Tonight I thought I would try my hand at some short exposure deep sky photography using my 8" SCT, DSLR in prime foucs & an app called DSLR Controller (similar functionality to EOS utility & Backyard EOS....
Total Fail.......
Basic problem is that I can't even see the brightest of stars to obtain focus prior to attempting to slew to a nebula. The bright stars are plain as day, even with the naked eye but, damned if I can see them on live view, even using 10x magnification for focus assistance.
Tried a multitude of different ISO settings up to 6400, had the exposure set for 30 sec exposure & nada, nothing in the live view. Slew to Saturn.. bright as, mars - ditto, back to a bright star... nothing...
Tried a few exposures just for stamps, yep.. captured a perfect donut.. so the star is there, just nowhere near focus... can't focus if I can't see it...
So, how the hell do I do this??
Any assistance, advice, anything really that might help me sort this out would be deeply appreciated...
Well more information is required to help us help you. Like do you understand the backspacing requirement for that scope? Do you have a camera adaptor? Etc
Hello Carlton,
Try to narrow down the problem. You mentioned that you can't see the stars even using live view at 10x. What if you try a camera lens, albeit even at lower focal length, with the control software, can you then focus a clear image in live view on the camera screen or on the screen (if it exists) in the software ? If you can thus get a clear image to focus then look to the telescope and its interface for the issue, spacing , focus range etc. if you can't get a clear focusable image with the lens, then your issue is with the camera side of things.
Can you see any details on Moon?
Maybe your camera is way out of focus.. making the starlight spread too much and therefore not easily visible/identifiable?
If you can see planets, use them initially to get your focus while you're learning your setup. They are far enough away to be considered at infinite focus. If you can't get a really clean focus on the planets then maybe it is to do with back focus etc. as has been mentioned. Once you have planets in focus, slew to a bright star and see how it looks.
I might do a mini hijack here because my question might help you too.
I don't have live view on my 5d but I see it mentioned a lot. I take exposures then review them when focusing. So my question is, isn't live veiw the camera holding the mirror up, then taking multiple exposures in the same way a video camera works ? If that is the case and it has a reasonable refresh rate, you would only be able to see the absolute brightest stars. When I'm setting up, if I've forgotten to switch to bulb and I take a very short exposure, I generally get very little on my screen. Is this how it works ?
Yes.. and there is enough light (provided the focus is close) to see bright stars on the screen and even use Bahtinov mask for example to obtain correct focus.
Yes.. and there is enough light (provided the focus is close) to see bright stars on the screen and even use Bahtinov mask for example to obtain correct focus.
Ok cool. Thanks for that.
It show be mentioned then that prime focus on a camera is a long way from focus on an eye piece. If you can at least see planets then they are a good place to learn the approximate turns on your focuser to get it close enough that the light isn't too dispersed to see the star.
The camera is an EOS 1100d; I have an adapter that I can attach a nosepiece to & fit the camera to my 8"SCT sans lenses - ie: Prime focus.
I can & have taken photos of planets & the moon; I have no trouble at all seeing them through live view on both the back of the camera, on my computer or in the app (on an android tablet) that I am using. If I attempt to take still images of planets I find that they are rarely in tight focus due to the seeing conditions up here in Cairns... the visual seeing can be quite reasonable but, even then you can see the planets shimmering, this translates to just not quite in focus in the camera.
After trying to get a starfield & nebula in frame last night, (Swan Nebula) which, I could clearly see in an eye piece both with & without a UHC filter, I found that I simply could not see anything in live view, nothing, not even a hint of light. Took the shot anyway, which did result in some fuzzy light but, nothing in focus.
Slewed to a bright star, tried again - again, nothing in liveview. Took the shot anyway (30 sec exposure at ISO 800) and got the donut shape of an out of focus star but, still cannot see anything in the live view image. Fiddled with focus & kept taking shots, got a smaller donut but, decided this was a very hit & miss way to attempt to focus & gave up on that method.
Slewed to Saturn, achieved reasonable focus but, again could see the planet shimmering in the live view image, still had plenty of focus range left in either direction (I know this because I could get the image to move in & out of focus in both directions), slewed back to nebula, still could see nothing in live view, took a shot anyway at 30 sec, ISO 800. Got some stars but, no nebula so, figured that my FOV was probably slight off the nebula. Looked in my finder scope (60mm that takes 1.25 eyepieces & has a helical focuser), couldn't find the nebula, clouds rolled in & I gave up in frustration.
Slightly different subject but, related. Attempted some video of mars too, image waaaay to bright. Need to look up more about adjusting 'something' too avoid the overly bright video images too. But, I'll read up on that later.
Moon & planet shots taken recently posted below, the saturn shot is a single exposure, the Jupiter shot is multiple exposures stacked in Registax but, the seeing conditions were not perfect & the focus is a bit off on the planet shots (first attempt at prime focus). As you will see, the moon shots are fairly tight for focus.
I understand that perhaps I am not in focus when trying to see the stars through live view but, if I use a planet to do initial focus (which I can without drama), how can I be sure that I have the desired object (nebula in this case) in my FOV when I slew back?
Well... this is a mystery then... you should be able to see brighter stars in Live view.
I can - using either my 60D or 450D.
Try to see if you have a star in your optical viewer (camera eyepiece) before activating live view.
Try to set ISO to AUTO.
BTW, does liveview work at all on terestrial objects at daylight?
Ok. Sounds like you're most of the way there. I'll discribe what happens with my set up although it's likely you have darker skies than I have and you're using an 8" SCT where as mine is a 5".
Yes continuiosly taking exposures to reduce the size of the donut is a crude way to get focus, it's exactly what I do or at least how I learnt my setup. I haven't been imagining long ( 9 months or so ) but it didn't take long to learn roughly how far to turn my focuser and in which direction from my 21mm eye piece to prime focus in the camera. This only gets you close though. I then fit my bahtinov mask ( home made for about $5 ). I then take a shot while pointing at a bright star. I keep doing this until the defraction lines are right then the focus part is done.
One key thing to keep in mind though is that your goto might not be 100% accurate. What I normally do is goto the object with my eye piece in and fine tune it to be spot on. I then save the object as a user object. I then slew away and goto my user object to make sure it is framed exactly where I want it to be. Only then do I fit the camera and go through the focusing process. i generally use the brightest star near the object I'm planning on imaging.
Your darker skies and extra apature give you the advantage of being able to see the nebula you want in an eyepiece , I can't. I have to look for star patterns to know I'm where I need to be.
When I start taking my exposures, unless it's super bright like Orions nebula, I actually can see very little in my review. Even when I load them on my computer, in each single sub, I don't see much apart from stars. It's only when is stack them I can actually see what I've taken.
To give you an idea, the first pic is a single sub of the eagle nebula @ iso3200 x 22 seconds. Now if you can imagine seeing that on a small screen on the back of the camera, it's not much to " see ". Put 500 or so of them together and process it and you get the second pic.
I guess what I'm trying to say is don't expect to " see " too much with live view.
This is obviously on equipment that is nowhere near as capable as yours and with skies that are so light polluted that if it's cloudy, I can literally read outside at night.
Take your time to get focus, even if it means taking lots of shots " reducing the size of the donut " then don't necessarily be surprised if you still can't " see " things in live view.
Well... this is a mystery then... you should be able to see brighter stars in Live view.
I can - using either my 60D or 450D.
Try to see if you have a star in your optical viewer (camera eyepiece) before activating live view.
Try to set ISO to AUTO.
BTW, does liveview work at all on terestrial objects at daylight?
Yes, live view works on terestrial objects in daylight.
Quote:
Originally Posted by RyanJones
Ok. Sounds like you're most of the way there. I'll discribe what happens with my set up although it's likely you have darker skies than I have and you're using an 8" SCT where as mine is a 5".
Yes continuiosly taking exposures to reduce the size of the donut is a crude way to get focus, it's exactly what I do or at least how I learnt my setup. I haven't been imagining long ( 9 months or so ) but it didn't take long to learn roughly how far to turn my focuser and in which direction from my 21mm eye piece to prime focus in the camera. This only gets you close though. I then fit my bahtinov mask ( home made for about $5 ). I then take a shot while pointing at a bright star. I keep doing this until the defraction lines are right then the focus part is done.
One key thing to keep in mind though is that your goto might not be 100% accurate. What I normally do is goto the object with my eye piece in and fine tune it to be spot on. I then save the object as a user object. I then slew away and goto my user object to make sure it is framed exactly where I want it to be. Only then do I fit the camera and go through the focusing process. i generally use the brightest star near the object I'm planning on imaging.
Your darker skies and extra apature give you the advantage of being able to see the nebula you want in an eyepiece , I can't. I have to look for star patterns to know I'm where I need to be.
When I start taking my exposures, unless it's super bright like Orions nebula, I actually can see very little in my review. Even when I load them on my computer, in each single sub, I don't see much apart from stars. It's only when is stack them I can actually see what I've taken.
Okay, thanks heaps for that; this gives me a much better understanding of what I will or won't see in live view, I presume even if I have it hooked up to the computer or tablet, I still won't see anything of substance. I don't yet have a Batinov mask but, it is on my wishlist... currently upgrading eyepieces but, will definitely get one in the not too distant future.
Quote:
Originally Posted by RyanJones
To give you an idea, the first pic is a single sub of the eagle nebula @ iso3200 x 22 seconds. Now if you can imagine seeing that on a small screen on the back of the camera, it's not much to " see ". Put 500 or so of them together and process it and you get the second pic.
I guess what I'm trying to say is don't expect to " see " too much with live view.
This is obviously on equipment that is nowhere near as capable as yours and with skies that are so light polluted that if it's cloudy, I can literally read outside at night.
Take your time to get focus, even if it means taking lots of shots " reducing the size of the donut " then don't necessarily be surprised if you still can't " see " things in live view.
Have you had any better success in seeing anything on live view if connected to a computer or tablet where you get a better screen size?
Quote:
Originally Posted by RyanJones
Sorry, it would only let me upload one pics at a time. This is the final one.
Okay, this really gives me hope that I am in fact on the right track, I had just expected to see something in live view, at least a bright star.
I haven't hooked my camera up to a laptop and my camera is the first of the 5D's so it doesn't have live view so i couldn't tell you. I would expect that you would be able to see some of the brightest stars but as Bojan confirmed for me earlier, live view is effectively lots of super shot exposures. I'd imagine that would limit what you will see in it to only the brightest objects. Hence why you have no problem with the moon or planets. Given that my single exposure I posted was 22sec, I wouldn't have expected to see anything at all in a live view that has a refresh rate of maybe 10th of a second or less. Remember the human eye has an approximate refresh rate of around 24 frames per second so anything that appears in the screen as smooth motion when you move it will effectively be taking 24 or more frames per second. That's a really short exposure.
Please however understand that my input is not based on experience with your exact equipment or seeing conditions. I'm just piecing together my experience with my lesser equipment and my understanding of how live view works. I am happy to be corrected by someone that knows better than I or has experience with your particular setup.
I use Bahtinov masks on all of my scopes because the eye cannot be trusted. A Duncan Mask works as well on SCTs but mainly for situations where your using a Barlow.
Your experience & explanations have been invaluable; when I get some more time I will get out & play some more. Your information has given me the confidence that I can indeed get there with the equipment I have, I just need to persevere & experiment more until I get there.
Now considering what to use to make an easy to see mark on my focuser knob so I can learn how many turns from eyepiece focus to camera focus.
How did you make your own Bahtinov mask?
Cheers
Carlton
Quote:
Originally Posted by RyanJones
I haven't hooked my camera up to a laptop and my camera is the first of the 5D's so it doesn't have live view so i couldn't tell you. I would expect that you would be able to see some of the brightest stars but as Bojan confirmed for me earlier, live view is effectively lots of super shot exposures. I'd imagine that would limit what you will see in it to only the brightest objects. Hence why you have no problem with the moon or planets. Given that my single exposure I posted was 22sec, I wouldn't have expected to see anything at all in a live view that has a refresh rate of maybe 10th of a second or less. Remember the human eye has an approximate refresh rate of around 24 frames per second so anything that appears in the screen as smooth motion when you move it will effectively be taking 24 or more frames per second. That's a really short exposure.
Please however understand that my input is not based on experience with your exact equipment or seeing conditions. I'm just piecing together my experience with my lesser equipment and my understanding of how live view works. I am happy to be corrected by someone that knows better than I or has experience with your particular setup.
You're more than welcome. Feel free to PM me if you have any other questions and I'm more than happy to help where I can.
Re: Bahtinov mask. I printed the design from a PDF I found online. ( there's quite a few out there if you google it ) I got a sheet of plastic type cardboard from a craft shop so it doesn't get affected by moisture. Basically just taped the design to the sheet and cut it out with a steel ruler and craft knife. I won't lie, it took a while but it works
Incidentally I used the same material to make a dew shield / light shield.
What a frustrating night that must have been. It won't be the last of the sort
While you're still setting up there's no reason for limiting to ISO 800. Just crank up the ISO as far as to see more in live view? Mine can do ISO 24000, I think 1100D can do ISO 6400? Still more light than with 800.
That won't give you outlines of the nebulae, either, but hopefully more stars for focussing, orientation and framing of the desired object. It's great that you have your laptop with you outside. So after importing your first high-ISO-testphoto you can push up the rgb-levels to see even more and maybe adjust your framing.
Just don't forget to set your ISO back to 800/1600.
To reduce noise you a) disable live view during the actual photo session so the camera doesn't produce so much heat b) AND you can turn on "noise reduction" in the camera settings on high ISO and high exposure. c) OR take "darks" at the end of the session with the dust cap on the scope and let a stacking software subtract the noise pixels from the stacked image.
Another thing is when attaching a camera it can pull your scope off line a bit, my 700d would pull the mak I had down at the back end tilting it up enough to pull a star out of live view. Make sure your finder is spot on to assist any movement caused by adding weight. I could get stars with an ep and would track, when I put the camera on prime it would be gone and would have to go back using my finder scope. Then live view it to centre and take a pic to check zoom, at ISO 3200 for a few seconds is enough to capture the star. Using a bahtinov mask and live view on 10x zoom can cut the need to take shots but I did just to be sure.
I picked up my mask off ebay for 12$ and works a treat, done on a 3D printer from a guy in Melbourne. Will be buying another from him.
