M31 help needed

[WireD64]

I seem to have hit a wall will my processing of M31, im not really sure what steps to take next in processing or if there is even any data left to bring out.

Heres my latest processed image. And below is a link to the tif file in dropbox, I would really appreciate if anyone could have a go at processing it so I can see what data I have left.

https://www.dropbox.com/s/f0sz02u8n4druni/Autosave.tif?dl=0

[StargeezerTim]

Looks really good to me... Well done!

The only things I would try are increasing the contrast in the dust lanes using curves and perhaps some mildish sharpening.

I have also found that using wavelets (registax, if I remember correctly) on galaxies may bring out some fine detail. Tim.

[JamesF]

I wonder if the black point can be dragged up a little, too.

To pull much more detail out I think you might need to go for longer exposures, but obviously the core is already about as far as you'd want to take it.  I believe one approach to that is to take two sets of exposures; a longer set for the outer galaxy and a shorter set for the core.  Then combine the two in processing.

James

[Atreta]

as tim said above, looks pretty good for me too.

[Astrosurf]

What processing software are you using?

Alexxx

[WireD64]

Thanks for all the advice. I shall get some more exposure time in then, I dont think I can push the black point up anymore it started to look a little off when I pushed it up.

I'm using Pixinsight.

I've just been doing it by trial and error and looking at other peoples photo's to see where i'm lacking the detail but as said I think I need more subs to start bringing anymore out.

Would still love to see what someone could do with my tif file in the first post so I have something to compare.

[Charic]

You have produced a great image here.

This link has a hidden image? ...  http://3dimka.deviantart.com/art/Space-Surfer-Stereogram-57113973.....if folk 'know' how to view these hidden images, you should see a Borg surfing Saturn?  I can clearly see it! and once you see it, its easy to establish the 3D effect. For those who cant manage/see  these images, sorry!

How does one produce these images, does your software enable you to do something similar say with M31?

[NGC 666]

I tried to edit your TIFF file.

All I did was (Photoshop) use GradientXterminator to smooth out the gradient, the levels tool to get rid of the light pollution, and a few tweaks with noise reduction and clarity (Lightroom). I tried not to blow out the centre of the galaxy

.

You got most of the data in the image out in your edit, but not the faint bits at the top of the galaxy. There is pretty much no more data to stretch out of the image without it getting unbearably noisy.

Depending on the amount of subs, you should:

- If you took around 10, 20, 30, make it around 50 subs with about 5 - 10 darks, flats and bias frames.

- If you took around 50, taking any more at the same exposure length won't help that much (they become less effective if you stack more and more subs). Therefore, increase the exposure time if you can.

in order to get less noise and more data - thus more galaxy.

Flats help especially with removing the gradient in photos - particularly useful with such a diffuse and large target as M31, which has a similar colour to the sky glow. It is therefore difficult to remove the sky glow without removing the galaxy.

Hope the helps.

[WireD64]

Thanks NGC 666, Thats exactly what I needed to see and glad that I got pretty close then.

I took 20 lights and 15 darks, no flats or bias as im still learning that bit.

Is it true that I can take my bias frames at any point, the camera doesnt need to be in the scope and I can leave the cap on the camera and just take around 10 of the shortest exposures.

Also, for some reason I cannot view the large version of your processed version, it says I do not have permission to view.

[JR1987]

Thanks NGC 666, Thats exactly what I needed to see and glad that I got pretty close then.

I took 20 lights and 15 darks, no flats or bias as im still learning that bit.

Is it true that I can take my bias frames at any point, the camera doesnt need to be in the scope and I can leave the cap on the camera and just take around 10 of the shortest exposures.

Also, for some reason I cannot view the large version of your processed version, it says I do not have permission to view.

I had almost the same conundrum about a week ago to the day. 

I tried again a couple of days later and was alot more successful. And I really believe it was because of the data. 

Get as much exposure as you can, it makes all the difference.

When you say you got 20 lights, What was your exposure time and ISO?

Also are you tracking with a guide cam?

p.s were using the same camera! its rare to meet other 100d user for some reason!

[WireD64]

Exposure was 60seconds and ISO 800 and not guiding at the moment, trying to go step by step and want to really understand my setup before adding guiding into the mix.

And yeah was with the 100D, i know what you mean, the camera seems to be overlooked although its pretty much a 700D in a smaller body. StargeezerTim also has one

[NGC 666]

I don't actually know how to upload a photo properly (help would be handy).

As far as I know, bias frames remove hot pixels, and are taken when the cap is closed, so you don't need the camera to be attached to the scope.

[StargeezerTim]

Thanks NGC 666, Thats exactly what I needed to see and glad that I got pretty close then.

I took 20 lights and 15 darks, no flats or bias as im still learning that bit.

Is it true that I can take my bias frames at any point, the camera doesnt need to be in the scope and I can leave the cap on the camera and just take around 10 of the shortest exposures.

Also, for some reason I cannot view the large version of your processed version, it says I do not have permission to view.

You can take the Bias next day though I tend to just get 20 quick exposures before I go to bed after a nights imaging. You can also Darks at any time, providing the temperature is within + or - 5 degrees C. I sometimes take some darks before imaging and more later. Bias and darks can be taken with the the camera 'capped'. It doesn't need to be anywhere near the scope! Tim. 

[WireD64]

Perfect, I might do those tonight then, and stack the image again, see what difference that makes.

Next I need to understand how to take Flats and how I know that im taking them at the correct lighting brightness, I see people mention the ADU but how do I know what that is?

[JR1987]

Exposure was 60seconds and ISO 800 and not guiding at the moment, trying to go step by step and want to really understand my setup before adding guiding into the mix.

And yeah was with the 100D, i know what you mean, the camera seems to be overlooked although its pretty much a 700D in a smaller body. StargeezerTim also has one

Try and get as long as you can.. 60 seconds will start to give you an image but to really pull data out you wanna be exposing for more like... well alot of people on here do 5 minutes but that might not be all that productive in light polluted milton keynes. 

I think I can see a slight bit of tracking problems in your stars, (which on a second look could just be coma) which take it from me.. will drive you NUTS when you start exposing for longer. 

You have the 200-P like I do.. its really easy to turn your finder scope into a guide scope with a little adaptor bought from Modern Astronomy. 

Tracking with PHD is very easy and will maybe take one scope session to figure out properly, then tracking errors will be a thing you wont have to worry about.

I really recommend it if your using a EQ5 as they are not quite as sturdy for imaging when they have a big old 200-P on top. But there are images ive seen on here, today infact taken with the same setup but with guiding and they are fantastic and sharp as can be! 

[NGC 666]

I take flats by going out in daylight, cloudy or not, covering the scope in a white shirt, and taking photos which are half way between dark and completely white. It may be worth taking batches of different exposures to be sure the histogram is on the middle. It doesn't have to be terribly accurate, just not completely white.

It is good practice and more accurate to take the flats with the camera in the same rotation and focus as the light frames. In doing so any dust blobs or gradient in the image will be reduced.

Also use RAW format, as it gives better results with calibration frames.

[WireD64]

Try and get as long as you can.. 60 seconds will start to give you an image but to really pull data out you wanna be exposing for more like... well alot of people on here do 5 minutes but that might not be all that productive in light polluted milton keynes. 

I think I can see a slight bit of tracking problems in your stars, (which on a second look could just be coma) which take it from me.. will drive you NUTS when you start exposing for longer. 

You have the 200-P like I do.. its really easy to turn your finder scope into a guide scope with a little adaptor bought from Modern Astronomy. 

Tracking with PHD is very easy and will maybe take one scope session to figure out properly, then tracking errors will be a thing you wont have to worry about.

I really recommend it if your using a EQ5 as they are not quite as sturdy for imaging when they have a big old 200-P on top. But there are images ive seen on here, today infact taken with the same setup but with guiding and they are fantastic and sharp as can be! 

Yeah i had a very slight tracking issue, as I roughly did a polar alignment, just put polaris roughly in the right position and away i went, I was testing out a lot of stuff to make sure my observatory PC was working correctly as it was the first time used it to control the mount.

And yes, there is definitely some coma going on so I am going to pick up a Baader MPCC this weekend too.

I do want to guide but want a few more sessions figuring out the basics and getting everything else set right.

I take flats by going out in daylight, cloudy or not, covering the scope in a white shirt, and taking photos which are half way between dark and completely white. It may be worth taking batches of different exposures to be sure the histogram is on the middle. It doesn't have to be terribly accurate, just not completely white.

It is good practice and more accurate to take the flats with the camera in the same rotation and focus as the light frames. In doing so any dust blobs or gradient in the image will be reduced.

Also use RAW format, as it gives better results with calibration frames.

Been using RAW for everything

So would I be using the different exposures to change the lighting level

Is the sensor temperature important for the flats then? or because flats arent dealing with noise, only gradients and dust bunnies that it can be taken at any temperature but the optics must remain the same as when the lights were taken?

[NGC 666]

I would change the brightness of the flats by changing the exposure time, and not the ISO, because you want the lowest amount of noise as possible.

The temperature doesn't matter - not dealing with noise.

You don't strictly have to have the camera in the same position as lights. You might not even have to have it in the scope. But stick as close as you can to the light frames (camera orientation wise) and the 10 - 20 flats will work best.

Try to get the most even light distribution going into the scope with flats (hence the shirt without creases) because you will then have the best representation of the gradient and dust imperfections in the optical tube.

Flats aren't perfect, so I advise GradientXTerminator.

[NGC 666]

You can of course, like me, keep reusing calibration frames. It saves having to take them all over again after every imaging session. Speaking of which, the clouds seem unending for the last week and as far as the forecast forecasts.

[NGC 666]

This is the full sized image I attempted to upload previously:

[WireD64]

Thanks once again, all very useful info, Im a sponge for it at the moment.

The clouds might continue over the weekend as I shall be purchasing some stuff, sorry about that

I think all my questions for the time being are answered so I look forward to what I can achieve in my next session!

[des anderson]

JUST BRILL....what detail,you must be proud of that

[WireD64]

Very! Cant wait to get out again now and improve on it.