Help with astigmatIc 14 inch mirror

[mdstuart]

So thank you to astrobits..Nigel who tested my mirrors and they all seem fine which is good.

So Nigel suggested I look at alignment as it was all out.. Moved the spider 1cm away from the main mirror so the secondry now lines up better under the focuser tube..

Cheshire view attached which looks close...will retest.

Mark

Sent from my BlackBerry 9320 using Tapatalk

[Moonshane]

that's great news.

collimation, collimation, collimation that's what you need

if you want a view that's best

then you must take time to test,

collimation's what you need

:0)

[Rustysplit]

Great news Mark. I bet you are relieved?

[John]

I'm very pleased to hear that the mirrors are OK Mark

[estwing]

I'm very pleased to hear that the mirrors are OK Mark

+1

[mdstuart]

After moving the secondary its a bit better but still there above 100x

So belt and braces..three blobs of silicon as recommended by Nigel....three not four!!

Epoxy on waiting for it to harden.

Mark

Sent from my BlackBerry 9320 using Tapatalk

[mdstuart]

Well that sorted it!

It was the main mirror mounting! Stars are now pretty much perfect..

You cannot imagine how that makes me feel..

Nigels three blob strategy works!

So I feel some galaxy hunting might now be in order!

Mark

Sent from my BlackBerry 9320 using Tapatalk

[estwing]

that's great news Mark! you must be over the moon!

[Moonshane]

great news Mark - now enjoy it!

[Rustysplit]

Result!!

[Paul M]

I've been following this thread with crossed fingers that each step would bring a solution!

There is more good news too.....I'll happily give you that £100 for it

[mdstuart]

Over the moon is an understatement. I can easily split the double double now with the 12mm eyepiece...NGC7331 just blinded me!

Mark

Sent from my BlackBerry 9320 using Tapatalk

[Astrobits]

Ah Ha!

When we tested the mirror the OTA was horizontal and consequently the mirror was not resting on it's back. Any distortion caused by the cell would not show up until the telescope was pointed upwards.

I have recently been contemplating just this scenario and how to do tests on the mirror at various elevations to clarify the actual performance of mirror cells. Probably need a structure like a small version of Lord Rosse's telescope

Nigel

[Moonshane]

it just goes to show how great dobs are. even when all seems lost, a simple mod and you have a heavenly scope once more :0)

[8kids]

that's great news.

collimation, collimation, collimation that's what you need

if you want a view that's best

then you must take time to test,

collimation's what you need

:0)

If you want to be a Dob fixer..........Yeah!

[estwing]

well done Nigel..great work.

[jetstream]

Over the moon is an understatement. I can easily split the double double now with the 12mm eyepiece...NGC7331 just blinded me!

Mark

Sent from my BlackBerry 9320 using Tapatalk

Congratulations Mark!Hats off to all those who helped you!