First attempt om M31 with skywatcher star adventure pro

[MrZuiko]

Hi All,

This is my first attempt at Andromeda with the skywatcher star adventurer pro last night taken with my Nikon D300 stock a 200mm nikkor f4 ais lens ISO 800 and a stack of 44x1 minute exposures with 20 dark and biases frames.

I originally set out to take 100 lights but the clouds had other ideas! processed through siril v0.9.12 and adobe cs6.

Very happy with the result although I thought I would be able to track for longer,I have calibrated my polar scope but I think it's not 100% perfect may have to look at that again!

What's the longest exposure I should be getting with perfect pa? would auto guiding help in which case I have no idea what equipment I should buy limited budget lol or should I invest in another camera body say D7200,D7500 or different lens or short tube refractor?.........so many questions sorry folks!!

How can I improve with the processing etc other  than from taking more light frames any help and advice would be very much appreciated.

 

Clear skies.

Ash.

[rl]

superb..

[alacant]

1 hour ago, MrZuiko said:

can I improve with the processing

Hi

Lovely shot.

It would be better though to use more of the information in the data you captured in the final result.

Cheers

 

[MrZuiko]

Thanks for the kind words.......processing this kind of photograph is not my strong point! how would you be able to get more out of the data that I had collected? can anyone point me in the right direction regarding processing,stretching etc.

Ash.

[MrZuiko]

11 minutes ago, rl said:

superb..

Thanks could you offer any advice to this newbe regarding processing and auto guiding etc.

 

Ash

[rl]

Processing is very much my Achilles' heel. I willingly leave that complicated subject to others...

To my eyes that was a well-guided set of exposures..not much more to say really. An autoguider is always a good insurance policy as you go to longer exposures with longer focal lengths.

What I really like about that shot is that M31 does not fill the frame. there is a sense of the vastness of space around it, while there is still enough detail to be interesting. And the contrast is good..the centre is not too burned out and the starry background is black. A bit more H-alpha would not go amiss but that's nitpicking and probably down to the stock camera response.. i'd be quite pleased with that on my observatory wall.

Edited August 15, 2021 by rl

[alacant]

1 hour ago, MrZuiko said:

can anyone point me in the right direction regarding processing,stretching etc.

Post the data if you like.

Edited August 15, 2021 by alacant

[MrZuiko]

2 hours ago, alacant said:

Post the data if you like.

Hi thanks I'll do just that,would be great to see what an experienced astrophotographer can extract from the data.

Many thanks in advance!!

 

Ash.

result.fit

[alacant]

Hi

A few pointers:

• lose the dark frames
• take flat frames
• dither between frames (even if it's RA only)
• leave some dynamic room for the galaxy
• be gentle with the background sky (you took a lot of the galaxy with it!)
• cover the camera viewfinder
• use a long dew shield/lens hood
• ...and of course, take loads more frames. Will the sa do longer exposures perhaps?

But hey, loadsa credit for having a go with whatever you had.  

A few minutes in StarTools gave this...

HTH

Edited August 15, 2021 by alacant

[MrZuiko]

2 hours ago, alacant said:

Hi

A few pointers:

• lose the dark frames
• take flat frames
• dither between frames (even if it's RA only)
• leave some dynamic room for the galaxy
• be gentle with the background sky (you took a lot of the galaxy with it!)
• cover the camera viewfinder
• use a long dew shield/lens hood
• ...and of course, take loads more frames. Will the sa do longer exposures perhaps?

But hey, loadsa credit for having a go with whatever you had.  

A few minutes in StarTools gave this...

HTH

No way is that from the data I posted.....what did you do?  that's  so so much better I see I have a great deal to learn about processing!

If you be so kind could you break down what you did so that I can go back and re-edit my data,how did you know that I had not covered the eyepiece? I have "astronomy tools  do they have similar actions?

What you have acheived is nothing short of amazing....please show me the light.....pun intended!!

 

Ash.

[ollypenrice]

Let's look at the histogram of your image:

We see the histogram peak is jammed up hard against the left hand edge of its frame. That peak contains the faint and interesting stuff in an astrophoto. The flat line to the right contains the stars. By moving the lower left hand slider in too far you have thrown away (or 'black clipped') much of you signal.

Alacant has been careful not to do that so his histogram will look different and will have a short flat line left of the peak.

Yup!  If you subtract your histogram from Alacant's, what is left is what you threw away by black clipping. All that faint stuff is found on the left hand side of the histogram peak.

That little flat line left of the peak must always be there. The temptation is to black clip in order to cut out gradients but resist that temptation!

Olly

 

Edited August 16, 2021 by ollypenrice
typo

[alacant]

11 hours ago, MrZuiko said:

break down what you did

Hi

StarTools: simply open the .fit and stay as close to the default values as possible. For your image, I made a second pass using the deconvolution and superstructure modules.

21 hours ago, MrZuiko said:

adobe cs6

PS is what we call stretch-and-hope-for-the-best software. It consists of a series of unrelated modules working on non-linear data which have remained largely unchanged since the 1990s. Fortunately these days, there are alternatives.

I suppose that in the end however, if you're producing images with which you're satisfied, you'll use the software with which you are most familiar.

11 hours ago, MrZuiko said:

I had not covered the eyepiece

Very much a guess, but there is stray light over much of the central region of the stack. The wipe module may support my suspicions though. Note the rectangular effect which wipe reveals. This could also be a passing cloud or haze which is present on some frames. Examine the individual exposures before stacking and reject those which are sub-standard. Be ruthless!

Cheers and HTH

Edited August 16, 2021 by alacant
inglés

[rl]

Thanks @alacant and @ollypenrice. 

I think we've all learnt something from this one..

[ollypenrice]

4 hours ago, alacant said:

 

PS is what we call stretch-and-hope-for-the-best software. It consists of a series of unrelated modules working on non-linear data which have remained largely unchanged since the 1990s. Fortunately these days, there are alternatives.

 

By PS, do you mean Photoshop? And are you referring to the Photoshop Levels stretch? If so, yes, it's a standard logarithmic stretch. However, By using Curves instead of Levels you can shape any stretch you like. There are also plenty of pre-packed stretches available in other programs. However, in my view the completely hand-made Curve stretch gives the finest control but is the hardest to execute.

Olly

[powerlord]

18 hours ago, alacant said:

• cover the camera viewfinder

 

Hi Alacant,

can you explain that one ? do you mean the optical viewfinder on DSLR ? I'd never though of covering it before for anything. Are you saying that with the mirror up, you've still seen light getting into the sensor ?

cheers

stu

[Astro Noodles]

4 minutes ago, powerlord said:

Hi Alacant,

can you explain that one ? do you mean the optical viewfinder on DSLR ? I'd never though of covering it before for anything. Are you saying that with the mirror up, you've still seen light getting into the sensor ?

cheers

stu

It's true, Vlaiv pointed that out to me. It's especially detrimental to calibration frames if the viewfinder isn't covered. There should be a small rubber or plastic cap attached to the strap somewhere.

[powerlord]

huh. don't think I've ever even SEEN such a cap ever on a camera. Looks like ebay time...

[powerlord]

struggling to find anything ? I found a seller selling caps for nikon eyepeices but not canon.  we are taking about the eyepeice yes ? not the 3" viewfinder.

if so, anyone got a link to seller ? I'm clearly looking for wrong key words.  can't find anything on thingiverse either - if I can I can just print a few out.

[Tiny Clanger]

7 minutes ago, powerlord said:

huh. don't think I've ever even SEEN such a cap ever on a camera. Looks like ebay time...

I'm no astro photographer, but II bought one for my 3300 through amazon years ago , for long exposure photography in daylight you really need one , do check the model though, another ad. suggests the one I got works for D50, D70, D70s, D80, D90, D300s, D610, D3100, D3200, D3300, D5000, D5100, D5500, D7000, D7100 ...

Heather

[Astro Noodles]

Here's mine. It just slips over the viewfinder. Should be attached to the strap somewhere.

[vlaiv]

44 minutes ago, powerlord said:

huh. don't think I've ever even SEEN such a cap ever on a camera. Looks like ebay time...

https://www.slrlounge.com/purpose-behind-rubber-thing-canon-camera-strap/

[alacant]

1 hour ago, powerlord said:

struggling to find anything

Hi

This seller supplies caps for all cameras.

Cheers

[alacant]

2 hours ago, ollypenrice said:

hardest to execute

Then remove the difficulty? Fortunately these days you don't have to manipulate graphs and histograms to get decent images. 

Cheers

Edited August 16, 2021 by alacant

[MrZuiko]

Hi folks,thanks to everyone for helping,especially Alacant for the help with re-working my original image have learnt lots here regarding covering the eyepiece against stray light and stacking only the best frames and ditching "dark frames" I'll give the data another look and see if I can replicate what's been accomplished here.

Thanks everyone clear skies.

 

Ash.

[ollypenrice]

2 hours ago, alacant said:

Then remove the difficulty? Fortunately these days you don't have to manipulate graphs and histograms to get decent images. 

Cheers

We're helping a beginner here so this is really for another thread, but let's just say that I don't agree.  Actually a thread on assorted ready made and hand-made stretches would be a good one, I think.

Olly