So I finally got my MPCC and have it attached to the camera via Canon EOS T-ring.
Problem is that my 2 inch adapter is huge and is causing a lack of in focus. Furthermore connecting the MPCC directly into the focuser is a no go as the focuser is too big.
I don't want to raise the primary and am reluctant to buy a low profile focuser. I read that someone had similar issue and they were able to get the 2" adapter cut to meet the requirements. I may need the same and if someone can help me/point out where to, with the cutting part I would be very grateful.
All you need to do is connect the MPCC to the Tring and insert that into the focuser, you dont need any extensions.
The MPCC, once screwed into the Tring should be at the optimum distance for the imaging chip, and actually my require 10mm of out focus.
Would be better if you did post pics, so we can see what you mean, though.
Focuser is too big?? Is it bigger in diameter than 2"? On a Skywatcher?
So my problem is that the 2" adapter is great but I lose my focus point as the adapter increases the distance to the secondary. And without the 2" adapter my MPCC is too small to put in the focuser..If I could somehow cut the 2" to only have 1cm profile then it could get interesting..
"The MPCC has a 2" barrel and thus forms its own nosepiece which is great BUT to get a 2" pushfit on your focus tube you have to put the supplied 2" adapter into the non-standard throat (57mm dia. approx) of the focus tube and this extends out by 36mm whereas the 'T' thread adapter that is exposed when you unscrew the 1.25" EP holder is flush with the end of the focus tube. 36.0 - 10.0 means that you have extended the system by 26.0mm and therein lies the problem"Source
Wow, that is......silly! Why...57mm?
What you could do is buy a better focuser, which would be my thoughts, and drop kick that one as far as you can!
The other thought is to have a small collar/reducer made that has a flange on it to stop it falling in that sits in the focuser draw tube and allows the MPCC to go inside it. I will draw a piccy of what I mean and post it shortly, gotta take the kids to school now.
Scrap that, it wont work!! Can you have the adapter that you've got machined short enough to retain the locking screws and give you focus?
Other than that, it will be another focuser, unless someone else has seen this before.
Yes, I had exactly the same issues as described here. I've managed to get by nicely with the "Vash fix" you've referenced earlier.
One thing I'd suggest first is put your T-ring on your DSLR, then screw the MPCC on to that. Point the OTA at the most distant tree/object you can (at least 50m away) and check where you will need the camera/MPCC to sit (just hold it manually in the focuser yourself, and watch where the camera ends up for prime focus). Do this with no adaptor at all in the focuser. On my telescope I found I would be right if the focuser was 3-4 mm out from max inward travel. However, JJJeanette has one of the new black diamond 8" OTAs and still couldn't get focus - its a close thing (I have the older blue 8" OTA). If you're in that situation, only thing would be to use the adjustment screws on the main mirror to gain a few mm, or cut down the OTA.
I can relate totally to your fear of not wanting to cut the OTA. Apart from not wanting to hurt my baby, I didn't want to have to use a spacer for visual.
Current cut down ht of my 2" adaptor is now 22mm
This is a close thing - you have to get it down enough for focus, but also leave room for the odd filter mounted on the front of your MPCC, however leave a decent amount of adaptor to hold everything steady. I got an extra thumbscrew drilled as did Vash, but actually never use it - the fit is surprisingly firm. Note that even though I didn't have to cut the OTA, I do have most of the focuser tube obstructing incoming light now the focuser is screwed in so far, so in some ways you probably are better cutting the OTA perhaps.
You'll need to find an engineering machine shop that does small custom jobs in the Yellow pages. The apprentice did mine in 10mins on the nice industrial lathe they had, 1000 times better than I could have done with a hacksaw.
Good luck! I haven't taken any pics as all the gear is packed away from the kids, but give me a yell (PM or post) if more info required. Vash's pics are exactly what I have now anyway (see post #35 in his thread).
Regards,
Rob
p.s. I actually think the Skywatcher crayford focuser is pretty good - enough so that you usually have plenty of other weak links in the chain to sort out as a higher priority (tracking, flexure, software, processing, etc, etc). Once you start spending a few hundred dollars or more on a new focuser I worry about spending too much on a $500 OTA. You do need to use the locking screw, and that will slightly affect focus, but you soon get a feel for that.
Yugant
Like Rob and yourself, I had the same issue. I just got my adaptor and cut it down with a hacksaw. In total my adaptor is now 25mm in length. And like Rob said, leave enough room on the adaptor to hold everything. Mine is 13.2mm above the collar. After I cut the adpator I drilled and tapped 3 holes to secure the MPCC. It took me about 5 minutes to cut it using the hacksaw. Works perfect.
If you can't find someone to do it, and you try it yourself, I found it easy by drawing a line around the entire circumference. Then as I cut, I just rotated the adaptor in the vice to make sure I stayed on the line. Ended up nice and square.
So I finally got my MPCC and have it attached to the camera via Canon EOS T-ring.
Problem is that my 2 inch adapter is huge and is causing a lack of in focus. Furthermore connecting the MPCC directly into the focuser is a no go as the focuser is too big.
I don't want to raise the primary and am reluctant to buy a low profile focuser. I read that someone had similar issue and they were able to get the 2" adapter cut to meet the requirements. I may need the same and if someone can help me/point out where to, with the cutting part I would be very grateful.
I'll link the pics later today Once Im back home.
Take Care.
Purchased a standard GSO Crayford and put that on the SW_BD 254mm. Attached Baader MPCC to Canon 400D.
Inserted the nose piece from the MPCC into the crayford and Bobs your Uncle.
Have around 2mm of travel to achieve focus for DSO which is no problem.
Hi Mate! Did the GSO focuser size match the existing SW focuser or did you drill new holes?
Regards
Nope. Had to drill new holes. Not to hard. Tape some material on to the inside of the tube, under the hole of the focuser, and tilt it slightly forward so you catch all the shavings. Also the new holes will be covered by the original focuser if you need to resell.
A simple and unobtrusive modification has been done.
- No chopping the tube
- No dodgy GSO focusers
I did some machining work which manav will post up here soon,
I reamed out the draw tube collar to just allow a 2" piece though, not a tight fit but firm.
then using a 2" adaptor piece i lathed down the collar to just have the end piece that inserts into the drawtube collar, to this i drilled and tapped 3 holes that had 3 1.5mm grub screws, i also added an additional thumb screw for the 2" drawtube collar.
now with the new collar adapted to the MPCC permanantly you can slide it in and out just as you would with the 2" and 1 1/4" set.
even if you could make it work those skywatcher focusers are absolutely horrible, the standard gso 10:1 crayford is actually a pretty decent focuser. as a bonus you can get the JMI motofocus to fit them and it works an absolute treat.
i still use my jmi motofocus on the Tak.
the low profile 10:1 gso is another matter entirely, avoid at all costs...
even if you could make it work those skywatcher focusers are absolutely horrible, the standard gso 10:1 crayford is actually a pretty decent focuser. as a bonus you can get the JMI motofocus to fit them and it works an absolute treat.
i still use my jmi motofocus on the Tak.
the low profile 10:1 gso is another matter entirely, avoid at all costs...
Hi Tj,
I agree about the GSO 10:1 focuser. It's quite well made as you say and
with some tweaking can work even better. I motorised mine myself.
I'm interested in why you don't like the low profile version?
I was about to buy one just to pull it to bits and rebuild it from
the ground up with better tolerances.
FWIW as far as Baader MPCC adaptors go , if it's any help here
are some details of one I recently built. It has adjustable spacing
centred around 55mm.
Posts 14 and 17 in this thread: http://www.iceinspace.com.au/forum/s...ad.php?t=56332
i bought a low profile 10:1 focuser for a 6" astrograph and it was just junk, it couldnt handle any weight at all it was either all or nothing.
in the end i think it pretty much fell apart, i just gave up on it.
the drawtube on them is also really short so it may actually end up too short for what your trying to do
The standard rack and pinion focuser on the skywatchers is just that snot! but the one thats on my 10" is fine. sure it flips around abit but hey its standard kit.! for people who cant afford to go out and purchase 150-200 dollar focuser modifying the ring to fit is perfect if you can do it yourself, its free if not get somebody to do it for you and it shouldn't cost you much at all aka 30 odd should see it done.
Ive had no problems with the skywatcher crayford focuser to date, though i will be upgrading it will be for precision reasons and in anycase im going to build one myself an external crayford type. Its just lucky im hanging around engineering type people (being a engineer myself ) especially those in Mechatronics so i have spoken already and a friend of mine is going to be writing a ascom compatable driver for a PWM motor, virutally giving me a computer controlled motor... easy as.
As Brendan described above the drawtube collar has been modified to allow 2inch MPCC to fit in perfectly without any obstruction. Furthermore, the 2" adaptor was cut to allow enough infocus. I have attached the instruction/design sheet Brendan composed and hope it helps future astronomers.
Thanks Brendan for your assistance I just wish I was in Perth so this transition into astrophotography would have been so much smoother.
Take Care and God Bless you all!
PS: Sorry for the late update life's been busy recently..
Last edited by Manav; 17-05-2010 at 11:22 PM.
Reason: Update
Custom adapter for MPCC and Skywatcher Reflectors
Why...57mm?
Can you have the adapter that you've got machined short enough to retain the locking screws and give you focus?
