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Post by Deleted on Feb 2, 2020 22:44:06 GMT
My setup last night was the ASIair Pi3 on the AZ-GTi in equatorial mode and the SW ED72 scope with the ZWO 224. It was the first time I used the AZ-GTI in equatorial mode using polar alignment on the ASIair. It all worked and I saved the tarantula . Nothing to write home about and it was a bit out of focus so I wont post it. On YouTube there are a number of instructional videos on how to set up .There seems to be conflicting views as to whether you need to align the scope first up on the mount before switching to ASIair for polar alignment and plate solving. Tadej Skofic has a video giving instructions for the ASIair and AZ_ GTI using a DSLR. This may interest you ,Howie. He 2 star aligns with synscan first with the DSLR and then switches to ASIair . I cant do that as I need a screen to align with synscan and I cant have synscan and ASIair on the one wifi on the ipad. It would need another screen.
So I made sure synscan on the mount and ASIair were in sync and went straight to polar aligning on ASIair. It worked ok but NGC2070 was a bit off centre. It was easily centred .
It appears to me that a 2 star align prior to polar alignment is not necessary, but I am still not sure. For me, the AZ-GTI is much easier in the alt/az mode. cheers Paul
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Post by howie1 on Feb 3, 2020 1:41:25 GMT
Paul
Thanks Paul for the info re Tadej Skofic DSLR video. I will go take a look at it.
FYI ...You never have to do a star alignment first IF you have a camera assisted platesolving PA routine.
Short story is ... with a camera platesolved routine where the routine asks you to rotate in RA 90 or 2x60 degrees, you will perfectly adjust AZ and ALT bolts to point the mount at the pole. That leaves you with only RA and DEC to correct which you do by doing a star alignment.
Long story ... which you may find boring but I love this techo stuff LOL ... The camera PA platesolving routines (should) all do the same process. This is to take two or three images around the pole, one image at 90 degree's to the other image (Sharpcap). Or in the case of Polemaster, three images around the pole, each image at 60 degrees to the other two. What that rotation and two or three platesolved images does ... is work out if the camera is not exactly in-line with the polar axle of rotation of the mount. And then apply the correction to handle the out-of-alignment it finds from the two or three platesolved images.
Very long story ... When you first get an EQ mount, you are supposed to collimate your polar scope cross hairs. You are told to peer through the polar scope of the mount in daytime, at the tip of a distant power pole. You are told to lay the RA over 90 degrees left so the counterweight bar is horizontal and line up the cross hairs in the polar scope on the tip of the distant pole using JUST the AZ and ALT bolts. Easy to do. But, then you are told to rotate the mount 180 degrees in RA and see where the cross hairs move. When you rotate the mount 180 degrees, you will see the polar scopes cross hairs rotating up and away from the tip of the pole and finally at the end of the 180 degree rotation the cross hairs will be over to the right well away from the pole. It is not collimated. It is not in-line with the mounts actual axis of rotation. You correct it via three grub screws until right through that 180 degree rotation the cross hairs in the polar scope stay exactly on the tip of the distant pole. That is the correction ... your polar scope is now precisely aligned with the axis of rotation of the mount.
With the camera it does that collimation process by comparing the two or three images from the camera. In all (underline all) those images platesolving knows what every star is in the image, and can thus triangulate exactly where the pole actually is ... in all the images. If your camera was absolutely precisely in-line with the RA axle then the offsets to the pole would be exactly the same in all the platesolved images. But, that would be incredible ... !!! ... as the camera is never absolutely perfectly in-line! Sharpcap has the camera in the guidescope or OTA where due to DEC error or cone error it is pointing maybe several degrees off the mounts axis off rotation. Even with Polemaster they also do the rotation thing despite the camera being inserted via an uber precision (?) adaptor right into the polar scope hole!. But, the camera routine, when it finds a difference in the offsets to the pole in the two or three images, it can calculate a correction for the out-of-alignment, and places the corrected line and length of line onto the image. You then adjust ONLY the AZ and ALT bolts to move the star into the circled target at the end of the corrected line. Bingo ... you are polar aligned within a few arcsecs.
But, that does not mean you are star aligned ... we've only corrected the AZ and ALT bolts to point the mount precisely to the pole. We have not adjusted the RA and DEC yet! So after the PA you must perform a one star alignment (if you have zero cone error and little backlash) or (if you do have cone error or backlash) a two or three star alignment. For the 2 star alignment, you should select stars on both sides of the meridian ... which means you have to know your star names and where they are to force the two star alignment process to use both sides of the meridian. If you dont need that hassle of looking up two stars ... just use the three star alignment (as three stars alignment will automatically slew to three stars on both sides of the meridian). Unless you have a Celestron mount where I think four is recommended as a minimum. Dunno about iOptron as I've never used one.
Whew.
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Post by howie1 on Feb 3, 2020 1:45:45 GMT
Paul ... aren't you getting a new ASIAIR PRO when they come out? What are you doing with your old version 1 AIR? Did you do that trade-in deal for the PRO? If not, I'd like to buy your version 1 AIR if the price is right. cheers
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Post by Deleted on Feb 3, 2020 6:35:57 GMT
Howie,I have an ASIair Pro on order. I havent done the trade in deal. The price will be right. I will message you.
Polar Align To do the polar align and then a 2 star align or vice versa, I am pretty sure I need 2 ipads. 1 for synscan and the other for the ASIair. The ASIair is sync'd to the mount via an EQMOD cable. Synscan and ASIair do sync well. I dont know how to do a star align on the ASIair, just the Polar align. Now, if it is possible to star align on the ASIair then ,sure, I only need 1 ipad.
Very Long Story Howie, I had major trouble with polar aligning before sharpcap. It was the too hard basket. I used alt/az exclusively. I had the HEQ5 for more than 12 months before I used it. Now I have a number of alt/az mounts that I never use.... except for the AZ-GTI. I am giving the AZ-GTI a proper go in EQ mode . I still think the EQ setup is a bit clunky but the ASIair seems work well in this mode, and the combination of AZ-GTI,ASIair and ED72 and 2 ipads is still a very light kit . cheers Paul
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Post by howie1 on Feb 3, 2020 12:06:48 GMT
Howie,I have an ASIair Pro on order. I havent done the trade in deal. The price will be right. I will message you. Polar Align To do the polar align and then a 2 star align or vice versa, I am pretty sure I need 2 ipads. 1 for synscan and the other for the ASIair. The ASIair is sync'd to the mount via an EQMOD cable. Synscan and ASIair do sync well. I dont know how to do a star align on the ASIair, just the Polar align. Now, if it is possible to star align on the ASIair then ,sure, I only need 1 ipad. Very Long Story Howie, I had major trouble with polar aligning before sharpcap. It was the too hard basket. I used alt/az exclusively. I had the HEQ5 for more than 12 months before I used it. Now I have a number of alt/az mounts that I never use.... except for the AZ-GTI. I am giving the AZ-GTI a proper go in EQ mode . I still think the EQ setup is a bit clunky but the ASIair seems work well in this mode, and the combination of AZ-GTI,ASIair and ED72 and 2 ipads is still a very light kit . cheers Paul Got your pm Paul. I've sent you a reply just now. Thanks. I hear you re sharpcap polar align! Tis a beautiful thing! Means I don't level tripod and just immediately do the PA as my setup step #1. After that I just do one star alignment using hand control and I'm up and running. Very easy setup of a GEM these days! Tony and several others in my astro club love their EQ'd AZ GTi's! cheers Howie
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Post by Deleted on Feb 4, 2020 11:42:59 GMT
Well, I shouldnt believe everything I am told on YouTube. For the AZ-GTI EQ and ASIair, I only needed to polar align the mount and did not need to do a 2 star alignment. I used plate solve for the first time. I used the zwo 178 on the ED72. The images are single and previewed in colour but for some unknown reason they only save in b&w. It is a pretty simple setup with the AZ-GTI, ASIair, 178 and one ipad . This is a 30 sec single of the tarantula. It wasnt quite centred . cheers Paul
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Post by Dragon Man on Feb 4, 2020 16:24:06 GMT
Oooo, nice sharp focus Paul. Looks pretty good to me
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Post by Deleted on Feb 4, 2020 21:55:50 GMT
Ken, there is a focusing histogram on the ASIair, but at present I still use the trusty Bahtinov mask. Last night,my main aim was to sort out the plate solve which I had never done before. Next task will be to sort out plate solving on Sharpcap
A lot of the ASIair enthusiasts on YouTube use the little Pi as their preferred computer. At home, a laptop with sharpcap, ethernet connections and big screens which are permanently setup will always be my preference. At a dark sky site, the ASIair will be a quick and easy setup with no laptop . Now I that I know how to setup the EQ with polar align and plate solve,I expect to be able to get some dimmer objects and get some single exposures out to a minute or 90 seconds.
Also,guiding seems to be reasonably straightforward on the ASIair, if I can trust the Youtube, but that is heading down a path that I dont really want to go. cheers Paul
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Post by howie1 on Feb 5, 2020 1:58:50 GMT
Well, I shouldnt believe everything I am told on YouTube. For the AZ-GTI EQ and ASIair, I only needed to polar align the mount and did not need to do a 2 star alignment. I used plate solve for the first time. I used the zwo 178 on the ED72. The images are single and previewed in colour but for some unknown reason they only save in b&w. It is a pretty simple setup with the AZ-GTI, ASIair, 178 and one ipad . This is a 30 sec single of the tarantula. It wasnt quite centred . cheers Paul Yup ... thats what that bloke did who I watched all night when I did that review. PA then no star alignment needed ... just use the object database wtihin the AIR, GoTo, then when it lands do the precise goto / platesolve and the targets were all (for him) bang in the centre of his first high gain short exposure. No star alignment. Now you know why I've sent you a response re getting your old AIR. I've messaged you Paul ... let me know when you can. Cheers. Howie
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Post by Deleted on Feb 5, 2020 22:00:01 GMT
Prior to putting the AZ-GTI into EQ mode , I was using synscan to control the mount with 1 ipad and then ASIair on another. It all worked fine for alt/az but I wasnt using the powerful features of polar align and plate solve. Looking back at a couple of my posts ,I kept repeating that I thought the AZ-GTI was too clunky etc in EQ mode and I would only use it in alt/az. Whilst the setup still looks top heavy , it seems to work a treat. Sometimes it would be nice to be able to delete what I have previously said . cheers Paul
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Post by ChrisV on Feb 9, 2020 22:08:10 GMT
Nice one Paul!
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