I picked up this very common no name made in China scope recently second hand as an el cheapo finder scope for my frac.
The tabletop tripod is not my testing subject, only the optics ad the optical tube assembly will I be commenting below.
The specification sticker on the scope’s focuser says the scope is a 70mm focal length 300mm coated lens telescope, so a focal ratio of F4.3! I am keen to test this claim, as it is very fast.
The focuser is a 1.25 inch barrel, but the plastic eyepiece adapter ring is super thick, and stop the opening down to fits its two 0.965 inch Huygenian eyepieces of H20mm and H6mm. First thing I notice is that the objective lens does not look coated. I can see there is a baffle inside the scope tube, not far from the objective lens, and the focuser draw tube reach not far behind the baffle with its own baffle inside and quite far towards the objective end. I did a light test with the stock 0.965 H20mm eyepiece to see if it operates at full
The torch light test shows the telescope tube baffle acts as an
After taking the scope apart and darken the doublet objective lens edges with a sharpie, I moved the baffle as far back as possible towards the eyepiece end by flipping it around and changing over to a shorter focuser draw tube and swapping over to a 1.25 eyepiece adaptor ring, the light test shows the scope operating at 60mm, a 10 mm improvement. You can use instead a Stanley knife to slowly scrape off the plastic to ‘open up’ the eyepiece adaptor ring from 0.965 to 1.25 inch if you do not have a 1.25 inch eyepeice adapter to swap with.
The only way to reach full
The doublet achromat optics on this ‘F35070’ scope is fine operating at full 70mm
To focus without a diagonal with the shortened focuser draw tube, I use those made in China 2 or 3x plastic shorty barlow lens to lengthen the barrel to achieve focus.
In summary, after the above modifications, it is a much more capable 70mm scope or finder scope.
PS: My scope comes with a 5x24mm finder scope, but the objective lens on the finder scope is a singlet plastic lens and the finder scope has been stopped down to 12mm with a baffle. I find the plastic singlet lens operates better than the glass singlet lens when operating at full