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The "No EQ" DSO Challenge!


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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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8 minutes ago, SteveNickolls said:

Thanks Nige, I'm quite chuffed seeing as the moon was almost full last night. Never expected to capture the areas of nebulosity.

Cheers,
Steve

The second image is amazing, so much colour and detail I would be very proud of that image, VWD.

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17 hours ago, Nigel G said:

The second image is amazing, so much colour and detail I would be very proud of that image, VWD.

+1 to that Steve. Considering the state of the moon it looks surprisingly contrasty. Fingers crossed for tonight!

Ian

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Well despite almost a full Moon last night I had a go imaging M92 and M57. There was a gusting breeze here and I found a number of satellite trails and some cloud had also affected a few of the frames. The images were all taken with the SkyWatcher Startravel 102mm refractor and Synscan alt-az mount and Canon 600D DSLR. The frames were stacked using DSS and further processed using StarTools.

M92

x45 Thirty second light frames at ISO 1600, x50 dark, x50 flats and x50 bias frames.

M92SGL.jpg

M57

x41 Thirty second light frames at ISO 1600, x50 dark, x50 flats and x50 bias frames.

M57SGL.jpg 

DSS was happy with 88% and 80% of the light frames taken.

Cheers,
Steve

Edited by SteveNickolls
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Here's a couple of Altazographs from last night (19 April 2016). I'm struggling to think of new targets, as with a southerly aspect and the raging moon (though I did image that :icon_biggrin:) I'm confined largely to the south-west, east and north-east (above the houses). I stuck to starry objects, and went with M67 and M13. All imaged using Altair Wave 102mm f7 SuperED APO, Fuji X-T1, Nexstar 6/8SE Alt-Az mount. Used flats for the first time too.

For M67 I used about 50 frames each of lights (30s), darks, flats and bias, stacked in DSS, processed in Star Tools, and tweaked in Lightroom.

M67 Autosave fdb ST-2 LR1.jpg

 

For M13 I used the same flats, darks and bias frames as in M67. The lights were a bit of a problem, because after the first 50 I realised that the field tracked through some overhead power wires, so I had to do another 50 frames. Checking through them I ended up with only 26 x 30s lights to stack! Stacked in DSS, processed in Star Tools, and tweaked in Lightroom.

M13 Autosave fdb ST1 LR1-1.jpg

 

Thanks for looking, and I hope you like.

Ian

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22 minutes ago, SteveNickolls said:

Well despite almost a full Moon last night I had a go imaging M92 and M57. There was a gusting breeze here and I found a number of satellite trails and some cloud had also affected a few of the frames. The images were all taken with the SkyWatcher Startravel 102mm refractor and Synscan alt-az mount and Canon 600D DSLR. The frames were stacked using DSS and further processed using StarTools.

 

Nice images Steve. I particularly like the ring Neb, very colourful, something I'd like to capture when it becomes favourably positioned.

Ian

 

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Ian & Steve,  nice and clear images, you both done well considering that bright moon at the moment. 

I'm a bit of a nebula fan, that the first time I have seen the ring neb, I'm going to have to find that one ☺

M13 a cracking shot.

WD guys.

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20 minutes ago, Nigel G said:

I'm a bit of a nebula fan, that the first time I have seen the ring neb,

Hi Nige, when the Moon moves out the way and we have some clear sky there's a lot of nebulosity around the constellation of Cephus to have a go at. Good luck too imaging M57 in Lyra.

Thanks too Ian for the kind comment. Btw did you find using flats improved the resuting images?

Cheers,
Steve

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My experience is if I have no flats I get awful result from StarTools. They end up very noisey. It might be because I never have as many lights as you all seem to get.

Edited by happy-kat
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40 minutes ago, SteveNickolls said:

 

Thanks too Ian for the kind comment. Btw did you find using flats improved the resuting images?


 

I tried using flats for the first time Saturday,  Something went wrong though. Flats are taken at twilight or through a white sheet or white screen is that right?

I took mine as the sun was just above the horizon pointing scope to the southeast. The flat images were really odd, I  can't post one until I get my new pc, 

They were light at the bottom fading to dark at the top, not a faint ring as I was expecting . Anyway they didn't work I had the reverse of that in the processed image.

any tips on taking flats are very welcome ☺

Nige.

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11 minutes ago, happy-kat said:

My experience is if I have no flats I get awful result from StarTools. They end up very noisey. It might be because I never have as many lights as you all seem to get.

I'm guessing but probably processing clusters is less troublesome because the stars are significantly brighter than background, and you can adjust the black point. With nebulae I find it's often a fine line between faint nebulosity and noise. It'll be interesting to process such an image with and without. As I say, this is the first time I've used flats, so I've nothing to go on.

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16 minutes ago, Nigel G said:

I tried using flats for the first time Saturday,  Something went wrong though. Flats are taken at twilight or through a white sheet or white screen is that right?

I took mine as the sun was just above the horizon pointing scope to the southeast. The flat images were really odd, I  can't post one until I get my new pc, 

They were light at the bottom fading to dark at the top, not a faint ring as I was expecting . Anyway they didn't work I had the reverse of that in the processed image.

any tips on taking flats are very welcome ☺

Nige.

I presume you were using the tea-towel over the end? If you were, I imagine the light presented to the OG would have been uniform, in which case the distribution should reflect the sensitivity across the field. I have read that the histogram peak should be about 1/3rd of max. Clearly, one needs to avoid any chance of saturation. I did mine with a laptop screen and a sheet of opal perspex in front of the OTA. If anything, you'd expect the image to be brighter in the centre and darkening towards the corners.

Ian

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I've been aiming at the middle ground for my flats after reading budgetastro.Net

To me because flats are about the light fall off which mightn't show if exposed like a light on the histogram.

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2 minutes ago, The Admiral said:

I presume you were using the tea-towel over the end? If you were, I imagine the light presented to the OG would have been uniform, in which case the distribution should reflect the sensitivity across the field. I have read that the histogram peak should be about 1/3rd of max. Clearly, one needs to avoid any chance of saturation. I did mine with a laptop screen and a sheet of opal perspex in front of the OTA. If anything, you'd expect the image to be brighter in the centre and darkening towards the corners.

Ian

I took them without anything covering the tube, I focused on the moon turned the scope to southeast and shot the flats av mode on camera, and left the camera in the scope until time to start taking lights. 

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Hi Nige,

I've used flat frames twice now and made them the morning after imaging. I bring the telescope with camera still attached and mount indoors, leaving everything as it was outdoors so the optical path is as it was outdoors. The objective cap is taken off the tube. I fit two flat ironed tea towels across the objective and fix in place with an elastic band. I make sure no creases etc. For an even illumination source I open a new page in MS Word to get a white screen up on the monitor and place the OTA a few inches from the monitor screen. I change the camera to Av so it chooses its own exposure level. I use the same ISO setting as the light frames. Temperature is unimportant. When I did this today I noticed it darkening towards the periphery of the Live View screen so I take it there is some difference in the illumination across the shot when I image objects. I took x50 exposures (I think they were 1/50th second each).

Hope this helps.

Cheers,
Steve

Edited by SteveNickolls
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9 hours ago, Nigel G said:

I took them without anything covering the tube, I focused on the moon turned the scope to southeast and shot the flats av mode on camera, and left the camera in the scope until time to start taking lights. 

I think that's likely to be the problem Nigel, it's just recording the variation of the light it's seeing in the field of view. I understand that whilst the 'scope needs to use the same focus position as when imaging, you need to present it with a uniform source of light, but this doesn't itself have to be in focus. Hence the use of diffusers at the end of the OTA.

I've not seen any consistency on exposure levels, some say 1/3, others 1/2 of max. If you do as Steve does the camera should record it as mid-grey. I guess the main thing is that you accommodate the full range of light variation.

Ian

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That's kind of you to say so Carsten. It's taken us a while to get this far, but it is all achievable with our modest gear, and you should be no different. I've said it before, if you take lots of subs, then processing can make or break an image. Get that right and your image can zing. Personally, I've found the processing part the much more challenging and difficult to get right. I suppose that goes for any astrophotography, EQ or Alt-Az. That's why I think by starting with modest gear one can develop ones processing skills, and then later decide whether to get into the full works with all the fancy and expensive gear. It's not time wasted.

I use Star Tools, and it does have its quirks and I wouldn't say I've got it tamed by any means, but it can (can, not always!) produce some decent results without a great deal of effort. I dabbled with PixInsight on a trial, and although I can see it gives one great control, it does require a deep multi-stage process so far as I can see.

Keep at it!

Ian

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This thread inspires me a lot. Although I have an EQ mount, it's only an EQ3 and without guiding sub-lengths are limited. The message is clear stop eating my heart about about not getting 2-minute subs and take lots of 1-minute ones knowing that nearly all will be usable.

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26 minutes ago, Stub Mandrel said:

This thread inspires me a lot. Although I have an EQ mount, it's only an EQ3 and without guiding sub-lengths are limited. The message is clear stop eating my heart about about not getting 2-minute subs and take lots of 1-minute ones knowing that nearly all will be usable.

It's always worth a try Neil. I would imagine that even an EQ mount that isn't perfect at tracking will give you an advantage over an Alt-Az mount. I'm not so experienced at astrophotography that I fully understand the benefit of a 2 minute sub compared to a 1 minute one, but I presume that skyshine will limit you eventually.

I'm always reassured by the following thread: "To Stack or Not To Stack: 30x 1s = 1x30s?" (https://stargazerslounge.com/topic/245183-to-stack-or-not-to-stack-30-x-1s-1-x-30s/?page=1) by Martin Meredith.

I've seen Olly Penrice commenting that he finds darks to be a waste of time, particularly with dslrs, and uses dithering and bias frames as darks instead. I need to explore that further, but the lack of precise tracking with Alt-Az mounts and presumably a less-than-perfectly tracking EQ mount would do much the same thing as dither. So all is not lost!

Ian

Edited by The Admiral
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