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Old 10-11-2011, 08:47 AM
Poita (Peter)
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Recommend an OAG?

I have been using off axis guiding for some time with SCTs and would like to do the same with my 4" refractor.
Can anyone recommend an OAG, I am currently running a QHY8 camera, and I'd like to take the ED80 scope and guider off the mount and just have the 105/650 running with an OAG.
Any suggestions appreciated!
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Old 10-11-2011, 09:55 AM
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Marke (Mark)
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Peter I have found the Hutech to be really good and totally cusomisable
I posted some pics here : http://www.iceinspace.com.au/forum/s...ad.php?t=77439
They have 2 sizes , I have the OA5 I have never been lost for a guide star and havent had to touch
the adjustment for my setups.

Mark
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Old 10-11-2011, 09:56 AM
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Depends a bit on the camera I reckon. With me using a Starlight Xpress, then the choice was simple, really smile.
Starlight camera, Starlight OAG, and Starlight CFW, with a Lodestar (OK so it is Starlight as well). Believe me, I was concerned because almost every forum post you read tells you that an OAG is THE most frustrating thing to set up. In my case it was about 2 minutes from go to whoa. Really plug and play.
Using a QHY8 (or any OSC camera) makes life a bit simpler as you don't have the CFW to get in the road.
Try a few of the available ones out there, the Teleskop Service one at 9mm is good as well.
My decision was simpler obviously.
Gary
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Old 10-11-2011, 10:36 AM
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hehehe.... if you have the skill to be a technical twinkle finger then click on the here's

here -----> 3" OAG here
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Old 10-11-2011, 10:41 AM
Poita (Peter)
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Twinkle finger?
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Old 10-11-2011, 10:48 AM
gbeal
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Nice Brendan, nice, apart from the knob, LOL.
What prism did you use?
Gary
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Old 10-11-2011, 10:57 AM
Poita (Peter)
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Oh, I see, making my own you mean?
I have the equipment and expertise to do so, a mchine shop full of CNC gear, but don't know the ins and outs of designing one.

http://brendanmitchell.net/wp-conten...st-425x215.jpg
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Old 10-11-2011, 10:59 AM
Poita (Peter)
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I am using a QHY5 currently as an autopguider, but am considering upgrading to a lodestar. The main camera is currently a QHY8
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Old 10-11-2011, 11:00 AM
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you got it peter technical twinkle fingers I am adept at making 5h17 work! and creating something from nothing without plans. As for the prisim. there is no prisim! its very rudimentry in application! I had purchased a waste of space little scope that could barely see a street light for my son ages ago so i sacrificed the diagonal and inserted it onto a 45 deg post here is the blog that has a few more images once i get my ass into gear ill take a picture of the pick mirror

Oh yeah gary I was in a rush when i did that little knob as it was 930pm and my gf at the time was whinging to get out of there hahaha so i wizzed it up with a mind to redo it soon. 8 months later. Hopefully ill get the whole thing annodised and sorted out.
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Old 10-11-2011, 11:04 AM
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dude it is so simple its not funny......

its a hollow circle with what ever connection you have on one side and on the other side what ever connection you want. a 1/4" adaptor to a small hollow post and a piece of mirror. as long as you get a stable centroid to your guiding camera the rest is history and trust me i guide on bannanas! So don't listen to anybody that tells you you must guide on a perfectly round star its a load of Cr4p.... My stars tell you the truth. 26kgs of Newtonian mounted on a EQ6pro rated at less.....
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Old 10-11-2011, 11:22 AM
Poita (Peter)
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It looks pretty basic, I just hadn't really thought of doing it. With the constant rain here, I might have a go this weekend, I have a shelf full of old diagonals I could use for the mirror.
Anyone know which commercial units are worthwhile if this all goes pear-shaped
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Old 10-11-2011, 11:30 AM
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http://www.teleskop-express.de/shop/...enge-31mm.html

If you have a CNC shop. just think about what it is look at some photos and well its not much more complicated than that. Telescopes are not complicated creatures its a simple fact of a tube... with mirrors/lenses. get it square get it straight make sure its rigid and youll have no issues!
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Old 10-11-2011, 11:32 AM
Poita (Peter)
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Thanks Brendan,
at that price, I think I'll have a good go at knocking up my own. Especially as I'm unsure how well OA Guiding will work with a 4" refractor.
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Old 10-11-2011, 11:38 AM
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Itll work perfectly, that OAG is what is being used on a BD 120mm with a orion SSAG. Just remember the focus point is quick to move though but once you figure it out happy days
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Old 10-11-2011, 10:17 PM
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What is the BrendanShop.com charging for a custom OAG?
Why is this astronomer stuff always worth a arm and a leg?
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Old 11-11-2011, 07:39 AM
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Quote:
Originally Posted by Poita View Post
Thanks Brendan,
at that price, I think I'll have a good go at knocking up my own. Especially as I'm unsure how well OA Guiding will work with a 4" refractor.
It works perfectly fine Peter as I have already done it with mine
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Old 11-11-2011, 11:03 AM
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Yugent.... it depend how crafty you are to depend on the cost. I know who ever ends up with bertha will have a finely tuned machine. who knows i might drop the standard mirror out of it and drop in a hand figured piece!

Go for gold on your OAG they are easy, dispite the issues people have had with them. all i do is put mine in, and use the focuser to focus the stars dis regarding the primary cameras focus. then i know the difference between the primary focus and the camera focus. its elementary then to put the guide and imaging camera about the same distance and once you have focused the primary camera again you move the guiding camera the distance you measured previously. bingo your done.
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Old 12-11-2011, 05:58 AM
Poita (Peter)
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Quote:
Originally Posted by Manav View Post
What is the BrendanShop.com charging for a custom OAG?
Why is this astronomer stuff always worth a arm and a leg?
Small production runs. The cost for me to build say one oag would be huge if I had to charge for time. doing the initial drawings and design. To write the program for the cnc, make a couple of prototypes, test them, retweak the program for speed etc. would be a couple of grand. So to make one would cost say $2500. To make 100 might only cost $300 each. Then they have to be packaged, freighted, warrantied (add another $80). You want to make a prrofit, so add about 30% and round it up to $500, and the retailers will want to sell it for double, so $1000, add GST and you are at $1100. That is assuming no distributor taking their cut and no protection from currency fluctuations and that isn't much of a profit for the manufacturer.
If you make stuff for yourself and can write off the time and don't have to recover equipment and tooling costs etc. then that is a bit different, like servicing your own car.
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