photon08

Sorry for resurrecting this old thread.  I came across this issue while using ASTAP inside NINA.  My camera is ZWO 585 whose bin1 dimension is 3840 * 2160. I got this error when I use bin2, for which the image dimension is 1920 * 1080, which is higher than 1280 x 960 .  Despite the warning, the plate solving works fine so I'm not terribly worried. Nonetheless, 

My FoV is ~ 0.5 degrees and I have both D50 and D80, both of which should work for 0.5 deg FoV according to https://www.hnsky.org/astap.htm . 

On 05/04/2023 at 00:14, koen said:

By the way, how's the flexing of that whole assembly mounted on the camera flash shoe?

On my DSLR that's not something I'd want to mount a guide scope on...

I agree that it's far from ideal. My guiding accuracy is ~ 2" (instead of sub-arcsec I've seen many achieve).  If there were an alternative, I'd go with that, but I couldn't figure out one.  

I have FMA 180 and mounting options for that scope with DSLR + guidescope is pretty limited, I'm afraid.   With a newer version (pro version) of the same scope (FMA 180 pro), it's much easier, I think although I'm not sure a DSLR can be attached to FMA 180 pro (finder shoe at the top of the  FMA 180 Pro may interfere with the prism of my DSLR, Canon EOS 605D/T4i).  

2 hours ago, photon08 said:

Thank you for the reply.

 

I tried both. Unfortunately, that does not make a difference The first go-to is always off by 6 hours in RA (90 degrees in RA) and the scope points to the ground. 

The time comes from my phone/tablet and it's correct for both AsiAir app and Synscan app.  AsiAir app has the correct UTC offset, too. 

Thank you, @fwm891 !   Going Home (using ASIAir's 'Go home' button in the mount menu instead of manually turning back the scope with an arrow) before issuing a goto command to a target makes all the difference !   Now everything works perfectly (I haven't yet tested the automatic meridian flip with ASIAir, though) 

For the record, what I did this time is as follows:

1. Turn on ASIAir and AZ-Gti. They're connected via an EQmod cable with the scope pointing roughly at the North pole 
2. In ASIAir, connect to the mount (EQmod,  serial)
3. Run the PA in ASIAir
4. In ASIAir, go home using 'Go home' button in the mount menu of ASIAir
5. Go to a target past the meridian (i.e. Western hemisphere; e.g. Procyon) to confirm that the CW is down and the scope is up
6. Go to a target before the meridian (Eastern hemisphere such as Arcturus at 11pm in early April) to confirm that the CW is down and the scope is up
7. Go to another target past the meridian (e.g. Castro) to confirm the correct pose again. 

Thank you everyone for chiming in and help !

19 hours ago, happy-kat said:

Have you got it right sided mounted for when in eq mode?

The mount looks odd as the weights look higher then the scope in the second picture

Thank you for the reply. 

I'm pretty sure it's RHS. See my photo attached below. It's pointing toward the North pole. Without a EQ wedge (i.e. AZ mode)  and the scope  pointing North and being level, it'd be on the right hand side of the mount when viewed from behind the scope (me standing south of the mount and looking in north), wouldn't it? 

As for the second picture, that's my problem #2 in my original post. When goto is issued to a target in West (past the meridian: HA is between 0 and 12h; e.g. Capella, Procyon,  Rigel around 8pm in late March), the scope takes that incorrect pose (picture #2 in my first post)  even though the goto was issued from a position pretty close to the target in the correct pose (picture #1 in my first post).  

After this goto, all other goto's to targets past the meridian result in this incorrect pose even though in terms of RA and Dec, the scope is correctly centered. 

20 hours ago, fwm891 said:

What’s your starting point? Scope pointing north weights down? After PA do you return to ‘home’ position before slewing to a target? Clocks set to correct time?

Thank you for the reply.

I tried both. Unfortunately, that does not make a difference The first go-to is always off by 6 hours in RA (90 degrees in RA) and the scope points to the ground. 

The time comes from my phone/tablet and it's correct for both AsiAir app and Synscan app.  AsiAir app has the correct UTC offset, too. 

On 18/04/2022 at 07:21, herne said:

Thought I'd chip in with my experience of using this little mount for astrophotography using an eq wedge.  Equipment list:

Az-gti with eq wedge (firmware updated).

Astro-modified Canon 700D.

William Optics Z61ii + WO adjustable field flattener.

ZWO ASI 120mm mini mono camera + Astro Essentials 32mm guide scope.

ZWO ASIair pro + LynxAstro ftdi EQDIR USB adapter cable (connects AZ-gti directly to the ASIair pro).

Optolong L-enhance 2" filter.

Homemade counter balance weight.

iPad + ASIair app to control things.

 

I have an almost identical set up except that I have an ASIAIR Plus (and my camera and scope are different, but that shouldn't matter for my issues I'm going to describe).  I use an Eqmod cable to connect AZ-GTI with wedge and ASIAir plus. I choose 'Eqmod' in ASIAir's mount selection pull down menu. 

I have a couple of mysteries to solve re: Goto and meridian flip.   

Apparently, others do not have these issues and I must be doing something wrong.  If others could share what exactly do in terms of PA and goto's after that with the above set-up, I'd be very grateful.

I posted what I did in gory details at https://www.cloudynights.com/topic/870296-az-gtieq-mode-and-zwo-asiair-plus-counterweight-pointing-up-past-the-meridian-west/ . I'll repeat it here if it's better.   

Simply put, I have two issues. 

1. My first goto after the PA is always off by 90 degrees (6 hours) in RA.  For targets in SW, the scope is pointing downward toward the ground. 
2. To work around issue #1, what I do is to slew, RA,  manually (using ASIAIR app) by approximately 90 degrees and issue another Goto from ASI Air. Then, my second issue pops up, Even though the scope is pointing very close to the target and  is in the correct pose (my target is in south west  so that the telescope is above the level and the CW is below the level; the first picture below),  the Goto does a totally unnecessary meridian flip and puts the telescope below the level (moving down and approaching the tripod with the tracking ) and the CW above the level moving up with the tracking (see the second picture).  All other subsequent goto to other targets in SW or NW keep this pose.

In addition, when I issue a goto to a target in SE (e.g. Arcturus (10pm, late March) and another goto to a target in SW (e.g Procyon or Betelguse),  the scope does not change the pose (no meridian flip) even though Arcturus is before the merdian and Procyon/Betegues is past the meridian 

Thank you very much for your help, 

A nice job !

The other day, I came across now discontinued Meade field derotator.   It's brilliant and simple at the same time, IMHO. It does not require an external computer to control. Instead, it gets the current alt/az and the location (only latitude matters)  from the mount and calculates the rotation rate to counteract. I guess the downside of this simplicity (the direct connection with a mount) is that it can work only with a set of mounts it's designed for unless there is a standard to read alt/az and latitude from a mount. 

I wish there was one available for my mount (Orion XT10g;  Skywatcher synscan hand controller is used so that it'd be compatible with any skywatcher alt-az mount in terms of communication protocol, I believe).  Without that, my option is limited to getting a field rotator that supports the field de-rotation for alt-az to hook up to a computer.