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JGM1971

The "No EQ" DSO Challenge!

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2 hours ago, AnonymousAnimosity said:

These two were taken with a 50mm 1.8 lens on an unmodded Pentax K-S1 camera and an old Manfrotto tripod. 

I shot about 1300x4" lights for Andromeda and 1100x4" for Orion. About 30-40 darks and flats each. Stacked them in DSS and processed with Startools. 

Any criticism is welcome! 

Wow you got the witch head nebula too!

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4 hours ago, AnonymousAnimosity said:

These two were taken with a 50mm 1.8 lens on an unmodded Pentax K-S1 camera and an old Manfrotto tripod. 

I shot about 1300x4" lights for Andromeda and 1100x4" for Orion. About 30-40 darks and flats each. Stacked them in DSS and processed with Startools. 

Well, that just goes to show what can be done with the ultimate Alt-Az mount - one that is stationary! Great perseverance there AA, a fine achievement.

Ian

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4 hours ago, AnonymousAnimosity said:

I shot about 1300x4" lights for Andromeda and 1100x4" for Orion. About 30-40 darks and flats each. Stacked them in DSS and processed with Startools.

I like how you managed the colors in both pictures. This is something I never get it right. What ISO did you use? Nice read noise reduction on both pictures. Congratulations! 

Cezar

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On 24/04/2019 at 21:34, antaeus said:

I like how you managed the colors in both pictures. This is something I never get it right. What ISO did you use? Nice read noise reduction on both pictures. Congratulations! 

Cezar

Thank you, I used ISO 1600 for all the shots. Compared to my processing attempts with GIMP, Startools proved to be far quicker for noise reduction and a good colour balance. 

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Posted (edited)

These are rough and rushed but ive been having some sharpcap  issues of late. I've only been getting a few exposures  before stacking going south. Re installed it now and it looks updated and ive watched a couple of vids and learned a few things about the histogram.  Hopefully I'll  be having another crack at these soon.  M104 was the most I've managed at about 9 minutes worth of 20 second exposures, thec rest were just a few exposures each. No darks or flats on any due to my issues. Nexstar evolution 9.25 @6.3  with an asi294 mc.  I would say processed but it was more of a butchering in gimp and snapseed.  

PSX_20190426_180836-01.jpeg

PSX_20190328_203520-01.jpeg

Stack_7frames_214s-02-01.jpeg

PSX_20190404_055626-01-01.jpeg

Edited by Manners2020
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Posted (edited)

Here i am again, now with a Nexstar 102SLT on the stock AltAz goto mount. It is actually easily possible to shoot DSO's with an AltAz goto Mount, not even remotely as hard as EQ users tell you.

Here are my efforts from just 1 single night, around 3 hours of being outside and aligning the mount, focusing, testing settings and searching for targets. All frames were taken 05.22,2019 night, through 05.23.2019 morning.

All of the following Pictures were shot with a Nexstar 102SLT on the stock AltAz Goto Mount with a stock Nikon D3400 at prime focus, no extensions tubes, filters, coolers, heaters, field flatteners or anything else.

 

Messier 81 and Messier 82, Bode's Galaxy and Cigar Galaxy.

49x15" ISO6400

15 darkframes

1011143153_M81M82final.thumb.png.408116fb2e57a82bca48d1ff18d22ebd.png

 

 

Messier 57, the Ring Nebula

10x13" ISO6400

9 darkframes

i forgot to defringe in Photoshop... But i got the central star in the Nebula which is a plus 😛

1835688207_RingNebulafinal.thumb.png.974e39c1c277be834961e7d3a0294e40.png

 

 

NGC 6992, a bit of the (Eastern?) Veil Nebula

28x13" ISO3200 (shouldve used 6400 here)

9 darkframes (this was the last DSO and the camera battery was dead)
couldnt defringe because i would lose the Nebula's color.

313936249_VeilNebulafinal.thumb.png.82d31b6e232ed362fdbede07502d8eb6.png

 

 

Messier 51, the Whirlpool Galaxy

28x10" ISO6400

9 darkframes


every EQ user ive seen said/wrote that anything within 30° of zenith is impossible with an AltAz mount, which isnt true at all. In my location at this time of the year, Messier 51 is almost 82° high.
No matter what EQ Users tell you, Astrophotography is very much possible and fun with AltAz mounts.

311030092_WhirlpoolGalaxyfinal.thumb.png.3b3128547bce60f239d94579fe27e31f.png

 

 

Messier 13, the great Cluster in Hercules.

i deleted the RAW files and cant remember the settings, but it was ISO1600.
i cant get rid of the gradient because i didnt do any flatframes AND the Moon (can you believe how much i hate this Moon guy :P?) was 99.81%. Anyways, this was the first DSO i shot with the Nexstar 102SLT.

1732737587_M13finalcropped.thumb.png.6c77aa4067926bf7c69e34c1725e0106.png

 

 

Messier 27, the Dumbbell Nebula

18x13" ISO3200

9 darkframes
38602066_DumbbellNebula.thumb.png.e6272e5f9c4f5abd82f6ace2070da8bb.png

 

Everything was processed in DeepSkyStacker, Photoshop and Lightroom.
Very basic processing, Deepskystacker: Stacking ofc. Photoshop: histogram strecht, color correction, LP removal, contrast. Lightroom: noise reduction and final WB correction.

I had to crop the images because they were over the maximum filesize that Stargazerslounge allows. Huge because the D3400 shoots in 6000x4000 and Deepskytacker loves huge files.

I still got questions tho. If i take more lightframes and darkframes for, lets say M81 and M82, and stack upwards of 200, will the SNR improve by a lot? it seems to me that stacking 20-150 frames will reduce noise by a lot, but anything over that doesnt do anything. Is there a limit at which the SNR cant improve anymore?

Criticism is very welcome!

Edited by LOL221
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Posted (edited)

That's a great set, I particularly like m57.

I have found 100+ lights with 30 flats, 30 dark flats and bias makes a difference and if do use darks then it is 30 again. Too few darks I find adds noise.

There is a point of diminishing returns but me me that is controlled more by how long I will stay outside or whether the object is moving out of view.

For uploading as I bin my images they are always nice and small file size so are around 3 MB each only.

Edited by happy-kat
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Just now, happy-kat said:

That's a great set, I particularly like m57.

I have found 100+ lights with 30 flats, 30 dark flats and bias makes a difference and if do use flats then it is 30 again. Too few darks I find adds noise.

There is a point of diminishing returns but me me that is controlled more by how long I will stay outside or whether the object is moving out of view.

For uploading as I bin my images they are always nice and small file size so are around 3 MB each only.

I never thought about the possibility that too few darks can add noise... I have to make sure to remember that darkframes are just as important as lightframes haha.  What exactly is binning? I may be confusing it with drizzle. Also, if a gradient is barely noticable, are flats really needed? I tend to crop images more and more, except for targets that are too big for my FOV like M31.

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Posted (edited)

I have found dark flats as important as flats to help with the background sky noise regardless of whether there are gradients.

Binning is a function I use in StarTools it does two things, makes the image smaller (easier to then process) and condenses the signal at the trade of resolution (a large image I find is cumbersome to work with and thins signal clarity).

Edited by happy-kat
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18 minutes ago, happy-kat said:

I do like this image of yours.

1166567774_1277072095_RingNebulafinal.png.9e24d845dff5178e3a2076c24e5b6b8bv2.png.a8482fd44c2a00dc97ab9fca3ec2e760.png

Thank you!
I actually dont like it "that much", the stars are bloated and im not a fan of that. But this image brings me to my next question. I shot the Ring Nebula at 1800mm focal length (8" 1200mm dobson and 1.5x apsc crop factor dslr) and this one at 990mm focal length (102slt 660mm and 1.5x apsc crop factor dslr). There is hardly any difference in the size of the Nebula, even tho its almost 2 times the focal length on the 8" dobson. 

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51 minutes ago, happy-kat said:

I have found dark flats as important as flats to help with the background sky noise regardless of whether there are gradients.

Binning is a function I use in StarTools it does two things, makes the image smaller (easier to then process) and condenses the signal at the trade of resolution (a large image I find is cumbersome to work with and thins signal clarity).

How do you actually do dark flats? from the name of it i guess its like a dark frame but the same exposure time of a flat frame?
Oh so thats binning. Its like the custom rectangle in DSS, isnt it? i have never actually used that, gotta give it a try and see if it goes any smoother. Thanks!

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Binning is a StarTools function and I don't think it is like the custom rectangle in DSS.

Take you flats... Stick the lens cap on and take your dark flats using same settings as for the flats..

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The crop factor effects field of view the camera essentially sees rather then actual magnification. I'm not up to speed with working out pixel resolution to answer your question mathematically.

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11 hours ago, LOL221 said:

I shot the Ring Nebula at 1800mm focal length (8" 1200mm dobson and 1.5x apsc crop factor dslr) and this one at 990mm focal length (102slt 660mm and 1.5x apsc crop factor dslr). There is hardly any difference in the size of the Nebula, even tho its almost 2 times the focal length on the 8" dobson. 

The crop factor is irrelevant to my mind. Assuming that your images are processed in exactly the same way, then one should be twice the size of the other. If you bin one and not the other, or if you crop the frame differently in processing, then that could account for it. Another thing springs to mind, depending on your settings, DSS will only give you a resultant image for which data in all frames is available. So, if there is significant drift over the imaging period, such that the frames don't completely overlap, then the image that DSS will produce will only cover the region where there is overlap, and so will cover a  smaller field. Such 'hidden' cropping could account for it.

Ian

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4 hours ago, happy-kat said:

Binning is a StarTools function and I don't think it is like the custom rectangle in DSS.

Take you flats... Stick the lens cap on and take your dark flats using same settings as for the flats..

Alright, thanks for the dark flat "tutorial" haha. Im gonna read up if APP has binning. I save some of my raw data so i can freely experiment.

4 hours ago, happy-kat said:

The crop factor effects field of view the camera essentially sees rather then actual magnification. I'm not up to speed with working out pixel resolution to answer your question mathematically.

oh that actually makes more sense... But i remember reading somewhere that to calculate your focal length at prime focus you do: Focal length of Telescope multiplied by Crop Factor of Camera, so in my cases 1200mm x 1.5x and 660mm x 1.5x.

3 hours ago, The Admiral said:

The crop factor is irrelevant to my mind. Assuming that your images are processed in exactly the same way, then one should be twice the size of the other. If you bin one and not the other, or if you crop the frame differently in processing, then that could account for it. Another thing springs to mind, depending on your settings, DSS will only give you a resultant image for which data in all frames is available. So, if there is significant drift over the imaging period, such that the frames don't completely overlap, then the image that DSS will produce will only cover the region where there is overlap, and so will cover a  smaller field. Such 'hidden' cropping could account for it.

Ian

I remember the settings in DSS for the Ring Nebula, may give it a go and see if the difference is really there or if its just my mind playing tricks on me. There was some noticeable drift but it wasnt anything extreme, maybe 1 or 2 mm on the Camera screen. I can sort that out quickly with the hand control of the scope. Thank you for the explanation!

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The crop factor came into use in photographic circles when sensors smaller than the standard 35mm film frame became available. Then it became customary to multiply the focal length of lenses by the crop factor to give an 'equivalent' focal length as if it were on a full frame camera, because until then photographers were used to full frame film cameras. Of course, it doesn't actually change the focal length of the lens, which is fixed by the physics, but really relates to the field of view when used on a crop sensor camera. This has no place when it comes to astrophotography. The focal length of the scope is its focal length. Full stop.

If you look at this page from this site, http://astronomy.tools/calculators/field_of_view/ , and select 'imaging' and put in you scope and camera details, it will calculate the field of view and resolution in arcsec per pixel.

Ian

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Posted (edited)

Hi all,

as it can be derived from my nickname, I am a fan and supporter of altazimuth DSO imaging. I take pictures from the balcony of my flat in downtown Turin, Italy.

Turin is the fourth biggest city in Italy and of course IL is an issue. According to Clear Outside mine is a Bortle 9, 17.6-17.8 sqm sky.

I also have to deal with the "proximity IL" of the illumination of the internal court of my building.

So the border conditions, to use a mathematical expression, are far from optimal, quite the opposite.

Nevertheless I am quite satisfied of the results I was able to obtain so far with my AZ-GTi and my small scopes and camera lens.

I have created my own site advocating for altazimuth DSO imaging, where I described all of my equipment.

Basically so far my scopes are two short refractors, the ubiquitous 80/400 and a rarer Bresser 102/460, and two catadioptric ones, a mainstream SW MAK-90 and a less known Meade 2045D.

Recently I have realized than, when paired with a cheap 0.5x focal reducer (mine is branded Telescope Service, but I reckon they are all based on the same design), produces surprisingly good results.

The two pictures I'm showing here, which are my latest so far, have been indeed realized with the MAK-90 and the aforementioned focal reducer, even if the effective reduction is rather like 0.56-0.57, for a focal length around 710 mm and an overall focal ratio of about 7.8 .

M81 is a stack of 126 20s exposures, and M51 a stack of 140 20s exposures, all taken with a ZWO ASI 178MM.

The images were acquired with Nebulosity 4.2, stacked with Astro Pixel Processor and post-processed with StarTools.

 

M81-20190523-126x20s-720mm.thumb.jpg.bb8f18039e4c6741c854dbb196860f4a.jpg

 

M51-20190524-140x20s-720mm.thumb.jpg.03510e84846f63579d19986a92dd4754.jpg

 

Edited by AltAzAstro
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On 24/05/2019 at 19:18, The Admiral said:

The crop factor came into use in photographic circles when sensors smaller than the standard 35mm film frame became available. Then it became customary to multiply the focal length of lenses by the crop factor to give an 'equivalent' focal length as if it were on a full frame camera, because until then photographers were used to full frame film cameras. Of course, it doesn't actually change the focal length of the lens, which is fixed by the physics, but really relates to the field of view when used on a crop sensor camera. This has no place when it comes to astrophotography. The focal length of the scope is its focal length. Full stop.

If you look at this page from this site, http://astronomy.tools/calculators/field_of_view/ , and select 'imaging' and put in you scope and camera details, it will calculate the field of view and resolution in arcsec per pixel.

Ian

Oh wow... So i was the one who got it wrong. I use that website a lot to see if a target will fit into my frame, i just cant work with the FOV calculation. I just dont know how much, lets say 2°x1.5° FOV is like i dont know how to "interpret" it, if that makes sense. Anyways i got clear skies tonigh with very nice seeing so ill see what i can get. Is the Wizard Nebula doable with an unmodified DSLR?

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12 minutes ago, LOL221 said:

I just dont know how much, lets say 2°x1.5° FOV is like

Well the Moon is 0.5° in diameter. Also, if you use star map programmes, such as Stellarium or Skysafari, you can judge from the coordinate lines, or you can input the FoV/scope and camera details and it will show you a frame on the sky map.

Ian

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On 25/05/2019 at 10:53, AltAzAstro said:

Hi all,

as it can be derived from my nickname, I am a fan and supporter of altazimuth DSO imaging. I take pictures from the balcony of my flat in downtown Turin, Italy.

Turin is the fourth biggest city in Italy and of course IL is an issue. According to Clear Outside mine is a Bortle 9, 17.6-17.8 sqm sky.

Impressive images considering that you get them from such heavy light pollution zone.

I have recently purchased a Pyxis LE rotator and was giving it a try. No guiding yet, I am planning to get an OAG and a guiding camera. I am in the process of learning on how Pyxis LE works, still tweaking the settings. For me, it shows promising results.

NGC6888
- 9x120sec, 30 darks, 50 bias, 60 flats, ISO 1600,
- Antares f/6.3 placed inside Pyxis LE, FR obtained f/5, 
- Optolong L-Pro filter threaded on Pyxis LE,
- Pyxis LE rotator

- FujiFilm X-A1,
- Meade LT-8 ACF.
NGC6888.thumb.jpg.e73a1a60d766f81b1820897d87254f1f.jpg

NGC7635
- 9x120sec, 30 darks, 50 bias, 60 flats, ISO 1600,

- Antares f/6.3 placed inside Pyxis LE, FR obtained f/5, 
- Optolong L-Pro filter threaded on Pyxis LE,
- Pyxis LE rotator

- FujiFilm X-A1,
- Meade LT-8 ACF.
NGC7635.thumb.jpg.595f4a4608a70b875aa8e9029e6bd746.jpg

Thank you,
Cezar

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Sorry for replying just now.

A very nice start, congratulations!

All is well that starts well ... keep going.

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Just found this thread, cool idea!

This was back in February when I first pointed my camera up at night!

1036673621_Andromeda2-5.thumb.jpg.d0cdab5eed298149003dd5e26b9286fc.jpg

This was 10"x211, ISO 400, Canon 80D with 50mm f/1.4 @ f/2.0. 14 darks, 22 flats, 31 bias. Stacked in DSS and edited in PS and LR. I think I've come a good ways since then, but so cool to see what's doable with a fast, untracked system. 

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On 24/04/2019 at 15:49, AnonymousAnimosity said:

These two were taken with a 50mm 1.8 lens on an unmodded Pentax K-S1 camera and an old Manfrotto tripod. 

I shot about 1300x4" lights for Andromeda and 1100x4" for Orion. About 30-40 darks and flats each. Stacked them in DSS and processed with Startools. 

Any criticism is welcome! 

2077605779_Andromeda-stack1290editnuovo.thumb.jpg.3f0340180c4918dd522a95008e86f14a.jpg

1222717807_Orioneedit21-4jpg.thumb.jpg.d1d82118cf6cf9c40becbad7f392b64d.jpg

 

That is amazing, you have even got the horse head in there. I've been trying to get that for ages. 2 questions is your sky really dark and 2nd can you confirm that your exposure time  was multiple 4 second exposures? If it was I am totally inspired to have another go myself when I finally get my gear again.

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