Ursa Major 6" f/8 Planetary Dobsonian

Worth knowing before you buy

Does the Ursa Major 6" Dobsonian outperform a small refractor like an 80mm achromat?

Forum members consistently say it should significantly outperform an 80mm achromat, citing the longer 1200mm focal length and much larger aperture. However, one new owner reported the opposite experience until it was diagnosed as a collimation issue — once collimation is addressed, members are confident the 6" Dob is 'way, way ahead' of an 80mm scope on planets and DSOs.

How difficult is collimation on the Ursa Major 6" Dobsonian, and are the GSO mirror cell springs and screws adequate?

Multiple members flagged the GSO mirror cell's Phillips/Allen collimation screws and weak primary springs as potential issues worth addressing, with Bob's Knobs thumbscrews recommended as a replacement for tool-free adjustment. However, FLO (Steve) directly clarified in the forum that current GSO-manufactured scopes sold under the Ursa Major branding have improved springs compared to older models, and that advice about replacing them is often outdated — members are advised to check first before assuming replacement is necessary.

How does the Ursa Major 6" Dobsonian's Crayford focuser work, and which screw does what?

New owners repeatedly found the focuser confusing, as it has multiple screws with no clear labelling in the instructions. Forum members clarified that on this focuser the bottom screw is the focus lock and the top is the tension adjuster, and that the focuser should move smoothly across its full travel once tension is correctly set — there is no intentional coarse/fine two-stage focusing mechanism.

Is the straight-through finder scope supplied with the Ursa Major 6" Dobsonian adequate?

Multiple owners found the stock straight-through finder uncomfortable or nearly unusable, particularly at steep angles. Several members strongly recommended upgrading to a right-angle correct-image (RACI) finder and/or adding a Telrad, with one owner at a star party saying they were 'lost' until someone lent them a 9x50 90-degree finder.

What is the Ursa Major 6" Dobsonian like to assemble, and how big is it?

Owners report assembly is straightforward overall, though the base can be slightly tricky — one owner noted the holes for attaching the uprights are not equidistant, and there was mild disappointment that the base uses wood screws straight into composite board. FLO's website is noted as the best source for exact dimensions, but members describe it as manageable enough to wheel to a nearby observing site on a sack barrow or platform trolley.

Is the Ursa Major 6" Dobsonian good value compared to similar-priced Dobsonians like the StellaLyra 8"?

Members broadly consider the Ursa Major 6" good value at around £269, and note it is significantly cheaper than the US equivalent when accounting for VAT. However, several members suggest that for a similar or slightly higher budget the StellaLyra 8" is a notably better-equipped scope, featuring a two-speed Crayford focuser, smoother alt-az movement, a RACI finder, and a cooling fan — making it a more serious consideration for those who can stretch the budget.