gazza

Wondering about choice of coma corrector? I have a Skywatcher F4 coma corrector (used for my 8" Quattro), but despite spending an evening changing spacings I was unable to get good images to the edge of a KAF8300 chip with the 130PDS. I tried a Skywatcher F5 coma corrector and this worked well (interestingly, at the same spacing as the F4 works in the Quattro), however I'm also interested in the Baader Mk111, as I've read of reflection issues with the Skywatcher. Can anyone advise as to the best choice here or have comments on the best coma corrector for the 130PDS? TIA cheers Gary

Machining the cell has fixed the triangular stars - thank goodness!! Now have to play with the spacing of the F4 coma corrector to optimise correction. It is not working as well at f5 at the sam spacing as provides perfect correction at f4 - can anyone who may be using this corrector with the 130PDs please advise their spacing? cheers Gary

Hi, just checked my mirror cell - the mirror was a very tight fit - it was impossible to rotate it using finger pressure. I have machined a tiny bit off the inside of the cell and the mirror now freely rotates. It looks like the casting was very slightly out of round. Should have checked this when I re-spotted the primary, but I didn't :-( I had loosened the primary clips, so I don't think these were the problem. Slight possibility of a clear night tonite for testing... Hopefully this will fix the triangular stars. cheers Gary

I thought the focus was slipping also, however I put the Bahtinov mask back on and checked - it still showed perfect focus so I'm not sure what is going on here. cheers Gary

Me either!!!! cheers Gary

Had loosened them when re-spotting the primary - perhaps not enough...Will loosen them some more. The mirror is also a very tight fit in the cell - tighter than I have seen before. Does anyone know if this is normal for a 130PDS? I may put the cell in the lathe and skim a couple of thou off it to give the mirror a bit more room. Puzzled Gary

Hi, These mirrors are not made in the same way that mirrors were ground in the old days. They use machine generate blanks that are accurately ground, certainly not millimetres out of shape and use high speed grinding/polishing machines that are worth lots of money. These things are not likely to grind an off centre optic. Pre these machines no-one measured the centre of rotation then because the grinding process averaged out the centre position and it would have taken some appalling technique to get an off centre optic. You are lucky that your centre spots are centred! Mine never have been and I've had half a dozen GSO and Skywatcher newts over the years. I've also ground and polished numerous mirrors from 8-12" f4-f6 over the years, done by both hand and machine, and always centre spotted the physical centre, and always achieved spot on collimation. A slightly offset donut can be used for collimation - If all you are using is a sight tube, laser and cheshire. A scope can look like it is collimated in this case. If you add an autocollimater in to the mix then you may start to see problems. These can also show up as tilt in the focal plane - which may not show up on small chips, but starts to show up on Kaf8300's and above in size. In the end, if using the factory spot works for you, that's great - me I'll keep measuring and spotting myself if it is off centre! YMMV cheers Gary

Hi, disappointingly my new 130pds is showing triangular stars. The focuser has been trimmed and is not impinging upon the mirror. Anyone else had this? Pinched primary in its cell? Secondary problem? Using Skywatcher f4 coma corrector. It is consistent right across the field. Also note the reflections on smaller stars. Have never seen this before....It was focused using a bahtinov mask, yet looks almost out of focus Suggestions appreciated. cheers Gary

I wonder where you heard this? I've never heard or seen any evidence of this factory testing for optical centre? On the contrary I've seen many scopes that were impossible to critically collimate accurately using a factory placed spot, which became easy once a centre spot was accurately placed - indicating that the optical centre was the mechanical centre......Could you please provide a reference, I'd love to know how they determine the optical centre..... cheers Gary

Hi, placed my first ever order with FLO last Thursday. Order shopped Friday, have received a text that item is "on board for delivery" today - and I'm 12000 miles away i Australia! Fantastic. cheers Gary

Hi, just got a 130PDS and have attached it piggyback to mt CPC1100 - see pic. Had to cut 20mm off the focuser, and fit a reatining ring to the bottom of the focuser tube so that it would not fall out. The centre spot was not centred, so removed it and replaced it with a Catseye spot. Put a piece of flock opposite the focuser. Also had to shift the secondary position as it was way to low. Scope is now collimated and ready to go. Will be using the Skywatcher (GPU) F4 coma corrector. Hope this works so I don't have to buy a Skywatcher f5 coma corrector...... cheers Gary