kirkster501

Thanks, actually it may be Metaguide that I was thinking of .

I also had this issue across three different rigs, 2x2 binning, twelve second exposures with object directly overhead and gave up and rely on the fact that my filters are claimed to be parfocal. So I focus with lum and switch back to Ha/OIII. Or I could work out the offset, focus with lum and apply the offset. I CBA to work out the offset since it is precious imaging time faffing around, we get so little as it is! 28 seconds is a long time for an AF focus sub when temperatures are dropping. Nine x 28s (actually, ten including the confirmation one at the end) and we are looking at six minutes to do an AF run. That's getting silly. Don't know about anyone else, I can never "trust" AF and when it runs there's always some trepidation that I have to get involved. It can work 99 times out of a 100. Then for almost no reason at all, it just starts playing havoc with gull wings and auto-abandoning the sequence "something terrible has happened" As an aside, is there any way you can say that an AF score of 78% (say) is acceptable and to NOT run another AF session???? I do not see how to do that? Often I find the focus point to be perfectly acceptable and yet SGP wants to rerun.

Great work Geof!

A few stars poking through the murk tonight so I thought I'd collimate my C925. I like using a camera to do this in Sharpcap. Is there a way for Sharpcap to keep bringing the star back to centre after you've touched the scope and disturbed the star from the centre of the FoV please? It's annoying have to recentre it manually again, which you have to do. I have found the mount control of my Mesu in Sharpcap a bit hit and miss as to whether it works.

Don't be discouraged - that is a good Pelican. Think of all the things you got right! You found it, framed it, tracked it. A couple more pieces of the puzzle in place and you'll be firing on all four cylinders! But focus.... that one is critical, all is lost without good focus. Get a Bahtinov mask or make one. Maybe your sky *was* ok? I'm just saying that if you have fuzzy subs you need to bin them or grade them accordingly so they contribute less to the integrated image stack.

^^^All that Bryan says. You need to eliminate this stuff. Skies have been dire of late, even in the few "clear" nights that we have had and I had some subs like this and had to throw them out. You have to be ruthless with subs ruined by cloud and maybe you haven't been? The filaments of detail are extrenely fine in these nebulae and any loss of clarity can wipe it out. I also think your focus is slightly off, exacerbating any issues aforementioned. There are many plates to spin and master in AP!!! Not easy because to eliminate problems or work around them requires precious and rare clear sky time, that we'd rather be imaging/observing in, and not resolving problems! Also, though I am not sure it applies here, the ASI1600 is well known for bright star artefacts. Search on here for this.

There is indeed. There is enough in the sky to do all the AP you could ever want with the Samyang 135mm. I have also done Virgo cluster and M81/M82 with mine plus tons more stuff. Also constellations and asterisms. I did one of the Coathanger last week that I shared on here as well as the Veil nebula. To do the full Veil you'd need to do a 4523412341 panel mosaic with a telescope! With the Samyang you can do it in one FoV.

Yep, making one is also an option too 👍

... and finally just to add, I love this widefield AP. If, god forbid, I had to divest myself of my telescopes and obs, I'd just keep the Samyang and mount to continue with this type of AP. and a pair of large bins for visual.

^^^^ and the reason for this is to prevent the blades of the iris causing diffraction spikes. The Samyang Iris design is pretty good (though not perfect) anyway. Some other lenses - like th eCanon 50mm nifty-fifty - can be quite bad. So we leave them wide open and use a step down ring to lower the aperture.

You can buy them from Amazon for about £12 for a pack of them of different size. We need a step down ring(s) to slightly lower the aperture to what would be the diameter of the open lens aperture at F2.8 (or whatever you want to use). Look at the Samyang's internal thread diameter on the lens and make sure the step down you buy has one in the step down kit matching that diameter. Of course, if your example works fine at F2.0 -i.e. fully open - then no need to do this. However, with mine I find my corners are off at F2 and I need to stop it down to F2.8

Just to close this thread off. I have sorted it out guys now and thanks for the help. The issue was down to bad habits of mine in not unparking/parking the mount properly and incorrect set up. I have now sorted it all out thanks to you folks

The science of this has gone over my head somewhat guys, I was basing what I said on my own experience allied top what Dr Glover says. Back to the Samyang 135mm, I am considering using a step down ring to lower the aperture to F2.8 (the sweet spot in my example) and leave the lens' iris wide open so as to minimise the slight star spikes. They are minimal on the 135mm anyway but be good to remove them completely.

All you need to know is your Sky Bortle number (from an online tool) and F ratio you are imaging at. From those you can determine your optimal exposure. Going longer than the optimal exposure, a number that is surprisingly small in suburban skies, adds almost nothing to the final image and is wasted time. That's what Dr Glover shows in mathematical terms and it matches my own experience FWIW. You'd do better getting more individual subs. Of course, very dark skies and it is worth going much longer.

It is indeed Superb. As is SGP to be fair. But it will surpass SGP before long, if it hasn't already. There is a slightly different mindset to drive NINA compared to SGP. A few things I don't like: 1. When I want to interrupt a sequence for some reason, it seems to want to park the mount and warm the camera up. I may not want to do that. I need to investigate since I'm sure it is me that is wrong and not the SW. 2. The Framing Tool with big chip cameras. The box represents the FoV on the background, it can be well big unless you download a *really* big and wide FoV (and that takes ages from NASA sky survey). I wish the FoV box had a "X" to represent the centre of the camera's FoV. You could then position it on the object more easily to get it in the centre. 3. The different options seem to be scattered all over the place., Sure, leave them there but would also be good to have them on a preferences menu bar too.

Great stuff, thanks for that Skipper-Billy. I thought there must be a way but struggled to find it last night.

One thing I can't yet work out how to do in NINA. SGP has a nice framing tool where you can loop exposures of say 2 or 3 seconds, without saving them, so you can hone in on your rough focus before engaging the autofocus. Anyone know how to do that with NINA? I was looking how last night but the clouds rolled in... There must be a way I'm sure. I will ask on Discord.

I find that there is little tangible benefit in the final, stacked outcome to warrant additional time to do longer subs Olly for broadband, due to my Bortle 5 skies. The sky background noise starts to drown out the data and that negates going over 300s for me. Narrowband can benefit from a bit more exposure. My empirical experience of this fits very well with what Robin Glover discusses here in his rational treatment of this subject. More exposures for sure, but each exposure does not need to be over 300s, again, in my Bortle 5 skies. Indeed, according to this, even 300s is too long at the Samyang F2/F2.8 ratiios, but I cannot bring myself to lower each sub to any less. I think we have an emotional "more is better" response to exposures and if 300s is good then 600s is better. As Dr Glover discusses here, this extra time is often wasted.

I only ever do 300s subs. I remain to be convinced that going longer makes any difference in my skies.

This is superb. I never tire of images of M31. I think it is surprisingly tricky to get the colour balance right and you have done that here in spades. You have that wonderful yellow glow that is hard to get right. The investment in the luminance has paid off handsomely giving you a lovely bright and detailed image. Chapeau to you mate, you should submit this as an APOD, it is a worthy contender. Yes there are a lot of background galaxies visible through M31 - and M33 as well for that matter. I am in the midst of a multi-year challenge to do a high resolution, multi-panel M31 with my TEC 140. Unfortunately the skies have not cooperated at all in recent autumns, this one included.

I'm not happy with this and will return to it, the data I have deserves a better final outcome than I achieved here. Upon reflection, I am not happy with the detail in the galaxy. The 1x1 luminance shows much more detail and it has somehow been lost in the LRGB combination in the midst of trying to control the star sizes. Star control is my perennial problem!

Lovely, top drawer, with spectacular resolution, nice subtle colour and great stars. If I may say, I think you could stretch the HII regions a bit more and it would be even better. A bit more, don't over do it.

Superb mate. A difficult target and it needs hours and hours of HAOIII integration to show the details. The Samyang 135 is a super lens for framing this object - I have done it myself too witjh mine - though will return to it when it clears to add to my data from last year. I have seen people do twenty hours plus on this, which is a lot of investment in a target under UK skies. You've got lots of the additional faint nebulosity around the Spaghetti as well. Keep at it.

A slight edit:

The Fireworks Galaxy with TEC 140 and Atik 460 and Astrodon LRGBHa (3nm). 36 x 5 mins Lum 1x1, 14 x 5mins in Each of RGB 2x2 and 14 x Ha 2x2. I think the data pool is in advance of my processing capabilities but this is the best I've done so far. Will keep playing.