Atik Infinity & Dobsonian

[Astrojedi]

There are 2 benefits 1. speed and 2. image scale. These in turn have additional benefits. The overall scope/setup becomes much more easier to use (with regards to finding objects, tracking accuracy required etc.)

The field of view at F6.3 for the 9.25" scope with the Infinity will be 0.35° x 0.26°. At F5 it will be 0.44° x 0.33° or about 26% increase which is pretty significant. Much easier to find stuff with gotos.

Wrt to speed, the difference between F6.3 and F5 is 2/3rds of a stop which means a 60s exposure at f6.3 will require ~40s at F5, a significant improvement.

But there is more to the story... Even this level of improvement could have a bigger impact if at f6.3 your exposure time if close to the threshold of your mount's accuracy/periodic error or close to preventing field rotation for objects close to the zenith or poles.

It makes a difference...

 

[Astor3]

Great explanation, many thanks for your time

[2STAR]

hi,thank you Astrojedi, ,it also answers some of my points regarding focal reducers

[2STAR]

I have placed a 'wanted' notice on here regarding a meade 3.3 focal reducer, if anyone knows of one anywhere please drop me a line, much appreciated.

Regards

Eric

[Astrojedi]

Best of luck.

Note that Optec here in the US also sells a 0.33x reducer for classic SCTs but it is more expensive than a second hand Meade 3.3 (assuming you can find one)

[2STAR]

On 2/19/2016 at 03:26, Astrojedi said:

Yes, they will work with any SCT and any other scope which has sufficient in focus.

Hi, hope you can advise, I have now got my Atik Infinity, I have a FR both Celsetron 6.3 & a loaned to me Meade 3.3, does the below**  combination look ok as I have never set s camera up before on a SCT Telescope.

**REPLACE VISUAL BACK WITH FR, CONNECT VB INTO FR, ATTACH CAMERA IN TO VB.

 

[Astrojedi]

2 hours ago, 2STAR said:

Hi, hope you can advise, I have now got my Atik Infinity, I have a FR both Celsetron 6.3 & a loaned to me Meade 3.3, does the below**  combination look ok as I have never set s camera up before on a SCT Telescope.

**REPLACE VISUAL BACK WITH FR, CONNECT VB INTO FR, ATTACH CAMERA IN TO VB.

 

That will work with the Meade 3.3 but for the Celestron 6.3 you will need more spacing as that FR has a longer focal length.

[2STAR]

2 hours ago, Astrojedi said:

That will work with the Meade 3.3 but for the Celestron 6.3 you will need more spacing as that FR has a longer focal length.

Ok, thanks again for your help. 

[DoctorD]

Hi

Here's my set-up with the F3.3 (note I have modified the spacing by removing one of the 10mm spacers to give 53mm instead of 63mm as shown below - this gives about F3.5 and much less coma distortion):

I must take a photo of my latest setup!

The actual CCD is 12.5mm back from the from of the Lodestar (standard CS lens spacing).

The F6.3 will need more than this but I'm not sure how much as I rarely use it for EAA (possibly another 50mm but I don't think it's all that critical).

HTH

 

Paul

 

[johnpd]

I have an Optec NGM .33x Focal Reducer that I use with a C-8. The NGM has a standard C-mount back installed on it for spacing purposes. It appears that the Lodestar/Ultrastar as well as the Atik Infinity are CS-mount lens spacing cameras. I assume I would need a 5mm spacer to convert from the C-mount distance to the CS-mount distance? Any idea as to the vignetting that might occur.

Thanks,

  JohnD