Difficulty guiding with ASI585mc Air

Photon08

Have you tried bin2 for the guide camera?
You can also use higher gain.

Btw, I agree that putting the guide sensor along the long side of the main sensor instead of the short side would make 585mc air work better with a telescope with a smaller imaging circle.

Sonixx

Hi givoli,

I haven‘t had any such issues wirh my 585air, but I am using it with a refractor.

It is important to highlight that you need to calibrate the setup every time you rotate the Camera. Also as said above, use binning and highest gain, especially when used with Narrowband filter.

Careful (un)focusing is critical, try to get the stars as round as possible, slightly defocusing the image often helps when off axis guiding.

Best regards,

Stephan

RUa7dc98

I've used mine all the last night. Asiair 2.3.3 and L-eXtreme filter. No problem at all and around 0.5" error. My rig is 71f from askar on eqm-35 and the asi585mc air only. Gain was set at 'high', 1 sec of exposure and bin1.
Shoot for all the nigh. Around 10 hours with automated meridian flip. Everything has worked very well. Many people mentioned problem with guiding and last asiiar version... Maybe you are using 2.4.x ?

Yesterday was my first try with the L-eXtreme and I was a bit nervous about this with built-in guiding sensor... But no problem at all. Hope this helps...

A6sGFz4a

RUa7dc98 Hi, I'm a complete newbie... and I think I made a mistake. I recently bought the same camera, the ASI585MC Air, along with a 1.25-inch filter set (Optolong IR/UV Cut, L-Pro, and L-Extreme) and a filter wheel. I opened the camera but haven't tested it; the filter set is sealed... because, on reflection, I don't think the 1.25-inch filters will work for the camera's image circle. The question is, what size filters do you use? Thanks in advance. Best regards.

Corsair

A6sGFz4a Pretty sure you need 2 inch filters.

RUa7dc98

Corsair you're right. 2" needed with the asi585mc air.

I use a 2" L-eXtreme and it works well. I'm pretty sure we could use 1,25" filter if we design some specific interface to place on a standard holder. The idea is to center the 1,25'' filter on the both sensors and not on the optical axis of the rig.

I'm pretty sure it would work but I'm not able to design such interface (kind of small round pla decentered adapter) and in case it is not working i would buy a 1,25'' filter for nothing.... 😅 So I decided to buy a 2'' filter.

Eric

Corsair Nah, 36mm are fine, ZWO has a diagram called "Image Circle Compatibility Reference" most of the way down the product page that shows 36mm filters cover the guide sensor:
https://www.zwoastro.com/product/asi585mc-air/

givoly

I will retry with trying bin2 and out of focus stars and report back... but guiding with the already existing 188mm focal length guide camera works perfectly. That said, it is my interest to obviate the need for a separate guide.

Eric

givoly I'm not sure exactly what your issue could be, are you using a filter or filterwheel in between the camera and the coma corrector? I have used my asi2600mc air with the Maxfield 0.95x coma corrector on my quattro 200p and it guided just fine, RMS in the 0.6-0.8" range. I used no filters and stars were mostly round, but that doesn't matter so much. What kind of coma corrector are you using? Are you making sure the focal length assigned to the guide settings is the same as the focal length as in the telescope settings?

Corsair

Eric oh right. Yep. I was just saying that if the choice was between 1.25 inch filters and 2 inch filters then it would have to be 2 inch. But 36mm (around 1.4 inches) is okay too.

givoly

Eric I'm using the correct focal length setting and the coma corrector is the Baader 2" MPCC Mark-III (https://www.baader-planetarium.com/en/2inch-mpcc-mark-iii-multi-purpose-coma-corrector-for-newtons.html).
The stars for the guide camera are totally distorted, regardless of the focus. I did not yet check out defocusing them significantly. Filter is Optolong L-Pro 2", well ahead of the camera in the optical path.

Eric

givoly I'll be honest with you, and it's something most don't like to hear, but the Baader MPCC M3 is a terrible terrible coma corrector. I used it for a while at the start of my Newt journeys, thought it was pretty serviceable, but once I got a decent coma corrector (like the Quattro 1x corrector or the TS Maxfield 0.95x, I had both at one point) the deficiencies with the MPCC M3 become immediately obvious. It's not surprising your guide stars are terrible. I'd recommend saving your pennies and upgrading that coma corrector as soon as possible. Like I said, with the Maxfield 0.95x corrector the stars on my ASI2600mc Air guide sensor are pretty good, mostly round.

That may or may not fix your guiding issues with the cam, but it almost certainly won't hurt. If you are using a strain wave mount, most SWG mounts like to be guided "fast" with exposures in the 0.5-1s range and star quality can absolutely play a role in guiding quality with those mounts. I use an iOptron HAE29C-EC, the encoder helps, allowing me to extend my guide exposures to 3s+ and have higher quality stars, fwiw.

givoly

Eric I have over a dozen telescopes, numerous tracking mounts. All are still still traditional and didn't yet get strainwave/harmonic. That will come too. In this case, two newts, 750f5 and 200f4. Both suffer from this issue and don't work well with the 585air. I will consider other coma correctors, though for the image circle, I'm really not suffering. I've always used 294mc pro and smaller sensors to get by without stressing the coma issues. It's really just this, effectively off-axis-guider, within the smart camera body, that is demanding of the quality image circle. So buying an expensive corrector for this, is a bit counter intuitive. Also note, I currently have a 170mm or 180mm guide camera that works perfectly - and cheaper than an expensive coma corrector 🙂 And the actual image circle is just for the 585 sensor in the middle... it has no issue with stars end to end in either of my newts.

Btw, Quattro is advertised for full frame image circle. Which makes me wonder whether to try it out without a coma corrector... maybe it will perform better... the coma isn't bothersome within the 585 sensor's size anyway...

Eric

givoly All of these Newts need coma correctors, you may not see much coma on a 585 sensor without one, but on a 533 or larger sensor you absolutely will. With my Quattro 200p I used the ZWO OAG-L with a 290mm mini, paired with the EFW and 2600mm and the stars are a little elongated in the OAG, but not too bad. I used a guidescope with the 150pds and early on with the Quattro without any real problems, just wanted to eliminate any possibility of differential flexure with the mirror system so I switched to an OAG. I think ultimately I'll go with a 2600mm Duo or maybe the Air and splurge on some 2" filters eventually, but I gotta save my pennies for that for a while. The 2600mc Air worked quite well with the Quattro and I'll probably use that with a paracorr t2 coma corrector for galaxy season.