Optimising Guiding Performance with ASIAIR Plus and AM5 mount - Forums

I noticed when processing my latest image today that a lot of my subs had elongated stars that were very noticeable so I had to throw out quite a few. My guide scope was a bit loose on the first night so the likely candidate was differential flexure. I don't think that was the only issue though.

I hadn't weighted down the carbon fibre tripod and given how light the AM5 mount is, particularly with a Redcat 51 on top, it occurred to me that this could be a problem with any amount of wind or vibration.

As I was also imaging with the Redcat 51 and 2600MC Pro the images are under-sampled so Ive been aiming to collect a lot of subs to facilitate drizzle integration in Pixinsight. I was dithering every sub frame and I noticed it would take my guiding a long time to settle down after dithering. I also feel like this was affecting my guiding performance and the numbers were fluctuating from 0.6 ArcSeconds up to 2-3 ArcSeconds.

I'm aware of the complexities of guiding but I'm just curious if anyone has faced particular challenges with ASIAIR/AM5 guiding in this respect?

I had trouble with my AM5 because I thought the defaults were specific to the mount.

What are your Max Dec and Max RA guide settings?

Try 200-400 ms

Check the RA Aggr and DEC AGGR settings, they are usually too strong. Mine were 100 and 70%.

Try 35-50% range

If possible, use 1 sec exposures on guide camera at 0.5 (or 0.25) guiding speed.

I used to use my AM5 with my Apertura 75Q (FL 405mm) (with EFW, EAF, etc it's about 11lbs) without weights on the end or tripod and through windy nights. The only time I had consistent elongation across the field was when I had poor polar alignment. The ASIAIR protocol doesn't always get it right and it's cost me a couple of nights in the past. I usually run polar alignment 2 times in two different starting locations such as one at Polaris and one starting from zenith. When the alignment is on, I usually get 0.2-0.6" guiding. I typically guide with 2s subs as well shooting through dual narrowband filters. My parameters are 15-20% on RA and 55% on DEC. I had those set after hearing I needed to lower aggression but I have never fine tuned them since I was happy with my guiding. These settings worked on my Esprit (30 lbs) as well but I have that weighed down with a counterweight and a 20lb weight in the pouch for peace of mind.

Hard to judge if it has anything to do with the settings or not. I agree with the comments above regarding the aggression. AM5 needs fast exposures to correct for the large PE. So probably won't go more than 1s. I have used it from an Askar FRA400 all the way to a C11 at a fl of 2065mm.

Your image scale is 3.1" per pixel. You are significantly under sampled, so it would be very difficult to have trails unless something is massively off. In your case it like was just the winds.

On those windy days you might just want to cut your exposure durations to 30s-60s and deal with the significant more data, but can salvage a lot more integration time.

Ah, my 120 USD mount does better than an 2K USD AM5, that something to celebrate!

andrea tasselli:
Ah, my 120 USD mount does better than an 2K USD AM5, that something to celebrate!

Just today my Toyota Corolla also beat a broken F1 formula car too! All around a joyous day indeed.

Was the F1 car running or just by the side of the road by any chance? Because my "Corolla" has been running for past two hours with 0.58" rms in Ra and 0.28" in Dec. Considered that basically I rescued it from the tip it ain't too shabby, this "Corolla".

andrea tasselli:
Was the F1 car running or just by the side of the road by any chance? Because my "Corolla" has been running for past two hours with 0.58" rms in Ra and 0.28" in Dec. Considered that basically I rescued it from the tip it ain't too shabby, this "Corolla".

Well when that F1 is running, it was carrying a 35 lb C11 payload at a FL of 2065mm at 0.3-0.4" for hours on both the Dec and RA, while weighing a fraction of the payload, and not needing anything more than a 10lb unbalanced counterweight. I also didn't spend any of my precious time building it or saving it.

Here is a thought. Maybe build a company that produces those amazing $120 Corollas, and sell them for $500. You'll beat all the giants.

Might be relevant, or irrelevant, but I wish ZWO would put an "Auto" setting for both DEC and RA guide aggressiveness settings

It's a pain to manually get it just right

It caused me 2 whole arcminutes of guiding accuracy (which is horrible for my setup) at default settings, and I had to spend literally 30-40 minutes trying to find the right aggressiveness

I finally made the conclusion to set both numbers between 45 and 65 percent (I forgot which was which; one was 45, the other was 65)

Then I could finally get a good 0.70" total guiding accuracy

Sometimes I was even getting 0.45", but my AVX cannot handle that accuracy for too long

I used the default guiding settings on my AM5 with ASIAIR for a long time. It was only one night recently that I started playing with them, when it was quite windy with some challenging seeing conditions - the default settings struggled. I think prevailing sky conditions play a big part in whether the default settings will be successful, or not, and indeed play a part in what you should change them to.

I can regularly guide my AM5 at ~0.3" RMS, sometimes slightly less. For me, a good night is 0.3", a standard night 0.5-0.6", a poor night 0.7-0.8" - give or take a little.

If you want a good answer for why I proposed the settings earlier, is comes from someone that knows a lot more about this than me. If you can follow the math and the logic, look at this:

https://bbs.zwoastro.com/d/15989-getting-the-best-performance-from-my-am5

Michael:
I had trouble with my AM5 because I thought the defaults were specific to the mount.

What are your Max Dec and Max RA guide settings?

Try 200-400 ms

Check the RA Aggr and DEC AGGR settings, they are usually too strong. Mine were 100 and 70%.

Try 35-50% range

If possible, use 1 sec exposures on guide camera at 0.5 (or 0.25) guiding speed.

*** Thanks mate. I do tweak RA and Dec aggr spending on how my guiding is performing. Good point about max guiding setting. I think it's set to something ridiculous like 2000ms and now I recall some of the advice from the PhD2 documents about reducing the max particularly when it's windy.

I always thought guide exposures should be 2-3 seconds otherwise you just end up chasing seeing?

***

Ashraf AbuSara:
Hard to judge if it has anything to do with the settings or not. I agree with the comments above regarding the aggression. AM5 needs fast exposures to correct for the large PE. So probably won't go more than 1s. I have used it from an Askar FRA400 all the way to a C11 at a fl of 2065mm.

Your image scale is 3.1" per pixel. You are significantly under sampled, so it would be very difficult to have trails unless something is massively off. In your case it like was just the winds.

On those windy days you might just want to cut your exposure durations to 30s-60s and deal with the significant more data, but can salvage a lot more integration time.

*** Ye, my stars came out fine in the end and that's by virtue of the image scale. I guess that's also why I'd recommend beginners start with small wide field refractors. It's a lot more forgiving. I still aim to get the highest quality data I can get though.

I hadn't actually heard about the need for short exposures with the AM5 so I'm glad I posted this question.

I have a feeling my issue was to do with the mount settling down after dithering. I was dithering every frame and the guiding wouldn't take time to properly settle down each time. And this affected shorter exposures more.

***

Ashraf AbuSara:
Hard to judge if it has anything to do with the settings or not. I agree with the comments above regarding the aggression. AM5 needs fast exposures to correct for the large PE. So probably won't go more than 1s. I have used it from an Askar FRA400 all the way to a C11 at a fl of 2065mm.

Your image scale is 3.1" per pixel. You are significantly under sampled, so it would be very difficult to have trails unless something is massively off. In your case it like was just the winds.

On those windy days you might just want to cut your exposure durations to 30s-60s and deal with the significant more data, but can salvage a lot more integration time.

*** Ye, my stars came out fine in the end and that's by virtue of the image scale. I guess that's also why I'd recommend beginners start with small wide field refractors. It's a lot more forgiving. I still aim to get the highest quality data I can get though.

I hadn't actually heard about the need for short exposures with the AM5 so I'm glad I posted this question.

I have a feeling my issue was to do with the mount settling down after dithering. I was dithering every frame and the guiding wouldn't take time to properly settle down each time. And this affected shorter exposures more.

***

There is a setting in the ASIair to adjust the settling time for how many seconds once it reaches below certain error in arcseconds. For example you can say that you want it to start the exposure after it settles under 1" for 3s or 5s if you want.

As to exposures for a harmonic mount with no encoders, you have to correct frequently due to the large PE, so exposures around 0.5-1.5 seconds are preferred.

I noticed when processing my latest image today that a lot of my subs had elongated stars that were very noticeable so I had to throw out quite a few. My guide scope was a bit loose on the first night so the likely candidate was differential flexure. I don't think that was the only issue though.

I hadn't weighted down the carbon fibre tripod and given how light the AM5 mount is, particularly with a Redcat 51 on top, it occurred to me that this could be a problem with any amount of wind or vibration.

As I was also imaging with the Redcat 51 and 2600MC Pro the images are under-sampled so Ive been aiming to collect a lot of subs to facilitate drizzle integration in Pixinsight. I was dithering every sub frame and I noticed it would take my guiding a long time to settle down after dithering. I also feel like this was affecting my guiding performance and the numbers were fluctuating from 0.6 ArcSeconds up to 2-3 ArcSeconds.

I'm aware of the complexities of guiding but I'm just curious if anyone has faced particular challenges with ASIAIR/AM5 guiding in this respect?

I used a 130/900 triplet Apo on my AM5 without counterweight guiding at 0.4-0.5 without any problem.
I use short guiding exposure, 1 sec or sometime less.
When driving is worse than 0.5 it is because there was a small earthquake (as you can see in the graph). It's true, I'm not joking.

Michele Campini:
I noticed when processing my latest image today that a lot of my subs had elongated stars that were very noticeable so I had to throw out quite a few. My guide scope was a bit loose on the first night so the likely candidate was differential flexure. I don't think that was the only issue though.

I hadn't weighted down the carbon fibre tripod and given how light the AM5 mount is, particularly with a Redcat 51 on top, it occurred to me that this could be a problem with any amount of wind or vibration.

As I was also imaging with the Redcat 51 and 2600MC Pro the images are under-sampled so Ive been aiming to collect a lot of subs to facilitate drizzle integration in Pixinsight. I was dithering every sub frame and I noticed it would take my guiding a long time to settle down after dithering. I also feel like this was affecting my guiding performance and the numbers were fluctuating from 0.6 ArcSeconds up to 2-3 ArcSeconds.

I'm aware of the complexities of guiding but I'm just curious if anyone has faced particular challenges with ASIAIR/AM5 guiding in this respect?

I used a 130/900 triplet Apo on my AM5 without counterweight guiding at 0.4-0.5 without any problem.
I use short guiding exposure, 1 sec or sometime less.
When driving is worse than 0.5 it is because there was a small earthquake (as you can see in the graph). It's true, I'm not joking.

*** Thank you 🙂 Ye, I've had some useful tips on here. I wouldn't have considered shorter exposures usually but I'll give it a go***

My guiding went wonky after an update. I changed my guiding speed to 0.75X, reset my time to 0.5 sec from 0.25 sec, and the system started working correctly. My problem may have been that the stars were overexposed and thus quite fuzzy. I was used to the old cameras that needed a longer exposure.

Michael:
I had trouble with my AM5 because I thought the defaults were specific to the mount.

What are your Max Dec and Max RA guide settings?

Try 200-400 ms

Check the RA Aggr and DEC AGGR settings, they are usually too strong. Mine were 100 and 70%.

Try 35-50% range

If possible, use 1 sec exposures on guide camera at 0.5 (or 0.25) guiding speed.

*** Thanks mate. I do tweak RA and Dec aggr spending on how my guiding is performing. Good point about max guiding setting. I think it's set to something ridiculous like 2000ms and now I recall some of the advice from the PhD2 documents about reducing the max particularly when it's windy.

I always thought guide exposures should be 2-3 seconds otherwise you just end up chasing seeing?

***

I started tweaking this last night, any solid recommendations for numbers?

I am inclined to set Max Dec and Max RA to 250

And set aggression to 40 for both as a starting point.

I am stuck with 1 second guide exposures, (asi2600mc duo) and my filter and lipo just dont let in enough light to do 0.5

Any other suggestions for this would be great.

Michael:
If you want a good answer for why I proposed the settings earlier, is comes from someone that knows a lot more about this than me. If you can follow the math and the logic, look at this:

https://bbs.zwoastro.com/d/15989-getting-the-best-performance-from-my-am5

I can also recommend Chen's solution linked by Michael. If you follow his calculations and use the periodic error report from your AM5, you will find good settings for your mount. I did this with mine and haven't had any problems since.

Michael:
If you want a good answer for why I proposed the settings earlier, is comes from someone that knows a lot more about this than me. If you can follow the math and the logic, look at this:

https://bbs.zwoastro.com/d/15989-getting-the-best-performance-from-my-am5

I can also recommend Chen's solution linked by Michael. If you follow his calculations and use the periodic error report from your AM5, you will find good settings for your mount. I did this with mine and haven't had any problems since.

I tried that last night but it was 3am, and I just couldnt do the math, will take a look again.

I found this surprising, but maybe helpful.

I have an AM5 with a C8 and an OAG viewing at 1500mm. At this field of view, I can often only find 1 or 2 guide stars and multi-star guiding is impossible. I normally update the guiding at 1 sec intervals. For whatever reason, I found that sampling at 2 second intervals gave me better guiding. I think what was happening is that I was chasing the seeing, causing the tracking to be unstable and over-correcting. Whether this was a one-time fix and a unique situation, or will result in real improvement in guiding will be determined on my next target.

Michael:
I found this surprising, but maybe helpful.

I have an AM5 with a C8 and an OAG viewing at 1500mm. At this field of view, I can often only find 1 or 2 guide stars and multi-star guiding is impossible. I normally update the guiding at 1 sec intervals. For whatever reason, I found that sampling at 2 second intervals gave me better guiding. I think what was happening is that I was chasing the seeing, causing the tracking to be unstable and over-correcting. Whether this was a one-time fix and a unique situation, or will result in real improvement in guiding will be determined on my next target.

Super surprising, considering all other suggestions keep telling me to decrease the frequency vs increase. Its all worth a test.

I usually keep moving toward higher sampling rates, but at F7 or F10 the stars get really dim. Out of frustration, I moved outside of convention.

I noticed when processing my latest image today that a lot of my subs had elongated stars that were very noticeable so I had to throw out quite a few. My guide scope was a bit loose on the first night so the likely candidate was differential flexure. I don't think that was the only issue though.

I hadn't weighted down the carbon fibre tripod and given how light the AM5 mount is, particularly with a Redcat 51 on top, it occurred to me that this could be a problem with any amount of wind or vibration.

As I was also imaging with the Redcat 51 and 2600MC Pro the images are under-sampled so Ive been aiming to collect a lot of subs to facilitate drizzle integration in Pixinsight. I was dithering every sub frame and I noticed it would take my guiding a long time to settle down after dithering. I also feel like this was affecting my guiding performance and the numbers were fluctuating from 0.6 ArcSeconds up to 2-3 ArcSeconds.

I'm aware of the complexities of guiding but I'm just curious if anyone has faced particular challenges with ASIAIR/AM5 guiding in this respect?

I had the same issue and the stars were elongated especially for exposures more than 30 sec. Have AM5N Mount with ASI Air Plus and Askar SQA55 refractor scope. In my view there are two areas one needs to take into account

1. Guide scope mounting and position. There can be some flex which may affect guiding . Changing RA/DEC aggression can help or alternatively using an OAG can be a good option as well my view

2. Also to check if Polar Alignment is perfect. Any large RMS error on PA process can result in elongated stars.

Sometimes I do get elongated Stars at the edges and try to correct with Star Processing feature in Siril 1.4 which is a great tool to bring stars in good shape.