Imaging with the 130pds

[sagramore]

10 minutes ago, richyrich_one said:

I didn't get as much data as I wanted but my first HDR.

ISO 800

20x5, 25x10, 20x30, 9x300

30 flats, no darks, library superbias

Stacked and processed in PI

Really not sure of the processing...

As always observations and suggestions gratefully received.

Really like it! There's a lot of nice detail in the core of yours compared to mine - I perhaps should have taken some much shorter exposures like your 5s and 10s ones. Something to remember for next time. Perhaps I can even add some data to mine another night.

Thanks for sharing, it's a great looking image.

[Robp]

1 hour ago, sagramore said:

Really like it! There's a lot of nice detail in the core of yours compared to mine - I perhaps should have taken some much shorter exposures like your 5s and 10s ones. Something to remember for next time. Perhaps I can even add some data to mine another night.

Thanks for sharing, it's a great looking image.

As long as your shorter exposures are not over exposed in the core area than they are fine. If they are to bright once you try and combine them you can usually manipulate the shorter exposures by a linear stretch to make them darker. Once something is over exposed then you have gone to far in exposure time and need to drop it down.

You can usually get away with a set of long subs, and a single set of shorter subs. You don't need lots of different sets of shorter sub exposures.

When you stretch you can use layers to preserve the outer core area (I use Photoshop) and then combine the shorter core subs to your longer ones using something like this:

http://www.astropix.com/HTML/J_DIGIT/LAYMASK.HTM

There may also be some information helpful to you in one of my Orion threads:

 

I've ordered some ADM dovetail clamps http://www.firstlightoptics.com/dovetail-bars/adm_vdpa_adaptor.html to attach my guide scope rings to. Should make life easier transferring my guiding from one scope to another

Are there any other Galaxy targets worth going after with the 130pds?

[sagramore]

I haven't tried it yet but I imagine the Triangulum M33 would be a great size for this scope and a DSLR! Or perhaps those galaxies that are grouped, like M81/M82 or the Leo triplet so you can catch them all in one frame.

Edited March 9, 2016 by sagramore

[richyrich_one]

On 09/02/2016 at 13:10, Uranium235 said:

Just had a closer inspection of it, and the coma seems worse on the right hand side of the image. That would suggest some tilt in the imaging plane, as a short term solution you can focus your telescope with a star placed on that side of the frame (not centrally placed), that should help balance out the field a bit.

I noticed a fair smattering of hot pixels too, but oddly - they dont seem to be travelling in the same direction across the frame. Its almost as if they are subject to a rotational pattern... was your PA good enough? or did you rotate the camera at all during the shoot?

 

Edit: The presence of coma on the right side may suggest that the spacing or placement of the corrector (in the drawtube - ie: tilt) is too close. Fortunately, the Baader does have some tolerance, so you can increase the spacing in steps of 0.5mm if possible (mine turned out to be 57.5mm). You will know when you have gone too far becuase the coma distortion will become a radial distortion.

What does this radial distortion look like?

 

[Uranium235]

Radial distortion looks like image rotation.

[richyrich_one]

18 hours ago, Uranium235 said:

Radial distortion looks like image rotation.

Thanks Rob. Not sure I understand the answer. The only thing that springs to mind is a whirlpool effect.

[StamosP]

Does anyone know what's the minor axis diameter of the secondary of the 130pds?

It must be pretty small, when i had a long collimation session yesterday i found out that the primary's reflection could barely fit in the secondary...

[Adam J]

Hey all, I just started out in this hobby and have a 130P-DS, I have taken a few pics so far and its seems to be going quite well, however.....

I have a problem with my diffraction spikes. At first I thought that it was an issue with focus but I have now totally discounted that.

Basically I have 6 and not 4 like I am supposed to. See pictures. 

Edited March 14, 2016 by Adam J

[belfieldi]

Hi Adam,

 

Check that your spider vanes are not twisted, the vanes on my 130P-DS were slightly twisted when mine scope arrived and that caused the two extra diffraction spikes in my images.

Clear skies

Ian

[belfieldi]

Adam,

 

BTW, that's a cracking first image and welcome to the forum.

Ian

 

[Adam J]

1 minute ago, belfieldi said:

Hi Adam,

 

Check that your spider vanes are not twisted, the vanes on my 130P-DS were slightly twisted when mine scope arrived and that caused the two extra diffraction spikes in my images.

Clear skies

Ian

Ian where they offset in angle like mine or parallel ?

[belfieldi]

Hi Adam,

 

The spikes on my image were very similar to yours. It's easy to check your vanes, you just need something with a straight edge to put against each vane to check them out (make sure your scope is horizontal, then there's no chance of dropping anything on the primary mirror). If a vane is twisted, just slacken off the nut for that vane and 'tweak' the vane straight then tighten the nut back up.

Ian

Edited March 15, 2016 by belfieldi
typo

[Starlight 1]

   I do not think its your spider vanes the rest of the Stars only have 4   Alnitak is a big Star doing this to your image.

[Adam J]

1 minute ago, Starlight 1 said:

   I do not think its your spider vanes the rest of the Stars only have 4   Alnitak is a big Star doing this to your image.

It has not done it with other peoples images with similarly over exposed stars.

 

[belfieldi]

Just had a look at some of my images, the extra spikes are only evident on the brightest stars, slightly fainter stars appear to have the classic 4 diffraction spikes.

[Adam J]

1 minute ago, belfieldi said:

Just had a look at some of my images, the extra spikes are only evident on the brightest stars, slightly fainter stars appear to have the classic 4 diffraction spikes.

Do you mean current images or old images from before you tweaked the spider vanes?

[belfieldi]

3 minutes ago, Adam J said:

Do you mean current images or old images from before you tweaked the spider vanes?

Sorry Adam, I meant the images before I tweaked the vanes. Can't be certain that this is the cause of your extra spikes, but it's only a couple of minutes to check and prove it one way or the other. 

[Adam J]

Just now, belfieldi said:

Sorry Adam, I meant the images before I tweaked the vanes. Can't be certain that this is the cause of your extra spikes, but it's only a couple of minutes to check and prove it one way or the other. 

Yeah will give it a go  thanks for the help.

[Starlight 1]

7 minutes ago, Adam J said:

It has not done it with other peoples images with similarly over exposed stars.

 

Just looking at old post and yes it do look like spider vanes , try some were with out a big Star to see if it still show 6 if it do them it can only be the vanes doing this.

[belfieldi]

7 minutes ago, Adam J said:

Yeah will give it a go  thanks for the help.

Glad I could be of help. You're never short of someone to help you out on SGL

[richyrich_one]

Another possiblity is anything interfering with the light path. I get this effect when the scope starts to track below my obs wall.

Out of round dew shield might do it too.

[richyrich_one]

Although your star halo looks complete, so may be not.

[Uranium235]

1 hour ago, Starlight 1 said:

   I do not think its your spider vanes the rest of the Stars only have 4   Alnitak is a big Star doing this to your image.

Twisted vanes only affect bright stars, smaller ones are unaffected. However, as mentioned - something may be protuding into the lightpath. But my money is on the spider vanes.

[sagramore]

Hi everyone. Two more photos to add to the 130-PDS party  I have posted them "properly" with the respective write-ups in the threads linked under each image, but both were taken with the 130-PDS on an NEQ6 mount, unguided, with an unmodified Canon EOS 550D.

 

M97 Owl Nebula and M108 - full thread here: https://stargazerslounge.com/topic/265499-messiers-97-owl-nebula-and-108-galaxy/

 

M101 Pinwheel Galaxy - full thread here: https://stargazerslounge.com/topic/265501-m101-my-first-48-minutes-of-the-pinwheel-galaxy/

 

The Pinwheel certainly needs more data, it's a deceptively dim subject! I think I should wait until I get autoguiding set up though first.

Thanks for looking!

 

Hamish / sagramore

[richyrich_one]

 

 

Originally put this in Deep Sky Imaging, I think it deserves to be here also...