Just curious Greg, you are 100% an astroimager right?...so this usually means pointing to and staying on just one or maybe two targets a night so why all the worry about Tpoint and syncing perfectly with TheSky etc etc . What's wrong with just pointing to within the native out of box few arc mins, composing your frame shot and off you go, don't need any more than EQ6 or Meade capabilities for that
The high quality native tracking of teh PME coupled with normal autopguiding is as perfect as you need too, all this extra capability all seems a bit of overkill
I can see where you're comng from Mike - I have been a little disappointed by the GOTO accuracy of my AP mount vs my Meade LX90, but it is adequate for imaging.
However, wouldn't accurate pointing make mosaic composition easier? I'm a long way from that - just did my first combination of a long and short exposure image tonight though!
Just curious Greg, you are 100% an astroimager right?...so this usually means pointing to and staying on just one or maybe two targets a night so why all the worry about Tpoint and syncing perfectly with TheSky etc etc . What's wrong with just pointing to within the native out of box few arc mins, composing your frame shot and off you go, don't need any more than EQ6 or Meade capabilities for that
The high quality native tracking of teh PME coupled with normal autopguiding is as perfect as you need too, all this extra capability all seems a bit of overkill
Maybe I am missing something?
Mike
Initially pehaps but apart from the capacity of the PME I want PEC and errors under 1 arc sec. Accurate go-tos are also important at long focal length.
If I have any problem with Tpoint I will just drift align and see how she looks. Then add the bells and whistles as go along, PEC mainly.
I got the mount counterweights solved today (weights from a gym shop and some magnetic tape to reduce the hole size. It was close to being in balance with the 3 counterweights as it turned out.
I got the mount at the right angle and installed the driver got it working on my computer. I got the Planewave focuser and temperature control working as well. The usual difficulties in doing the above with new equipment but I am ready to image now. If tomorrow night is clear then I should be up and running. The Starlight Express Lodestar in installed but it needs a special autoguiding cable it did not come with grrrr.
So the ST402 may do that work whilst waiting for the cable.
All systems go now.
The PME is quite user friendly so far.
Greg.
Quote:
Originally Posted by DavidTrap
I can see where you're comng from Mike - I have been a little disappointed by the GOTO accuracy of my AP mount vs my Meade LX90, but it is adequate for imaging.
However, wouldn't accurate pointing make mosaic composition easier? I'm a long way from that - just did my first combination of a long and short exposure image tonight though!
DT
Alt Az is easier to do accurate go-toos. With my NJP mount I found polar alignment the key thing for accurate go-tos. If go-tos wee off it was mainl polar alignment was not accurate enough.
You can plate solve and sync like you said during an imaging run, but it can cause problems, especially near the meridian. If the mount gets confused and thinks it's on the other side (or hemisphere) it is a pain to fix it up. This can happen if you have flipped to the west, and then plate solved, then re-slewed to the target and then plate solved again and this last slew has in fact taken you to the east side without a flip. With TPoint you are doing the same thing (i.e. plate solve / syncing) but its all done in advance.
So when you do a meridian flip - the target is always dead nuts in the right spot. I always leave my camera at 180 degrees, so the images register perfectly, but I can now see why camera rotators are so popular.
There are other advantages too, but the meridian flip is the main reason I use it.
Just curious Greg, you are 100% an astroimager right?...so this usually means pointing to and staying on just one or maybe two targets a night so why all the worry about Tpoint and syncing perfectly with TheSky etc etc . What's wrong with just pointing to within the native out of box few arc mins, composing your frame shot and off you go, don't need any more than EQ6 or Meade capabilities for that
The high quality native tracking of teh PME coupled with normal autopguiding is as perfect as you need too, all this extra capability all seems a bit of overkill
Maybe I am missing something?
Mike
Mike
Sub arcminuite pointing and calibrated/auto composition nudging with a random camera angle (with a rotator) become important over 2m FL.
Yes, all the extras are a pain, but only need setting up just once on a permanent rig. I havent needed to sync even once in over a year now after the initial set up, pointing is always within arc/secs from power up. And one click "point here" for compostion on a constantly changing camera angle saves a huge amount of time compared to hand nudging with the directions confusingly changing every night (cam angle).
I used to spend up to 30min every night syncing/searching for objects just out of view and hand nudging on the G11 at 3m FL. I can get the whole obs powered up and imaging/focused/guiding within 10mins with the PME now.
Polar align to arc/secs takes 10mins tops with Tpoint/pinoint/AAG auto too, much faster than drift align, so tempting to do more often, to make sure its bang on (I found polar align drifts over a period of 2 mths or so 5-15 arcsecs depending on the weather, the pier must be moveing a bit).
Add up say 20min reduced time each night over a year, and the time saving is substantial.
Alt Az is easier to do accurate go-toos. With my NJP mount I found polar alignment the key thing for accurate go-tos. If go-tos wee off it was mainl polar alignment was not accurate enough.
Greg.
The more I use the AP mount, the more I realise what you say is true. The Meade system also uses "modelling" (I think), which is lacking from the AP controller.
The more I use the AP mount, the more I realise what you say is true. The Meade system also uses "modelling" (I think), which is lacking from the AP controller.
DT
What do mean by "modelling", PEC or pointing?. Either can be done via pempro or Tpoint/sky. AP is an excellent mount, seems a shame not to use these tools.
My understanding (and this may well be wrong) is that many mounts use "modelling" to improve pointing accuracy by compensating for slight inaccuracies in polar alignment, measured during the "alignment sequence". It's nothing like what Tpoint does, but it helps.
There are many posts on the AP Yahoo Group that mention the lack of modelling in the AP controller. It may be added to revisions of the firmware...
I'm very happy with the AP mount, it's accuracy is fine for my current imaging demands - at Duckadang, the objects were always within the camera's field of view (DSLR at 600mm focal length) - but I'll have to learn what to do as I try to work at longer focal lengths.
Well, on a quick look, Sky X includes AP mounts. Tpoint/pinpoint pointing modeling is done entirely within Sky. Given the cost of the AP, it would seem a small investment to get those tools. Geez cheap skate, get with the cool gear .
TheSky6 + TPoint will make an AP mount (or Gemini or MI500 or anything else controlled by TheSky) point like a PME, so to speak. The all-sky modeling is a software implementation that takes catalog/user coordinates, corrects them via the TPoint model and sends the mount the "fixed up" coords.
The Gemini controller actually also does the same thing for the Losmandy mounts, except the model is simpler, only about 7 terms, but it works really well. The multi-star alignment routines offered by Meade and Celestron AFAIK only correct a few terms (polar offsets, cone angle and flip backlash IIRC).
What only the PME (well, actually any MKS4000 controlled mount with TheSky+TPoint) can do is Protrack, where the fixed-up corrections are sent in real time and the mount tracks out polar error, tube flexure, gear eccentricity, counterweight bar deflection, etc. Those who don't want to spring for TPoint (250USD)can get MaxPoint (150UD), it does about the same thing, but not the Protrack part.
The only other mount out there, that I know of, that can do something like Protrack is the PWI Ascension 200, they use a Sidereal Technology controller (which does the real time correction, software on the PC does the model). The ASA mounts in theory could do the same thing, but I don't see it advertised anywhere, do they have software for them?
Straying a off-topic a little...What I find interesting is that ASA direct drive mounts state on their webpage that plate solving/adaptive optics are no longer necessary with the hires encoders. But no encoders can deal with things like tube flexure or axis non-orthogonality, a bit of advertising bluster perhaps...
Greg
Did you see today's APOD taken with a CDK17 by Tony Hallas??
You need to get that scope all fired up!
James
Yeah I like it. If I posted an image like that here I'd get a caning
for oversaturation. The colours are a bit over the top but that is his style.
Yep, I'm getting there. Started doing test images tonight.
I did a drift alignment and was getting round stars 2 minutes
unguided which I thought was impressive given the long focal length.
I am not sure I have the correct autoguiding cable for the PME.
I think its just a standard SBIG ST4 style cable.
When I try to move in focus mode in CCDSoft there is no movement but I can move using the joystick to centre the object.
I'll try to autoguide next session with it.
Greg.
Last edited by gregbradley; 20-08-2010 at 03:00 PM.
Well, on a quick look, Sky X includes AP mounts. Tpoint/pinpoint pointing modeling is done entirely within Sky. Given the cost of the AP, it would seem a small investment to get those tools. Geez cheap skate, get with the cool gear .
Thanks Fred!
I do have SkyXSAE, but no Tpoint. The pointing accuracy of my portable setup suits my current needs, but it's good to know it can be improved in due course!
Thanks also to Eric for a thorough explanation of what the modelling does on various mounts.
(Probably should let this thread return to its original topic - Sorry Greg)
If you are using CCDsoft to control the guide camera you should use 'direct guide' for autoguiding with the PME - this is in the advanced settings for autoguiding - no cable required - commands are sent through to the mount directly.
So I don't need a special cable for my guide cam just the images from the guide cam then direct guide through the Sky and CCDsoft.
Where is the menu for chosing direct guide? Is it in the Sky 6 or in CCDsoft?
Thanks for the tip - I like the sound of that.
Greg.
It's in the CCDsoft camera control window, in the Autoguider settings section - I think the default is 'camera 'relays', No RJ12 from the camera to the mount is required with the PME whe using direct guide. A good feature in CCDsoft.
Thanks very much Guy. I found that and it is now working. Thank you!
What does Pro Track do and how do I access it?
Per the Bisque website it sounds like it improves trakcing accuracy.
Also I bought this PME second hand. I am wondering if Precision PE PEC curves are saved in the flash memory of the mount or if the program has to be running to get the PEC affecting the tracking?
Greg
If the previous owner did the PEC, then it will be saved in the flash memory in the mount and you can use it no problem.
I attached a screen print of mine so you can see what it should look like.
(The Sky->Telescope->Options->More settings->PEC)
Of course to be safe you could always record it again when you get a suitable night.
James
PEC is stored in the mount. The memory may have a PEC model loaded already. You can use Precision PEC (yet more additional SB software) or PEM PRO or equivalent to record the PE in CCDsoft, import to PrecisionPEC, process it and then upload it to the mount. Precision PEC is pretty basic but is tailor made for the PME, Sky and CCDsoft. To use Protrack you need a really big Tpoint model - 200 points or much greater (which is where automated mapping comes in handy) - and you need to have the right terms added to your miodel (as well as good alignment). It has taken me quite a while to get the hang of the terms in Tpoint, but I wouldn't describe myself as an expert. From there you can activate Protrack in TheSky. If set up optimally, the PME should be able to track unguided for 10 minutes I'd guess with the 17., possibly more At the least, the autoguider shouldn't have to work hard. The big challenge is not to have the guiding chase the seeing.