A real beginners first astro photos

[5haan_A]

So I have finally managed to put together my first image. I'll be honest its been very tough, and the results are far from perfect. Since around April I have tried and tried some more to get all the equipment working to a point where I could put something together. First there was the software to get my head round. Then there were the guiding issues, and then after all of that there were things like darks, flats and bias to think about. I bought some books did some reading and finally got to a point where I could have some first attempts. 

 

My initial sessions were thwarted by issue after issue. Firstly polar alignment was much harder than I initially thought, that was until I found out about sharpcap. For guiding I use PHD2 and that wasn't easy to get right. Essentially there was four months of non stop problems and learning from them to get to a point where I could realistically get an image.

 

The below was shot using:

Scope - Esprit 100 

Mount -  EQ6 Pro

Camera - ZWO 224 MC

Guide- ZWO 120 mini

Software - EQmod, Cartes du ciel, APT, Nebulosity 4 and some lightroom to finish off

 

First image is of the Whirlpool Galaxy. It's the first time I managed to throw it all together with some success. My focus isn't great, the guiding could be better, and the image composition leaves a lot to be desired, but I'm happy because the last four months are finally bearing some fruit. 

Feedback is more than welcome, I really do want to improve. I can't wait to see where I will be a year from now. 

I used 20 45 second lights and 15 45 second darks. 

 

[JamesF]

For a first image, I think that's very good indeed.

If you're worried that focus might not be spot on, try a Bahtinov mask.  You can buy them, but it's quite possible to make one yourself from a sheet of card or plastic.  I 3d print mine (have one on the printer just finishing off at the moment, as it happens).

If you're happy with your guiding then I'd try for some longer exposures I think.

James

[alan potts]

Yes nice first image, I think I may have picked something easier though, never easy any galaxy. As James said try a bit longer exposures.

Alan

[5haan_A]

6 hours ago, JamesF said:

For a first image, I think that's very good indeed.

If you're worried that focus might not be spot on, try a Bahtinov mask.  You can buy them, but it's quite possible to make one yourself from a sheet of card or plastic.  I 3d print mine (have one on the printer just finishing off at the moment, as it happens).

If you're happy with your guiding then I'd try for some longer exposures I think.

James

Thank you. I'll look into the mask. I think I saw that FLO are selling some reasonably priced ones. Although it would be cool to 3D print one of my own.

 

2 hours ago, alan potts said:

Yes nice first image, I think I may have picked something easier though, never easy any galaxy. As James said try a bit longer exposures.

Alan

Thanks. Any suggestions on an easier target? 

[5haan_A]

I have some questions on post processing. 

How do I get rid of that circular thing in the bottom left section of the image. Its quite dark but it's there. 

Theres also a blue squiggle near the bottom right of the galaxy, how do I get rid of that? I dont think it would have dark subtracted because it was in one of my lights. 

Where do you guys think is the best place to finish off an image, I was using nebulosity and lightroom. I didn't mind nebulosity too much, but with light room I had to convert the .fit file to .jpg before doing a histogram stretch etc.

 

On the histogram stretch is there some material that explains it well? Perhaps a book that's dedicated to post processing astro images.

Colour, I shoot using a colour camera, because I had thought that it would mean my images would look like the ones NASA Hubble telescope produces with all that vibrancy. My images started with a sickly glow that I could only reduce slightly. What's the best way to bring out colour in an image.

How do I make the background black? 

Thanks for the feedback.

 

[fwm891]

Great start. I remember when starting with PHD putting in the focal length of the imaging telescope not the guiding scope that caused me no end of problems. Try some longer exposures and match the dark exposure length to the light exposures.

[vlaiv]

Like others said - it is great start.

You probably have more data in there that could be pulled out with proper processing, but like imaging, processing also has a learning curve - and with practice you will get better at that as well.

15 minutes of total imaging time is short, and you should not expect great results out of it - so for next target - do a bit more - results will be much better if you go for an hour or two, or even four hours total (that is about as much as one can get on single target per night)

Now to address your questions, and some general tips.

21 minutes ago, 5haan_A said:

How do I get rid of that circular thing in the bottom left section of the image. Its quite dark but it's there. 

This can only be corrected with flat calibration. You need to take flats for your setup to correct any vignetting / dust shadows that appear on the image. Look it up on internet. Best way to do flats is to have flat panel, but in absence of one people use T-shirt and do flats when it is still some light out (either in the evening at setup time, or early in the morning after night session). You can also use laptop/tablet screen with some white image displayed full screen. Aiming scope at uniformly lit white wall can be used as well.

You need to take your flats while everything is still set up, because flats need same focus, same camera orientation and all the dust to be in the same place, so there is probably no chance to do it now to correct this image. You can try to correct it in post processing though - select with circular selection just that part of the image and adjust brightness a bit to make it the same as surrounding. It is easy fix in this case since there is not much of anything in that part of the image.

26 minutes ago, 5haan_A said:

Theres also a blue squiggle near the bottom right of the galaxy, how do I get rid of that? I dont think it would have dark subtracted because it was in one of my lights.

This is produced by hot pixel. Simple way to deal with this is to use sigma clip stacking method. For it to work the best you need a lot of frames - it is statistical method that estimates if some values are too large or too small and does not include them in result. One more reason to get more frames and have longer total imaging time. With 20 frames it will still work, so give it a go.

28 minutes ago, 5haan_A said:

I didn't mind nebulosity too much, but with light room I had to convert the .fit file to .jpg before doing a histogram stretch etc.

This is a big NO-NO. Only time to use jpeg in astro photography is when you have finished image and you want a small file to put on web (post here or elsewhere). Jpeg has two features that make it's use highly problematic in astro processing. First is that it is only 8bit per color format - you loose much of precision in 8bit formats. Ideally you want to use 32bit (tiff or fits) as your intermediate save format between processing steps. Sometimes you can get away with using only 16bits but I strongly recommend against this as well. It's best to use 32bit format.

I personally use Gimp 2.10 for much of my processing. Others use Photoshop, and very often dedicated astro processing software like Pixinsight (which is probably too complex for you at this stage, get a bit more practice in both imaging and processing before you consider purchasing it - it has way too many options that will just confuse you at this stage).

Have a look at recent thread for simple processing steps in Gimp:

 

34 minutes ago, 5haan_A said:

Colour, I shoot using a colour camera, because I had thought that it would mean my images would look like the ones NASA Hubble telescope produces with all that vibrancy. My images started with a sickly glow that I could only reduce slightly. What's the best way to bring out colour in an image.

This is somewhat advanced topic - proper color in astro images. For the time being you should just try to do color balancing your self with color mixer / curves to get the feel for it, and leave color calibration for later. You can increase saturation in processing if you want a bit stronger colors, but don't over do it - it gives unnatural feel to the image if you push it too much.

37 minutes ago, 5haan_A said:

How do I make the background black?

This is generally done via histogram manipulation - curves and/or levels. However, your background is fairly dark and in general you don't want your background to be completely black - it creates artificial feel in the image and you run a risk of clipping your signal. Most natural looking astro image has black color (or rather very dark gray) having value of about 4-5%.

If you like, you can post your unprocessed stack (try to save it as 32bit format, and if you can't - at least 16 bit) and I'm sure people will do some processing on it so you can see exactly how much data there is in your image and what sort of result you should be striving for (maybe even get some processing tips for your image that you can try yourself for practice).

[JamesF]

vlaiv missed the other reason to avoid JPEG, which I'm sure he intended to mention.  That is that it uses "lossy" compression.  In other words, it throws away actual data on the assumption that it can generate something approximately the same when the image is uncompressed.  In an astro image this can create all sorts of unpleasant artefacts and it's not something you want to do repeatedly.  As he says, it should be left until the final step if you need to use it to reduce image size, but keep the files it was created from so you can go back and reprocess if necessary.

James

[Viktiste]

That image is lightyears better that my first attempt at astroimaging. A very good start.

[vlaiv]

12 minutes ago, JamesF said:

vlaiv missed the other reason to avoid JPEG, which I'm sure he intended to mention.  That is that it uses "lossy" compression.  In other words, it throws away actual data on the assumption that it can generate something approximately the same when the image is uncompressed.  In an astro image this can create all sorts of unpleasant artefacts and it's not something you want to do repeatedly.  As he says, it should be left until the final step if you need to use it to reduce image size, but keep the files it was created from so you can go back and reprocess if necessary.

James

Yep, just realized that I started with two reasons, but listed only 8bit .... it's time to go on a vacation and give ol' brain a rest ...

[alan potts]

2 hours ago, 5haan_A said:

Thank you. I'll look into the mask. I think I saw that FLO are selling some reasonably priced ones. Although it would be cool to 3D print one of my own.

 

Thanks. Any suggestions on an easier target? 

For starting out I would have personally picked a star cluster or a globular cluster. M13 is a nice large one where you can see plenty even with limited data, don't try an be as good as some of the people on here straight away, what they do is superb but very difficult to get to the standard they are at and takes time, step by step. I tell you I not great but I have fallen from a few steps, all of this AP can cause even the best imagers problems, don't forget conditions are changing all the time which will not help.

[Neiman]

Haven’t taken an image yet as just started - but I’d be proud of that as a first image.

[5haan_A]

4 hours ago, Neiman said:

Haven’t taken an image yet as just started - but I’d be proud of that as a first image.

Thanks. I do feel proud. I was showing some people in the office today and there was a bit of head scratching going on when people were getting their heads around how it was possible to get picture of a galaxy. I was more than happy to explain.

 

4 hours ago, alan potts said:

For starting out I would have personally picked a star cluster or a globular cluster. M13 is a nice large one where you can see plenty even with limited data, don't try an be as good as some of the people on here straight away, what they do is superb but very difficult to get to the standard they are at and takes time, step by step. I tell you I not great but I have fallen from a few steps, all of this AP can cause even the best imagers problems, don't forget conditions are changing all the time which will not help.

I'll try make my life easier and focus in on something a little easier next time.

 

Thanks for that incredibly insightful advice Vlaiv. There's a lot to chew through with your post, but I'm going to work through it. I like the idea of switching to GIMP, it seems very powerful and that post you shared seems very helpful. I had used some flats in the pre processing, however I think that the dust particle in the equipment must be new. 

 

 I'll share the stacked .fit file when I get back home and see if there was more that can be pulled out from the data.

[5haan_A]

Here is a stacked version of the image before any processing.

m51_01092019.fit