Atik 314L+ / EFW2 / OAG spacing

[Starflyer]

I'm looking at getting the 314L+ / EFW2 / LRGB filter set as my next upgrade.

I was going to marry it up with the Atik OAG, but after reading Steve's review this means I won't be able to achieve the correct spacing with my TRF-2008 or Baader MPCC.

This kind of puts a dampener on things and I was wondering if anyone has a solution to this, a different OAG, or some other solution? I was loving the idea of an OAG with a helical focuser... why couldn't Atik have designed their OAG to complement required accessories

Thanks in advance,

Ian

[johnrt]

Would one of these fit? it only adds 9mm to the imaging train.

http://www.teleskop-express.de/shop/product_info.php/language/en/info/p641_Off-Axis-Guider---nur-9mm-Baulaenge---T2-Anschluss---fuer-CCD.html

[Starflyer]

That's something I'd looked at John, I'm not sure how it attaches to the Atik filter wheel though - still confused.

[Merlin66]

Can you fit the OAG/ filter wheel before the corrector???

[Starflyer]

That's one option, but I was hoping to get away from guiding on Seagull shaped stars. This camera's so common now, someone must have already have the setup I'm after.

Cheers,

Ian

[ollypenrice]

Baader and TS are very expert on all this. A quick enquiry might mean they'd link you to an adapter.

Olly

[steppenwolf]

I found an elegant solution to this issue by producing a hybrid filter wheel/OAG combination. I particularly liked the ATIK EFW2 but as you have read, the maths doesn't work out with the ATIK OAG if you are using a focal reducer. I really liked the SX OAG but this is not compatible with the ATIK EFW2 - UNLESS you make it so!!

The SX OAG has a small locating collar on its rear face so I had the front plate of the ATIK wheel machine to accept this collar and then had a series of holes drilled and tapped for attachment of the OAG. This results in a very neat combination which with the 17.5mm backfocus of my SXVF-H9 CCD camera gives me the correct spacing for use with a focal reducer.

[Starflyer]

Thanks Olly, I did consider the TS 9mm OAG and asking them about one of their adapters, but the OAG itself doesn't get great reviews.

Thanks Steve, that sounds like the solution I'm looking for. I have a friend who manages a good machine shop and I'm sure he could manage the mod. What's involved to get the locating collar to fit, is it just enlarging the hole in the front plate of the ATIK wheel, or milling a circular recess into it?

I think the 314L+ is 13.5mm optical backfocus, so I'd need 4mm of spacing to get near the optimal distance. Does that sound right, or do I need to take into account the filter glass too?

What spacer and/or other adapters would I need? Sorry for all the questions but I'm trying to avoid 'adapter hell' where it all arrives and I realise I need to order and wait for another adapter to arrive before I can start using it all

Do you think I could use a couple of the Baader delrin spacers on either side of the EFW2 / OAG package to get the extra 4mm?

Thanks in advance for any advice,

Ian

[steppenwolf]

is it just enlarging the hole in the front plate of the ATIK wheel, or milling a circular recess into it?

Just enlarge the hole (maintaining the centre perfectly of course!) to match the collar.

You do need to allow for the insertion of the filters in the light path which will increase the distance of the focal plane from the focal reducer.

The Delrin rings are great for adding up to 1.0mm to an interface but 'T' threads are not deep at the best of times so I'd prefer not to use them for more than this distance per interface.

[Explorer 190 MN]

Is this thread still alive?

I have been looking at fitting my SX OAG to my EFW2.

I notice someone said the optical path needs to be longer with filters roughly how much longer? I need to shave off 7mm to get 56.5 mm from reducer to sensor

[Merlin66]

by 1/3 the thickness of the filters.....

[Tom Habaj]

To be more precise in your calculations you need to include all glass between corrector and chip i.e. cover glass, optical window. For example my camera has 3mm optical window which adds 1mm to focal plane.

[Explorer 190 MN]

by 1/3 the thickness of the filters.....

Thanks for the information.... now where is my micrometer....