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I have recently purchased an Orion Mini guide scope and I'm keen to start autoguiding using my Altair GPCAM2 224. However, I have a MacBook and it's not playing ball. I've managed to get BETA versions of Atair Cam and PHD2 drivers on my Mac but the frame rate on Altair capture is horrendous and PHD2 doesn't recognise the camera. Therefore I'm resigned to having to shell out on a windows based laptop. I'm looking to the second hand market at the moment but all I want is the minimum specs I need to capture. I will use the Mac to process images.
Altair states minimum requirements are :
Windows PC Hardware Requirements: Minimum CPU: Equal to Intel Core2 2.8GHz or Higher Minimum Memory: 2GB or More USB port: USB2.0 High-speed Port
It doesn't say if this is IntelCore2 single, duo or quad. I'm presuming single here. Even still is that the minimum for just capturing data? What are others using. I'm really reluctant to start shelling out another £100+ on a used laptop just for autoguiding.
My current setup for astrophotography is an eq5 pro mount with a 200p telescope, using a canon 1000d camera, I’ve been looking at what I could upgrade to improve my astrophotos and my top priority is getting a light pollution filter and it in the middle of a city. But next I’m torn, between getting an autoguiding system and getting a new mount (heq5 or neq6 if I could find one used) I recognise I will need both eventually it’s just about which to get first. I’m that respect if I were to get the auto guider first, I would probably have to find a different way of mounting it because of the weight limit, I found a old thread that referenced mounting the autoguiding system to the counterweight bar which would not increase the weight, I see a few problems with this but for the sake of saving the weight I figure it’s a good idea.
Im not sure what autoguiding kit I would get but I’ve seen that the st80 is highly regarded and probably a Astro ccd around the £150 mark.
Any advice on which to get first for my setup would be appriciated and what mount and autoguiding system that is advisable.
Thanks in advance.
Im living in a fairly light polluted area, and have a Skywatcher 200p on an eq5 pro mount (which does have a synscan hand controller which has an autoguider port) and ive got a webcam which ive converted to fit in a standard eye piece. My question is, when i connect it to the finder scope what wires do i need to buy to use it for autoguiding, i figure i need a st4 to usb cable, but everywhere ive looked has said i need a GPUSB device, im planning on using PHD guider but have also heard i may need eqmod and would just like some clarification on what i actually need to purchase
Now that I have my CGEM on a permanent pier, I figured that I should get much better accuracy in guiding quality, especially at 2032mm (F10) focal length on my 8" SCT.
I spent a bit of time getting guiding results that are at the very least acceptable and thought I’d share my experience with anyone who is looking for info on PHD autoguiding.
In the pasten setting up for each astro session and using PHD I was generally getting RMS about 2.2-2.6ish and after stacking and processing, the soft effects were able to be negated to a great point, revealing detail and with results that I was quite happy with (on a good night) imaging at 2032mm using a modded Canon 40D.
The stars were round and generally I was able to use most (if not ALL) of the subs generated, even when I was exposing through Halpha or SII for 30-40 minutes per sub. That in it self, I thought, was pretty good for the setup that I'm using... or... I'm just easily pleased.
I use a OAG for my exposures so guiding on the same FL as imaging.
That said I did spend a bit of time playing with PHD settings, as well as the backlash setting on the CGEM, along with autoguide rates to try to get better guide graph.
After a spending a bit of time on both polar alignment as well as tweaking the autoguiding parameters in PHD, I was still getting a graph that showed large jumps, see pics… Nowhere near the near flat line that a few imagers were getting. Although the RMS level at 2032mm did improve, now I’m getting numbers of between 0.83-1.3, so it is definitely an improvement but still didn’t look flat.
The test exposures I done at those RMS levels using the 40D at ISO100 on a 40 minute exposure showed round stars and the frame exposure looked good.
I decided to investigate to try to improve the graph, and when turning off the guide commands the graph showed large bumps generated by star movement caused by the atmosphere, the graph was very similar, although slightly higher RMS, due to the star moving around obviously due to seeing.
At this stage I put my larger graph RMS in comparison to other very flat graphs to perhaps me guiding at 2032mm on a 1/4” CCD and others guiding using a much smaller/shorter FL guidescope where such large seeing related star movements are not picked up at a shorter FL, I base this on the fact that when imaging and guiding while using my 80mm/500mmFL frac where I generally got a RMS of 0.3ish.
Using the size of the pixels and CCD on the focal length the results are 0.548 arcsecs per pixel so multiplying that by the RMS I get the guiding is 0.45 – 0.71 arc seconds accuracy (?) which if I’m right, sub arc sec accuracy is OK for AP. I used http://www.celestialwonders.com/tools/imageScaleCalc.html for the calculation.
NOTE That until I had decent backlash set on the handset I was still getting intermittent saw tooth like spikes in DEC and RA, and the guide star did spontanously jump large distances periodically.
The way I adjusted the backlash on both RA and DEC was by centering a star on the laptop screen and at 1X guide speed moving forward, forward, back, forward, back, back, adjust the backlash and repeat until the star responded instantly.
Also my autoguide rate is set at 40% for both DEC and RA.
My PHD parameters that seem to give the best guiding at 2032mm are below:
RA Aggressive: 50
RA Hyster: 10
Max RA Dur: 350
Search Reg Pix: 15
Min motion: 0.15
Calib Step: 500
Time Lapse: 0
Dec Guide Mode: Auto
Dec Alg: Resist Switching
Dec Slope: 4.5
Max Dec Dur: 350
Star Mass Tolerance: 1.00
Dither Scale: 0.05
Hopefully some of this helps someone.
Also if I'm missing something and anyone has advice to improve that graph, please feel free to share.