Hickson 44

[Magnum]

Spent the last 3 clear nights collecting photons on this target, was loosing it below my west wall by 1am each night so took longer than expected. The Hickson 44 / Arp316 Galaxy group in Leo. Captured with the dual Rig, Luminance in 1 scope and colour in the 2nd scope. Total of 14 hours of data ( 7hrs in each ). The 4 main galaxies are all different catagories , we have an elliptical, a spiral, a Barred Spiral and an Irregular, plus a multitude of faint background galaxies.

Mount EQ8 Pro

Telescopes: Meade 127mm F7.5 Triplet refractor 

: Altair 102mm F7 Triplet refractor

Camera: Atik 460EX mono CCD, Atik 383L plus CCD.

Guider: OAG plus SX Lodestar CCD.

Software: All done in MaximDL & Photoshop.

Exposures: 14 hrs worth of 6 min subs.

Calibration: NONE

 

[ollypenrice]

Lovely clean image of a great target.

Not even flats? 

Olly

[Magnum]

2 hours ago, ollypenrice said:

Lovely clean image of a great target.

Not even flats? 

Olly

Thanks Olly, No flats.

 I just run each stack through Maxims Flatten Background process, use the complex 8th order, then click 20 or more points around the image. that sorts any minor vignetting or gradients. as for Dust bunnies, I find as im really fussy about not allowing dust onto the filters and cover glass of the camera when assembling it all, they stay clean as everything is permanently sealed unless I swap cams etc, then the Rocket blower gets used before putting back together. 

Lee

[ollypenrice]

2 minutes ago, Magnum said:

Thanks Olly, No flats.

 I just run each stack through Maxims Flatten Background process, use the complex 8th order, then click 20 or more points around the image. that sorts any minor vignetting or gradients. as for Dust bunnies, I find as im really fussy about not allowing dust onto the filters and cover glass of the camera when assembling it all, they stay clean as everything is permanently sealed unless I swap cams etc, then the Rocket blower gets used before putting back together. 

Lee

Seems to work! You might run into difficulties if trying to extract very, very faint stuff like IFN of tidal tails, maybe. Anyway, super result.

Olly

[Magnum]

15 minutes ago, ollypenrice said:

Seems to work! You might run into difficulties if trying to extract very, very faint stuff like IFN of tidal tails, maybe. Anyway, super result.

Olly

It works better with Narrowband to be honest as that doesn't let light pollution gradients in, but as I use my CLS filter as Lum any gradient is very slight, and have the Idas LP2 in front of the RGB filters so they are protected too. I did have to work a bit harder on this than with narrowband. I have Bortel 5 Sky so not great for trying to capture faint stuff in LRGB, im much happier doing Narrowband.

Lee

[newbie alert]

That turned out well Mr magnum...class image from a unknown target ( for me anyway)

Well done

[Magnum]

3 hours ago, ollypenrice said:

 

Olly do you think I stretch my images enough? I don't like them too overdone like a lot I see on FB, but at the same time ive had comments that im not stretching the faint bits enough, and or my background is too dark.

I always make sure I leave a gap so im definitely not clipping, and am not a fan of light grey backgrounds, So I always send my final image to my iPad before posting, as iPads are known to have the best factory calibration of any screens, and is what the majority of people view things on these days, so seems the best chance of knowing how others will see them. Obviously laptops and desktop monitors are a total minefield as some maybe calibrated totally wrong. 

when ive posted images on the light side, then seen how they look on some laptops they seem to magnify any noise in the image, then on SGL ive noticed anything I post on here ends up looking a tad darker with slight posterisation.

Am I worrying about it too much, or have you had similar thoughts?

Lee

[ollypenrice]

3 minutes ago, Magnum said:

Olly do you think I stretch my images enough? I don't like them too overdone like a lot I see on FB, but at the same time ive had comments that im not stretching the faint bits enough, and or my background is too dark.

I always make sure I leave a gap so im definitely not clipping, and am not a fan of light grey backgrounds, So I always send my final image to my iPad before posting, as iPads are known to have the best factory calibration of any screens, and is what the majority of people view things on these days, so seems the best chance of knowing how others will see them. Obviously laptops and desktop monitors are a total minefield as some maybe calibrated totally wrong. 

when ive posted images on the light side, then seen how they look on some laptops they seem to magnify any noise in the image, then on SGL ive noticed anything I post on here ends up looking a tad darker with slight posterisation.

Am I worrying about it too much, or have you had similar thoughts?

Lee

I always measure my background sky level in Photoshop. There's a current discussion about background sky values here: 

I think you've made a good call on the stretch. The barred spiral on the lower left is beginning to show a little grain as it is, so it's presumably at its limit. I have an image of this target with 12 hours' data but with more aperture (140mm) and from a darker site, I imagine. The outer halos are a little brighter but there's nothing faint in mine which isn't in yours.

Olly

[Magnum]

Thanks Olly, its good to have a 2nd opinion. I measured the background in the one I posted to be about 19-20. ive seen you say 30 in the past I think.

I will go read that thread.

cheers

Lee

[ollypenrice]

6 minutes ago, Magnum said:

Thanks Olly, its good to have a 2nd opinion. I measured the background in the one I posted to be about 19-20. ive seen you say 30 in the past I think.

I will go read that thread.

cheers

Lee

No, not 30. I've always regarded 23 as an upper limit but I tend to work with it higher than that and bring it down as a last adjustment. (You can't bring it back up when it's gone!) When I started I used to make my backgrounds darker than that and a guy on the French forum commented unfavourably, recommending 23. Around the same time Nik Szymanek said something similar.

Olly

[Magnum]

Just now, ollypenrice said:

No, not 30. I've always regarded 23 as an upper limit but I tend to work with it higher than that and bring it down as a last adjustment. (You can't bring it back up when it's gone!) When I started I used to make my backgrounds darker than that and a guy on the French forum commented unfavourably, recommending 23. Around the same time Nik Szymanek said something similar.

Olly

ok thats good then so im only about 3-4 counts below that, I will try 23 next time.

[gorann]

On 29/04/2020 at 10:42, Magnum said:

Thanks Olly, No flats.

 I just run each stack through Maxims Flatten Background process, use the complex 8th order, then click 20 or more points around the image. that sorts any minor vignetting or gradients. as for Dust bunnies, I find as im really fussy about not allowing dust onto the filters and cover glass of the camera when assembling it all, they stay clean as everything is permanently sealed unless I swap cams etc, then the Rocket blower gets used before putting back together. 

Lee

Great image! Like you Lee, I try to keep everything clean and I have acturally never used flats. If by chance some grains of dust have creaped in they are very easy to take care of in PS (with curves, layers and the brush tool), and that takes much less time than taking flats and calibrating. And I mainly use OSC and there flats seem to mess things up (at least the few times I have tried to use them). And the little vignetting I get with my current set ups is easy to get rid of in processing (DBE, Gradient Exterminator etc).

Edited April 30, 2020 by gorann