TheSkySearchers

Posted: **Wed Nov 27, 2019 3:24 pm**

Hello everybody,
I'm thinking about changing over to OAG, I'm looking for one that I can screw the 2" snout from my Sony a6000 into with the L-enhance filter screwed on into the focus tube. Then attach the camera to the backside and a 1-1/2" guide camera on top. I've looked over several online but the thread size isn't that clear on some. If you are using what I'm looking for please let me know what OAG you are using. Oh, BTW I'll be attaching to a Mak-Newton telescope that takes both extension tubes, long and short that came with the telescope to get the focus. I'm using a guide scope mounted on top of the rings at the moment but I'd like to loose a little weight and maybe piggyback my a6000 with an OEM lens sometimes.

Thanks,
Dano

Posted: **Wed Nov 27, 2019 4:28 pm**

I am using the QHY CCD OAG with my Ritchey Chriten.

You will have to do some head scratching and calculating for the various adaptors and extension rings. The hardest part is getting the focal plane of the guide camera and the imaging camera EXACTLY the same!

Here is a sketch I did to calculate the spacers and adaptors. This was with a filter wheel and a ATIK 3983L+ ut the concept is the same. Note the calculated 9mm spacer for the guide camera.

20171213_202910 by Tom Whit, on Flickr

Here is a link to the users manual that helps explain some of it.

https://note.youdao.com/ynoteshare1/ind ... &type=note

Here is an image of my current set up with a focal reducer included. The filter threads on to the front of the focal reducer not shown here.

ver 2 by Tom Whit, on Flickr

Posted: **Wed Nov 27, 2019 4:41 pm**

Are you using a field or comma corrector ?, what is your imaging focal length, oag are great for removing differential flexure and are good to get the right guiding resolution , but they have a few flaws.

I have a t ring for a mirrorless sony a 7, pretty sure the as6000 is mirrorless as well, the t ring i have has a 42 mm female thread, with a recess that can be removed to make it a 48 mm female.

This oag has the 42 mm male and a 48 mm male thread to go into a sony or typical 42 mm t ring.

http://www.sirius-optics.com.au/zwo-oag ... uider.html

now if you need room for a comma corrector, orion sell a thin version , but you'll need some sort of lower profile t-ring, assuming you have a similar one that i have that machined to fit 55mm back focused correctors.

https://www.bintel.com.au/product/orion ... PoEALw_wcB

here is the " t-minus' t ring for sony, you may be able to fit a slim oag and a coma corrector with it.

https://www.telescopeadapters.com/t-min ... eries.html

Posted: **Wed Nov 27, 2019 5:39 pm**

UlteriorModem wrote: ↑Wed Nov 27, 2019 4:28 pm I am using the QHY CCD OAG with my Ritchey Chriten.

You will have to do some head scratching and calculating for the various adaptors and extension rings. The hardest part is getting the focal plane of the guide camera and the imaging camera EXACTLY the same!

Here is a sketch I did to calculate the spacers and adaptors. This was with a filter wheel and a ATIK 3983L+ ut the concept is the same. Note the calculated 9mm spacer for the guide camera.

20171213_202910 by Tom Whit, on Flickr

Here is a link to the users manual that helps explain some of it.

https://note.youdao.com/ynoteshare1/ind ... &type=note

Here is an image of my current set up with a focal reducer included. The filter threads on to the front of the focal reducer not shown here.

ver 2 by Tom Whit, on Flickr

WOW that's quite a set up you have there but just the opposite of what I'm after. I don't want to step up from M42 to M48.

Posted: **Wed Nov 27, 2019 5:42 pm**

yobbo89 wrote: ↑Wed Nov 27, 2019 4:41 pm Are you using a field or comma corrector ?, what is your imaging focal length, oag are great for removing differential flexure and are good to get the right guiding resolution , but they have a few flaws.

I have a t ring for a mirrorless sony a 7, pretty sure the as6000 is mirrorless as well, the t ring i have has a 42 mm female thread, with a recess that can be removed to make it a 48 mm female.

This oag has the 42 mm male and a 48 mm male thread to go into a sony or typical 42 mm t ring.

http://www.sirius-optics.com.au/zwo-oag ... uider.html

now if you need room for a comma corrector, orion sell a thin version , but you'll need some sort of lower profile t-ring, assuming you have a similar one that i have that machined to fit 55mm back focused correctors.

https://www.bintel.com.au/product/orion ... PoEALw_wcB

here is the " t-minus' t ring for sony, you may be able to fit a slim oag and a coma corrector with it.

https://www.telescopeadapters.com/t-min ... eries.html

I'll check out the links you provided. My telescope is ES David H levy that doesn't require require comma corrector. Focal length is 731 mm.

Posted: **Wed Nov 27, 2019 5:46 pm**

that doesn't require require comma corrector.

Neither does the Ritchey Chriten. That's a focal reducer. See the RC is a native f8 (2,000mm)

Anyhow I hope the links and pics helps somewhat. There is quite a bit of figuring things out when it comes to an OAG. Be sure to include funds for spacer rings, tubes, and adaptors. They aint cheap!

Posted: **Wed Nov 27, 2019 5:56 pm**

'$$adapters$$ "

Posted: **Wed Nov 27, 2019 6:07 pm**

I use an Orion TOAG (Thin). It has worked for my Canon 70D and ASI120MM. When I converted to the ASI294MC for a primary camera it was a snap. Well, not actually, more like two screws to tighten the TOAG to the camera. It's light weight. But one thing that took me a long time to get correct was to get both cameras in focus. The guiding camera (ASI120MM) was apparently out of focus just a tad. When I put the ASI294MC on, it became really apparent. But between the ASI and Orion I had the exact adapters to get both camera's into focus. It's so much easier to get a guiding star now.

TheSkySearchers

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