Quote:
Originally Posted by gaston
Hi David,
The short answer is yes.
Below more details:
They are two options to use the ONAG with a FR.
First:
Attached the FR in front of the ONAG (SP), this way imager and guider cameras will see the FR.
In this configuration you would place the imager focal plane (IFP) at a distance (q) from the FR flange in the order of FR back focus (DFR) nominal distance.
A FR can work at a different back focus distance (q ) than the nominal one q=DFR. Doing so will change the reduction factor (h) though.
There is simple relationship here:
h=1-q/f, where f is the FR focal length, about 276mm for the OPTEC 0.62x.
However if the FR is also a corrector, you have to keep q close to the DFR nominal value. For instance the Celestron/Meade 0.63x FR-corrector (field flattener) will work fine if you stay in a range of q= DFR +/- 25mm (1”).
The Optec Lepus 0.62x is designed for corrected scopes, such as the SCT (ACF, EdgeHD), it acts as a simple FR, not a corrector. It is very forgiving on spacing, as we should expect.
Canon DSLR cameras have 44m back focus, and most T-thread to DSLR adapters will add an extra 8mm or so to the back focus, leading to 52mm of back focus.
The ONAG has a 66mm back focus. You will also need an custom adapter to connect the OPTEC FR to the ONAG SP (T-thread). We can make one for you, its expected back focus will 11mm.
Therefore the total back focus from the FR flange to the IF) will be 52+66+11=129mm, or 129-105=25mm, about one each more than the FR DFR (105mm).
This would result in a new reduction factor of h=1-129/276=0.53x, or 14% more reduction.
Second:
Place the FR at the ONAG IP, in front of the imager, this way you can use the standard adapter for the Lepus FR with your DSLR and be at q=DFR. You will need our AFR reducer for the guider port, because the guide does not see the Optec focal reducer in this context. You will also need a T-thread to 2” female adapter to attach the Lepus at the ONAG IP, like you do with your TCS-S.
I use this option in some configuration, I also have a TCS-S focuser, very handy. You can see an example on the website www.innovationsforesight.com main page (C11+TCS-S+AO-8+ONAG+Celestron 0.63x FR).
Since the Lepus is not correcting for the SCT field curvature I would recommend the first option.
For further information you may want to visit the website, I would also suggest you download the ONAG’s user manual (ver. 3.0) from:
http://www.innovationsforesight.com/Site/Tecnical_Information/ONAG_UserManual_V3_0.pdf
Clear skies!
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Gaston i am more than interested now, i will PM you