Yearofthegoat

Sorry for the necropost but it might help someone...

It looks like the OP hadn't inserted the black eyepiece holder tube into the draw tube, before inserting the eyepiece into the holder tube.

Made the same mistake with my 150. There were two holder tubes, each for use with different diameter eyepieces. Without them the eyepiece is too far into the draw tube = no focus.

He seems to have improved his delivery this series.

It's never going to satisfy everyone - and doesn't (shouldn't) intend to. There are lots of other resources out there for more detail on the science. I watch this with my kids who are 8 and 9, and they don't have much trouble following it. Which is great.

Has s/he missed off a zero?!

Maybe being nice to persuade you to vote Remain in the next referendum

Seriously, that's a great price. Am very envious, would love my own observatory but had to compromise with Mrs Goat and we got a summerhouse. It's better than the open air at least.

Yep, I've come to a bit of a dead end now with regards to centring a Canon DSLR with an MPCC fitted into a SW Crayford focussser. Unless there's some adapter out there I haven't come across yet.

FUFMPCC - not enough thread

Baader M54a ClickLock - too tall

HoTech SCA (w/ adapter) - too tall (as far as I can find out)

Compression rings - tilt due to clamping across the undercut in the MPCC nosepiece

But! I might still go with a ClickLock for visual - makes life easier for that anyway.

- And apparently doesn't grip an MPCC without introducing tilt, which can ruin the effectiveness of the MPCC.

Thanks for posting back.

That security is exactly what I wanted from the ClickLock system.  A real shame that they don't work with the focussers of possibly the most popular scopes out there.

Cheers Ady that would be great.

Thanks - I just popped over to OVL and the focussers have exactly the same specs,  so the outcome should - sadly - be the same unless there's quite some flexibility in the manufacturing!

If the ClickLock, with its 30mm depth, is short by max. 10mm then the Hotech with 19mm depth should -just- be okay.

Might just get one and see. I suppose I could return it if it didn't work out.

That's a great bit of info ?

I dug out my emails, and I must have mis-remembered, as I contacted Baader about the MPCC MkIII and EOS cameras, not the ClickLock, sorry.

A bit OT, but they said the MPCC MkIII should work fine, by the way:

Dear Yearofthegoat,

the MPCC is designed for a distance of 55mm - this has been the T-2-standard since the times of chemical photography. If the sensor is placed in this distance, the MPCC will correct the coma and keep the image quality in the center.

The T-2-standard has been "softened" a bit because there are newer cameras (Micro-Four-Thirds, Astro-CCD-cameras) which can easily be placed in a different distance, because the T-2-thread on their housings is closer to the sensor. I did a quick google-search, most threads I had found concern either Schmidt-Newton-telescopes or CCD-cameras (where you have to take care of the correct distance and can't use standard adapters), or users who use a low-profile T-ring or inserted an off-axis-guider.

The first MPCC was designed long ago for f/4.5, the MPCC III works fine between f/3.5-f/6 (and without less vignetting than a triplett-coma-corrector). If it somehow doesn't work, there is either something strange in your setup or a problem with the shipped unit of the MPCC - in the latter case, it is a warranty-case (then you have to contact your dealer about replacement/repair), in the first case, we'd need to see an image or description of your setup - then we can better judge where the problem may be.

If you want to use an off-axis-guider, you might want to use the RCC coma corrector and the RCC Off Axis Guider.

Best regards,

Alexander Kerste
BAADER PLANETARIUM GMBH

Thanks for posting the pics of the ClickLock - it looks like I'll need to go for something else as I really don't fancy messing with the mirror (well done for doing that, though!). It's a shame as I would like to eliminate the thumbscrews.

My 150PDS (and your mate Adyj's I guess) has the same focusser as your 250PDS, so I'm thinking maybe a Hotech SCA T-Adapter, and just use the normal thumbscrew stuff for visual (since it's not as critical an issue).

I've yet to get a coma corrector, so I'll need to check that w.r.t. focus with the Hotech in place.

I looked into this a while ago and wrote to Baader about it. I wanted to do away with the thumbscrews of the focusser drawtube clamp and the 2" and 1.25" eyepiece holders.
 

I didn't get round to doing it until now, so I'll dig out my email from Baader but do you have the S57 going into the original Skywatcher focus tube clamp?

44 minutes ago, carastro said:

I know nothing about statistics, I just do what works.  The skywatcher finderscope on your 150PDS will work OK as a guidescope, I had one and that's what i used.  No need to buy a guidescope and worry about how to mount it.  Just need a guide camera and the relevant  finderguider adapter.

My 150PDS came with a 6x30 finder - but I read elsewhere on here it isn't suitable for guiding. Also, I couldn't find an adapter to attach a camera anyway.

Thanks @bobro

Will give this a whirl once I get some filter holders.

Ah yes, H20. Can't live with it, can't live without it.

I looked at the Eksma site the other day, but today I can't seem to find the 25mm lenses, only 25.4mm. Is it me, am sure they were there... will have another look.

Very interesting. That second image looks good and the lenses aren't especially dear at about €20. Seems a good way to save some money with a bit of effort. Will you test them further e.g. playing with spacings etc? Thanks

I'm in a similar quandary. For my setup the pixel ratios guider:imager come out as follows:

Orion 50mm: 3.7

Skywatcher ST80 1.5 (both rounded up)

How important are these factors compared with:

- risk of flexure (ST80 on the 150PDS rings vs Orion on a finder post on the rings)

- added weight (ST80 is heavier)

- aperture / guide star brightness (80mm aperture @F5 vs 50mm aperture @F3.2)

I'm leaning towards the ST80 but the Orion would be lighter and a bit cheaper. Another option may be the Celestron 70mm travel scope, which is a bit cheaper again.

Lastly, does a bit more weight actually add to stability, provided the mount isn't overpowered?

Questions, questions.

Or, just pick any one of them and see how it goes?!