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The "No EQ" DSO Challenge!


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Hi guys. Newbie here. My first DSO image while waiting for my first telescope.

Andromeda taken with a Canon 50mm lens and a tripod last night. 4s X 120  F/ 1.4 ISO 800. 

It's just a white blob, but i thought I'd share it anyway :) 
 

post-47316-0-56903500-1444809376_thumb.j

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I'm still fairly new to imaging, but have had a good start with Planetary and Wide Field images. Obviously, like most of us, it's the Deep Sky stuff I'd like to glimpse, but time, location and more im

Assorted shots with a Nexstar 102SLT and a Canon 1000D. 30sec subs at ISO1600. Total exposures range from 5 mins (M20)  to ~1hr (M31). NigelM

this was taken a couple years ago on my AZGOTO mount with 130p...... about 50 x 5 sec subs, no calibration frames

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Read this section with great interest. Recently bought a Celestron Evolution 8 for visual use, but couldn't resist trying out my old Canon 400D on the back of it. Bought an intervalometer off ebay for £8.50, hooked the camera up (no modifications) and gave it a go. No focal reducers, so shot at f10, iso 400. 60 frames of 20secs, 15 darks, flats and bias. Pushed it all through DSS and fiddled about with it using Affinity Photo (good photo prog on Mac).

It isn't going to win any prizes, but it's amazing how excited you can get when you see your first efforts rewarded with a non blank image!

completed.3adj

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Hi guys. Newbie here. My first DSO image while waiting for my first telescope.

Andromeda taken with a Canon 50mm lens and a tripod last night. 4s X 120  F/ 1.4 ISO 800. 

It's just a white blob, but i thought I'd share it anyway :) 

Welcome Astronator. That's a lot more than a white blob. I'm looking forward to seeing what you achieve with a telescope!

Ian

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Hi guys. Newbie here. My first DSO image while waiting for my first telescope.

Andromeda taken with a Canon 50mm lens and a tripod last night. 4s X 120 F/ 1.4 ISO 800.

It's just a white blob, but i thought I'd share it anyway :)

Pretty good looking"blob"

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  • 3 weeks later...

Attached is an image showing an example of a DSO image that can be obtained using an Alt-Az mount.

When obtaining the image the equipment I used comprised :

Camera : Modified Canon EOS 1100D DSLR plus Light Pollution Filter.

Telescope : SkyWatcher 130PDS Reflector plus Coma Corrector.

Mount : SkyWatcher AZ GOTO.

Capture Software : BackYardEOS.

This was imaged on 06 Feb 2015.

Exposures were, 30s at ISO 1600, effective f/4.5, using 20 Light frames and 20 Dark frames.

The rather short exposure and high ISO being necessary with an unguided AZ type mount in order to prevent star trailing and field rotation.

A second set of exposures was also obtained in order to achieve more detail in the bright core of the nebula. This core was over exposed in the first set, whose purpose was to obtain detail in the nebulosity.

Exposures for this second set were, 30s at ISO 200, effective f/4.5, using 20 Light frames and 20 Dark frames.

When stacking, I was very selective and used only 9 and 8 of the 20 Light frames in each set respectively after rejecting any frames showing signs of star trails or star distortion.

Deep Sky Stacker (DSS) was used for all stacking.

The output file from DSS for each of the above two sets was processed using both Photoshop CS2 and StarTools.

The two different results were then merged using the Layer Masking facility in Photoshop in order to obtain the required High Dynamic Range of this nebula.

This prevents the bright core being overexposed, while allowing the detail in the nebulosity to be seen.

This Layer Masking technique is that advocated by Jerry Lodriguss on his website.

The final image obtained is better than a similar attempt a year previously, as the star shapes and colours are improved.

Firstly, I believe that this is because I used a reflector telescope rather than the non-apochromatic refractor in the previous year. Secondly, because I now used a DSLR that had been modified.

This modification allows more of the red content of the nebula to be recorded.

post-48190-0-42091800-1449144498_thumb.j

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  • 1 month later...

Well, after posting about my rather feeble attempt at M31 using a spotting 'scope, I've now acquired a proper astronomical 'scope and I've been keenly awaiting the arrival of Orion so that I could have a try at imaging the glorious M42. Being so bright, it represented a rather easier challenge than many.

This is with a Fuji X-T1 through an Altair 102mm f/7 Super ED, all mounted on a humble Nexstar 6/8SE mount, 19 January 2016.

About 100 x 15s subs, 1600ASA, stacked in DSS and processed in Star Tools. I took about 100 darks and 60 bias frames (no flats), but I forgot to do these at the time so they were done early the following morning, after leaving the camera out to cool in the still frosty morning. Given that this is my first proper DSO image and that I'm still trying to figure out how both DSS and ST work, I'm pretty pleased with the outcome. Even with a 15 second exposure the core is blown out, so it'd be nice to get some more data with shorter exposure. Also some banding is visible, which I guess might be to do with not taking the darks at the time of the original exposure?

I then moved a little to the east and had a go at the Rosette nebula. As above, but 130 x 10s subs. I think it needs a lot more data though.

Ian

 

Rosette ST fits1 v2.jpg

 

 

M42 STprocess v2 rot crop.jpg

Edited by The Admiral
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Hi, they are two lovely images which you should be proud of. Good to know the number of exposures, duration and ISO you have been using. I often think of DSS and StarTools as the perfect marriage, by that I mean they work together to a common end but don't necessarily make it easy to know what they are both doing in the background to help the other!

It just shows what can be achieved with an alt-az mount. Keep up the good work.

Best Regards,
Steve

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Some impressive results and a good idea for a thread. 

Erm, would it be considered unsporting of me to go and beg some time on this Alt-Az instrument up the road from me? 0.8M Ritchey Chrétien, direct drive, field de-rotator and a price tag of 6 million Euros...

Well it isn't an EQ!!! :evil4:

(There's always one...)

:glasses10:lly

 

 

Marcs telescope.JPG

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9 minutes ago, ollypenrice said:

Some impressive results and a good idea for a thread. 

Erm, would it be considered unsporting of me to go and beg some time on this Alt-Az instrument up the road from me? 0.8M Ritchey Chrétien, direct drive, field de-rotator and a price tag of 6 million Euros...

Well it isn't an EQ!!! :evil4:

(There's always one...)

:glasses10:lly

 

 

Marcs telescope.JPG

I love way there is an eyepiece hanging off the end, just seems out of place somehow! A bit like a formula one car with a saddle bag.  :) 

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This is a great thread & I'm seeing some pretty impressive results. I haven't actually tried imaging with an Alt Az mount myself although it does make me want to blow the cobwebs from my 6SE Nexstar & have a go just to see what I can manage.

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Thank you Steve and Olly for your kind words.

As you say Olly, it is not an EQ mount :icon_biggrin:, but what a beast. Are there any images from it that can be viewed?

7 minutes ago, tich said:

This is a great thread & I'm seeing some pretty impressive results. I haven't actually tried imaging with an Alt Az mount myself although it does make me want to blow the cobwebs from my 6SE Nexstar & have a go just to see what I can manage.

Well tich, you should go for it, you might be surprised at what can be achieved with modest equipment. This thread has shown that dedicating large monetary sums and huge amounts of time aren't at all necessary to get into astrophotography, and for those thinking of dabbling in the black art, it's a good way to start without being sucked into the all-consuming black hole to which many have fallen!

I'm currently reading a book called "Astrophotography on the Go - Using Short Exposures with Light Mounts" by Joseph Ashley, and it seems a good primer.

Ian

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  • 2 weeks later...

Here's my attempt at the Flame Nebula and the Horsehead. It's not a great success because the cloud rolled in before I'd barely managed to capture 70 frames, and on some of them a finger of thin cloud passed over the target area. Still, it's succeeded in showing both NGC2024 and IC434, and a suggestion of NGC2023 and IC435. I just need a lot more imaging time. Oh this weather!

Details: Fuji X-T1 through an Altair 102mm f/7 Super ED, all mounted on a Nexstar 6/8SE mount, 3rd February 2016. 64 x 15s subs, 1600ASA, stacked in DSS and processed in Star Tools. I took about 50 darks and 50 bias frames (no flats).

Ian

 

Autosave002 ST v1rot.JPG

Edited by The Admiral
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Hi,

Here is my first attempt at imaging the Rosette Nebula/Cluster. It was taken on the 2nd February 2016 using a SkyWatcher Startravel 102mm refractor on a Synscan alt-az mount. There are 62 light frames (each of 30 seconds at ISO 1600), 53 dark frames and 50 bias frames making up the image. My camera is a Canon 600D. There would have been more light frames but...rain stopped play. Images stacked in DSS and processed using StarTools.

Cheers,
Steve

NGC2237SGL.thumb.jpg.d9f90ca7fb95e44df1e

This closer image resulted from messing more in StarTools!

NGC2237CloseupJPEG.thumb.jpg.3c12ddc61e3

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I currently have a NexStar 90SLT and I just can't get these pictures because the alignment is always off causing star streaks. The mount is always level, the legs fully extended, I always use the highest power eyepeice I have to center the star, and I always make sure the stars are far apart. I don't get how you can get these amazing images with the same mount as me when I can barely get 30s exposure pictures without a trail?? 

Also, if anyone can explain what all these things are people keep saying like "bias, sub, lights, darks, etc."

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Hi Herzy,

Thanks for the post and your image. We're all still learning here but I notice you have a f/14 telescope which will make for less bright images taking much longer to get an image, and there's the possibility that in that time your local light pollution and/or field rotation will do their best to prevent you getting a good image. As a very very general rule of thumb 30 seconds is around the upper ability of these alt-az mounts to track for imaging purposes. The Admiral put me on to a good read, "Astro-photography on the Go" by Joseph Ashley which is specifically written for using short exposures with light weight mounts. Its ISBN is 978-3-319-09830-2. Also what camera are you using Herzy?

This page explains about the various frames-http://deepskystacker.free.fr/english/faq.htm

I use Deep Sky Stacker for stacking and then StarTools for image processing. DSS is free, you can try out StarTools for free but to save images you would need to pay the fee for a licence key.

HTH

Cheers,
Steve

Edited by SteveNickolls
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Hi Herzy, don't get too disheartened, it is an uphill challenge but I think has its rewards in the end! But there are a lot of things that can impact on your image.

In addition to what Steve said, your 'scope has a focal length of 1250mm, and the longer the focal length the more demands it will place on your mount. This is because any movement in the mount, either intentional or unintentional, will show up more than with a 'scope with a short focal length of, say, 500mm. So, what can you do about it? My two-pence worth would be:

  1. Place the tripod on solid ground.
  2. Keep the legs as short as convenient.
  3. Mount the 'scope/camera so that it is balanced on the mount.
  4. Avoid imaging when it's windy.
  5. Use mirror lock-up on the camera.
  6. Operate the camera using a remote release.
  7. Keep the exposure time as short as possible consistent with getting results.

Keeping the exposure short? At one end of the scale, if you image bright objects, like the planets or the moon, then your exposure time can be sub-second. As Steve pointed out, field rotation may be evident when you exceed 30 seconds, depending on where in the sky you are pointing. But for deep sky objects you will need to experiment to see what is the longest exposure you can use with your mount so as not to give star trails. In your image of M42 it looks as though the exposure has led to saturation in the core of the nebula, so perhaps even 30 seconds is too long at that ISO.

You won't get the best results, or indeed any result, by using just the one exposure. What you need to do is take dozens, or hundreds (yes, hundreds!), of exposures each less than 30s. You then combine the best of these into one image in specialist software, a process called stacking. For planetary imaging such free software are Registax and Autostakkert, and for DSO imaging, DeepSkyStacker. The images of your target object are termed "lights" in stacking parlance. You can improve the output of stacking by taking account of noise by taking a lot of images with the 'scope capped, so as not to admit any light, using the same exposure length. These are termed "darks". By repeating the darks, but using the shortest exposure your camera can take, you can account for the camera's read noise. These are termed "bias" frames. And finally, you can correct for unevenness of sensitivity by using exposures called "flats".

As final thoughts, when you set up your mount:

  1. Make sure it is as level as you can. Use a proper spirit level, not one of these buttons with a bubble in the centre which I've found to be hopelessly inaccurate.
  2. Enter you precise location.
  3. Enter you time as precisely as you can, say within 5s.
  4. Centre the star as closely as possible (you indicate that you are doing that).
  5. Make sure that the 'scope doesn't slip on the friction clutch when you swap from the eyepiece to the camera. This is a problem I've had, and I've now found that with my red-spot finder well aligned I can use the camera's live-view to centre the star, so avoiding the need to swap.

I hope this helps, but as you see, there are quite a few things that need to come together to get a satisfactory image.

Ian

Edited by The Admiral
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