Moravian G2-8300 Front Glass

[AngryDonkey]

Hello,

I'm just trying to work out the 'proper' back focus for my reducer. I've already added 1mm for my Astrodon filters (which are 3mm thick) but now I am not sure if the Moravian G2-8300 (with internal filter wheel) has front glass which also needs to be taken into account (and I don't have access to one at the moment)? Does anyone know if it does and f so how thick it is?

Thanks,

Mike

[AndyUK]

Hi Mike - I too have a Moravian G2-8300 with internal filter wheel.  The only thing you need to take into considersation when it comes to spacing are the filter widths (and I too have Astrodon's and allowed 1mm ).

[AngryDonkey]

Thanks Andy, that's what I thought but you can't be too sure about these things! 

[LightBucket]

How do you know how much to add on for filters, I have Baader..., or do you take it off.... ?, as you can tell bit of a newb...

[DaveS]

You add approximately 1/3 the filter thickness, assuming a refractive index of 1.5.

[ollypenrice]

On 29/06/2017 at 15:41, LightBucket said:

How do you know how much to add on for filters, I have Baader..., or do you take it off.... ?, as you can tell bit of a newb...

You don't have to be a newbie to be confused by this! It has been endlessly discussed by the great and the good of AP.

I've never factored in the chip window myself and haven't heard of anyone else doing so. It's never been a problem and on one of our setups the spacing is very critical. I think you can ignore the chip window as others have said.

Olly