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Despite woeful viewing conditions tonight, I did some playing around with my scope to see if I could achieve focus with the 15mm EP. The following is a synopsis of what I did & results.
1. Ensured diagonal seated home properly in focus tube. Not able to achieve focus with 15mm GSO EP, really, really close but, not quite.
2. Carefully disassembled focuser, screwed everything down firmly to ensure all firmly seated to OTA, reinstalled focuser & ensured that it was firmly seated. Not able to achieve focus with 15mm GSO EP. Again, really, really close but, not quite.
**Using the moon & then checking against a fleeting star (between clouds) I established that the 15mm almost looks in focus until you double check it against a star. This might explain why I believed I had achieved focus previously.**
3. I removed the 1.25" adapter (which has a 10mm lip) & carefully lowered 15mm EP into 2" diagonal. Hey presto, not far in it achieves focus. I estimate needing to lower this EP by approx 1 - 2mm in the LP to achieve focus.
I don't believe there is a problem with the scope. Although having a somewhat rudimentary understanding of Light Path mathematics & how focus works I think that if there was a problem with the scope it would affect all EPs, not just a couple of FL. It could be that this particular FL GSO EP (along with the 20mm GSO SV) just don't suit this particular setup.
Is this possible?
Options:
I have a few that range in not so expensive to relatively expensive:
a. Find a 1.25" adapter that has less than 10mm lip
b. Try different brands of EPs through trial & error. Could get expensive.
c. Try 1.25" diagonal although this is mildly inconvenient as I have a 30mm 2" GSO SV which works just fine.
d. Try Baader Hyperion EPs which can be used as either 1.25" or 2" Eps. This is moderately expensive.
e. Give up?? Not really an option.
What do you think is the best option; personally I think option A would do it but, not entirely sure what is out there. Any advice would be good.
Some photo's of the rig attached as previously requested by Brian.
1. 15mm GSO SV 1.25" EP inserted, not quite at focus but, no inwards travel remaining.
2. 9mm TMB Planetary 1.25" EP inserted, at focus. Approx 7 - 8mm of focuser tube showing.
3. 30mm GSO SV 2"EP inserted, at focus. Approx 12 - 14mm of focuser tube showing.
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