Imaging with the 130pds

[Tiny Small]

1 hour ago, Uranium235 said:

Or alternatively, you could not let it bother you

 

I did that for a long time. It finally got to me the other week though so I ended up doing both. I also finally got it collimated last night with the aide of a Cheshire. Took the primary out to clean and give it a new centre spot, took the secondary out to clean and just started from scratch. It's a good job I did too as everything was miles out. The only bit I had trouble with was keeping the secondary looking round whilst aligning it to the primary. In the end , and after about 4 iterations, I settled for 'pretty round' though not perfect. Also, keeping the primary screws equidistant from the edge of the field of view resulted in the centre spot being a couple of mm off so I moved the spot to the centre and although the screws aren't equidistant anymore, they are all still visible so it should hopefully be okay. I'm just awaiting a star test now.

Edited October 14, 2016 by Tiny Small

[Thalestris24]

2 hours ago, Uranium235 said:

I had no problems with the drawtube protuding into the lightpath because I used a custom built adaptor to sink the corrector inside the drawtube (the only one of its kind I believe).

For you the only option would be to either move the primary up the OTA a bit (to push the focus point out a bit), or shorten the drawtube by about 10mm (most people choose the latter). Or alternatively, you could not let it bother you

 

Hi Rob

Isn't this only a problem if you use the SW coma corrector/reducer? I don't recall having any such difficulties with mine using the Baader CC and either dslr or qhy8l.

Louise

[richyrich_one]

FWIW I had to move my mirror up 15mm to lose the "bite".

[carastro]

Thanks Rob, I'll see if it affects the stars which it did on my 150P image.  I won't be moving the mirror up that's for sure, beyond my capabilities, but I know some-one who might take a bit of the focusser tube should it be necessary. 

Fitted the 2ndry replacement bolts today, the 2ndry needed a slight tweak afterwards, and oh my goodness they were so much easier than fiddling around with Hex keys, especially as my hex keys are all fitted to one gadget in a swiss army knife style.  So thanks for that tip Louise.

Just sorting out the coma corrector connections now, as usual none of the threads fit.  

Carole 

Edited October 14, 2016 by carastro

[carastro]

Quote

Isn't this only a problem if you use the SW coma corrector/reducer? I don't recall having any such difficulties with mine using the Baader CC

Feeling a bit peed off now as I just sold a non reducing coma corrector with the 150P which fitted my Atik camera/EFW, and ordered a SW coma corrector that reduces, now I find it causes a problem as above and additionally I can't fit the coma corrector to the EFW as the threads are wrong.

To add to my frustration, I possibly have the adapter I need  M48 to T2 (I think), but it is very thin and stuck on another adapter and I can't even get a grip on it because it is thin to get it off.  

Carole 

Edited October 14, 2016 by carastro

[Uranium235]

1 hour ago, Thalestris24 said:

Hi Rob

Isn't this only a problem if you use the SW coma corrector/reducer? I don't recall having any such difficulties with mine using the Baader CC and either dslr or qhy8l.

Louise

Unsure as Ive never used the Baader without the custom adaptor, but with it the drawtube is almost completely clear of the primary without modification.

[Stub Mandrel]

1 hour ago, carastro said:

To add to my frustration, I possibly have the adapter I need  M48 to T2 (I think), but it is very thin and stuck on another adapter and I can't even get a grip on it because it is thin to get it off.

Put in freezer, then briefly warm the outer ring in your hand before quickly trying to separate them.

[Thalestris24]

2 hours ago, Uranium235 said:

Unsure as Ive never used the Baader without the custom adaptor, but with it the drawtube is almost completely clear of the primary without modification.

Hi Rob

I've not actually used my 130pds in ages...  Still, it has a qhy8l attached plus a spacer plus the Baader MPCC which goes into the focus tube. I never had any cut-off stars. I've never understood your need for a custom adapter - please explain! Maybe I'm missing something here but my Baader goes all the way into the focus tube. I'm sure it would benefit from a third focus tube thumbscrew though!

Louise

[John78]

1 hour ago, Stub Mandrel said:

Put in freezer, then briefly warm the outer ring in your hand before quickly trying to separate them.

That and put on your marigolds, you'll get anything undone wearing marigolds.

[Thalestris24]

2 hours ago, carastro said:

Feeling a bit peed off now as I just sold a non reducing coma corrector with the 150P which fitted my Atik camera/EFW, and ordered a SW coma corrector that reduces, now I find it causes a problem as above and additionally I can't fit the coma corrector to the EFW as the threads are wrong.

To add to my frustration, I possibly have the adapter I need  M48 to T2 (I think), but it is very thin and stuck on another adapter and I can't even get a grip on it because it is thin to get it off.  

Carole 

Oh dear, sorry Carole... Personally, I've never seen the need for a reducer on the 130pds - I like it at 650mm. It's probably the reducing effect of the SW cc that causes stars to be impinged by the focus tube.
Certainly the Baader has T2 and M48 threads too

Louise

[Uranium235]

58 minutes ago, Thalestris24 said:

Hi Rob

I've not actually used my 130pds in ages...  Still, it has a qhy8l attached plus a spacer plus the Baader MPCC which goes into the focus tube. I never had any cut-off stars. I've never understood your need for a custom adapter - please explain! Maybe I'm missing something here but my Baader goes all the way into the focus tube. I'm sure it would benefit from a third focus tube thumbscrew though!

Louise

Probably easier to explain in pictures:

That threads directly onto the drawtube and provides an all threaded connection with built in coma correction and tilt control.

[Thalestris24]

1 minute ago, Uranium235 said:

Probably easier to explain in pictures:

That threads directly onto the drawtube and provides an all threaded connection with built in coma correction and tilt control.

Ahh I see! I imagine having a threaded connection is good - but presumably not absolutely necessary and the cc would still go in the focus tube without the custom adapter?

[Uranium235]

I found to going all threaded to be a must-have due to the weight of the imaging train, as im a fan of mosaics - and if you have a dodgy side/corner... you cant mosaic, so I needed a perfect field.

The cc (baader M48 cell) screws into the underside of the adaptor as you can see. Additionally, I adapted the SWCC by hacksawing off its stop collar - turning it into an M48 cell so it could also simply screw in.... that allowed me to chop and change at will.

Absolutely rock solid, and also allows for threaded collimation so its repeatable every single time.

Proof of the pudding: (10 panel mosaic)

[Thalestris24]

It seems to be very handy to have engineering skills and to have the wherewithal to be able to apply them!

[Uranium235]

2 minutes ago, Thalestris24 said:

It seems to be very handy to have engineering skills and to have the wherewithal to be able to apply them!

Thats what I love about astrophotography, its the perfect mix of computing, science, and engineering

 

[carastro]

Quote

Put in freezer, then briefly warm the outer ring in your hand before quickly trying to separate them.

Edited October 14, 2016 by carastro

[carastro]

Something weird has happened to the reply box, thus my quote in the previous post, but would not let me add a comment.

I'll give that a try, even if it's just to prove it is the adapter I need.  

I'd love to be able to screw directly to the focusser like Rob does, I just bought a click lock adapter for my refractors as all that expensive equipment on the end of two small screws which were starting to not tighten properly, plus sometimes my EFW and Camera would rotate when taking the cover off at Star parties (even being careful). So then subsequent data wouldn't match up.

I've actually asked the buyer (who bought my previous SW150P and coma corrector if he'd like to swap CC as he uses a DSLr and might be better for him anyway.  Waiting to hear back but I think he's travelling today.

Carole   

[Thalestris24]

14 minutes ago, Uranium235 said:

Thats what I love about astrophotography, its the perfect mix of computing, science, and engineering

 

I suppose that's what attracted me to it but I lack proper (mechanical) engineering skills and, living in a 1-bed flat, I'm limited to what I can do anyway, sigh.

[carastro]

Some-one requested a photo, so here it is with my ED120 finderguider sitting on it. 

Just about managed to fit it into the FOV by standing with my back against the obsy and the camera up against my face.  Lol.

Focusser is in that position due to collimating.  

 

Edited October 14, 2016 by carastro

[dyfiastro]

Hi everyone

I am going to be without a mount for a week or two so intend stripping the 130 to flock it and check focuser collimation etc..

Is there anything other mods that can be done whilst I have it apart that will help?
I know I have a little bit of tilt when attaching my camera so I am also going to see about adding another screw to the tube but is there any other decent options out there that will work with a baader MPCC?

thanks in advance

[Susaron]

2 hours ago, digitalcyanide said:

Hi everyone

I am going to be without a mount for a week or two so intend stripping the 130 to flock it and check focuser collimation etc..

Is there anything other mods that can be done whilst I have it apart that will help?
I know I have a little bit of tilt when attaching my camera so I am also going to see about adding another screw to the tube but is there any other decent options out there that will work with a baader MPCC?

thanks in advance

In order to avoid tilt you can replace the original ring in the drawtube with one of these rings

https://www.firstlightoptics.com/adapters/flo-compression-ring-adapter-for-skywatcher-newtonians-m54.html

Cheers.

[Uranium235]

Personally, I would advise that you go with the third thumbscrew. Compression rings are fine for EP's, but not for coma correctors with attached cameras (been there, done that, chucked it in the bin).

[Thalestris24]

I tighten thumbscrews with the aid of pliers  I've no idea whether compression rings are good or bad - I imagine it depends on the load.

Louise

[dyfiastro]

Thanks for the info everyone, does anyone know what side the thumb screws are?

 

[Uranium235]

2 hours ago, digitalcyanide said:

Thanks for the info everyone, does anyone know what side the thumb screws are?

 

I assume you ment "size" and not "side".

Theyre M4, drill an M3 or M3.5 hole (personally I go for M3 for a better thread) then tap it out with an M4 tap (tap sets can be gotten from B&Q). Also its better if you have access to a bench drill (dont do it by hand!) to get a nice straight hole.

Then, you can nick a  thumbscrew off a barlow or other EP accessory (as theyre all M4).