Ags

Rural location matters because that determines how bright your sky background is. The contrast technique people are talking about on this thread works by attenuating the sky background but as yours is already dark I don't know if you will see the effect. M13 is a star cluster - I am talking about reolving the individual stars in M13, which is possible for scopes of 4 inches aperture and up, roughly. Technically, the greater magnification will attenuate the fuzzy glow of M13 itself, so I will stick my neck out and say that you should resolve more stars at high mag in M13 from your location.

Of course I understand that as do most other observers. But (unless you are at a very dark sky site) you will only see stars at the limiting magnitude at high magnification, and definitely not at such low magnification that exit pupil exceeds eye pupil. M13 is easily visible at the moment. Why not look at it with an eyepiece giving a 7mm exit pupil and one giving a 1 mm exit pupil and see which resolves more stars in the cluster? I am assuming you are in an urban/suburban location.

There is no other light to cause "increased brightness". The image you see in the eye is described fully by the light in the exit pupil. So if the exit pupil is larger than they eye pupil due to low magnification, the star is dimmer. It is astronomy 101 that you use high magnification to resolve faint stars in star clusters. This is a technique used by most observers. Who is wrong - your theory or all those observers?

Here is my latest version of M57 - 17 2 minute sequences of 240 frames (frame length being 500 ms clearly). I kept 40% of the frames. I think (after a bit of sharpening to see what's there) I am starting to pick out some detail in the nebula. Still very noisy but I think I can add to this. Also need to work on not overexposing the stars - this happens when i linear stretch the data for DSS (otherwise the stars are too faint to register). I think I can improve here though. @vlaiv - no drizzle in this version.

Have you tried? Don't knock it till you've tried it! 😂

Yes I figured out i need to use Global. I see Emil Kraaikamp uses frames of 1 second and still calls his results lucky imaging. I would go longer than 1/3 or 1/2 second, but the limiting factor is for me is tracking not seeing. The 6.3 reducer should let me add a few more milliseconds. Why won't my drizzle trick work?

I was just regretting selling that AZ3...!

Yes AZ mode - that is what limits my sequences to a couple of minutes. With a wedge I could be shooting 10 minute subs. Actually I could shoot subs of any length I liked - 1 hour would not be an issue, except for the fact I have to watch the screen and keep the target on the crosshairs! Maybe tracking will be better in EQ mode though...? My main issue with tracking is the ALT slips a gear tooth every minute - I guess in EQ mode my buggy ALT gear wouldn't be spinning so no problem.

Thanks @happy-kat. I am pleased too with the result, particularly at getting this definition at 1500 mm focal length on an AZ-GTi. Here is the results of using the global setting. Both are just quick stretches in Gimp. Before (using local alignment) After (Using Global alignment): Definitely more definition in the faint stars around the cluster.

I figured it out. There is a setting to apply alignment globally and not align every alignment point individually. I never understood why you would want to set Global, this is why - if you align at frame level then dim stuff stacks reliably. Use Local for the Moon, where there is always plently of local data.

I see it with all DSO targets. I suppose I could try longer subs.

Guess I could - but I am very close to the noise floor - so I may end up with the same problem just with bigger numbers. I do kind of do that as my camera is 14 bit but the data is so epicly dim I process it as 10 bit data, so I am stretching by a factor of 16. I am hoping an incoming 6.3 reducer will help but I wouldn't be using it with M57 anyway as it is tiny and bright.

Me too!

I am rejecting frames - in fact I am throwing away nearly half of them. Each frame is covered in a web of independent alignment points - and it seems if there is not enough signal from a star its local alignment point doesn't work. Here is my attempt at M57 from the same session. Focus was not the best on this one!

This nebula has phenomenal surface brightness.

Anyone?

I fail the reading emails test... And my current job is basically tech support by email and Teams! I am sure this job will make someone really happy! Especially if the annual performance-related bonus is paid in green and black!

I didn't see if this was full time, flexitime or zero-hour?

Forget the real living wage. Duz you gets staff discounts?

A Skymax 127 sits nicely on an AZ-GTi, while the 150PL would be undermounted on an EQ3 I think. You definitely don't need EQ for planetary imaging and I find my AZ-GTi and C6 very good for many applications. I studied images on Astrobin and came to the conclusion that 150 mm aperture was the least I needed for satisfactory images of the planets.

I was shooting M13 and M57 last night and I got promising but frustrating results. I was shooting with the following parameters: Scope: C6 @ F10 on AZ-GTi Camera: ZWO ASI 178 MM (non-cooled) Sequence: 500 x 333 ms subs Gain: 310 Binning: 2x2 ROI: full chip I processed in AS3! using 1.5 drizzle with Analyze set to focus on very small / high SNR. Why bin 2x2 then drizzle? Binning is to try help AS3 as with short DSO subs it can struggle to align the frames with all the noise. Drizzle then tries to get the detail back and unsquare the stars. Then I did a quick stretch in Gimp: I know a three minute sequence is not nearly enough but I have shot several - so the above is really just one "sub" with about 100 seconds of exposure (after 40% of the frames were discarded). Overall I am happy with the above, with the glaring exception of faint stars. The AS3! stacking seems to fail to align the faint stars resulting in any star below a threshold showing as a blob. My question is: how can I persuade AS3! to clean up the faint stars?

I do not use a barlow with my Skymax 102 because you already get high magnification (130-200x) using an eyepiece in the 7 mm to 10 mm range. On screen in the FOV calculator the planet looks small but when you have it in the eyepiece you will see that it is richly detailed and nothing like the dot you see on your screen. You have to remember that your telescope only gathers a fixed amount of light, and when you add a 2x barlow you are making the image 4 times fainter. When you look at a bright blue sky, do you see dots floating in your field of vision? If yes, you will see those same dots obscuring the planet when you use a very high magnification. For my pictures of the Moon and Saturn, I used a special astronomy camera (ZWO ASI 178 MM). That costs more than the telescope but you can buy comparable cameras (with a 30% smaller field of view) for less than half the price - and there are always second-hand bargains going. No eyepiece was involved - I inserted the camera in the diagonal instead of an eyepiece. For the Saturn picture, I also used a filter wheel and RGB filters to build a color image as my camera is monochrome. You mentioned Hyperions. I used to use a Hyperion 17 mm with fine tuning rings that gave me the options of 13 mm and 9 mm with the same eyepiece. In a Skymax 102 the hyperions are lovely eyepieces especially for planetary viewing. I had 3 eyepieces in the 9-10 mm range and the Hyperion with fine tuning rings definitely gave the best view. I sold my Hyperions when I got a different scope - I had a "fast" F5 Newtonian for a while and the Hyperions didn't give a good image there. I now use Explore Scientific 82 degree eyepieces which are in the same price bracket as the Hyperions but have a better field of view and they work in almost all scopes equally well. The Hyperions were a little more comfortable to use though!

Not my picture, but this is an impressive result for the Skymax 102: https://www.astrobin.com/291112/?nc=all

I have a Skymax 102 and it is a great scope for planets and Moon. I typically use a 10 mm eyepiece with no barlow - this is more than enough to show lots of detail on Jupiter while still keeping the image bright enough for contrast and color. In fact I often use a 16 mm eyepiece as the brighter image is easier for my aging eyes - and this still shows nice detail and color. I can go a little bit higher on the Moon, Saturn and Mars - for those I can use a 7 mm eyepiece (again no barlow). I have done some astrophotography with it, and I have attached some of my shots.

The 8-5 zoom is almost mythical in its reputation - there is nothing quite like it. I was so disappointed when these went out of production. At least I have the Speer WALER 10 mm - it's been the only constant in my small eyepiece collection.