Moving 200p primary mirror up for focus

[8324689]

Hi there

I have one of the old style blue Skywatcher 200p...

I cannot get the DSLR in focus especially with an OAG onboard. 

I see some threads concerning moving the primary forward but no actual directions on how to do it. 

Im sorry Im just a bit scared and not sure where to start....

I have all the gear set up outside and its a good night to image so hoping to still be able to do so tonight! Probably wishful thinking 

Any help really appreciated

 

Thanks 

 

 

Edited March 2, 2020 by 8324689

[8324689]

Do I just keep turning the Alan keys for collimation in the bottom.... Not sure how long they are.... Dont want my primary to fall off!

[DaveL59]

I don't know that scope but I'd not wind the adjusters too much without knowing how far you need to move the mirror and then check that the existing ones are long enough, you might also need longer springs so the mirror moves with the bolt adjustments. If you can remove the whole mirror cell then you'd be able to assess the bolts/springs and get an idea how far you might be able to adjust things vs the expected shift you're looking for.

Others with more knowledge of this scope are bound to appear with less generic advice but for sure be cautious in the meantime.

[8324689]

Thanks yes for sure I err on the side of caution. I havent touched it yet....

Was just hoping to get back out tonight but not looking good.....

May as well call it a night..... Again!!

Thanks

[bingevader]

No, not a quick job as I recall.

I seem to remember people removing the mirror and adding spacers.

Have a search, I'm sure there are topics on it, if not here then elsewhere on the line.

Not scary, just not quick.

I've taken my mirror out to clean it, which is easy if you are careful, but still, not a quick job.

[DaveL59]

13 minutes ago, 8324689 said:

Thanks yes for sure I err on the side of caution. I havent touched it yet....

Was just hoping to get back out tonight but not looking good.....

May as well call it a night..... Again!!

Thanks

ahh this pastime sure does teach patience but it'll be rewarded in the end  

[8324689]

Yes I have searched 2 pages on Google... will keep looking 

Plenty of chat about it but not actual procedure of doing it.

How long is enough... SHould I do it on an evening so I can check it on moon, do I have disassemble - reassemble then check it.....

 

All the BIG questions!

 

Im sure ill figure it...

[DaveL59]

its a procedure you'd want to do in daylight I think as it can be fiddly to get just-so. Of course knowing how far you need to shift it is key, then getting the longer bolts and springs to achieve it, usually easy enough to order online and get hold of in a few days. Then you'd need to collimate the rig and if you've some far distant views to test on that can help too, though with the moon visible in daytime you may well be able to confirm against that while its still easy to see what you're doing.

[DaveL59]

different scope but similar reason for doing it (eyepiece focus rather than camera but same principle)

a post or so above I'd listed the bits I got to do it but of course these could well be different on yours. 

 

This thread may also help

Seems the magic number is around 20mm shift of the mirror but you'd need to check the existing screws can accomodate that. Also if you'd then like to use it for visual you'd need an extension tube.

Edited March 2, 2020 by DaveL59

[8324689]

Yep thanks for this. If anyone is reading this having done it on a 200p pls chime in! Thanks

[adyj1]

I've done it on a small 1145p (needed moving a few inches to achieve DSLR focus) and a 150PDS (so that I could fit a Baader ClickLock) 

The adjustment screws were standard thread, and just needed to be countersunk metric bolts (sorry, the size escapes me). The tensioning screws, however, which have the knurled head for manual adjustment were a different matter, and were quite expensive for what they were. Ended up getting a flat wingnut-type things and ground the sides in a bit so they could turn properly next to the adjustment screw knobs... 

Hope this helps

Ady