Astrophotography

[hank]

Just been looking at Nytecams latest excellent image.
As someone who has only taken star trails and Moon shots, I wondered if it was possible to take galaxies with a DSLR.
On Googling for more info, I found this site -

Digital SLR Astronomical Imaging

I'm sure it makes it look easier that it really is!
What's the minumum set up needed to get interested. A half decent image would do to start with!

H.

[nytecam]

Hi Hank - for starters you need to make a simple devise [below] for your regular cam [photofilm or digital] to track the stars - no scope needed! The camera must take longish exposures say 20s - 60s to collect those faint galaxy photons. You can stack your star pics in freeware DeepSkyStacker to go 'deeper'.

Good luck and **MERRY **CHRISTMAS** EVERYONE**

Hand-driven Scotch Mount
Make a Scotch Mount: From Star Ware 1st edition
DeepSkyStacker - Free

[hank]

Thanks for the info.
I like the simplicity of the Scotch Mount. It seems ideal for beginners.
If I can source a 1 r.p.m motor I'll have a go making a motorised one.

Just wondering why 18 - 50mm lenses are used. I'd have thought that a 200 or 300 mm would be better, more 'reach' so to speak ?

H.

[nytecam]

Originally Posted by hank

Thanks for the info.
I like the simplicity of the Scotch Mount. It seems ideal for beginners.
If I can source a 1 r.p.m motor I'll have a go making a motorised one.

Just wondering why 18 - 50mm lenses are used. I'd have thought that a 200 or 300 mm would be better, more 'reach' so to speak ?H.

Yes a good compremise is 135mm f/2.8 lens [48mm clear aperture] on a DSLR eg not too heavy for the Scotch Mount.

Stars, as point objects, don't play by the same rules as regular daytime photography for it is physical clear aperture, not fast f/ratios that record fainter stars - strange but true Galaxies as 'extended objects' play by 'daylight rules'.

Some good winter targets for the tracked camera include the Orion Nebula [M42] in Orion's Sword, Flame Nebula next zeta Orionis [left belt star]. Horsehead 'dark' nebula [B33] nearby and many more like Pleiades[M45] and Beehive star clusters [M44] - for galaxies try Great Andromeda Nebula [M31].

The above objects in Orion are called 'emission' objects that glow principally in red hydrogen light so a red filter [or maybe red channel on the camera] can make them stand out better.

[hank]

Just an update:
The wood and hinge have been sourced from my shed! The wood is Teak!
I decided to motorise the mount and pivot it.
I bought a £6 CW/CCW 1 rpm motor, that was a bit of a con! It only goes CCW!
I have now ordered a motor that I am assured is CW. It's a mains 1 rpm synchronous motor. I have a length of M8 thread and have done the relevent calculations for hinge to thread distance etc.
I design in AutoCad, and have done 'my version', as no design that I've encountered so far, explains how to close the mount once it has opened - with a reduced drive, you can't just twist the thread and wind it down; if you have a stepper or DC motor, you may be able to reverse it, but it'll take some time! So I've done my own thing! ( Watch this space for the photos ! ).
I have access to Digital and CNC machinery, so it's well under way.
I just need the new motor and about a week to get it done.
I found a free application called 'Stellarium' which is pretty useful ( not as useful as posting for help on WAB though ! ).
I've seen a nebula in Orions sword on TV for a beginners target, I think it's the one recommended by nytecam (M42), so give me a week and a clear sky and I may be underway !!

H.

[nytecam]

Good progess Hank - yes photos are worth a 1000 words

"I design in AutoCad, and have done 'my version', as no design that I've encountered so far, explains how to close the mount once it has opened -"

Not quite sure what you mean but assume...to close the 'gate' [so drive is always engaged] use a strong rubber band.

I think the drive bolt [when fully extended] has to be hand rewound but sure there's a better solution!

[hank]

Nearly finished ! It just needs some type of sighting arrangement to align the hinge with Polaris.
The removable end plate is made of Phosphour Bronze, as is the pivoting pin. This is removed and the pivoting pin is 'spun' back down to reset the mount.
The motor is on a hinged platform to allow it to move as the mount opens.
The pivoting pin is captive in a precision slot in the top so that it moves in alignment with the motor.
I need some ideas for the sighting device. Will a tube be O.K ?










H.

[nytecam]

Great progress Hank and impressive workmanship Yes - a sighting tube or just squint along the hinge-line to point devise at Polaris - you're ready for the first guided pic - good luck