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Old 12-02-2016, 06:51 PM
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billdan (Bill)
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MPCC and OAG on the way

Well I turned 65 last month and retired from the work force yesterday.

So to celebrate I spent some of my dwindling Super, and purchased a MPCC-MkIII and the Orion Thin OAG.

I am hoping between the two there will be enough spacers provided to get the 55mm spacing required for the CC to work correctly. I worked it out I need a 25mm spacer. The width of the OAG is 10mm and the CCD chip to the front of the camera is 20mm.

If you hear on the news of an old bloke tearing his hair out, its me.

Regards
Bill
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Old 12-02-2016, 07:24 PM
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traveller (Bo)
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Hope you have enough hair to pull out Bill
I am just experimenting the same with my 10" SN, MPCC, Orion thin OAG with QHY8 ccd and QHY5L-II guider. Took me better part of 4 hours under the stars to get the cameras to focus, but not at the same time! I still have to play with some spacers to get them both right.
Anyway I have a better idea for the focusing distances now and will post a photo with measurements once I get successful focusing on both cameras.
Hopefully it will only take 3 hours tonight
Cheers
Bo
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Old 12-02-2016, 08:05 PM
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billdan (Bill)
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Gooday Bo,

I don't have much hair left on top, so its going to come off the sides.

Looks like we have similar setups, so yes please let me know the dimensions of the spacers you come up with.

My strategy was to get the CC working properly first with the QHY12 and then insert the guide cam and get that working.

Regards
Bill
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Old 12-02-2016, 09:28 PM
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traveller (Bo)
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Yep, I got the ccd working in next to no time, but is the guide cam that buggers you up each time. Position of the prism, how much it sticks out, not to mention patience in focusing....
Will post as soon as I have it working!
Bo
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Old 12-02-2016, 10:21 PM
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Eden (Brett)
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G'day Bill,

I found that to get the QHY12 correctly spaced with the MPCC-3, a couple of 1mm spacers were required, on an 8" F/4. The internal sensor-to-glass distance is 20mm.

With the Orion Thin OAG, care needs to be taken with the guide camera shaft -- it is secured with two small grub screws that are made from a soft metal. They can wear out after a few uses, causing the shaft to move around when the camera is attached. Otherwise, it's a great little OAG
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Old 13-02-2016, 02:19 AM
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billdan (Bill)
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Thanks for the warning on those grub screws Brett, I shall be very careful and try not to strip them.

From what you are saying I may also have to buy some 1mm spacers. I'll cross that bridge when I come to it.

Thanks
Bil
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Old 14-02-2016, 10:06 PM
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After a few hours of cursing and scratching my head, I think I got it all together now.
The image train from scope to CCD is as follows:
Focuser - MCPP (with MPCC adapter) - TOAG body - 18+5mm spacers - 13mm nose piece from the QHY camera - CCD itself.
For the guider, I had to screw off the C mount adapter and plonk the guider body into the 1.25" cup and secure it with the two grab screws from the side, secure enough.
I tested the setup under the stars, and the focus is spot on with the CCD but slightly soft with the guider, which is fine as it still allows for picking up guide stars.
This set up does have a downside: the distance from back of MPCC to CCD is now 62 mm (due to the extra 5 mm spacer added to the 18 mm spacer). However, if I remove the 5 mm spacer, I need to lower the guider by equal amount, and I just don't have any spaces left to remove between the guider and the OAG body (except the two adjustment flanges between the body and the guider "cup").
Anyway, this is the current set up for people's information.
Cheers
Bo
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Old 14-02-2016, 10:33 PM
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Update.
I managed to remove the side to side adjustment flange which is 5 mm tall. If my calculations are all correct, this will allow me to remove the 5 mm extra spacer between the 13 mm stock nosepiece on the ccd and the 18 mm spacer which came in the TOAG kit. I have now achieved the 55 mm between the MPCC and the ccd sensor.
Bo
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Old 15-02-2016, 01:19 AM
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billdan (Bill)
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Congratulations Bo, glad to see you have got everything setup and working, shame about having to remove the side to side adjuster.

I hope it doesn't compromise your ability to find guide stars.

Got an email from Aust Post they picked up the kit from Bintel on Friday and the Postie on his push bike will arrive here on Wednesday.

I'm sure I'll have more questions for you later when I have a go.

Cheers
Bill
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Old 03-03-2016, 02:42 PM
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billdan (Bill)
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MPCC/OAG Complete and working

Just to complete this thread and give you my experience of getting everything working. I had the flu and clouds etc, so I only got started last night. Still took me 3 hours to figure it all out.

Problem No.1 When I screwed the 18mm spacer between the QHY12 and OAG, the prism was sitting on the RHS corner of the QHY12 chip (which was useless IMO), so I created and printed off two 42mm washers 0.5mm thick and placed one on each end of the 18mm spacer. Now when its tightened down the prism is dead centre.

I also printed a 42mm washer 1mm thick and placed that on the MPCC T thread going into the OAG, this now gives me the exact 55mm as required for the MPCC to work correctly.

Problem No.2 As Bo said I also had to remove the 5mm tall side to side adjuster to get the lodestar to focus, but I replaced it with a plastic clone that I created and printed, I tried a 1mm, 1.5 and eventually a 2mm tall piece and that got me perfectly parfocal with both cameras.

I did a quick test last night.

The MPCC is behaving perfectly, round stars right into the corners, the only worry I have is the focus seems a bit soft compared to no MPCC. So I am keeping my fingers crossed that better collimation will cure this, which I'll try later this weekend.

What blew me away was the guiding, the best I have ever achieved with the Orion mini guidescope was 1.2 arcsec, but with the OAG I am now getting 0.55 arcsec guiding at 3sec exposures on the lodestar.

Cheers

Bill
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Last edited by billdan; 03-03-2016 at 03:39 PM.
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