Jump to content

stargazine_ep35_banner.thumb.jpg.a7c1791d7e682021778de0def357bdbb.jpg

C4 - Iris Nebula with DSLR (unmodified)


Recommended Posts

Last night was a bit of a miracle, there was more clear sky than predicted! I set everything up at dusk expecting to be able to do nothing more than practice polar alignment, but I actually managed to get some imaging in as well!

Admittedly I had to spend the first half of the night fighting SGPro in order to convince it to actually let the guider settle before opening the shutter again. The first hour of subs needed to be thrown away as they all had lines where PHD was trying to bring the guidestar into the right place after dithering, but SGPro has waltzed on ahead. It turns out that the integration of Sequence and Equipment Profile in SGPro is unclear and byzantine.

I managed to capture some of the dark dust surrounding the brighter nebula which I am pleased about. There is still a bit of a gradient from top to bottom, but I could not decide if it was more dust, so I decided to leave it in. The centre of the nebula is completely blown out unfortunately, I tried to take some shorter exposures, but even at 60 seconds, the core was blown out and I was getting no nebulosity at all.

Lights: 21 x 300s @ ISO400

Darks: 112 x 300s

Bias: 492

Flats: 54 x 1/8s

32760386254_31a2cc5dc0_c.jpg

C4 - Iris Nebula by frugal10191, on Flickr

Mount: Skywatcher AZ-EQ6 GT

Imaging Telescope: Skywatcher ED80 DS-Pro with 0.85x FF/FR

Imaging Camera: Canon 60D (Unmodified)

Guiding Telescope: Skywatcher ST-80

Guiding Camera: Starlight Xpress Lodestar X2

Software: Sequence Generator Pro, PHD2, PixInsight

I also tried to image the Elephants Trunk as some people have had success with unmodified DSLRs, but the 10x300s subs I managed before the clouds rolled in show no signs of nebulosity when stacked ;(

  • Like 6
Link to post
Share on other sites

Looks great. But it seems strange that the core is already blown out at 60 secs at iso 400.

Succes on a Ha target with an unmodified dslr is very much dependent on camera make and model. The manufacturer's choice of which wavelengths to block and the sensor's spectral response determines the outcome. I have had some succes with 7+ minute exposures on bright Ha targets (california and north america nebs).

Good luck

Link to post
Share on other sites

Great start,

but I agree with Wim that it is odd that the core would be blown out. Maybe it is not really blown out, just smeared out by the atmosphere and possibly by poor guiding or focusing. I have a 60Da (so same camera but more Ha sensitive), and you can see what I got from 39 x 480s on a ES127 ED running on its native f/7.5, all at ISO1600.

So, I cannot imagine that the core in your subs is blown out at ISO400. Did you protect it with a layer mask while you stretched the image?

http://www.astrobin.com/278815/C/

Link to post
Share on other sites

I was a bit surprised as well. SGPro had a definite spike on the right hand edge of the histogram indicating that the image had got some blown out pixels. If I open the RAW file in Photoshop it shows the centre of the nebula as 255,255,255. If I open it in PixInsight the Image Statistics show the Maximum as 15306, which is just slightly lower than the theoretical maximum of the 14bit sensor of 16384. If I then look at one of the 300s images, the Minumim, Mean and Median pixel values all go up, but the Maximum stays at 15306, which confirms that is as high as the sensor will go depite only being 93% of the theoretical full well value. Curse you Canon, first you take my Ha sensitivity, now you take 7% of my dynamic range ;)

Link to post
Share on other sites

Well, the centre of your core and some of the stars will be 255,255,255, but it should not be as much of the centre as it looks like in your image. As far as I know it is the same sensor in my camera as in yours.

Edited by gorann
Link to post
Share on other sites

Very nice effort given what you had to put up with.

I imaged this briefly last year when i had an ED80 Pro, i also used a canon 60D as i didn't have my Modded 600D back then, here is my 2 hour cropped effort.

 

ngc7023.png

Link to post
Share on other sites

Yes, that background sky looks overstretched since the "blue-green mottle" typical of DSLRs is quite visible. Also, for this object you probably aim at 5 h total exposure so do not worry yet. Now, just make sure that you got the focus right (I assume you use live view on your camera at 10 x on some nearby star that you can see in live view).

I am very happy right now since clouds are gone and I started exposing for the first time in a month. The Sky Quality Meter show 21.2. I am going for the Leo Triplets, and maybe later for the Sombreo.

A good video tutorial on noise for us DSLR users is this one by Tony Hallas (in case you have not seen it):

 

Link to post
Share on other sites
1 hour ago, gorann said:

Yes, that background sky looks overstretched since the "blue-green mottle" typical of DSLRs is quite visible. Also, for this object you probably aim at 5 h total exposure so do not worry yet. Now, just make sure that you got the focus right (I assume you use live view on your camera at 10 x on some nearby star that you can see in live view).

I am very happy right now since clouds are gone and I started exposing for the first time in a month. The Sky Quality Meter show 21.2. I am going for the Leo Triplets, and maybe later for the Sombreo.

A good video tutorial on noise for us DSLR users is this one by Tony Hallas (in case you have not seen it):

 

The noise on the DSLR is the bane of my life, but until ebay changes their pesky rules about me selling my own organs, a CCD is not on the cards ;)

I shall have a look at that video a bit later, but like yourself, there is a break in the clouds so I am trying to get some more data tonight.

Link to post
Share on other sites
41 minutes ago, gorann said:

Good luck tonight Frugal!

The Met Office promised that the clouds would not come any further north than the M4, they were wrong... I managed a single 5 minute sub before the clouds rolled in. :clouds1:

Link to post
Share on other sites
20 minutes ago, frugal said:

The Met Office promised that the clouds would not come any further north than the M4, they were wrong... I managed a single 5 minute sub before the clouds rolled in. :clouds1:

Rolling in here to just now but could be temporary, I hope.....

Link to post
Share on other sites

Regarding your image, you obviously had not blown out the core so now you "just" need the clouds to go away so you can get more data = less noise.

  • Like 1
Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By DrummerSP
      Hi!
      Firstly apologies if this is in the wrong section (this is my first post on any kind of forum!) and I'm aware its a question thats probably been asked thousands of times. Please let me know if I should post elsewhere or anything...
      So I've made some progress with astrophotography but as much as I try I get so confused with lenses and the specifics so thought I'd ask people who understand them more. My setup so far is a Canon EOS 550d, with a 70-300mm f4-5.6 lens all on a Star Adventurer pro tracker (recently upgraded from an Omegon LX3 mini track). The camera and lens were both second hand and passed down to me so I dont really know how old they are now but I've been getting good results so far (uploaded one of my recent images, still using the minitrack for reference)
      Basically I dont know if I'm better off upgrading the camera and sticking with the telephoto lens (from what I can find its a good lens), or would changing to a small telescope be better. If I was to, from what I've found the Sharpstar 61EDPH II would be a good choice?
      I've researched a lot and just dont understand the technical side enough to know where I'm better off putting my money. My budget would be around £1000, maybe slightly more for a camera as I do use it for other photography too. Any advice would be very appreciated, sorry for the long post!

    • By endless-sky
      I would like to share my fourth image.
      With my "lucky week" of imaging, along with M33, I managed to finish also this project. This is my longest integration to date.
      These are IC 405 and IC 410, also known as the Flaming Star Nebula and the Tadpole Nebula, respectively, taken over 7 nights, under my Bortle 5/6 home sky.
      Total integration time: 18h 29m 00s.
      Here are the acquisition details:
      Mount: Sky-Watcher NEQ6 Pro
      Telescope: Tecnosky 80/480 APO FPL53 Triplet OWL Series
      Camera: D5300 astromodified
      Reducer/flattener: Tecnosky 4 elements, 0.8x
      Guide-scope: Artesky UltraGuide 60mm f/4
      Guide-camera: ZWO ASI 224MC
      2020/11/18: Number of subs/Exposure time: 41@240s + 1@300s. Notes: L-Pro filter, no Moon
      2020/11/21: Number of subs/Exposure time: 48@300s. Notes: L-Pro filter, Moon 46% illuminated
      2020/11/24: Number of subs/Exposure time: 48@300s. Notes: L-Pro filter, Moon 75% illuminated
      2020/12/07: Number of subs/Exposure time: 15@300s. Notes: L-Pro filter, no Moon
      2020/12/13: Number of subs/Exposure time: 22@300s. Notes: L-Pro filter, no Moon
      2021/01/10: Number of subs/Exposure time: 37@300s. Notes: L-Pro filter, no Moon
      2021/01/11: Number of subs/Exposure time: 18@300s. Notes: L-Pro filter, no Moon
      Total exposure time: 66540s = 18h 29m 00s.
      Pre and post-processing: PixInsight 1.8.8-7.

      This image was particularly hard to process, since there are many bright stars and stretching the nebulosity while taming the stars was quite difficult. I am sure I didn't manage it as well as I would have liked.
      Here's a link to the full resolution image: Flaming Star Nebula (IC 405) and Tadpole Nebula (IC 410)
      Thanks for looking!
      C&C welcome!
    • By endless-sky
      I would like to share my third image.
      I finally had a "lucky week", since my last session, December 18th. I managed 5 clear nights out of the past 6 (has to be a record, at least for me and my area) and I was able to finish a couple of projects I had started long ago and start a few new ones.
      This is M33, also known as the Triangulum Galaxy, taken over 10 nights, under my Bortle 5/6 home sky.
      Total integration time: 10h 14m 00s.
      Here are the acquisition details:
      Mount: Sky-Watcher NEQ6 Pro
      Telescope: Tecnosky 80/480 APO FPL53 Triplet OWL Series
      Camera: D5300 astromodified
      Reducer/flattener: Tecnosky 4 elements, 0.8x
      Guide-scope: Artesky UltraGuide 60mm f/4
      Guide-camera: ZWO ASI 224MC
      2020/11/08: Number of subs/Exposure time: 11@240s. Notes: L-Pro filter, no Moon
      2020/11/09: Number of subs/Exposure time: 10@240s. Notes: L-Pro filter, no Moon
      2020/11/20: Number of subs/Exposure time: 15@240s + 4@300s. Notes: L-Pro filter, Moon 30% illuminated
      2020/11/21: Number of subs/Exposure time: 22@300s. Notes: L-Pro filter, Moon 45% illuminated
      2020/11/24: Number of subs/Exposure time: 20@300s. Notes: L-Pro filter, Moon 75% illuminated
      2020/12/13: Number of subs/Exposure time: 12@300s. Notes: L-Pro filter, no Moon
      2020/12/14: Number of subs/Exposure time: 8@300s. Notes: L-Pro filter, no Moon
      2020/12/18: Number of subs/Exposure time: 6@300s. Notes: L-Pro filter, Moon 20% illuminated
      2021/01/10: Number of subs/Exposure time: 9@300s. Notes: L-Pro filter, no Moon
      2021/01/11: Number of subs/Exposure time: 15@300s. Notes: L-Pro filter, no Moon
      Total exposure time: 36840s = 10h 14m 00s.
      Pre and post-processing: PixInsight 1.8.8-7.

      Image was Drizzle Integrated and then cropped to original sensor size (6016x4016), without resampling. So, it appears as if taken ad double the focal length (768mm instead of 384mm). Image scale 1.04 arc-sec/pixel.
      Here's a link to the full resolution image: Triangulum Galaxy (M33)
      Thanks for looking!
      C&C welcome!
    • By cwinstone
      Hello, does anyone know if my imaging train looks correct, and if it does, why am i still getting these coma errors?
      Could it be incorrect backfocus? Searching the internet makes me think my dslr is 44mm, adding the t ring (even tried a 1mm spacer too) gets me to the required 55mm (assuming that's correct)
      I have no idea how to solve this and i feel like I'm just throwing money down the drain fighting this in vien. Help would be much appreciated.
      Skywacher Evostar 72ed
      Reducer rotator for 72ed (needs this for extra distance to achieve focus, the reducer and adapter alone doesn't allow for enough outwards travel)
      Reducer/corrector for ed72
      Canon eos 650d


    • By Uncertainty
      Hi, 
      I am a complete novice and got into astrophotography in December of last year, I had some decent success using only my Canon 450D and stock 18-55mm lens. 
      Since then I have purchased a telescope and mount (Sky-Watcher Startravel 102 and the AZGTe WiFi GOTO mount), which arrived yesterday. Luck would have it that the skies were clear last night and I had a go at imaging both M42 and M31 (also tried m45 tonight just to see if I could fiddle around with anything to solve it, but no luck), both of which came out pretty dissapointingly.
      If someone could tell my what is is that is wrong with the star shapes in the images, and potential fixes, it would be greatly appreciated, as I don't want to waste another clear night if it is an easy fix!
      I have read about coma, but also that refractors don't have this issue, so I am completely baffled.
       
      Thanks in advance.
       
      M45 at 1 second exposure, M42 at 20 seconds and M31 at 30 seconds.


×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.