LX 200 Mirror lock,any one use one.

[paul mc c]

I have just got my self a dual speed focuser for my scope to do away with mirror shift.My idea of the mirror lock is obviously to lock the mirror and use the new focuser,now when i lock the mirror it becomes very distorted.like very bad collimation,until i loosen the lock,which defeats the purpose.

What is the best way of using a lock.

Paul

[Dave In Vermont]

I have a Crayford 10:1 Dual-Focuser on my LX90. What I do is set the scope's onboard focuser to about the middle-point of accuracy - and then use the Crayford for fine-tuning the view in my eyepiece. I then would not even bother to engage the mirror-lock on the LX200 - which I did have before I opted to use the LX90. If you lock the mirror, the focuser will lock the mirror in place - and that would effectively sabotage the dual-focuser from doing it's job.

In other words, try it without the mirror-lock engaged and see what this does for you.

I'm sure you'll get it sorted -

Dave

[Chris]

Is it a crayford SCT focuser to the rear port of the scope, or the duel speed upgrade to the existing focuser?

I'm guessing the first one in which case can you just engage the mirror lock and re-collimate the secondary mirror to get things all lined up again?

I'm interested in Dave's point about sabotaging the focuser if you lock the mirror as I thought RC's had a fixed mirror and a Crayford off the back, wouldn't it just work in the same way as an RC if you did this?

 

[Stu]

1 hour ago, Chris Lock said:

Is it a crayford SCT focuser to the rear port of the scope, or the duel speed upgrade to the existing focuser?

I'm guessing the first one in which case can you just engage the mirror lock and re-collimate the secondary mirror to get things all lined up again?

I'm interested in Dave's point about sabotaging the focuser if you lock the mirror as I thought RC's had a fixed mirror and a Crayford off the back, wouldn't it just work in the same way as an RC if you did this?

 

Those were my thoughts too Chris. The rear crayford is independent of the mirror focusing mechanism, so locking the mirror shouldn't affect it. As you say, I guess the mirror flops into its locked position so recollimation is necessary after locking.

EDIT Post corrected now, not sure how 'Those' became 'This evening'!, and licking your mirror is not a good idea! Locking!!

[Chris]

I know you love your scopes Stu, but I draw the line at "licking the mirror" lol

Seriously though, I'm glad someone else thinks this makes sense, and it's a nice easy solution for Paul

[Stu]

1 minute ago, Chris Lock said:

I know you love your scopes Stu, but I draw the line at "licking the mirror" lol

Seriously though, I'm glad someone else thinks this makes sense, and it's a nice easy solution for Paul

Funny  I just noticed and corrected it! I know from experience that saliva is good for getting snail trails off corrector plates but I don't recommend licking mirrors  

[Chris]

Sorry Stu, I've got a sad sense of humor and find slightly rude typos hilarious

I'll remember your corrector cleaning tip, you never know  

[paul mc c]

So if i use the mirror lock and then have to re colimate this means i will have to keep doing this if say i use a camera and then visually.......sounds very inconvenient.

I have good colimation on the scope,and after using rough focus with the stock focuser and then use the Crayford focus is great with no shift at all,which will be great for high power work.

I think using the lock is not really any use then.

[Dave In Vermont]

You know - people have bittery compained about the mirror-lock, and a plethora of other issues with Meade SCT's for at least 20 years - without Meade lifting a finger to solve all the issues associated/reported to them.

Don't get me wrong - Meade optics are outright fantastic! But their 'human-interface' had been appalling. As I've heard Celestron do so as well. But SkyWatcher has also gotten complaints about the mirror-flop issues as well. But there they fixed it! Meade? We'll see. But as an LX-owner, I suggest you look through Peterson-Engineering fixes for these:

http://www.petersonengineering.com/

I do recommend Pete Peterson's fix for the LX200, 90, etal - for the focur-knob regardless of what else you're doing. The declination-mechanism is a close 2nd.!

Hore it helps -

Dave

[Chris]

1 hour ago, paul mc c said:

So if i use the mirror lock and then have to re colimate this means i will have to keep doing this if say i use a camera and then visually.......sounds very inconvenient.

I have good colimation on the scope,and after using rough focus with the stock focuser and then use the Crayford focus is great with no shift at all,which will be great for high power work.

I think using the lock is not really any use then.

Hi Paul, I take it there is no way of using a camera off the back of the Crayford to get round this problem? If not then yes forget mirror lock and just enjoy the improved non shift fine focus of the Crayford  

[Chris]

30 minutes ago, Dave In Vermont said:

You know - people have bittery compained about the mirror-lock, and a plethora of other issues with Meade SCT's for at least 20 years - without Meade lifting a finger to solve all the issues associated/reported to them.

Don't get me wrong - Meade optics are outright fantastic! But their 'human-interface' had been appalling. As I've heard Celestron do so as well. But SkyWatcher has also gotten complaints about the mirror-flop issues as well. But there they fixed it! Meade? We'll see. But as an LX-owner, I suggest you look through Peterson-Engineering fixes for these:

http://www.petersonengineering.com/

I do recommend Pete Peterson's fix for the LX200, 90, etal - for the focur-knob regardless of what else you're doing. The declination-mechanism is a close 2nd.!

Hore it helps -

Dave

Hi Dave, I heard when the LX200 came out it had some real issues, but didn't they make improvements to fix lots of these problems over the first few years?

I've considered buying a classic LX200/90 for some time so have read Uncle Rods used CAT buyers guide a number of times over the years (nice read!). He says to avoid early 90's LX200's and buy a late 90's model which has had some of the issues addressed

http://skywatch.brainiac.com/used/used_sct.pdf

[Peter Drew]

I operate a couple of 16" SCT's which have seriously heavy primary mirrors which exacerbate any mirror flop. Any method that incorporates the stock primary mirror focusing system causes image shift which is annoying when trying to centre an object on a small imaging chip. Each has a dual speed Crayford type focuser for fine focusing. The "trick" is to use the stock focuser with the Crayford at half travel as already mentioned but make sure that the prefocusing is done moving the primary in the direction that maintains the collimation. I never use the mirror lock.