unable to get focused

[joelkujala]

need some advice on getting my 10" starwatcher dob focused , i have collimated it using a non laser coll and get sharp focus on the moon but anything further wont sharpen i have just bought a vixen 5mm but it wont focus , would laser coll be better and is it likely that the coll is the problem?
all advise is greatly appreciated .

[PCH (Paul)]

If your EP is currently set as far as it will go into the focuser, then try setting it further out and adjust the focus control from one extreme to the other. If still no joy, it would appear that collimation is probably out.

Cheers

[Zuts]

Originally Posted by joelkujala

need some advice on getting my 10" starwatcher dob focused , i have collimated it using a non laser coll and get sharp focus on the moon but anything further wont sharpen i have just bought a vixen 5mm but it wont focus , would laser coll be better and is it likely that the coll is the problem?
all advise is greatly appreciated .

Hi,

The moon is effectively at infinity, so if you can focus on the moon then you can focus on anything. In fact after focussing on the moon you should not have to change the focus.

So, if you are not getting nice sharp stars then maybe your collimation is still out. You should do a star test to check it.

remember your 10 inch likely has a focal length of 1250mm so a 5 mm eyepiece will give you a mag of 250, which is quite high if the seeing is not very good.

Most things dont require this mag, except for planets and the moon, galaxies and planetary nebula in good seeing conditions.


Paul

[mark3d]

as mentioned below you may need to just put the eyepiece not quite all the way in... i have to do that with one of mine.. i have to leave it out about 1cm

[Solanum]

Originally Posted by joelkujala

need some advice on getting my 10" starwatcher dob focused , i have collimated it using a non laser coll and get sharp focus on the moon but anything further wont sharpen i have just bought a vixen 5mm but it wont focus , would laser coll be better and is it likely that the coll is the problem?
all advise is greatly appreciated .

Your 5 mm EP is pretty high magnification in your scope and it may be that you have focus but the seeing is too poor for that magnification (240x at a guess). With my 10" I find that about 50% of nights the seeing is too poor for 200x magnification to show any more detail than say 130x and that on a bad night the view with 200x is WORSE than 130x. The moon is very bright and although if the seeing isn't good you won't see any more detail at 200x than 130x (for example) you'll still see some, whereas stars will look very blurred and won't look like points. Have a look at very faint stars (say mag 10 and below), do they still look out of focus, or do they look more like points?