When I'm not building Iron Man, I build my space observatory.

Sandbagger

Sr Member
When you say you need 6m focal length on the new CF open frame 'scope to zoom in far enough, does that mean you can literally push that front (collimator? lens? mirror?) end out of the dome hatch? Or buy screw-on extension frames or something? Or did you just mean you were limited to 2.7m regardless of what the subject needed?
The focal length is a calculation. Based on the distance of the light travel once entering the telescope and it's mirror (aperture) diameter. Hard to explain. The light comes into the scope, travels down to the primary mirror, is reflected back up the scope to the secondary mirror, then reflected once again back down through a hole in the centre of the primary mirror to the camera behind the scope. Therefore the telescope's native focal length is just under 2500mm. Now put in a 2.5x Barlow lens you have effectively doubled it. It's all about getting the image scale up so you can fill more of the chip with a small object like a planet with a small angular distance.

What's the difference between your star camera and the planet camera? Do they have built-in sensitivity settings or fixed lenses or something? What's the advantage of those over a DSLR mount?
My deep space camera is a CCD still camera, which is cooled with a peltier cooler and fan behind the chip to keep it 30 degrees below ambient air temp. It takes exposures as long as I like. Typically my exposures are 5 to ten minutes each and I take 20 or 30 exposures of a target for stacking. The advantage is that a CCD imaging chip over a CMOS chip in a DSLR is that it is less affected by digital noise plus it is cooled, reducing noise.

My planetary camera is a high-quality video camera, (typically seen in medical faculties to photograph biopsies etc.
which takes up to 60 frames per second. 3 minutes of video on a planet may yield thousands of fames to be sorted and stacked to produce a final image.

Is the steel I-beam construction sufficient to deaden your/vehicles' vibrations? Is the whole thing (or just the scope mount) on an isolation pad? I'm assuming even though you're stacking to avoid thermal noise, that each shot is probably about 30 seconds to get the hours of exposure time necessary, but if you mentioned vibration isolation I must've missed it. Maybe it gets averaged out by the stacking software, but I would think at those focal lengths it'd get pretty important.
I don't really go dancing around the telescope once it's imaging. Late at night vehicle movement is minimal to zero. But yes, the entire telescope mount sits on a pier that is full of rio, concrete and isolated from the main building, sitting on a cubic metre of concrete underground that is also isolated from the main slab via 25mm thick polystyrene foam.



Oh, and did you ever get the video for the BH&G segment? I saw the other two interview links, but wanted to see that one in particular.
I did. It's on the front page of my website. www.asignobservatoryii.com
 

RobTC

Member
The focal length is a calculation. Based on the distance of the light travel once entering the telescope and it's mirror (aperture) diameter. Hard to explain. The light comes into the scope, travels down to the primary mirror, is reflected back up the scope to the secondary mirror, then reflected once again back down through a hole in the centre of the primary mirror to the camera behind the scope. Therefore the telescope's native focal length is just under 2500mm. Now put in a 2.5x Barlow lens you have effectively doubled it. It's all about getting the image scale up so you can fill more of the chip with a small object like a planet with a small angular distance.
Oh, fair. It sounded like it was a physical adjustment rather than an optical one, for some reason.

My deep space camera is a CCD still camera, which is cooled with a peltier cooler and fan behind the chip to keep it 30 degrees below ambient air temp. It takes exposures as long as I like. Typically my exposures are 5 to ten minutes each and I take 20 or 30 exposures of a target for stacking. The advantage is that a CCD imaging chip over a CMOS chip in a DSLR is that it is less affected by digital noise plus it is cooled, reducing noise.
Yeah, that's a pretty hefty advantage there. Very nice. I wonder if long exposure photographers have figured out a way to use those things yet.

My planetary camera is a high-quality video camera, (typically seen in medical faculties to photograph biopsies etc.
which takes up to 60 frames per second. 3 minutes of video on a planet may yield thousands of fames to be sorted and stacked to produce a final image.
That's ingenious. Take a stationary video and stack it on itself! Love it. :thumbsup

I don't really go dancing around the telescope once it's imaging. Late at night vehicle movement is minimal to zero. But yes, the entire telescope mount sits on a pier that is full of rio, concrete and isolated from the main building, sitting on a cubic metre of concrete underground that is also isolated from the main slab via 25mm thick polystyrene foam.
Nice! It's superb construction, start to finish.

I did. It's on the front page of my website. www.asignobservatoryii.com
Oh, cool! Shame they banged on about that guy's cars for so long, but seeing the manually turning dome was fun!
 

Sandbagger

Sr Member
That's ingenious. Take a stationary video and stack it on itself! Love it. :thumbsup

Oh, cool! Shame they banged on about that guy's cars for so long, but seeing the manually turning dome was fun!
Well, planets like Jupiter actually do a full rotation in ten hours compared to our tiny earth doing it in 24. There's quite a bit of rotation in three minutes, so a short video of 3 minutes yielding a few thousand frames to stack is plenty!

Would you believe the BH&G film crew spent four and a half hours filming here?
 

Sandbagger

Sr Member
Six hours exposure of M78 reflection nebula in the Orion Molecular Cloud Complex, about 1,600 light years from Canberra.

QCvvye9.jpg
 

TKAmaterasu

Member
Oh wow, that's so pretty! So when you say six hour exposure, do you mean you leave the camera there and it just takes shots or something?


Sent from my iPhone using Tapatalk
 

Sandbagger

Sr Member
Stacked and processed 12 x 15 minute exposures, (3 hours total exposure) flats and darks subtracted. I thought the single frame last night was nice, but perhaps a little over-saturated. Whilst I like the extra dramatic feel to it, this one is far more natural. Detail is better too. Pretty happy with this one.

The Carina Nebula is a large, complex area of bright and dark nebulosity in the constellation Carina, and is located in the Carina–Sagittarius Arm. The nebula lies at an estimated distance between 6,500 and 10,000 light-years from Earth and approximately 480 light years across. To put that in perspective, the sun is about 8 light minutes away from Earth and our nearest star, Alpha Centauri, (one of the pointer stars near the Southern Cross) is just under five light years from Earth. Or about 95,000 years in a rocket ship.

C4JcJ8f.jpg


Just before the big camera got going on the Carina Nebula through the telescope, I piggybacked my little DSLR on top of the scope and used a standard crappy 18-55 kit lens to try for a widefield of the region using the telescope to track it. Stacking 61 images of 3 minutes each, the resulting image shows a slice of our milky way not far above the Southern Cross. You can clearly see the Great Carina Nebula and some open clusters of stars. As you can see, the rest of the mist is made of stars, gas, dust and needs a good vacuum.

RrpPGBM.jpg
 

Attachments

Sandbagger

Sr Member
Stacked and processed 12 x 15 minute exposures, (3 hours total exposure) flats and darks subtracted. I thought the single frame last night was nice, but perhaps a little over-saturated. Whilst I like the extra dramatic feel to it, this one is far more natural. Detail is better too. Pretty happy with this one.

The Carina Nebula is a large, complex area of bright and dark nebulosity in the constellation Carina, and is located in the Carina–Sagittarius Arm. The nebula lies at an estimated distance between 6,500 and 10,000 light-years from Earth and approximately 480 light years across. To put that in perspective, the sun is about 8 light minutes away from Earth and our nearest star, Alpha Centauri, (one of the pointer stars near the Southern Cross) is just under five light years from Earth. Or about 95,000 years in a rocket ship.

C4JcJ8f.jpg


Just before the big camera got going on the Carina Nebula through the telescope, I piggybacked my little DSLR on top of the scope and used a standard crappy 18-55 kit lens to try for a widefield of the region using the telescope to track it. Stacking 61 images of 3 minutes each, the resulting image shows a slice of our milky way not far above the Southern Cross. You can clearly see the Great Carina Nebula and some open clusters of stars. As you can see, the rest of the mist is made of stars, gas, dust and needs a good vacuum.

RrpPGBM.jpg
 

ReClaimer8015

Active Member
Some really nice pictures! Shows a lot of passion. Makes me quite envy of you.....
Your Observatory could be able to compete with the local one in my hometown!
What do you like to look at besides deep space objects?
 

Sandbagger

Sr Member
Some really nice pictures! Shows a lot of passion. Makes me quite envy of you.....
Your Observatory could be able to compete with the local one in my hometown!
What do you like to look at besides deep space objects?
I occasionally have a gander at the moon and sometimes will take a single frame. I have a planetary camera for doing the planets, but I'm not yet ready to spend the time working on the techniques yet. That will come in time. Most of my work is nebula within our own galaxy, though I have been working on other galaxies lately. 87 million light years away is my record so far.
 

ReClaimer8015

Active Member
thats very faaaaar away......:D
Think about it - you`re looking into the past of this universe in some kind of way...
 
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