CloudMagnet

On 11/10/2023 at 11:03, Fegato said:

Any expertise anyone can offer on maintaining a neutral background during Pixinisight post-processing would be welcome!

Here's the end result anyway. Not as pink, but a lot more faint nebulosity across the image.

 

I’ve never really used PixInsight for processing -I’ve always stuck to processing in Photoshop where colour balance can usually be sorted using a mixture of levels to balance black and white points along with Gradient Xterminator to get a uniform background. That’s always worked well for me. Comparing to existing images of the same target might also give an idea of how others have balanced out the colours before you go down your own route.

I think it just shows the value of processing an image more than once. I tend to do a rough first go at it to get a feel for the data and ways of bringing out details, before going back to the beginning and doing it all over again with what I have learned first time round.

The difference from where you started to now is really telling. I would say any further might be over-processed, I hope you are happy with how it turned out!

10 hours ago, Fegato said:

 

I've had another look this morning, and I'd obviously undone my SCNR at some point and not re-instated, so definitely some green. This might be a bit better?...

 

 

Yeah, looks a lot better. Might still need a bit of reduction in both blue and green levels for the background. At this point, is likely more down to personal preference rather than science but its still an amazing image regardless

Brilliant picture, the pinks look really natural so I think your “random” addition has worked. It might be my monitor but I think the background is a little green? Might be worth adjusting the background levels to help the colour balance.

Once APT is underway on an image plan and guding is solid, I get a deck chair out in the garden, recline back and just take in the stars. With hot chocolate in hand it becomes a really relaxing time to be with my own thoughts.

Will be great when JWST follows up with this. Amazing if it is truly a single star keeping in mind galaxies look like a small smudge at that distance in Hubble images.

I would say it is overdone in terms of the galaxies, but I don't think that is something you should worry about. Getting IFN to come out is a huge challenge unless you are at a dark site with long integration time, so it’s still a stunning image.

One idea is just process it twice. One time to maximise IFN, then one time just focused on making the galaxies as good as possible

Looks like it as the bottom of the picture will be closer towards the ground imaging at that orientation.

Although it costs, gradient XTerminator has always worked well for me to flatten the image and get a rough colour balance as well. A free option (but more basic) is to use the colour range tool in photoshop and then use it to select only the lighter part of the image. You could then use levels/curves to balance out the brightness difference.

The image as well would always benefit from more integration time. 1 1/2hrs really isnt too much and imaging with a dual pass narrowband filter would help bring out the contrast as well with the nebula. 5 mins is a really long exposure time to be using as well. Even with a narrowband filter I was using 2min exposures to stop blowing out Alnitak.

Agree, visually you are most likely to be looking at an object in the centre of the view only, where coma is never an issue- this is why people don’t really consider it necessary for visual stuff. Different story for imaging where the corners of the image have to look perfect as well.

10 minutes ago, Lee_P said:

Great pic, and I particularly like the framing. 

Agree, looks like the wall and pelican are giving each other a staredown before a fight

Whole picture looks great, starless helps bring out the contrast as well.

I had the same concern when I was imaging in my front garden for the Orion nebula with no light pollution filter, pointing nearly right at two LED bright streetlights. In the end the final picture was one of the best I had done and you wouldn’t have known that it was almost shot in bright daylight. I did most of the setup of the scope without a headtorch it was that bad.

One reason I think I got away with it was using a dew shield. It has a nice secondary purpose of blocking stray light, so even if you can’t get the lights dimmed/removed then all is not lost. Otherwise, stick to imaging high above the horizon and narrowband if possible.

I started out imaging with a 200p/EQ5 mount combination. I honestly wouldn’t recommend it for astrophotography. It’s perfectly possible, but you will have to manage a lot of issues that take patience and a lot of trial and error. Even then, you still won’t be able to get the best results. If you do plan for imaging, HEQ5 is a minimum for giving yourself an easier time, although it does take time to learn how to use the end result will be better.

First priority would be to have a go at some visual work to get used to the scope and check the optics are up to the job. Collimation of the mirrors would also be needed.

For the astronomy equivalent of plug and play, that is not bad going at all. That moon picture is sharp for a single frame but it does struggle with the dimmer nebula. Still not a match for a "true" deep sky setup, but the gap is closing I feel with what is possible out of the box.

5 minutes ago, AstroNebulee said:

Haha, I like that 😂. I'm going to pitch the idea to sky sports now 😂, on your suggestion of another scope I'd love to have another scope to set up, another az gti mount and scope would be great. One of my partner friends bf has a scope so I've suggested he brings his. The bins will definitely help and I've a laser pointer to use if needed and allowed (it's under 1). They all know I image just think it's piqued their interest. 

I'm just imaging golf style commentary now over an imaging session and its starting to catch on in my head haha.

But I do think its a good plan. getting people interested in space starts with doing simple things like this and showing them whats possible from your garden. Combining imaging with a visual scope, binos and naked eye viewing cant do any harm. Tell them to wrap up warm beforehand and have some warm drinks on tap as well and it should make a great night.

1 minute ago, geeklee said:

"Right everyone, it's time to head inside and process this. I've set up chairs behind my computer so you can watch me for the next X hours as I get this into something I think you'll really like..." 😅

"Oh wait, no- think I messed up the colour balance on one of the layers, need to delete 5hrs work and start again, is everyone still.... hello?"

I've been considering the same recently, problem is I just don't think astrophotography is much of a spectator sport. Most people's enjoyment starts and ends when it comes to the final polished picture but they don't really have much more than a passing interest in the technical stuff and hours of sitting around that goes on behind the scenes. Sure, scope slewing and platesolving can look cool but then sitting and talking through guiding errors, filter choice and polar alignment in the freezing cold will put most to sleep, compared to other astrophotographers that would talk all night about that stuff.

Your best bet could be to have a dual setup going, talk them through the imaging side and have that running in the background, but also have a visual scope to show them the real stuff as well- then you can give the finished picture the next day as a memento. Have some deck chairs so you can lay back, look at different constellations and watch for meteors. Combined with some drinks it gives a bit more variety to things.

I dont think it would be scope optics if you said on other nights your stars were round, what image scale are you shooting at? If your guide performance in arc seconds per pixel is higher than your image scale, then you will have issues with stars.

I would also look at the SNR of your guidestar, around 20 is quite low, a good way of increasing this is to make sure your guide camera is operating at 16bit rather than 8bit- you can change this on the"connect equipment" page on PHD2, i think its a tiny box next to the connect icon for your camera. You can also turn on 2x2 noise reduction on the camera tab in the advanced settings. You may need to change your gain settings but it should help improve SNR. in turn, that can help your guiding.

Another option could be camera tilt, making sure the camera is fully fixed and is level with your focus tube might play a part as well.

If all the stars in the image are pointing in the same direction, then I would first blame the wind. If you had coma then you would see the stars pointing in different directions, towards the center of the image so can rule that out.

You could also check against your guiding performance, wind usually shows as a sudden spike, like a dither. So if you can see big spikes in the guide graph then most likely wind. Reason why it pushes the stars in one single direction is wind is not random, in a single night, the wind will blow from an particular direction (west for example) so it will naturally push the scope in one direction as well.

My first real attempt at during the Orion Nebula some justice.

Taken on 11/1/22 as a two panel mosaic with a total exposure of around 3hrs- 45 second exposures.

ZWO 071MC Pro with UV/IR filter, Skywatcher 200p, EQ6-R Pro mount.

Well you want to be somewhere close at least, unless you are using very high magnification.

Just make sure you are pointing the mount exactly north and your latitude is set as close as you can and it should be fine. You will likely need to mess about with adjustments in DEC as the object will drift but you should get away with it.

On 20/11/2021 at 17:29, vlaiv said:

How about using IR pass instead?

IR part of spectrum is the least susceptible to seeing. 800nm + range won't be as "spread" over focal range to result in bloated stars (it will be focus shifted - but you can refocus to it).

Some cameras - especially some OSC models - have good / uniform QE over 800nm.

Interesting idea, you would still be able to focus without any issue (would require a very small adjustment) and as long as the QE of the camera was high enough to produce a good enough SNR then PHD2 wouldn't know the difference.

Could be interesting if the guiding would be affected by high cloud. I would assume that this setup would be more susceptible to losing the star as cloud tends to absorb IR well, whereas visible light tends to hold up better.

2 hours ago, StuartT said:

you haven't mentioned if you have any filters. I often image DSOs on full moon nights as I generally use an Optolong L Extreme filter (which basically makes the moon and streetlights irrelevant). It's only really useful for emission nebulae tho. I guess I tend to leave any broadband targets for moonless nights.

Yep, really the only things you can do is shoot narrowband and also choose an emissions target in the opposite side of the sky to the moon to further reduce the effects.

Broadband (if you really have to) should just be a case of shortening the exposures the limit the damage and accepting that the result won't be as clean.

Moving from mono to OSC is quite a big decision if you have already invested into a filter set/filter wheel as they will mostly become redundant. You also then need to look at the expenditure of new filters, this could be a light pollution filter and a dual/tri narrowband filter to collect OIII and HA at the same time. These don't come cheap and likely won't match up to true narrowband imaging with mono.

On the other side of the argument, the ease of OSC camera does make life enjoyable. You can finish an image on one night, rather than doing 1 or 2 channels, then needing to wait a couple of weeks for the next clear night arrive to get the last one. You also don't need to worry about multichannel processing.

1 minute ago, Astro Waves said:

So I do set the ASIAIR to dither every 5 images I think but is it worth it doing it more frequently than that?

Given you still have that banding, it would be worth doing more dithers. The fewer frames that share the same position as each others means that the chances of banding persisting will drop. It might also be worth increasing the size of the dither to make sure there is visible movement between frames. It might be the case your dithers now just aren't large enough.

I have the same as @Budgie1 above, I think it does make a small improvement to the guiding. The explanation I suppose is down to the star profile the PHD is looking at to identify any movement in the guide star, if you take away the UV/IR light that isn't correclty focused then it SHOULD provide cleaner data for PHD to use.

Small differences in fairness but given the amount of time and effort that goes into guding, it seems a cheap price to pay.

Still a lovely image, taking some more darks would be helpful to reduce that banding. 7 is a bit on the low side, I would aim for around 25 if possible. You also have the disadvantage of an uncooled camera. For the best results, your darks need to be at the same temperature (or as close as possible) to work the best.

I haven't used the skyguider pro, but I would look to introduce dithering into your process as well. It will shift the image around a few pixels between images and have the effect of cancelling out any banding as well, might be worth looking into.