Re: Pointing Model vs. OAG with PHD2

Bruce Donzanti

Thanks, Brian

I think between your response and that of Roland's, I will stick with the integrated OAG system.  In fact, I need to move the new MIDI version as I need 2" filters for my new ASI2600MC Pro.  Hoping to test things again Sunday night when it should be clear but it just doesn't;t make sense why this just stopped working.  I checked cables, 2- cameras, etc and both mount and guide camera connect but no stars on the PHD2 view- just snow but my images are fine.  I'll try to get a clear star view from the capture software using the guide camera and se what happens.  If I do, I should see it in the PHD2 view screen and it should calibrate but will see what happens. 

On Thu, Apr 23, 2020 at 11:12 AM Brian Valente <bvalente@...> wrote:
I think i have the same oag/filter wheel as you, and it does eventually work

what is your imaging resolution? 

re: unguided, I think it can work quite effectively, particularly with a quality mount like AP

in my experience (with losmandy not AP) ability to do unguided really boils down to excellent polar alignment, good periodic error correction, and generally good imaging "hygiene" (avoid cable snags, things are tightened down well, etc.). 

i was able to get 5 min unguided exposures @ around 1.1 arcsec/pix. not earth shattering but not too shabby

Personally i found setting up OAG to be easier than figuring out unguided. With unguided, there are so many small fiddly things you really have to nail down, and they can shift a bit every night, so i had to be constantly diligent. with AP there are less fiddly things related to the mount which will make your life a little easier

I encourage you to try it, but also a bit of caution that you will be inheriting other types of challenges.

On Thu, Apr 23, 2020 at 7:58 AM Bruce Donzanti <donza2735@...> wrote:
Hi Brian

The idea is to do unguiding.  I can do about 60s now but would prefer to do 120s unguided.  

Weather bad now so I am at a standstill at the moment.  The mount connects with PHD2 but no focus achieved, so no calibration.  I have no idea why.  Anyway, I agree that once the guide cam is in focus, it should remain that way but at times things seem to shift with the integrated OAG/filter wheel setup that I have.  I like it in that it is one piece of hardware vs two but for whatever reason(s), I seem to have to readjust things once in a while despite nothing shifting or moving.  That is why I want to at least explore this option which may not be a better way.

On Thu, Apr 23, 2020 at 10:49 AM Brian Valente <bvalente@...> wrote:
Hi Bruce

this is more from a PHD perspective (and also i know you've had some posts at SX forum)

Is your idea that you want to do unguided imaging vs. guided?

It seems you have an issue that is unresolved and you are still looking for the root cause, but once it's solved, you would not be refocusing your camera at all. just gotta figure out what's causing it


On Thu, Apr 23, 2020 at 7:37 AM Bruce Donzanti <donza2735@...> wrote:
I would feedback from those doing pointing models if would be advantageous for me to try it based on my specific setup on stick with OAG.

I am in a permanent observatory above my garage roof which is about 12 feet above street level. In the observatory, my C11" EdgeHD (with an 80mm piggybacked onto it) is on an AP1100 which is on top of a Pier Tech adjustable steel pier (can be raised 18 inches).  The steel pier lies on top of a cement pier that runs down below street level.  So, the scope itself is about 8 ft above the observatory floor, requiring me to use safety ladder to get to it but just about everything is automated now with few exceptions. My setup is well built, has excellent polar alignment and cable management.  I would have to recheck my PE on my 1.5 year old AP1100.  For guiding, I have been using PHD2 with an OAG for about 2 years but I find it to be finicky and I often have to get up on the ladder to re-focus the guide camera (one of the few non-automated steps).  Seeing and transparency in my area is generally not very good and I do not get many clear nights.  Typically, my seeing is around below average/average with many nights of poor and few above average/excellent. I am thinking of using the 80mm as the guide scope for the C11 since it has an autofocuser but I am still dealing with PHD2 and my so-so skies. 

With this as an introduction, would taking the time to learn to build a pointing model save me a lot of aggravation (i.e.,up and own on the ladder for the OAG adjustments or using the less effective 80mm) in the long run or am I just exchanging one set of problems for potential another set?  Would a pointing model be more or less advantageous for guiding in my sky conditions or just the same as using an OAG approach?



Brian Valente


Brian Valente

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