PHD2 and OAG and coma corrector calculation?

[ebdons]

Hi, not sure if this is an issue for PHD2, but my ES coma corrector increases the focal length of my newt by 0.6 percent? is it % or some other measurement? My scope has 812mm focal length, I'm not sure about the maths when putting in the specs when using an OAG and how much increase in FL do I put into the PHD2 specs. is there an equation to determine that or will PHD2 behave ok without the updated FL. ton

[Cornelius Varley]

10 minutes ago, ebdons said:

Hi, not sure if this is an issue for PHD2, but my ES coma corrector increases the focal length of my newt by 0.6 percent? is it % or some other measurement? My scope has 812mm focal length, I'm not sure about the maths when putting in the specs when using an OAG and how much increase in FL do I put into the PHD2 specs. is there an equation to determine that or will PHD2 behave ok without the updated FL. ton

Shouldn't the increase in the focal length be 6% (48.72mm) and not 0.6% (4.872mm) ?  

[alacant]

Hi

I'd tell PHD2 860 and make sure I recalibrated with the guide camera binned. Make a new profile.

Cheers

Edited September 3, 2019 by alacant

[ebdons]

Hi thanks for the quick response, I may have read the specs wrong on the ES CC as it stated that reduction factor was 1.06 percent is it? so 6% would make sense then, I'm using a lodestar x2 mono and it should be binned but I will check. thanks ton

[alacant]

Hi

Is it the pn208? If so, you're in for a treat:)

[ebdons]

Yes, it's the opticstar version but they are the same as I took the primary off and is was written in pencil on the backside "PN208" ES/18,  is it a good scope then? seems pretty good so far, I just got rid of the stupid secondary collimation crap and fitted it back with the same secondary mirror with a custom spider arrangement and now it stays in collimation for months even when I move it off and around the place. just need some clear skies to test it out now. ton

[alacant]

Hi. Yeah. It's a real gem. This was one of the recent snaps. There's a lot of misinformation on fast reflectors out there. As you've already discovered, best ignored!

 

[ebdons]

Yes I have been following your postings of images, all very good they are, that image is what no of subs etc filters etc, unless my browser won't display the small print, it is IE so not the best.

[alacant]

10 hours ago, ebdons said:

filters etc

Hi. Around 40 3 minute frames with a dslr. No filters.

[ebdons]

Hi all, this is the setup I think will work with a SX OAG from my filter wheel and a TS drawer system with the CC and QHY10, just got enough ccd clearance now set at 52mm (should be 55mm) gives me a bit of adjustment, just need to test it now I hope it works ok with the CC close to the OAG mirror. QHY10 has 20mm nose projection and that should be a maximum distance on most cams?. clear skies.

[Gerry Casa Christiana]

On 03/09/2019 at 18:37, alacant said:

Hi

I'd tell PHD2 860 and make sure I recalibrated with the guide camera binned. Make a new profile.

Cheers

Hi Alacant 

Whats the benefit of the guide camera being binned?

Thanks 

Gerry

[alacant]

10 hours ago, Gerry Casa Christiana said:

the benefit

Hi. Four times bigger pixels. More area to collect light. Easier to calibrate. More guide stars available.

HTH