80mm orion go scope + 3x barlow cannot focus

[roebedf]

Hi anyone had trouble focusing their new 3x barlow? Maybe someone could give me some tips. I have an 80mm go scope refractor with 350mm focal length and a 20mm eyepiece plus a 10mm eyepeice. magnification shouldnt have been a problem so i'm wondering if it has to do with something else.

thanks

[sunshine185]

If you use the 3x Barlow with the 10mm ep this will be pushing the scope to the absolute limit, even on nights of good seeing. Try both ep's on their own. A 2x Barlow with my 10mm ep on my dobsonian has been impossible 99% of the time due to the limited seeing, for high mags I generally aim for between 150-200x, any higher is usually a waste of time, the skies have never been good enough.

[Capricorn]

If using the 10mm and the 3x then too small a focal length for the scope. Add in that I guess the 10mm came with the scope, and the supplied 10mm items are generally poor, if the 3x is a budget one then expect that to be poor.

Puzzled by the scope 80mm and 350mm FL is nothing that comes to mind. That is FAST, f/4.37, and you will probably need a very good quality lens to resolve an image from it. Good quality being £200++

Until you start considering the TeleVue range of premium eyepieces, and their equivalent, I would not suggest anyone going below a 5mm eyepiece. The eyepieces are, I find, generally at their limit at 5mm.

Is this the starter scope sold by Orion ?? Seem to recall it has an f number down at the 4.4 range. If it it then will say expect coma and field curvature.

Don't believe the magnifications written on the box or for that matter stated by people. A scope will give what it can and no more. I would honestly expect yours, if it is the one I think, to have an upper limit of around 80x, and that may not produce a great image. Borrow a 5mm eyepiece, preferably not a plossl and see what comes out.

[roebedf]

Thanks for the replies. Yes it is a starter scope and 4.3 focal ratio. I see great with the 10mm eyepiece but figured 3x barlow would bring the 35x to 105x which is far below the 160x max. Even with the 20mm EP (50x) I couldn't find anything in the scope. Maybe defective or maybe I just need a 2x barlow.

[John]

The Orion 80mm GoScope is an F/4.3 achromat refractor. Given the chromatic aberration that the design produces I reckon 80x will be the highest it can usefully go - even that might be pushing it. Whatever the manufacturers "blub" says these scopes are for wide field, low power viewing. 160x would be way, way too much to get any sort of decent image I'm afraid.

[roebedf]

Im going to trade it in for a 2x barlow and hope that works.