Field Flattener Help for Orion Eon F6 110

[TechnoBill]

Hi All,
With my new Orion Eon 110 F/6 arriving within the next week or so, the next part I want to add is a field flattener. Its a little more difficult than normal as I have the added complication of the Orion Adaptive Optics unit. (See diagram below)
The A/O unit has 48mm threads front and back and adds at least 42mm to the imaging train (plus adaptors).

Most of the flatteners seem to have about a 50 to 60mm back focus requirement which means they would pretty much have to go on the front of the QSIwsg camera because that is its internal back focus length. BUT... they also often seem to have a 2" tube on the front which means I have to add another female 2" tube holder between the Camera and the adaptive optics, that's a lot of extra length in the train.

The ideal flattener would be one with threads at both ends so I can either put it where the Spacer is between the Camera and the AO or the other option is this one: https://www.teleskop-express.de/shop/product_info.php/language/en/info/p1010_Universal-2-Field-Flattening-Lens-for-Refractors-f-5-to-f-8.html
It would screw straight onto the front of the Ao unit and has a back focus distance of 109 so I guess it would be ideal for this setup. Its pretty pricey though and I have not found any reviews for it.

Also I don't know much about flatteners, wouldn't the "curvature" on each type of scopes focal plain vary? So are ideal flatteners adjustable in some way?

[White Rabbit]

I have the an Orion refractor and use thier flattner whilst my focal length is 714mm the flattener says is for focal lengths of between 300-600 it works fine.

http://www.bintel.com.au/Astrophotography/Reducers--Correctors--Flatteners/Orion-Field--br-Flattener/679/productview.aspx

[White Rabbit]

You'll need some spacers as well to get the correct distance between the flattner and camera chip/ep.

[TechnoBill]

But the orion has the two inch tube on the back which means it would probably need to go in front of the adaptive optics which put the camera a long way back from the flattener. I dont think it will work. It would be nice if the two inch tube on the front of the orion could be unscrewed so I can then put it onto the back of the adaptive optics in front of the camera (with the relevant spacers).



Yup have all sorts of those.

Bill D

[TechnoBill]

Well my new scope is in transit, should have it in a day or so. I was talking to the dealer about my flattener problem and they understood the issue I would have with the Orion flattener and the Adaptive Optics.

Then I popped the question and asked if they have the flattener in stock. On getting a yes I asked them if they could check if the 2" tube on the front of the flattener unscrews. Tada!!! Yes it does and reveals an female 2" thread.

Problem solved. I can screw the 2 inch tube from the flattener onto the front of the AO. With an adaptor, fit the flattener on the back of the AO just in front of the SQI camera giving it the correct back focus I hope. :-)

Its on the way with the scope. I will let peeps know if this works.

[TechnoBill]

Just in case others were following this thread with a similar setup.
I did not get this to work the way I want. I was able to fit the Orion Flattener between the AO and the Camera but I could not achieve focus. The issue is that the Orion Flattener appears to also be a reducer and as such with the AO in front of it. I could not get it forward enough to achieve focus.
It worked fine with the camera only (very wide field) but not with the added space of the AO in front of it.

The clouds came after 1 hour and it has not been clear since so I ran out of time to experiment.

So at this stage looks like I cant use the orion flattener on my 110 with a OA unit. I will need to see if I can get a flattener that does not reduce as well.

TechnoBill

[Peter.M]

Out of interest, why are you worried about an AO unit? Personally at the focal length your working at I wouldn't have thought it would help much. I dont know what the PE is like on the LX200 but you should just be able to use conventional guiding with good results.

[TechnoBill]

Hi Peter,
Habit I guess. Previously, when I used to image through the 12" lx200, no matter what I tried to guide it with I always seemed to get quite a few unusable exposures. Throwing the adaptive optics into the mix made that problem go away.

I tend to use it even when using the small scope as, it can even cater to slow vibrations from the light wind gusts hitting the scope.
But you are right I should give it another go with just the PEC on the lx and some guiding.

Just need a clear night hehe

Bill D