38 replies to this topic

[unimatrix0]

I managed to get a chance to image again last night, weather surprised me...  Think this is better, grabbed some subs of M101, stuck to 180 seconds and didn't have any that showed any star elongation till the meridian flip.  First time I have done that with this setup and didn't realize the ASIair defaulted to stopped guiding 5 min ahead of the flip.  Through me for a loop and wonder what the heck was going on... So a few subs lost on each side of the flip, but now I know how that works and so much easier than doing it manually!

 

IMG_0083.jpg

The stop happens, because - according to ZWO, it's harder to guide on top of the Meridian. It's best to avoid it by waiting 5 minutes past the Meridian.

[jaydeepappas]

That terrestrial image is not my main scope... I do use a bahtinov mask for that and it was dead on.

If the picture of M81/M82 is with your main scope then you are very out of focus. If you look at some of the bigger stars you can almost see the airy disks that show when you are doing a star test.

When you focus with the bahtinov mask, do the lines go directly down the center of the star and are they completely symmetrical with one another?

 

 

Your image is extremely out of focus. Your guiding numbers are also high, but getting your focus right for your main imaging scope is equally as important. Can you post a picture of an in-focus star field with the bahtinov mask on?

Edited by jaydeepappas, 26 May 2023 - 12:04 PM.

[SuperSirLink]

I am suspecting that is over exposure.  Yeah the it looked just like this:

 

 

Next time I have it setup, will grab a screen cap of the main scope.

Edit, also keep in mind that was a stacked image with the garbage subs included...

Edited by SuperSirLink, 26 May 2023 - 12:08 PM.

[jaydeepappas]

I will also add that with the 533mc you really don't need to be doing such long exposures for broadband imaging. Especially if you live in a higher bortle area.

 

A common misconception is that longer subs = more detail. But total imaging time is much more important than individual subexposure time. 60 minutes worth of 30 second exposures can be just as good or better than 60 minutes worth of 5 minute exposures as long as you are swamping the read noise of your camera. Longer sub exposure times can over saturate your stars and are more sensitive to guiding/tracking issues. For narrowband imaging - go for those 5 minute subs. But it is not necessary, and probably detrimental, for broadband imaging.

Edited by jaydeepappas, 26 May 2023 - 12:12 PM.

[SuperSirLink]

yeah, that night I really was really just trying to push the limits since it was the first time with the mount and guiding with ASIair.  3 min is probably longer than needed too, but again, still just trying to put it through the paces...

 

I am in bortal 5, but can easily get to high 3 / low 4 with a reasonable drive...  so I really just making sure I am getting the hang of guiding and finding the limits...

Edited by SuperSirLink, 26 May 2023 - 12:31 PM.

[matt_astro_tx]

You can definitely get better guiding numbers than that with the GTI.  I use the Star Adventurer and the other night my RMS guiding was below 1".

[SuperSirLink]

You can definitely get better guiding numbers than that with the GTI.  I use the Star Adventurer and the other night my RMS guiding was below 1".

my balance seems good on either side of the RA axis and DEC balance also seems good.  Could it be the meshing of the gears?  Any settings I should check using the Sky Watcher app? Have not touched that yet.

[vidrazor]

my balance seems good on either side of the RA axis and DEC balance also seems good.  Could it be the meshing of the gears?  Any settings I should check using the Sky Watcher app? Have not touched that yet.

Are you balanced, or see-saw balanced? I've noticed that for some reason, unlike single axis mounts, dual axis mounts essentially need Z-axis balancing. This is more important in DEC than RA, because usually in RA you're going to give it an eastern bias anyway (or should). Although there are Z-axis weight kits you can buy, you can make your own as well, and imagination can come in handy here. For instance, I put a heavy Velco strip on the C5 and merely attached a large bolt to it, and it balanced out. Depending on your scope, you can also get a top mounting handle that doubles as a Synta mount, and you can center mount your guide scope and computer to better balance the rig.

[SuperSirLink]

Balanced horizontal to the ground and if I tip either direction down about 10 or 15 degrees it stays put.  The only way I can think I could get better balancing would be to ensure the axis is not too tight.  Maybe my copy of the GTI just needs more tuning.  I have the opposite when the original SA came out, I seem to get better unguided exposures than others posting here.

 

I know what you are describing, but no easy way to do that in a way I can see that doesn't add a lot of bulk or weight.  The guide scope is mounted to a syntha style shoe off center.  So with the RA in home position there is some rotational imbalance when the DEC clutch is released.  No way I can see to get a top, centerline mount on the AT60ED...

 

Got a chance to stack my 3 min exposures from my second run of this setup and apart from the few frames around automated meridian flip (which is so much easier with the ASIair), every frame produced round stars.  Think I will try 5 min again to see if my improvements have helped.

 

Yes I know it is over exposed, that is showing as linear in Siril

 

[vidrazor]

I know what you are describing, but no easy way to do that in a way I can see that doesn't add a lot of bulk or weight.  The guide scope is mounted to a syntha style shoe off center.  So with the RA in home position there is some rotational imbalance when the DEC clutch is released.  No way I can see to get a top, centerline mount on the AT60ED...

 

Got a chance to stack my 3 min exposures from my second run of this setup and apart from the few frames around automated meridian flip (which is so much easier with the ASIair), every frame produced round stars.  Think I will try 5 min again to see if my improvements have helped.

 

Yes I know it is over exposed, that is showing as linear in Siril

It doesn't take much to Z-axis balance. If you're shooting with an AT60ED, you can put another Synta mount on it, as I did to mine. As I said, something as simple as attaching a weighted item like a bolt with Velcro can do it.

 

If you're overexposing at 3 minutes, going to 5 minutes isn't going to help. You don't even need 3 minutes on a target like that.

[SuperSirLink]

It doesn't take much to Z-axis balance. If you're shooting with an AT60ED, you can put another Synta mount on it, as I did to mine. As I said, something as simple as attaching a weighted item like a bolt with Velcro can do it.

 

If you're overexposing at 3 minutes, going to 5 minutes isn't going to help. You don't even need 3 minutes on a target like that.

Hmm, yeah that a thought... Was trying to keep the weight down, but can experiment with something like that.

 

Ha, because as I mention before, I am just testing the guiding and seeing how long of an exposure I can consistently get.

[matt_astro_tx]

I also have dual finder saddles on my AT60ED.  One for my ASIAir and one for my guidescope.

[SuperSirLink]

Think I figured out a way to balance out the guide scope.  When I get another opportunity, will see how that effects the guiding...

[SuperSirLink]

I am not using the synta mount foot that came with the ASIair, so my plan is to use that and a cheese plate I had and add some gimbal weights that have 1/4-20 threads and attach them to the cheese plate.  The SvBody 165 and ASI120mm add up to just over 400g, so that is my target.

 

My objective is to see how far I can push the exposure to find the limits of the setup where I no longer get consistent results, see what the best guiding rates I can achieve, then once I do that start playing with dithering and add that in.  I figured since I have never guided before this, I didn't want to add that into the mix and complicate any troubleshooting.

Edited by SuperSirLink, Yesterday, 07:39 AM.