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mradam67
2011-Nov-03, 06:00 AM
Hi All,

First time post so please be gentle :)

Ok so im after some help with my astrophotography - I've been at it for about 6 months now (when i bought my first scope)

Loving it and been able to get some awesome pics, I have a dobs 6" telescope, a nikon D3100, a barolw and also the attachment that goes from the barlow to the nikon.

Im able to shoot pics of the moon and just recently got a pretty cool picture of Jupiter but whenever i try to shoot the stars they're always just black and dont show anything (even if i set it to bulb)

Am i doing something wrong or do i not have the right equipment to be able to do this.. Im fairly new to this astronomy / astrophotography business so any help would be appriciated.

Im not sure if i can post pics of what i've taken yet as its only my first post

Thanks all and love what i've seen of the forums so far!

Adam

Hornblower
2011-Nov-03, 03:22 PM
Hi All,

First time post so please be gentle :)

Ok so im after some help with my astrophotography - I've been at it for about 6 months now (when i bought my first scope)

Loving it and been able to get some awesome pics, I have a dobs 6" telescope, a nikon D3100, a barolw and also the attachment that goes from the barlow to the nikon.

Im able to shoot pics of the moon and just recently got a pretty cool picture of Jupiter but whenever i try to shoot the stars they're always just black and dont show anything (even if i set it to bulb)

Am i doing something wrong or do i not have the right equipment to be able to do this.. Im fairly new to this astronomy / astrophotography business so any help would be appriciated.

Im not sure if i can post pics of what i've taken yet as its only my first post

Thanks all and love what i've seen of the forums so far!

AdamIt appears that you do not have the right equipment for anything other than snapshots of bright objects. A plain Dob is unguided, which means it will not track the object during a time exposure. A bright star will make a visible streak as it drifts across the field of view during the exposure.

I would suggest finding an astronomy club in your area and picking their brains about equipment and techniques.

RickJ
2011-Nov-03, 06:09 PM
As Hornblower says, attending a club's meetings and star parties is by far the best advice I can think of. You'll get far more out of all aspects of the hobby, not just photography.

Except for the moon you will need a driven scope as Hornblower says to get much detail in Jupiter and anything but streaks for stars.

Unfortunately, while a simple, inexpensive drive platform can be placed under your dob for driven planetary images what's needed for stars THROUGH the telescope gets expensive fast. Google Poncet table and Poncet platform or see ads in the astronomy magazines for information on these drive platforms. You can get star fields ith your camera alone however. Again the platform will help, just set the camera on it. But you can get good starfields with the camera on a tripod and 30 second exposures with a 15mm or so lens, 15 seconds with a 30mm lens etc. ASA 800 or so. Depends on when noise begins to be a problem. Not using a DSLR I'm not familiar with them.

A good book like Covington's Astrophotography for the Amateur will give you the basics. This book covers the basics for many types of astrophotography. The basics are the same for all. But once you get past them you need to know specifics for what you are trying to do. So after you have grasped what this book is telling you get one specific to DSLR work. Covington has one as does Jerry Lodriguss, in fact Jerry has several on the subject from beginner to advanced. (expect lots of damage to bank account as you move up).

I started nearly 60 years ago with film of course. I built a barn door platform for a simple $15 garage sale SLR (EXA) with a broken shutter. It would open but only closed when you wound the film. I just capped the lens to end the exposure. I got tired of turning the drive screw manually and rigged a wind up alarm clock mechanism to turn the screw at the correct rate and had a drive platform for less than $5. I added a way to guide it and got it to work with a 400mm lens (only once successfully) but it worked great at 135mm all the time. This allowed me to image many very faint large objects that cover several degrees of the sky such as Barnard's loop, the Cepheus OB1 Association and many others. Yes you have to have a very good knowledge of the sky for this hobby. A crude drive (something like a Poncet platform) was used for planetary work with my home made 6" f/12. I did a lot of sun work with it as well (no drive needed as the sun provides too much light rather than not enough.

Over the years I advanced as my knowledge and budget allowed. Now I'm retired, have my own observatory that runs automatically while I sleep collecting data for several observatories I work with around the world as well as my own pictures you see posted here of very distant objects barely within the grasp of the 200" when I was shooting very basic stuff with that barn door platform.

A club will likely have folks who can give you hands on help that will be far more useful than reading it in a book as a book often leaves you "Lost in Space" without the ability to ask questions nor can it point and say "Here's your mistake" like an experienced amateur can. Even if you must drive and stay over night it will be well worth it.

Back when I started the nearest club was 4 hours away. I learned more at their star party in one night than I'd managed in many years on my own. Blew my budget but saved far more in the long run. Later we formed our own club. It was the blind leading the blind but still we made far more progress than we did alone and had a lot more fun while doing it. One of the club's founders went on to be the designer of Deep Impact that punched a hole in a comet a few years ago and a principal behind LCROSS. Another early member headed the optics design team for the two 8 meter Gemini telescopes and is now heading the overall design team of The Thirty Meter Telescope. Many others went on to be physicists and professional astronomers. For being blind back then we did surprisingly well. The knowledge in a good club is the greatest asset there is for a beginner. The more you jump in and do rather than sit on the sidelines, the more you will get out of it.

Rick

mradam67
2011-Nov-03, 10:29 PM
Thanks for everyones help :)

I had a look and theres some astronomy clubs in Melbourne so i'll make some calls..

I've attached a few pictures I've taken - I've got some awesome pics of the moon and i just got my first shot Jupiter, can't wait for Saturn to come back up!

RickJ
2011-Nov-04, 04:21 AM
A couple hints for improving your images even with your limited gear.

First image only when the target is high in the sky. Your images show severe color fringing on Jupiter and some on the moon. This means the three channels aren't lined up thus blurring detail. Though in the case of Jupiter the detail is also lost due to the earth's rotation during the exposure. It may be convenient to image when the object is low but this is what causes the color fringes. The earth's atmosphere bends blue and red light differently acting like a prism. Try to shoot when the object is near the meridian and thus as high in the sky is possible. This reduces the amount of atmosphere you must look through and thus the prism effect.

If your camera supports AVI files, even if only 8 bit, shoot as long of a "movie" as possible without a drive. A drive will allow longer movies. Then use the free Registax program to find, align and stack the best frames in the movie. This creates a very low noise image that allows strong image processing to be applied without the image turning to a gaudy mess. A single image has too much noise for this type of processing. For planets a low light web cam is better as it takes faster and more images. Faster means you better freeze seeing so individual frames are sharper to begin with. It is an art to then process the image for best results. When learned you will bring out more detail than you saw at one time in the eyepiece.

When processing a single frame always use RAW data and save in JPG mode only as a very last step. Even then keep a lossless version at full bit depth for additional processing in the future. As this might indicate, taking the image is by far the easiest part. The real work is in the processing. Minor color fringing can be removed by separating the colors and aligning the three color layers then recombining. Not as good as avoiding the fringing in the first place but helps. Your moon shots suffer from poor contrast due to the wide range of intensities across the moon's surface from the terminator to the near fully lit portions of the moon. Here working in raw mode will allow you to adjust the full intensity range across the limited range of a monitor. I had to work with the already limited JPG but was still able to improve contrast and color. I did nothing to the color, it just happened when the image was more properly stretched across a monitors range.

I've also attached a calibration strip. You monitor should be adjusted to show each of the 17 intensity levels. The middle is easy but some monitors strain at the low and or high ends. This is less of a problem for newer monitors.

Rick

mill111
2011-Nov-05, 10:24 PM
Hi Adam.

Try to shoot a pic of Orion but without the barlow.
The problem with a dob is the infocus, most of the time the mirror has to be moved up into the tube to be able to focus.
Focus with the barlow works but it makes it harder to make any lenght of exposure.
Depending on where in Melbourne you live i could come and help you with your dob.

Martin.

gadieid
2011-Nov-07, 08:03 AM
Hi Adam
I will add some tips
For the moon you can avoid all colors problem by taking B&W photos. You shall measure the light from the terminator line between light and shadow in spot mode, otherwise the photo will be over or under exposed.
Shooting stars is much difficult and usually give unsatisfactory results. Without a guided scope you can try M45. It is a large and quite bright object.
The Barlow enable you to focus but you probably lose sharpness and contrast by using it. Try avoiding it. It is better to shoot smaller images but with more contrast.
Gadi

mradam67
2011-Nov-08, 01:45 AM
Thanks Guys,

I'll have to wait until the weather clears up a bit.. Its horrible in Melbourne at the moment.
Rick, my DSRL does shoot movies so i'll try that with Jupiter :)
Also Martin - Can you move the mirror up the Tube, i thought it was attached down the bottom of it??
This is the one i have: http://www.ozscopes.com.au/dobsonian-telescope-saxon-6inch.html