring adapter and some nice EPs it is then.

Wish you hadn't shown me astroboot - I'm going to get in trouble! :)

Edited by Nermal
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