Focussing with / without barlow

[1 of 5]

150pl with 10mm eyepiece.

Without the 2x barlow focussing is nice and easy with a slow transition between clear and blurred. With the barlow obtaining a good focus is much harder. Is this solely a function of the higher mag (ie would it be the same with a 5mm eyepiece) or is it specific to the barlow? It doesn't help that any contact with the scope on an eq3-2 results in considerable shake making focussing a matter of adjust slightly and wait, check and reapeat.

[Adamski]

Hello, Ive got the same scope and every time i increase mag i have to slowly wind the focus out a bit. with a 5mm ep you wouldn't be able to see anything cos the mag is too high for the scope. Also you might need to collimate. I think the highest mag ep would be 8mm,

Adamski

[John]

The 150PL is a little undermounted on the EQ3-2 mount I reckon so it's not surprising that you get vibrations when trying to view at 240x. You technique is probably the best to use though. As Adamski says, 240x is too much magnification much of the time - I'm finding 200x too much with my 10" newtonian tonight (due to seeing conditions) so I've dropped back to 150x which has improved the view of Saturn somewhat.

[Andy79]

150pl with 10mm eyepiece.

It doesn't help that any contact with the scope on an eq3-2 results in considerable shake making focussing a matter of adjust slightly and wait, check and reapeat.

Im with you on that

[chemtom24]

the barlow will make focussing a little trickier, and make the focus 'area' smaller (the amount of adjustment on the focus wheels). high mag will also make vibrations on the scope much more noticable, so you may have to adjust, wait, adjust, wait etc, until you decide its focussed.

as some have said your mag is too high for your scope i feel i should add this -

( i assume form a quick google that ur FL is 1200)

I had an astromaster 130eq, 650mm FL, 130mm primary. max mag by numbers is 50x per sq inch, = 50 x 5 = 250x

i had a series of barlows attached together, fiddled around abit, but managed to get saturn in view with the equivakent of a 1.8mm EP. 650/1.8 = 360x

Now im not saying this was a crisp image, far form it, but it was by no means a total blur either. so those whio say you wont see anything arent strictly true, (they are if your focusser doesnt have enough travel tho).

and by using my nximage with the 5x barlow, i must have had 650x mag, and got some ok images out of registax. so just so you know, it IS possible to go over the 'max mag' ;it wont be clean and crisp, but by all means you will certainly see something.

regards,

tom