can't focus with MPCC

[vash]

Well, I'd like to say I'm the proud owner of a baadar MPCC, from what I have heard they are worth it, so I just got mine today, got home clear skies ready to set up but I thought I might try and get it focused first, but I can't.

I have the camera attached to the T-ring - the MPCC in a 2 inch adapter. Problem is that my 2 inch adapter is huge and is causing a lack of in focus, First obvious solution is a smaller adapter but that will have to wait a day or 2 before I can get one.

I tried raising the primary as high it can got but it still isn't high enough, I did how ever find exactly how high it can go :doh:, turn out it's not high enough, after a bit of fiddling I got the knob back on and told myself not to do that again.

Or a low profile focuser is another thought, but I don't really want to spend that much.
Any other solutions I have missed, that can get me out imaging tonight with the MPCC?

[monoxide]

just checking but... are you sure its not enough back focus because the MPCC moves focus 10mm to OUT, i had a low profile focuser on my 6" newt and i couldnt focus because it was too low profile

[vash]

I've got the focuser wound in as close as I can get it too the scope and it's still out

[davewaldo]

I thought the MPCC worked as a 2" adapter so you wouldn't need one.

I thought the MPCC should sit inside the focuser, is this how you have it mounted?

Could you achieve focus before using the MPCC?

[vash]

I could achieve focus fine before but I was using the thread onto a small adapter that fits right into focuser, only problem is that the thread is too small for the MPCC, the MPCC is far too small to fit directly into the focuser although I just checked and it does fit directly into the ED80, but not the main imaging scope,

[gbeal]

I'm with Davewaldo, I use mine as the 2" section, sometimes with a nosepiece on the front, but also without, just the MPCC and the camera. Try this.

[vash]

I tried using just the camera and the MPCC directly into the focuser but on the reflector, the focuser is massive compared the the MPCC, so thats out the window.
I'll just go down and get a smaller 2 inch adapter tomorrow, cause there is not other way, it's twice the size it needs to bet for what I want it for, I understand it's lager for visual use but it's not designed for a camera.

[davewaldo]

Wow, sounds like you have a 3" or 4" focuser. Not what I expected on a 10" Skywatcher.

Good luck :)

[gbeal]

Got me beat too, any chance of a quick picture to put it all into perspective?
I assumed you had a 2" focuser, and that would allow plug and play with the MPCC.
Gary

[vash]

I just measured the the diameter of the focuser and it's 6cm while the 2 inch adapter measures 5cm, the MPCC fit's nicely into the adapter but not the focuser directly, I also measured the ED 80 and to no surprise in measured 5 cm too.

[gbeal]

Nope, I'm still lost.
How do you use the focuser normally? You use an adaptor I presume, and this fits within the focuser, correct?
If so why not use the adaptor in the focuser, and the MPCC/T Ring/Camera in that order?
Gary

[vash]

because the adapter and MPCC have different size threads thats what I first tried as it's what I use normally,
I've added a shot to show how much space I have around it from the focuser with out the adapters.

the black area around the MPCC is air.

[gbeal]

OK, so slip the 2" adaptor in (as if you are going to use it with a normal 2" eyepiece, and attach the T ring directly to the MPCC, then the camera to the T Ring.
Slip the whole shebang into the 2" focuser, and see what gives then.

[vash]

done that too, but my 2 inch adapter is a viewing one and doesn't come apart, which is why I'll be making a trip back to the scope shop tommorow.

here's a shot.

left to right
t-ring, MPCC, 1 1/4 adapter and 2 inch. you can see it's a little larger and is the problem, in all this.

I'll just set up and take a shot of omega glob and when I get the right adapter do it again to see the difference.

But thanks for all the help and support,

I did come so close with moving the mirror up too, I could almost get some trees in focus.

[Hagar]

Ashley,,, TREES.. Your telescope will have a totally diferent focus spot when looking at the night sky. Seeing your MPCC will fit down the focuser draw tube it may pay to fit the MPCC to your camera and while holding it, move it into the drawtube with the draw tube fully in and see if you can reach focus. If not try it the other way even if it is outside the drawtube. By focusing this way you should be able to find which way you need to go to reach focus and roughly by how much.
Just a note. If it is the 10" you are working with, you may be in a position I was in a few years back. My only way to focus the camera in the Dob was to cut 48mm off the bottom of the Dob tube and reposition the primary mirror. Balance will then be out. An added weight was needed to balance the Dob again.

Good Luck

[vash]

I have it set up with the 2 inch just then While it cools down and managed to find Rigil and tried to focus this is as close as it gets, move the focuser out more and it gets bigger.

Like I said, not going to worry too much, I'll get a smaller 2 inch adapter and all my problems will go away. till then I'll just aim at a smaller target.

[vash]

I have it set up with the 2 inch just then While it cools down and managed to find Rigil and tried to focus this is as close as it gets, move the focuser out more and it gets bigger.

Like I said, not going to worry too much, I'll get a smaller 2 inch adapter and all my problems will go away. till then I'll just aim at a smaller target. I see Jupiter is rising, might be time to break out the LPI, see how I manage with it.

[gbeal]

Sorry Ash, and call me thick if you like, but I can't see the problem.
The T ring I understand, as too I understand the MPCC (I own one myself). The 1.25" has me beat, and I am assuming it and the 2" screws onto/into the draw-tube section of the focuser, is this correct?
If so, I can only assume you have tried the MPCC in the 2" section, while it is screwed onto the draw-tube. If this is so, then you likely have the chip too far from the primary, like Doug did.
One thing you could do with this is have an adaptor made that screws into the draw-tube and allows the MPCC to slip in, like a sleeve. That would get the T ring all but hard up against the end of the draw-tube. Try what Doug suggests, find the position required first and sort out how to achieve the result.
Gary

[gbeal]

Hmm, you posted while I was typing, seems the camera is too far away after all. Try a shot with you holding the T ring and camera up against the draw-tube, focus it with the viewfinder of course.

[AlexN]

thats the same problem i get, the 2" dr adapter is too long, and i cant reach focus. I was going to get an adapter made to go from the focuser size adapter straight to t-thread, then realised i wouldn't be alle to use filters. If you can find a low profile 2" adapter, can you pm me with where you got it from..

[vash]

I got focus doing what doug said and it's close to where it normally is with out the MPCC, it's just I don't have the required adapter at that length. If I got a 2 inch adapter the same as my 1 1/4 I wouldn't have a problem.

[Ian Robinson]

I was thinking of having two focusors at one stage - my new 2" low profile custom made heavy duty crayford and 90degrees around the tube a 2" ultralow profile helical focusor (stands 1" high fully racked in ! that I happen to have in draw and has never been used) to do prime focus stuff , rating the secondary as required.
Wonder if something like that might be a solution for you ?

I have the

[vash]

well It turns out that the focuser's are unique on the skywatcher reflectors, which is why they are a little bigger, only problem is that there is no smaller 2 inch adapter, I got another one and will have to either cut it in half or go to a machine shop and get them to do it, or I saw the JMI motor focuser there and it's price tag which would be more than the scope.

So I'm off to find a machine shop then.

[AlexN]

Ashley, I had this same thought today... looking at my 2" adapter, I thought... I might just take that to work, cut it down so its 1cm tall and get the fitter at work to tap threads in it for the screws... should come up trumps.

[vash]

yep, thats exactly what needs to be done, I don't have any tools that can do anything along those line but I was given a free 2 inch adapter to get cut down so that good, one for the camera and one for the eyepiece.

The reason the focus tube is larger is to cut down on vignetting which is good but not when you need to attach certain things. Though that JMI is very nice, Costs more than the scope though.

[gbeal]

Before you attack the adaptor, ask a friendly machinist. The older the machinist the better I find, as they are normally more inclined to assist.
What I think you want is something that will either fit tightly into the focuser tube, or screw into the focuser tube. On the end of that you need a thread, M42x0.75 I believe, the standard T thread. So you can then simply screw your T ring to this, and have it virtually touching the top of the focuser.
Make sense?
Gary

[AlexN]

gary. That is step 2 in my 'get the thing to focus!' plan.

[monoxide]

if you are atleast half serious about taking some images it would be best to replace the focuser completely with something like a gso 10:1 low profile,
they are cheap enough and will save you a lot of bother in the long run.
there are a number of things that can go wrong when imaging but focus is the one thing that you can always nail.

i dont know how easy it would be to fit it to the skywatcher but i guess you would just have to drill 4 new holes, if your still not sure or dont want to do it yourself you could take it to the machinist you were going to take the adapter to (with both mirrors removed from the ota) and say 'i need this to fit here' im sure it wouldnt cost much if you were to get them to roll a bit of scrap flat that would bolt to the focuser and the tube and it would be far superior to the standard focuser.

on top of that i always thought it was a waste of time trying to collimate anything to any degree of precision when the focuser tube slops around enough to ruin it anyway.

[AlexN]

the skywatcher crayford focuser on my tube is very nice as is.. I wouldn't mind a 10:1 but i suppose every little bit helps.

[davewaldo]

I wouldn't recommend the GSO 10:1 low profile focuser. From what I have seen they have issues with tube sagging under weight.

I think the standard GSO 10:1 would be a great focuser. And from what I read in this thread, it would probably come to focus. By that I mean you would be able to sit the MPCC into the GSO focuser and this setup would be similar in height to your existing focuser.

Might be easier and better than trying to machine a new part. If you imaging, your going to want 10:1 focus eventually.

:)

[vash]

The only problem I have with the focuser is that it's harder to fine tune, other than that it's fine, If I where to update the focuser I would go for the non motorized JMI, after having a play with it at the shop I can understand why it's at it's price, plus the MPCC will fit into it no problems.

[AlexN]

yeah the JMI focusers are SMMMOOOOOOTH!!

[vash]

I did just make myself a slow control for the stock focuser, a thin screwdriver on the screw in the middle of the focus knob ( just be sure not to undo it), not as good but I can turn the focuser a lot slower with it than the knobs.

[monoxide]

i wasnt trying to imply that the gso 10:1 was a high quality focuser just that it would more than likely be easier to drill 4 holes and bolt it on and have it come to focus rather than getting bits machined to fit a standard skywatcher focuser only to upgrade it to a 10:1 later on anyway.

the low profile version may not be perfect or buttery smooth but you have to expect that for $100, the low profile wouldnt come to focus on my newt so i ended up swapping the 10:1 part over to my standard gso focuser, the result when i added motofocus was impressive giving me VERY fine focus control. plus when it comes to imaging id rather be exposing than tweaking focus by hand then waiting for the vibration to settle before inspecting again, now instead of guessing focus by eye i can watch the FWHM on the laptop screen and within 1 minute i know my focus is as good as its going to get.

you could argue that for the price of the gso 10:1 + motofocus you could get a JMI but i can guaruntee that it would be a lot harder to focus with the non motorised JMI even if it is of a better quality than the gso.
i should also mention that if you are into planetary observing, a setup like i mentioned can make a massive difference in the detail visible, only after seeing this did i realise how much of a difference it really did make.

[vash]

well, it's a bit too late now, I got the new adapter back from the machine shop, as soon as I got home last night I had the dob out and focused on Jupiter, And I could!!

I gave it another go this morning on the moon, not the best time to image it but hey, it shows I can focus finally and I have a little bit of travel left too.

thanks to everyone for going through all this.

here's a pic of the new adapter with the old and the moon test shot (there a bit of JPEG compression).

can't wait to get it under the stars now.

[AlexN]

how much did it cost u??

[vash]

I think it was about 40 bucks, A little more than I was hoping but If you look around you could find somewhere cheaper, these guys where down the road from where I work so I just picked it up on the way through, more convenience than anything and I needed it done.

[gbeal]

Perfect result. Now get some DSO's done.

[vash]

yep, I real happy now, only thing is I'm back working again, I might set up tonight and put in an all nighter. If it's clear which I doubt it will

[AlexN]

best of luck with the weather mate!