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Real-time Observing with a DSLR

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#1 jgraham

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Posted 19 August 2013 - 03:26 PM

I've always used my cameras for observing, even with my teeny tiny CCDs that I experimented with back in the late 1980s. (I think that I've still got my original camera tucked away in storage somewhere). For real-time observing my trusty old Meade DSI's were by far the best since the software gave me a lot of capabilities for observing in real-time and the DSI IIIs have such nice chips, but these days I do most of my imaging with DSLRs (a modified Canon 550D). I've done a bit of real-time observing with my DSLR, but until now I haven't done much in the way of dedicated observing with it. My interest in observing with my DSLR was renewed while I was imaging NGC6522 and 6528 in/near Baade's window in Sagittarius. As I was grabbing the source images with my DSLR on my SN8 I was also looking for them with my Lightbridge 16 and while I could easily see NGC6522 I wasn't so sure about NGC 6528. Fortunately, the live source images coming from my DSLR make great finder charts and I was able to easily locate NGC 6528 on those and use that information to locate it in the Lightbridge and of course once I knew where to look the rest was easy. This got me interested in trying my DSLR in a dedicated observing session and with the bright moon in the sky this is a good time to do it. My first run was last night with the brilliant moon and lousy transparency and it did great! I started with M26 in Scutum using 30 second exposures and ISO 800 and working my way up through Aquila, across Sagitta and Cygnus, and ended looking through the crud at the Double Cluster in Perseus. I used Backyard EOS (BYEOS) to control my camera and to display the images in real-time and Starry Night Pro via EQMOD to control my scope from inside my house. The latest version of BYEOS includes some basic image processing controls (zoom and a simple form of curves), but I found the easiest thing to do was to just adjust the gain (ISO) and exposure settings. If I saw something particularly interesting it was nothing to switch to imaging mode by grabbing 16 source frames for later processing and then move on to the next target.

Soooo, to make a long story short (too late) I thought that this was very promising. What's particularly nice about using a modern DSLR for observing is that it provides access to a large, high quality array and a relatively low cost (I paid $495 for my 550D body from Amazon). The stock array works fine (I used mine stock for the first 18 months) but the modification just makes it that much better. I'll be making another run this evening, but at the moment I don't see why DSLRs can't be added to the list of cameras that are well suited for electronically assisted astronomy.

Just for yucks, this is the SN8 that I'm using for real-time DSLR observing.

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#2 Puck Ja

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Posted 19 August 2013 - 04:59 PM

John:

Nice setup! Sorry for the OT question. Where did you get that nice long counterweigth shaft for Atlas? Is it for old style (3/4" ID) weight? Thanks!

#3 jgraham

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Posted 19 August 2013 - 07:40 PM

My Atlas came with a counterweight shaft extension that screws onto the end of the stock shaft. And yeppers, that's the 3/4" shaft.

Heh, heh, the biggest problem that I have encountered so far using my DSLR for observing is that when I come across an interesting object there is a great temptation to stop and take a picture! :) To satisfy that urge I'll grab a few quick ones to process later.


#4 JimT

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Posted 19 August 2013 - 07:47 PM

Sweet set up. :waytogo:

#5 Dragon Man

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Posted 20 August 2013 - 08:38 AM

. . . but at the moment I don't see why DSLRs can't be added to the list of cameras that are well suited for electronically assisted astronomy.

No-one said they aren't.

There isn't actually a 'List' of cameras suited for this section. Just what people conceive to be accepted.

DSLR's have been used many times for Live Broadcasts on NightSkiesNetwork and gave great results.
Their only downfall is the length of exposure needed compared to so-called 'AstroVideo' cameras. But they do the same job.

If you go to the Main Index page of Cloudy Nights and go to the heading 'Video and Electronically Assisted Astronomy' you will see it says:
'This forum is dedicated to 'semi-live' electronically assisted viewing of astronomical events and targets. Discussed devices include (but are not limited to) the Collins I3, StellaCam, Mallincam and other 'semi-live' output devices'.

A DSLR with 'Live Preview' fits the bill nicely as for "electronically assisted viewing".

Any camera that allows observers to 'View' an object Live/Semi Live is acceptable.
It's only when it is used for Imaging that it gets debatable, as this isn't an Imaging section, but an 'electronically assisted viewing' section.
That even includes those simple electronic eyepieces even though no-one seems to use them any more.
http://jjmaden.tripo...130ate/id5.html

Well, that's my 1.9 cents worth (that's how much U.S. 2 cents is currently worth here) :lol:

:waytogo:

#6 jgraham

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Posted 20 August 2013 - 08:59 AM

Coolness. Isn't it great to have so many options? What a great hobby!

Heh, heh, even in my own mind I separate observing from imaging. I'm observing when I'm sitting at my control center looking at a fresh image on the screen with a magnifying glass deciding how to tweak the next image to show this or that better or having the scope slew to the next target in the background while I'm studying the image. When I image I set up the parameters, get the camera going, and either go outside and enjoy the view or go visit with the missus while the camera does it's thing. Sometimes I combine the two and sit there studying the images as they come in, particularly late at night when the house is quiet. The field of view of the DSLR is so large and at such a good resolution I often spend as much time looking at the background as I do the foreground. The new real-time curves added to BYEOS (which does not influence the saved images) is a big help with that.

I must be getting old... all of my computer monitors have magnifying glasses sitting next to them. :)

It is about to turn rainy here, but the next chance I get I'll grab some screen shots.

Fun stuff.

#7 Dragon Man

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Posted 20 August 2013 - 09:15 AM

Coolness. Isn't it great to have so many options? What a great hobby!

Yes John.

I would use my DSLR for Live viewing/broadcasting too, but it is only a Canon 350D which doesn't have Live View. :(

For my Live Viewing and broadcasting I switch between 2 Phillips Toucam's, a Samsung SCC-A2333 (SCB-4000), and a Mallincam Xtreme.

I also have an el-cheapo old Planetary camera and a Starlight Xpress SX MX-5C I want to try too.

Options, Options, we need more options :lol:

#8 jgraham

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Posted 20 August 2013 - 11:56 AM

More coolness. I started with a 350D many years ago and quickly upgraded to a 400D. I wish I could have gotten a 450D, which has one of the nicer DSLR chips, but I grabbed my 550D as they were close to being phased out. The chip in the 550D is so darned quite and clean it is a joy to use. I use my 350D for high-risk imaging (long duration time lapse imaging where there is a possibility it may get damaged) and my 400D is still my primary camera for nature photography. The 550D is my dedicated astronomical camera which is why I didn't mind having it modified with a Baader filter. This modification not only increases the red response but also gives a much better S/N in the red and in the overall image (the blue and green were already pretty good) and I think this makes a significant contribution to how clean the individual real-time images look.

#9 Lorence

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Posted 20 August 2013 - 02:06 PM

Any camera that allows observers to 'View' an object Live/Semi Live is acceptable. It's only when it is used for Imaging that it gets debatable, as this isn't an Imaging section, but an 'electronically assisted viewing section.


I'll raise the bar a notch by saying that many processing functions are no more than electronic filters.

I've been experimenting with MaximDL to process images from my Universe on the fly. I used to drop the Universe images directly into DeepSkyStacker Live then view as they were being stacked. Now I drop the images into Maxim which "Filters" each image then drops them into DSS Live to be viewed as they are being stacked.

I see no difference between sliding a mechanical filter in front of the camera or an electronic filter behind the camera.

It's sky to screen. With a propagation delay that is inherent in any deep sky near live viewing.

#10 donnie3

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Posted 20 August 2013 - 06:41 PM

jgraham, that sounds very interesting! I have a canon xsi and have not used it for over a year. I never thought of using it for just live views. what settings do you use when viewing (quality setting) I might just try this when I get a chance. thanks for writing about it. donnie

#11 jgraham

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Posted 20 August 2013 - 07:24 PM

That's an interesting question. I use Backyard EOS (BYEOS) to control my camera via a computer and you can change the quality settings through this software. What is significant about that is you can set it up to save the preview images in one format (JPEGs) and images in another (RAW). You can also set it up to save the preview images. For the real-time display is doesn't make a big difference which one you use, though JPEGs display a lot faster. BYEOS offers several features that are convenient for real-time observing such as a night vision mode, complete control over your camera, focusing tools, tools for centering and framing, histograms to guide you on setting your gain and exposure, and the latest version offers a simple and effective curves which comes in very handy to adjust the brightness and contrast under light polluted skies that tend to washout the background when you expose long enough to brighten the object. I observe under the red zone skies of my back yard so this can be a handy feature to have. Another feature that comes in very handy for real-time observing is Canon's in-camera noise reduction. This does a great job cleaning up the images making the one-at-a-time real-time images much nicer to look at. Furthermore, since we tend to use fairly short exposures while observing (30-60 seconds) the time penalty of using the noise reduction function isn't a problem, at least not for me.

#12 mpgxsvcd

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Posted 23 August 2013 - 09:14 AM

There is no reason why using a Canon camera with BYEOS isn’t considered electronically assisted observing. Of course there are other cameras that can do it but this method is quite good contrary to popular belief.

The biggest difference is that it is much harder to get an Ultra Fast scope to work well with the larger chip cameras. The smaller the chip in the camera the easier it is to reduce the focal ratio. That is why so many people claim that some cameras can image at much shorter durations. They are usually comparing a super fast scope with a not so fast scope.

Using a fast scope really is the key to real-time imaging. Most people will tell you that sensitivity is the key. In most cases you are lucky to get a 1-2 stop difference in sensitivity with comparable priced sensors. There really isn’t any “Magic” that can make a sensor more than 10 times as sensitive as some people have claimed.

It is relatively easy to reduce the focal ratio from F10.0 to F2.0 simply by adding a hyper star or stacked focal reducers. With a large chip camera like Full Frame or even APS-C you really need to have the right sized scope to work at those focal ratios with those cameras.

If you simply use a smaller chip then it is almost trivial to reduce the focal ratio.

What a lot of people don’t recognize though is that the larger chip cameras can simply use less of their sensor to capture a cropped region that still has the same sensitivity as the full sensor but less resolution.

Smaller scopes in cropped sensor mode with focal reducers can work very well even with larger sensor interchangeable lens cameras. You won’t believe how much better live view will be with a really fast scope.

The nice thing is that the large sensor cameras can work in both wide field full sensor size mode and cropped sensor mode. The smaller chip cameras can only work at their small sensor size and lower resolution.

All of the solutions are great for their individual strengths. I too am glad we have so many options. I just wish more people would accept that other cameras can be used in the exact same way that the smaller chip cameras are used.

#13 Dragon Man

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Posted 23 August 2013 - 11:04 AM

. . . I too am glad we have so many options. I just wish more people would accept that other cameras can be used in the exact same way that the smaller chip cameras are used.


I believe they are starting to Travis, which is good :waytogo:

#14 jgraham

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Posted 23 August 2013 - 11:34 AM

Ahah! The forecast for tonight is clear with good transparency. I'll see about grabbing some example screen shots. I also started a folder in my imaging directory called 'Observations'. Since you can set up BYEOS to save your preview images as JPEGs I can use this to store them. These come in real handy as a record of my observations (in addition to my notebook) and something to refer to if I want to go back and take a dedicated imaging set. I took a peek at my preview images from a couple of nights ago and they looked pretty good. It'll be interesting to see how this work when it is actually clear. :)

#15 mpgxsvcd

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Posted 23 August 2013 - 11:49 AM

. . . I too am glad we have so many options. I just wish more people would accept that other cameras can be used in the exact same way that the smaller chip cameras are used.


I believe they are starting to Travis, which is good :waytogo:


I agree with that. I started in this forum almost 2 years ago. It was extremely one sided back then. Now we have so many options being presented. They are not always accepted but not all of them merit being accepted.

The nice thing is that now we have viable options in pretty much any price range and options that work with pretty much any configuration.

Two years ago there were not any HDMI or other high resolution options available for consumers. Now there are several.

We didn't have many options for doing near real time processing and now there are some really promising ones.

I love the fact that we are still using the same style of telescopes and mounts that have been used in past generations. However, our imaging devices have improved drastically in the last two years despite the actual sensors remaining almost the same. What has changed is the processing power behind them.

#16 Dom543

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Posted 29 August 2013 - 09:50 PM

This is an interesting thread.

Jgraham, do you know what binning BYEOS is using for real-time viewing? Or can you set the binning? How do these real-time views compare to the live-view on the screen of the camera? I assume that that is also a heavily binned image.

Thanks,
--Dom

#17 ccs_hello

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Posted 29 August 2013 - 10:32 PM

I think many of us own Canon DSLRs for astro purposes.
My post in DSLR forum showed some recent C's DSLR models when using Magic Lantern firmware (some are alpha and some are production releases) should show promises
as they have desirable features as some selected Panny's mirrorless bodies do.

Clear Skies!

ccs_hello

#18 jgraham

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Posted 29 August 2013 - 10:32 PM

That's an interesting question. You can adjust the image scale to anything you want so you can easily zoom in and out, but I don't know what model it uses when the scale is not 1:1. I basically use the still frames shown by BYEOS for observing. The actual live view function is used primarily for focusing and/or framing bright targets.

I 'discovered' another really handy feature of the newest version of BYEOS. You can set it to save the images to your computer, camera, or both. As I type this I'm using my camera to observe and record a set of variable stars in Cepheus. For these images I remove my light pollution filter since I use the green channel for my photometric data. However, without my light pollution filter the colors are really whacked. To fix this I take a reference image of a fairly blank region in the area that I'll be observing and save this image to my camera. I then use this as my camera's reference image for a custom white balance. Voila! From this point on the colors look great without any hint of light pollution.

A couple of nights go I grabbed a set of screen shots that I'll post as soon as I get a chance. The weather here is about to turn wet, so it'll give me something to do.

The more I use my DSLR for observing the more I like it! With the automatic noise reduction turned on the single still frames are clean and clear. This combined with the adjustable scale and my magnifying glass makes it very easy to study each image. And now I've got the real-time color balance under control as well. Very nice.

#19 Whichwayisnorth

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Posted 30 August 2013 - 08:57 PM

When I do outreach I bring my laptop, my T1i, and plenty of battery power. Then I use the camera either in live mode for things like moon and planets or I take short exposures and stack them using DSS live stacking to show more distant objects. Draws quite the crowd.

#20 runner70

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Posted 31 August 2013 - 10:14 PM

Any advice on using a Canon Rebel for "real-time" observing? What is the compare/contrast of this dslr to the Samsung 4000? At some point, I'd like to combine image capture with image intensification.

#21 jgraham

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Posted 31 August 2013 - 10:22 PM

I just posted a set of example screen shots. Like any new technique it takes a little getting used to. For example, I startec with video and webcams, moved to using CCDs for several years, now I am using my Canon T2i. A DSLR is a different twist, but I am really enjoying the large, high quality chip in conjunction with the Backyard EOS software.

#22 Moromete

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Posted 09 September 2013 - 07:52 AM

John, since I'm using an unmodified Canon 550D (T2i) I thought it would be interesting to see a comparison between ISO 1600 and ISO6400 on same DSO, something I haven't found on net yet.

I was curious to see how bad will look M27 at ISO 6400.

Below is a single image of M27 at ISO 6400 of 120s. No processing, no crop. I used only in-camera Dark Frame Substraction on Auto, Noise Reduction on Low.

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#23 Moromete

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Posted 09 September 2013 - 07:55 AM

Same image at ISO 1600 of 482s (so 4 times longer than ISO 6400 to gather the same ammount of photons).

No processing, no crop. I used only in-camera Dark Frame Substraction on Auto, Noise Reduction on Low.

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#24 Dragon Man

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Posted 09 September 2013 - 08:49 AM

Micromete,
The first image has better colour balance, but more noise.
Not that a bit of noise matters when doing near-live viewing or broadcasting.

To me, the first image is the most pleasing.

#25 mattflastro

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Posted 09 September 2013 - 10:00 AM

Same image at ISO 1600 of 482s (so 4 times longer than ISO 6400 to gather the same ammount of photons).

No processing, no crop. I used only in-camera Dark Frame Substraction on Auto, Noise Reduction on Low.

if these images are even the smallest size your 550 can produce, they've been either cropped or scaled down to fit the CN size requirements.
Since it appears the image scale is different in each image, they've probably been scaled down to fit CN .
I'd be interested to see a comparison of the original scale images, no scaling down.
Just a corner of each image would suffice.






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