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How does this work?!?!

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Hi all,

Spoke to FLO today about piggybacking an ST80 using the ADM Vixen Dovetail Plate Adapter (VDPA), but I can't for the life of me figure out how it possibly works. Could anyone try and explain to me please how it works?

If anyone has one on their scope could they please send me a pic?

Cheers

Cam

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Spoon

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I would imagine you need a vixen dovetail bar fitted to the top of your main scope. You then screw your ST80 to the VDPA through one of the holes and then clamp the VDPA to your top dovetail.

That's what I'm thinking, but surely, by looking at the picture, you'd have to mount the dovetail upside down?

Cam

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Tinker1947

Tinker1947

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They look quite good to me to be fair, for £130 for the rings, two VDPAs and a dovetail. Would I need the 90 or 100mm rings for the st80?

I e-mail FLO and they adviced on the size, this was some time in the past, i would recommend another e-mail they will respond in time for a order to be dispatched today.....

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Astroboffin

Astroboffin

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They look quite good to me to be fair, for £130 for the rings, two VDPAs and a dovetail. Would I need the 90 or 100mm rings for the st80?

The ST80 comes with its own tube rings, which are fixed in size for that scope, I used them, then there is no chance of any flexure, just bolt the two clamps to the mount holes on those rings and away you go.

if you bought the ST80 secondhand and there were no rings with it, then they can be bought for around £19 from outlets such as here:

http://www.wexphotographic.com/buy-sky-watcher-80-90mmmm-tube-ring-set/p1530814?cm_mmc=googlebase-extension-_-astronomy-mounts-_-tube-rings-and-plates-_-sky-watcher-tube-ring-set-for-80mm-90mm-refractors_1530814&utm_source=googlebase-extension&cm_mmc=google+-+warehouse+cameras+%26+lenses-_-shopping+-+other+products-_-&mkwid=3iw12qr3&pcrid=72342100209&gclid=cjwkeajwpyeqbrdowq2drlcb-ucsjaasiylj9wnptgvekvzg3urtidwhdnnej5oq4c2tq6adgsxalroc8e3w_wcb

These are the ones for the ST80, personally I would go for these, as they are much cheaper and as I said before no chance of flexure and perfectly aligned right from the off

Regards

AB

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Spoon

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They look quite good to me to be fair, for £130 for the rings, two VDPAs and a dovetail. Would I need the 90 or 100mm rings for the st80?

The ST80 comes with its own tube rings, which are fixed in size for that scope, I used them, then there is no chance of any flexure, just bolt the two clamps to the mount holes on those rings and away you go.

if you bought the ST80 secondhand and there were no rings with it, then they can be bought for around £19 from outlets such as here:http://www.wexphotographic.com/buy-sky-watcher-80-90mmmm-tube-ring-set/p1530814?cm_mmc=googlebase-extension-_-astronomy-mounts-_-tube-rings-and-plates-_-sky-watcher-tube-ring-set-for-80mm-90mm-refractors_1530814&utm_source=googlebase-extension&cm_mmc=google+-+warehouse+cameras+%26+lenses-_-shopping+-+other+products-_-&mkwid=3iw12qr3&pcrid=72342100209&gclid=cjwkeajwpyeqbrdowq2drlcb-ucsjaasiylj9wnptgvekvzg3urtidwhdnnej5oq4c2tq6adgsxalroc8e3w_wcb

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Tinker1947

Tinker1947

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The difference between the SW tube rings and the adjustable tube rings is just that, my ST-80 is aligned perfectly with the main scope, when it come to Polar alignment or centring a DSO for imagine i use the PHD screen with the bulleyes option, if its in the centre of the bullseye is in the centre on my camera sensor, you need tube rings with adjusters to do this, for me the extra money has been well spent, as for flexure there is none....

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Spoon

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The difference between the SW tube rings and the adjustable tube rings is just that, my ST-80 is aligned perfectly with the main scope, when it come to Polar alignment or centring a DSO for imagine i use the PHD screen with the bulleyes option, if its in the centre of the bullseye is in the centre on my camera sensor, you need tube rings with adjusters to do this, for me the extra money has been well spent, as for flexure there is none....

Does the £130 kit from FLO come with everything? Rings, VDPAs, dovetail etc?

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Astroboffin

Astroboffin

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The difference between the SW tube rings and the adjustable tube rings is just that, my ST-80 is aligned perfectly with the main scope, when it come to Polar alignment or centring a DSO for imagine i use the PHD screen with the bulleyes option, if its in the centre of the bullseye is in the centre on my camera sensor, you need tube rings with adjusters to do this, for me the extra money has been well spent, as for flexure there is none....

For guiding it only need to be close, infact as long as all is fitted straight and tightened down, it will be in perfect alignment without any fiddling around to do, assuming the mount holes in the OTA are in alignment then all should be good, works perfectly for me and I image through the piggybacked scope and the gotos are spot on for it.

Regards

AB

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Tinker1947

Tinker1947

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For guiding it only need to be close, infact as long as all is fitted straight and tightened down, it will be in perfect alignment without any fiddling around to do, assuming the mount holes in the OTA are in alignment then all should be good, works perfectly for me and I image through the piggybacked scope and the gotos are spot on for it.

Regards

AB

Your missing my point of the guide scope being aligned with the main scope precisly, i can use the handset option to Polar align, for me this is sit with the mount one side a pc the other watch the pc PHD screen and adjust the T-bolts ect with out stinting through finder scope, for DSO the PHD screen shows them i centre them and sync then in Stellarium/CdC with out moving from my chair, all very compfy stuff to do, no back aches, bruised knees ect.....without the adjustable tube rings tracking will still work the scope doesn't need to be perfectly aligned, my way is just a lot quicker and comfortable....

My set-up...

60a5f565-72d0-42d1-88e3-60773aab5905.jpg

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Astroboffin

Astroboffin

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Your missing my point of the guide scope being aligned with the main scope precisly, i can use the handset option to Polar align, for me this is sit with the mount one side a pc the other watch the pc PHD screen and adjust the T-bolts ect with out stinting through finder scope, for DSO the PHD screen shows them i centre them and sync then in Stellarium/CdC with out moving from my chair, all very compfy stuff to do, no back aches, bruised knees ect.....without the adjustable tube rings tracking will still work the scope doesn't need to be perfectly aligned, my way is just a lot quicker and comfortable....

My set-up...

60a5f565-72d0-42d1-88e3-60773aab5905.jpg

Sorry I think your predictive text has run riot in that post.....

Yes I see you point....I think, so you basically use the guide scope as a huge finder with a camera to see the view on the PC screen, rather than use the actual finder scope, so you need absolute perfect alignment for the gotos to be spot on.

Have I got that correct?

If so I still don't think you need it to be perfect due to the differences in the FOV, a slight mis match would not really be noticeable, in my method the two scopes are perfectly parallel, so basically looking at a piece of sky about 6 inches apart, which in the grand scheme of things is nothing.

Does that make sense to you, I think it does to me....lol

Regards

AB

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Spoon

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Right ok I think I get it, but judging by the FLO photo of the VDPA you would have to mount the dovetail upside down provided the setup went 8" scope rings -> dovetail -> VDPA. Or am I missing something big here? Does it take the above order or do you do 8" rings -> VDPA -> dovetail? Notice the difference in orders.

Cam

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Tinker1947

Tinker1947

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Sorry I think your predictive text has run riot in that post.....

Yes I see you point....I think, so you basically use the guide scope as a huge finder with a camera to see the view on the PC screen, rather than use the actual finder scope, so you need absolute perfect alignment for the gotos to be spot on.

Have I got that correct?

If so I still don't think you need it to be perfect due to the differences in the FOV, a slight mis match would not really be noticeable, in my method the two scopes are perfectly parallel, so basically looking at a piece of sky about 6 inches apart, which in the grand scheme of things is nothing.

Does that make sense to you, I think it does to me....lol

Regards

AB

The guide camera is a lodestar they don't have a huge sensor so with the PHD screen a little is a lot on the DSLR Sensor, and getting them perfect is for Polar Alignment, last time i aligned a 3 minute sub unguided showed round stars, i will next time out check the sub length to show a tracking error......

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Tinker1947

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On my tube rinds the 250P-DS ones they have 1/4" UNC threaded studs sticking out these go through the dovetail bar and the knurled knob normally used for a camera base locking knob holds them in place..as per the my first picture....

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On my tube rinds the 250P-DS ones they have 1/4" UNC threaded studs sticking out these go through the dovetail bar and the knurled knob normally used for a camera base locking knob holds them in place..as per the my first picture....

Right ok but your dovetail has a slight indent on it, so how would you mount it on say the Skywatcher ones

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I just popped out and had a look, the Dovetail bars sits straight onto the P-DS tube ring lug, with the knurled knob holding it in place...

Aaaaahhh right I've got it now. I was really confused at to how it all fitted together. Cheers everyone

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