I've taken delivery of my MPCC and I've been wondering how I insert it into my imaging train. With my 8" Skywatcher newt I have been attaching my DSLR, using a T-mount adapter, to the 1.25" eyepiece holder. I unscrew the eyepiece holder to reveal a thread which then screws into the T-mount adapter. This places the body of the DSLR up against the focuser.
It's obvious that the MPCC screws directly into the t-mount adapter. However, the only way I can see to then attach it, and my DSLR, to my newt is to use the 2" eyepiece adapter, which is 3cm long - ie it moves the DSLR body 3cm from the focuser. If I do this will it still give me prime focus?
Obviously I could just test it out but it's cloudy - again - here in Brisbane so I thought I'd ask.
I'm so confused!!!
Cheers,
Mario
PS The focuser is the standard focuser that comes with the 8" Skywatcher dob.
The MPCC is M42 so much bigger than your 1.25" eyepiece holder. You need to fit the MPCC on the camera at the correct spacing first (55mm) then fit it on your focuser. Is your focuser barrel 2" ID? If not you're out of luck.
If you mean can I put the MPCC straight into the focuser barrel, the answer is no. It's the standard focuser that comes with an 8" Skywatcher Dob. However, the MPCC fits into the 2" eyepiece adapter no problems which then fits into the focuser.
Hmm call me stupid but if the mpcc fits in the 2" eyepiece adapter, shouldn't it also fit in the 2" focusser??
In my books, 2" is 2" and is the same as you guess it
Unlesssss you are talking about the 2" to 1.25" adapter and the mpcc is 1.25"
If you still can focus with the MPCC outside the focuser with the correct spacing then you're good to go, although you might get balancing issue and flex. I would change the focuser to a 2" barrel and slide the spacer/MPCC assembly inside it. That's what I do on my 5" newt.
The adapter is 2" but the focuser barrel is slightly wider. The adapter fits in to the focuser barrel OK. The MPCC fits into the adapter OK. The MPCC does not fit into the focuser barrel.
As mentioned it's the standard focuser that comes with the 8" Skywatcher Dob. I'm hoping there's someone out there that has come across this issue with this type of scope before.
Here's the setup. I think I got the adaptor from Peter Tan. Obviously the MPCC fits right into the SW 2" adaptor and focuses, IIRC, about 1cm out. All up it gives you the 55mm you need with the 1000d
I mostly use it with my QHY8 Pro now, so use a different adaptor, 42 to T of suitable length (about 30mm), also from Peter Tan.
Thanks for the images. I guess I need to get outside and try it out and work from there. Hopefully tomorrow night will be clear here in Brisbane and I can give it a go.
Thanks everyone for your help on this issue... it's nice to know that I can always ask a question and get help.
It is a bit of a can of worms unfortunately Mario. Whoever designed the Skywatcher crayford must have been smoking something fairly strong on the day.
Have a read of these threads for ideas. Broadly, options include:
- new low profile focuser
- cutting down 2" adaptor (what I've done and works for me)
- cutting OTA to move mirror closer
- putting longer screws on mirror
- reaming out inside of current focuser barrel
Oo, I'm gld you mentioned that Rob. I confess, Mario, that my SW f5 was purchased used from JJJ, and IIRC, she had the OTA cut down for DSLR use. I believe it was 980mm long, so cut down about 20mm.
So you may have a focussing issue after all! Sorry!
I thought about cutting down the 2" adapter as it looks like it's the easiest of the options! How much did you cut-off your adapter to get it to work? How did you measure that distance? Where exactly is the start of the MPCC in regards to the focuser?
I've jut read the links you suggested. It looks like I need to machine out the focuser collar to allow the MPCC to slide into the barrel and also cut down the 2" adapter as per Brendan's instructions. Is this what you needed to do?
Brendan, are you out there??!!!
Thanks Rob, the fog is lifting on this little problem... or as I tell people at work when they come to me and say "I've got a problem" I reply "We don't have problems here, only solutions!!!" Or perhaps a better reply would be "Shtarker dis is KAOS... ve don't have problems here!!!"
Thanks Rob, the fog is lifting on this little problem... or as I tell people at work when they come to me and say "I've got a problem" I reply "We don't have problems here, only solutions!!!" Or perhaps a better reply would be "Shtarker dis is KAOS... ve don't have problems here!!!"
Cheers,
Mario
LOL Mario - that's the spirit - don't let this lick you - its worth it to get it all going!
I'd suggest a simple experiment to see whether a cut down adaptor will work - take out your 1.25 or 2" adaptor to leave just the focuser, attach the MPCC to your DSLR T-Ring, point the scope at an object at least 500m away (or a star at night) and see if you can reach DSLR prime focus with the MPCC right up against the inside of the focuser adaptor (with focuser right in) - you'll be looking through the camera viewfinder to judge this of course.
For me, infinity focus is about 8mm back from the max "in point". As long as you have at least 5mm or so then you can get it to work by cutting down the 2" adaptor - mine is now 22mm high - I could dig out the name of the place that did it if you want. Just be aware you end up with a decent amount of your focuser tube down in the lightpath, but I haven't seemed to suffer too much because of that.
Brendan's mod is intruiging, but I'm surprised there was that much metal to take out. Theoretically it should be the best fix as you can use other 2" accessories and eyepieces optimally. I'd suggest a private message to Super Bbrendan (Bmitchell82) - he is often on the lookout for jobs to perform like this at reasonable prices. You'd have to post to WA, but he was very prompt machining up an adaptor for my finderscope/guidescope.
This has all been gone though before... you do not need to chop the OTA to get it to work, a small modification will see your current 2" focuser work properly.
just remember its not just the lip you need taken out, its also the collar to attach to the MPCC if you don't have this the modification will not work as you will have a 8-10mm band of metal holding the whole camera and the thumb screws will tilt it quicker than you can say in like flynn.
