First Attempt @ AP

[Benjam]

After reading “ Every Photon Counts” I decided my first attempt would be Andromeda. I’ve taken 40, 30 second exposers at iso 400 for my lights and 30 darks, though with the lens cap on. I still have to do my bias and flat frames. I’m using a entry level DSLR (Canon 1300D) which hasn’t been Astro modified. I’ve downloaded DSS but that’s all the software I have, as yet.

With no experience, I would like some honest feed back on the image below. It’s still in its RAW formula. Will I be able to squeeze anymore detail out? Is it in Focus?? Do I need a different camera??? Is the tracking ok???? 

All feed back will be much appreciated

 

 

Ben 

Edited October 20, 2019 by Benjam

[AKB]

I had a very quick go and came up with this.

The data are very quantised, which, perhaps, suggests that something is not quite right...

...focus looks pretty good, though.  Great start.

Tony.

[MimasDeathStar]

I may be wrong here but if its been through DSS then shouldn't it be in a TIFF or FITS format not RAW? Have you applied any sort of stretch there, I'm surprised there isn't a lot lot lot more detail there than you've captured.

What scope / lens/ f ratio are you using to capture this.

I think you're tracking and focus look great.

[Nigella Bryant]

I'd up the Iso to 800/1600 to start with. Looks in focus, I wouldn't go buying another camera yet, get used to the one you have. Modded camera's don't make much difference on galaxies only ha nebulae. Is the image one raw sub or the stacked? 

[MimasDeathStar]

Having looked at it again - is this just a single raw frame that you've posted for our reference?

I can see a few hot pixels so it doesn't look like it may have included the darks properly when you stacked it? Or maybe you haven't stacked them yet? As @Nigella Bryant says, the optimum range for the 1300d is in the 800-1600 iso range.  

[Nigella Bryant]

Added a stretched image of yours plus an image of M64 taken at ISO 1600, 12inch f4 Newtonian and Canon 1000d modded camera, 20x30sec subs. 

[Adam1234]

24 minutes ago, Nigella Bryant said:

Added a stretched image of yours plus an image of M64 taken at ISO 1600, 12inch f4 Newtonian and Canon 1000d modded camera, 20x30sec subs. 

I've heard alot about 'stretching'  images, what does this actually mean?

[Benjam]

Thank you for the responses so far. 

This is just one raw photo I picked from random out of 40 at iso 400 and a 30 second exposure.  I haven’t done anything with the picture, this is straight from BY EOS. 

8 inch Edge HD scope 

0.7x focal reducer 

Canon 1300D 

 

I have also messed about with the moon, sun and Jupiter only once before but this was my first attempt at a galaxy. I don’t have any editing software (apart from DSS, which I haven’t used) so I’m not sure what the finished results would look like.

 

 

Ben 

[spillage]

Try stacking the images you have in deep sky stacker and then stretching the image. You can use startools for free to help you process the image. You just cannot save the image unless you purchase it.

[Andy R]

51 minutes ago, Benjam said:

I don’t have any editing software (apart from DSS, which I haven’t used) so I’m not sure what the finished results would look like.

Try having a look at GIMP for editing too. it’s free and there are tutorials on YouTube for AP image editing. it’s not the best but certainly better than a kick in the teeth, failing that as spillage says StarTools does a free version just have a research for best DSS settings to use for best results. Nice solar/lunar images btw

 

[ollypenrice]

Don't expect images to look like much when they come straight from the camera or the calibrated stack out of DSS. Processing is a big subject. You could do a lot worse than enlist the help of Steve Richards via his book: https://www.firstlightoptics.com/books/dark-art-or-magic-bullet-steve-richards.html

Olly

[Kev M]

11 hours ago, Benjam said:

After reading “ Every Photon Counts” I decided my first attempt would be Andromeda. I’ve taken 40, 30 second exposers at iso 400 for my lights and 30 darks, though with the lens cap on. I still have to do my bias and flat frames. I’m using a entry level DSLR (Canon 1300D) which hasn’t been Astro modified. I’ve downloaded DSS but that’s all the software I have, as yet.

With no experience, I would like some honest feed back on the image below. It’s still in its RAW formula. Will I be able to squeeze anymore detail out? Is it in Focus?? Do I need a different camera??? Is the tracking ok???? 

All feed back will be much appreciated

 

Try a simpler target, like M57

 

 

 

Edited October 21, 2019 by Kev M
typo

[cjdawson]

I'm seeing lots of great stuff in your first image.

1. You have good focus

2. You managed to get something fuzzy in the image, which is good news.

3. Looks like you were able to stack the images well, so that means that your tracking/guiding is good too.

 

For next time, I'd recommend turning up the ISO 800/1600 or even 3200 if you can.   When capturing your subs try to make sure that the histogram data spike isn't butting up against the left hand end of the graph.  A good starting place would be to try and get it to be at least 1/3 of the way from the left, between 1/3 and 1/2 is good.

Also, take more photos as well.   The more the merrier.  You cannot capture too many subs.  😉

[Nigella Bryant]

15 hours ago, Adam1234 said:

I've heard alot about 'stretching'  images, what does this actually mean?

I use curves in photoshop cs. Free photoshop app can be used and under that the light information can be increased by altering the exposure value,  highlight and white balance. You'll also need to change the black background as you increase the light information.  Processing actually takes longer than taking the subs in the first place. Main thing is, you enjoy getting the most out of your sub's and that final processed image.

[Benjam]

Looks like I’m not a million miles away and heading in the right direction.  I’ve just ordered a second counter weight for my AVX mount, as I think this will help too. I will definitely change my ISO settings, will 30 second exposure still be ok? Or should I try for 90 seconds or longer?? 

Eventually I would like the Starizona hyperstar with a F2 focal and a Altair Hypercam 183 pro. 

 

Thank you for all the helpful advice, I really appreciate it. 

 

Ben 

[ollypenrice]

On 20/10/2019 at 23:59, Adam1234 said:

I've heard alot about 'stretching'  images, what does this actually mean?

The data coming from the camera is described as 'linear' because if pixel B recorded twice as much light as pixel A it will look twice as bright in the image. If pixel B is 10x as bright as pixel A it will look 10x as bright. This is fine for daylight photography but doesn't allow astrophotos to present all the information they really contain.

The histogram is a graph or map of the brightness distribution in the image. At the initial linear stage it will run in a straight line from dark to bright, like this:

The histogram is easier to see in the Levels window:

This graph shows all your pixels. Left to right shows dark to light while the vertical axis shows the number distribution of pixels in the image. Not surprisingly we see a huge number of very dark pixels on the left - the background sky - and a very small number of very bright ones on the right, the stars. Unfortunately the bit we are interested in, the galaxy, is not really much brighter than the background sky so doesn't show clearly and it is made up of pixels of similar brightness so we can't see much structure in it.

When we 'stretch' the image (which we can do in Levels or Curves) we brighten all the pixels but we brighten the dark ones by much more than we brighten the light ones. this will brighten the galaxy and increase the contrast between its darker and brighter regions. We avoid reversing any pixel values, though, so the image remains honest. Here I've modified the curve:

So that's what stretching means. It is the most important single intervention in processing and can be done with an endless variety of added subtleties.

Olly

Edited October 22, 2019 by ollypenrice

[Adam1234]

2 hours ago, ollypenrice said:

The data coming from the camera is described as 'linear' because if pixel B recorded twice as much light as pixel A it will look twice as bright in the image. If pixel B is 10x as bright as pixel A it will look 10x as bright. This is fine for daylight photography but doesn't allow astrophotos to present all the information they really contain.

The histogram is a graph or map of the brightness distribution in the image. At the initial linear stage it will run in a straight line from dark to bright, like this:

The histogram is easier to see in the Levels window:

This graph shows all your pixels. Left to right shows dark to light while the vertical axis shows the number distribution of pixels in the image. Not surprisingly we see a huge number of very dark pixels on the left - the background sky - and a very small number of very bright ones on the right, the stars. Unfortunately the bit we are interested in, the galaxy, is not really much brighter than the background sky so doesn't show clearly and it is made up of pixels of similar brightness so we can't see much structure in it.

When we 'stretch' the image (which we can do in Levels or Curves) we brighten all the pixels but we brighten the dark ones by much more than we brighten the light ones. this will brighten the galaxy and increase the contrast between its darker and brighter regions. We avoid reversing any pixel values, though, so the image remains honest. Here I've modified the curve:

So that's what stretching means. It is the most important single intervention in processing and can be done with an endless variety of added subtleties.

Olly

Thanks for that, that was very helpful! 

[Benjam]

I had a second attempted tonight at Andromeda, ISO 1600 with a 90 second exposure. I took 50 lights, though by the end Andromeda wasn’t central, more to the right hand side of the frame. I managed to save 27 and will have a go at stacking tomorrow. 

 

Ben 

Edited October 23, 2019 by Benjam

[Benjam]

On 21/10/2019 at 11:54, cjdawson said:

I'm seeing lots of great stuff in your first image.

1. You have good focus

2. You managed to get something fuzzy in the image, which is good news.

3. Looks like you were able to stack the images well, so that means that your tracking/guiding is good too.

 

For next time, I'd recommend turning up the ISO 800/1600 or even 3200 if you can.   When capturing your subs try to make sure that the histogram data spike isn't butting up against the left hand end of the graph.  A good starting place would be to try and get it to be at least 1/3 of the way from the left, between 1/3 and 1/2 is good.

Also, take more photos as well.   The more the merrier.  You cannot capture too many subs.  😉

Halfway through tonight’s session I remembered you mentioned something about the histogram, not knowing anything about histograms, I found the setting on BY EOS and took a screenshot to show you. I didn’t change any settings. 

 

 

Ben 

[cjdawson]

The histogram looks good to me.

The important things are

1. the big spike is not a single pixel wide

2. it's away from the left hand edge of the graph - means that you have no pure black which is good, black in AP is actually a dark grey.  A pure black means that you've under exposed.

3. it's not touching the right hand edge of the graph - means that you have no pure white.   Same thing as pure black, except this time means over exposed.

 

Looking at the histogram, to move it right, expose for longer, or use a higher ISO.    The longer the exposure the more light you capture, the better the final image will be as there's more data to work with.  At least that's the rule of thumb.

Just remember that each time you increase the ISO, you also increase the level of noise in the sub frame.  So taking more sub frames will counter that little gremlin.

[Nigella Bryant]

Doing well Ben. 

[alacant]

On 21/10/2019 at 00:05, Benjam said:

8 inch Edge HD scope 

0.7x focal reducer 

Hi. Great start and well done.

But remember that even with a dslr, you're imaging just the central bit of the galaxy so I think your shots are good. Just don't expect to see the whole spiral.

HTH, clear skies and good luck.

 

[Benjam]

4 hours ago, alacant said:

Hi. Great start and well done.

But remember that even with a dslr, you're imaging just the central bit of the galaxy so I think your shots are good. Just don't expect to see the whole spiral.

HTH, clear skies and good luck.

 

Thank you, it gives me confidence. 

Just out of curiosity, what equipment would I need to capture the whole spiral? 

 

Ben 

[cjdawson]

Funny you should say that,  I just purchased a setup that I think is capable of getting the whole thing in one go!

Camera: Canon 70D (though my ZWO ASI1600MM-PRO would also work here)

Telescope: William Optics SpaceCat 51

Mount: Sky-Watcher Star Adventurer Pro pack

Tripod: Sky-Watcher Stainless steel 3/8"

Guide Scope: ZWO Mini guide scope

Guide Camera: ZWO ASI290MM (Had this looking for a good use)

Guide computer: Raspberry PI 4, running PHD2.   (ASIAir looks very interesting for this application as well)

 

The key think here is that the SpaceCat is only a 250mm Focal length, which is what gives the wide field of view.   This is much much wider than I could get with my LX-90 and all the most powerful focal reducer that I could get my hands on.

[alacant]

55 minutes ago, Benjam said:

what equipment would I need to capture the whole spiral?

Hi

You may already have it; a 300mm lens.

HTH