Stuart1971

Yes I get that, and I will post a log as soon as I can get out and my biggest issue it RA correction going back and fourth, this is with 0.9x guide speed and have now been told by a few EQ8 users that this is way to high and too aggressive, hence going to try 0.5x, to try and stop the oscillation…. ‘I did adjust the aggressiveness right down to 15, and with this I saw figures of 0.65 RMS…

Can you explain on what mechanical issues, the mount is in excellent working order, with albeit backlash on the DEC axis, which doesn’t seem to be an issue with guiding in just one direction, and I was using 0.9x guide speeds, which apparently is too high, so am changing to 0.5x to try…. Also you think my guide set up with 8.6 micron pixels could not be made better…..🤔🤔 So what other mechanical issues am I missing here….??

Backlash in RA is moot, as it’s always traveling in the same direction, same in DEC when guiding in one direction opposite to drift….👍🏼

Backlash on RA….🤔🤔 no that’s not an issue…

I guide in DEC with south moves only as with my EQ8 there is some backlash and this solves that issue, but my RA is not great, one thing I have yet to try is changing the guide rate from 0.9x (which was recommended on NINA discord) to 0.5x, as the issue seems to be over correcting all the time, and the only way I have dealt with it in the past is to set aggressiveness right down to 15, that seemed to help… It’s just the pixel scale with the Lodestar means that any guide star is all on one pixel, which makes centriod calculation for PHD2 a lot harder and hence guiding is not as good… ‘Now I could double the focal length of my guidescope with a 2x extender which would then half the pixel scale….🤔 or another option, which would be cheaper, is to get a different guide cam with much smaller pixels…🤔🤔

Well not really as I already have the figures, but wanted peoples thoughts on good imaging v guiding pixel scales…based on the kit I listed above… ie, what is a good guiding image scale, v my actual imaging image scale…?/ That calculator tells me nothing about that….👍🏼

Cost and All that aside, also i use a polemaster anyway for PA…

Hello, I image now with a Tak FSQ85 @ 450mm f5.3 with a QHY268c which has 3.6 micron pixels, so I am imaging at 1.72”/pixel I use a Tak FS60cb for guiding @ 355mm f5.9 and currently use lodestar X2 with 8.3 x 8.6 micron pixels which guides at 4.76”/pixel, and I am finding this not to work very well and guiding is at best 0.7 - 1.0 RMS, I can’t help but think that smaller pixels would help…. So I am thinking of getting a ASI120 mini or similar with 3.75 micron pixels, which would give me 2.18”/pixel… thought on what would work well for my set up….? Thanks for looking….

What does binning make guiding better, as I thought smaller pixel sensors for guiding do a better job, I have been using a lodestar X2 with 8.3 micron pixels and found it not so good and have now got a camera with 3.75 micron pixels to try, if I bin that I am practically back where I started……🤔🤔

The lights flash to indicate that PEC is being recorded, but not to the mount, that’s a separate thing…👍🏼

AAP…?? What’s that…?

As you are imaging at 0.85 “/pixel, in theory your guiding should be at least 0.85 RMS, but some say it should be half of your imaging resolution which would be just above 0.4 RMS, but at the end of the day you want round stars….have you tried applying PE, periodic error correction for your mount….? Also there is an algorithm in PHD2 for the RA drive called Predictive PEC, give that a try too, it may well sort you out….

Well, I actually have the EQ8, and because of that I tried GSS, but the only really difference for this mount, is that in GSS you can perform an Autohome, which you can’t in EQMOD, and that was not really an issue, there were other things that just worked better in EQMOD, so stuck with it… As far as PEC is concerned, there is no difference between the two for this, as at the end of the day they should be the same as the PEC on the mount is not going to change it’s just the way the different softwares record it that will probably vary, can you then record the PEC curve into the motor controller with GSS, so it’s there all the time…?? I would assume so, it I don’t know, this can be done with EQMOD and is very useful….

You would have gotten the same Improvement with EQMOD PEC, it doesn’t interfere with PHD2, as long as you don’t use the `PHD2 built in PEC algorithm…at that same time, that’s when you have issues…. GS, is ok, but it does nothing for me that EQMOD does not, and it can be buggy too…

No, ignore that, I had that the wrong way round, I was tired last night when I replied…..you would need to increase the focal length of the one you have, so a Barlow would be needed, so a 2x Barlow would make it 240mm, and a 3x would make it 360mm, but then your f ratio would increase I think your best to either go for the 50mm one you linked too last night, and try that, it should be ok, as it’s much better than you have ATM, and it’s generally regarded quite highly for guiding….

I think you have that the wrong way round, a Barlow will make it f8 a reducer does the opposite hence the term reducer…..👍🏼 But it’s a Barlow he needs not a reducer, I did have that the wrong way round….

My mate actually uses this and so do many others….and swears by it, it’s 250mm focal length…so still use the reducer…. https://www.amazon.co.uk/Telescope-Guidescope-Helical-Finderscope-Astronomical-default/dp/B08CZL8C91/ref=sr_1_6?crid=1HGDO79JAH83D&keywords=60mm+telescope&qid=1644535653&sprefix=60mm+telescope%2Caps%2C59&sr=8-6

The other option is to get the one you linked to, and add a cheap 0.5x reducer to the front nosepiece of the guide camera Something like this, and that will turn that guidescope into approx 360mm, which would be perfect…. https://www.firstlightoptics.com/astro-essentials-eyepieces/astro-essentials-05x-1-25-focal-reducer.html

That would give you a guiding pixel scale of 3.2”/pixel, so much better, and just under the 4x…..but only just……so maybe with your scope and camera you want to be looking for a guidescope with around 320-360mm or thereabouts….focal length but that one you linked to would be much better….👍🏼

So,you are imaging at a pixel scale of 0.85 “/pixel and guiding at an image scale of 6.45”/pixel, and if we use the maximum 4x rule, then no, your guide image scale is much more than 4x, in fact it’s over 7x….the imaging scale, you really need a longer focal length guidescope…..sorry if it’s not what you wanted to hear….but you should be aiming for a guiding image scale about 1-3 times the imaging image scale….👍🏼

Looks great… What about strong winds getting under as that would take off and go for miles…..😮😮

This is actually very good advice, as people tend not to read really long threads that list issues, as by the time you have got to the end, you, well I forget what was at the start…😂, maybe break it down to bullet points and then we can answer one at a time in order…. ‘One positive is your amount has a very low backlash and that graph is very good, so if it’s any conciliation check mine here, it’s awful and the 3200 ms of backlash, yet I can still get good round stars….so don’t get too hung up on any of the settings, if the stars are good then just enjoy, PhD2 is a very good tool, but can sometimes give you a headache with all the info…

This is not normal to have to touch the port selection box, but if it works then hey ho….👍🏼

Hmmmm, 🤔🤔

Here