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Just got an Off Axis Guider

Catanonia

By Catanonia
in Imaging - Discussion

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Catanonia

Catanonia

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Thanks for the great service from Rother Valley, Just recieved a Lumicron Off axis Guider for my refractors.

So watch this space for reviews and comments on how I get along with it. Looks nice, but expensive at £200.

Hopefully can get some really long exposures now with no worries of flex etc.

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Catanonia

Catanonia

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Hopefully 1st attempt tonight mate.

Will try and post something afterwards.

Having to mix and match at the moment. I align using the guide scope and PHD crosshairs, but can't do that easily with OAG, so I am using the guide scope with QHY5 and phd to align and then moving it to the OAG for guiding.

I do it this way as I get BANG on alignment with the goto system rather than rough alignment with the finder scope.

Hopefully it will work if I can get all the focusing correct.

Fingers crossed.

I might end up using the spare web cam on the 2nd scope for alignment via PHD so i don't need to swap the QHY5 over.

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Catanonia

Catanonia

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ok 1st impressions so far tonight.

1. Very easy to fit onto a refractor and comes with the T Adapter for Canon EOS range. I could easily use my wide T Adapter in place of the supplied one.

2. QHY5 fits perfectly into the 1.25 slot.

3. Focusing the guide camera is an absolute &&&*& No easy focuser, it is held in place by 2 thumb screws and you must slowly wedge it in place and check focus on phd live view. If it the QHY5 is slightly off angle, with the area of the scope it is using you get bad egg shaped stars. Focusing on a guide scope took seconds with a b mask, with OAG i struggled to focus by eye on the screen yet alone even attempting a B mask because of the crappy way of focusing with the grub screws.

Basically I screw the guide cam where i thought focus would be, then check, then un did the screws, moved it a nats &*(& and tried again and again.

Now I was centered on capella, but of course Capella isn't in view so no way of focusing on it with the B mask.

Might have to play and align 1st, then get Capella onto the OAG chip to focus next time, that will be a fun guessing game :)

3. The light from the prism to the guide cam seems much much dimmer making aquiring a target very difficult. It may be me, but not sure.

4. Of couse you are limited to guide stars and it is a hoping came when you have framed your target, that you have something bright enough to go for. See above.

Oh well only 1 hour into the test and just properly getting dark. Lets see what happens,.

Cat

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Merlin66

Merlin66

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If you set the OAG so the pick off prism is sitting say along the dec axis, then you can focus the guide camera on a bright star by just moving the scope slightly in Dec, then moving it back again to centre the same star on the imaging camera.....

Get's easier with practise...

Ken

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Catanonia

Catanonia

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If you set the OAG so the pick off prism is sitting say along the dec axis, then you can focus the guide camera on a bright star by just moving the scope slightly in Dec, then moving it back again to centre the same star on the imaging camera.....

Get's easier with practise...

Ken

yup trying that now on vega, is hard..... might have to re-set up again to do it properly.

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Catanonia

Catanonia

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ok on the plus side.

Just done 4 x 15 min subs on M33 and not a hint of eggy stars. So yes it works, but not as easy as a seperate guide camera.

Still getting to grips with it, but jury is out yet. 50 - 50 but more swinging towards liking the OAG at the moment.

Going to test a 30 minute exposure now, see what happens... 15mins on the ED120 guided via the ED80 was difficult.... lets see

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Merlin66

Merlin66

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Sounds good so far........

What about posting a couple of photos of your set-up?

If you set the guide camera and use a locking ring (or similar) then you don't have to go through the focus- focus routine the next time you use it.

Just set up the target object in the imaging camera and then see what the "best" guide stars are......

( Same issues as a two chip self-guiding SBIG)

Ken

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Catanonia

Catanonia

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Holy f%& wow ... sorry for the mild outburst :)

30 mins guiding with the ED120 off axis and the QHY5 / PHD

M33 in bad light pollution and mist from Sandbach tonight. 30 mins YES 30 MINUTES sub........

Got about 1.5 hours worth of them now :eek:

Here is a raw sub with a Clip LP filter inplace and totally unaltered other than reduced in size from 3888 pixelsand converted to JPG

ED120 OAG via Lumicon OAG and PHD / QHY5 via EOS 1000D Baader modded with CLS CLip LP filter.

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Catanonia

Catanonia

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So.... now you've had time to sleep on it.....

Did it work for you???

Yes and no to be truthful.

Need to work out properly how to focus the guide camera by aligning with either RA or DEC so I can get a B mask on a bright alignment star. Then it should solve alot of my issues.

Setup time has increased by about 15 mins, but this should come down when I get used to it.

Will certainly persist with it and hope can sort out the focusing issues with the grub screws.

Love the fact that once I am focused and guiding, I can take what ever length subs I want now. Fantastic, leave the imaging for 30mins with the LP filter and the results show for themselves.

AT work at the moment, so can't process the data, but am sure will have much better images and detail with the longer subs.

Cat

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Merlin66

Merlin66

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Sounds promising......

If you can fit a locking/ spacer collar to the nosepiece of the guide camera, once this is correctly positioned you no longer have to worry about setting the guide.

Just drop the guide camera in, frame and focus the target object in the imaging camera and let PHD select what ever star is there in the field to guide on......

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Catanonia

Catanonia

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Sounds promising......

If you can fit a locking/ spacer collar to the nosepiece of the guide camera, once this is correctly positioned you no longer have to worry about setting the guide.

Just drop the guide camera in, frame and focus the target object in the imaging camera and let PHD select what ever star is there in the field to guide on......

not sure how this would be possbile as the 1.25 opening is snug and no room for anything else.

Only way i can think of is a collar that goes over the guide came 1.25 barrel that is precisely machined to the right thickness, but this would be a b&*(& to make precisely.

Do you have an example picture or site / product.

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Merlin66

Merlin66

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Thats the one!!

I use one of these parafocal rings on the nosepiece of the QHY5.

Depending on the backfocus of the camera (ie MX7c vs DSLR) I have to add a 1.25" x 25mm extension tube to the guide port, but once its set up its "plug and play"

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Catanonia

Catanonia

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Cat,

What about uploading an image of your set-up showing the OAG, the imaging camera and the guide camera? Make it a bit easier for others ( who haven't tried OAG yet) to understand??

Ken

good idea, will make a separate thread in a few days explaining how i have done it as well as the basics.

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Merlin66

Merlin66

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For the Doubting Thomases....

The size of the pick -off prism is 10mm which will cover the full CCD chip in a QHY5 so the area being guided on is as large as can be accommodated by the camera at the focal length of the scope. ie if you used the same guide camera on a guide scope with the same focal length you'll see the same field of view.

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