StuartT

So I'm on the NINA forum again tonight, and he said just set backlash to 1000 for a test. Here's what I got. I've no idea what this means, but I assume you do?

yes, in fact the direction in Pegasus motors s reversed, so I already corrected that setting. So now, positive means the focuser moving out of the tube. The max setting was 38,000 (fully out). But I still can't see where to enter that limit in NINA I have a clear night again (yay!) so I have set the backlash down to 140 and this is the focus curve I get now. I'm guessing focus is around 24600, but I doubt I can get it any better than that with this curve ??

oh dear... And I was pleased with myself for connecting the thing up! I am not all that good with tools and stuff. Maybe this is why the NINA guy said it was slippage and not backlash then?

Ok, so the NINA guy (Iseborn) progressively got me to increase the backlash until we reached 800, so I am not sure it's that. But I really don't understand any of this stuff (or really what backlash is, to be honest) so I may have misunderstood. Here are the settings we ended up at.

The guys on the NINA Discord channel were super helpful. There was a bit of fiddling, re-trying, fiddling and each time I uploaded my graph and they told me what numbers to change. I literally had no idea what any of it meant, or what my graph was supposed to look like 🤣 but I just did what I was told. I think the initial step size was 40. Ended up at 120. I don't think we managed to get it 100% right. They were concerned about the flat part of the curve remaining - apparently they think this is slipping (which I think is the grub screws not being tight enough...). Not sure how much that matters... the autofocus does at least work more or less ok

It's such a big target, I only got part of it with my 150mm frac. Only 1.5h integration time, but quite nice, I think

Thanks everyone. I managed to get it sorted out last night and got a nice autofocus curve in NINA 🙂

ok, I'm not really sure how far out the max extent of the tube is, so I shall have to bit by bit add 1000 to the number in NINA until I get to the end.. Hope I don't overdo it. A bit trial and error! so when I reach that max number, do I enter it in NINA somewhere?

thanks so much! super useful! Ok, so I have loosed the grub screws and wound the focuser all the way in, then a little way out (as I wanted one of the grub screws to be on the flat part of the shaft - that seems important!) And I opened the Pegasus app and reversed the motor direction. Now... I have set the focuser position in NINA to zero. Is that what you mean by syncing it?

err.. ok. I can't use the focus knobs with the motor attached so I shall have to take the damn thing off and re-fit it with the tube wound in, right? One issue I have is that entering a positive number in NINA moves the focus tube inwards. Shouldn't it be outwards? Otherwise, setting it to zero with the tube all the way in will mean NINA can't move it (as it doesn't seem to like negative numbers!). COnfused

I've never had a motor focuser before and I have just fitted a Pegasus universal motor focuser to my Esprit (controlled from a Powerbox). When I attached it, the focus tube was at mid position (which seemed sensible) and of course it's now 'locked' to the focus motor. In NINA, the position is showing as zero and entering a positive number moves the focuser inwards (which I think is to a more distant focus), but NINA doesn't accept negative mumbers, so how would I move the focuser in the opposite direction? Is there a 'motor focuser 101' I need to read somewhere? I've never thought of focus as being a 'number' before. It's always just been turning the knob clockwise or anti clockwise!

wow! Excellent job!

Ok, vlaiv. I clearly misunderstood you. I was reading this remark as negative about binning: But I understand now what you are saying (I think). Thanks for taking the time to explain. I did not. This is bit beyond my knowledge at the moment. I am still very new to all this. I think I was taking this from various other sources about CMOS cameras.

I avoid guiding by keeping my subs short (35s). This gives me round stars with my setup. I read somewhere that guiding used to be more crucial with CCD cameras because you needed a longer exposure to swamp the read noise. But with newer, low read noise cameras like mine (ASI 2600MC) this is much less significant, so there is little advantage in doing smaller numbers of long exposures compared to larger numbers of short exposures. Plus, it saves all the hassle of setting up guiding! So I'm confused. Earlier in this thread, you seemed to be saying that binning was not a good strategy? Or maybe I am misunderstanding you.

Ok, I should probably point out that a) I am using a 150mm apo with reducer (focal length 808mm) b) I am not guiding. But given that my focal length and camera are both fixed, there is not much I can do about pixel scale anyway, right?

why so much yellow glow then? Were you looking toward a city?

How do I measure FWHM? I assume you mean the FITS image that comes out of Astro Pixel Processor? ok, this is a simple solution! So I can set binning in NINA to 2x2 I think. Does this mean I can increase exposure time and still have round stars?

Thanks vlaiv. I can always rely on you for a detailed answer. So would you say my current setup is ok (0.958)? Which side of the 1-2 is it best to stray on (oversampled or undersampled)? Because we only have the cameras and scopes we have, so we have limited ability to change pixel scale unless we buy a new expensive piece of equipment.

So I have gathered that the ideal pixel scale is 1-2 arcsec per pixel (depending on seeing). But I have seen very nice images significantly more oversampled than this rule. For example, this image from astrobin https://www.astrobin.com/full/p2adjl/0/ is at 0.658 arcsec/px and looks good to me. My setup is at 0.958 and I was a little concerned I was oversampling, but maybe I don't need to worry. View on the 1-2 arcsec/px rule? When is it ok to break it? Thanks

Interesting. I only have SharpCap 3.2. Didn't realise there was a new release. I'll check it out. Totally agree that the polar alignment is fab. I use SharpCap for planetary (at least in my modest, newbie way). The version I'm using is 1.10 HF4 Beta 1 which is great but very occasionally will freeze on you. The newest official release is 1.10 HF3 and is completely stable.

I suspect NINA will be the one to do that. It's already gradually adding the functionality that other things have. Though not yet guiding

what time of day was this? It looks like the sun was either just set, or just about to rise

Last night I tried the Eastern Veil again, but this time adding an Astronomik UHC filter. This is only an hour of data and it obv needs more, but I really like how it's brought out more of that lovely blue/green (though I am surprised that it seems to have supressed the red, given that the UHC transmits everything from 640nm onwards) Eastern_Veil_with_UHC_filter-RGB-session_1.fits

thanks for this. reboot - yes change COM port - yes, I always do that when connecting my mount (even before getting a powerbox) as the mount connection depends on the right COM port being selected. try USB2 - no, I have not tried this. I shall do tomorrow.

Thanks for bothering to explain all that. Very helpful. In the meantime, it's a clear night, so I have connected up the old fashioned way as I don't want to miss those lovely photons because of messing about with plugs and cables. 😉 I'll try the powerbox again in the morning.