New toy...this could become an expensive hobby!

[UTMonkey]

Great, keep them coming.

 

[nev]

and if you zoom right in to the dark bit, you can just see ...

:mrgreen:

 

[Paul.J]

Those are great images Jim

 

[Jensmith]

Wow, love the Orion Nebula shot.. Have seen it through my telescope but it didn't look like that!

 

[jimi43]

Wow, love the Orion Nebula shot.. Have seen it through my telescope but it didn't look like that!

Hi Jen

Thank you my friend....it's just a beginner shot..I need to capture more data but that leads me on to explain why you can only see a faint grey cloud with the naked eye.

The emissions of photons from a nebula are very weak...Orion is particularly bright for a nebula as is Andromeda to the West.

But the eye is not capable of retaining the photons sent out for long...nor is it particularly tuned to the wavelength of the light...we have developed eyes that work on Earth and throw the image away quickly so we can detect motion.

A digital camera sensor either CCD or CMOS is capable of storing those photons and in those wavelength...as long as you remove the filter built into the camera for land use. This allows energy from the nebula to be recorded better as it is in the red...Hydrogen Alpha and Hydrogen Beta wavelengths around 600-700 nm.

I take many shots of a shorter duration however as not only do the photons from the nebula build up in long single shots but so do those from our nasty light pollution.

So we take many shots capturing a bit of the data each time of exactly the same spot...the telescope electronics follows this spot with great accuracy.

Then we "stack" all these individual pictures...one on top of the other and line them up...the light from the nebula then grows...the more shots you take...the more data you have to process.

The computer then brings these all out as one series of colours and one image with a total length of many minutes or even hours.

This shot of the "Whirlpool" Galaxy which has such a large black hole in the centre it's pulling a near galaxy into it...

...I took using the same number of exposures with the same duration as Orion...but as you can see...the detail and the colour is very poor...I have to take this again with FAR more data to get anywhere near a good picture. It's not a matter of magnification...it's a case of sky clarity and duration of imaging.

That's about as simple as I can explain it without getting overly technical...there are other processes involved but the light you see is the light that's there...it's just that our eyes can't see it all in one go.

Cheers

Jim

 

[mickthetree]

Thank you so much for taking the time to explain that Jimi!! I've always wondered why that is so. I have a small beginners scope that I get out when I can. Brilliant shots too. I love to look at the moon.

 

[StarGazer]

Jimi,

Sorry, didn't see your reply straight away.

I build parts of scientific instruments for large (4m-8m) telescopes located in remote observatories (e.g. la Palma, Hawaii, Australia, Chile) so not the telescopes themselves although the telescope design impacts on the individual instruments as each one is unique. Just starting work on a new major upgrade for a telescope in La Palma which will replace an instrument I commissioned there nearly 20 years ago.

Mainly spectroscopy rather than imaging although I have had the opportunity to look through an eyepiece on the 3.9m AAT and the 4.2m WHT.

SG

 

[bugbear]

... look through an eyepiece on the 3.9m AAT and the 4.2m WHT.

That must be extraordinary. Would I be correct in guessing that telescopes like that don't (normally) even have an eyepiece, but are almost always rigged with "sensors" of various kinds?

BugBear

 

[StarGazer]

Hi Bugbear,

Correct, usually a very expensive cryogenic camera or spectrograph. In the early days of each telescope an eyepiece might be used to verify primary mirror alignment and the telescope pointing model, although these days small webcams are so plentiful that the requirement for a temporary eyepiece has all but gone.

SG

 

[Jensmith]

Thank you Jimi for the explanation. Fascinating and informative. That explains why it looked like a bright grey cloud.

It must be so exciting putting the images together and seeing what you end up with!

 

[Paul.J]

Another great image Jim,thats one of my favourites teh Whirlpool,so will ook forward to your next image of it =D>
Can i ask what set up you have Jim?

 

[bugbear]

Another great image Jim,thats one of my favourites teh Whirlpool,so will ook forward to your next image of it =D>
Can i ask what set up you have Jim?

Err. Guess what this thread is about!

BugBear

 

[Paul.J]

Another great image Jim,thats one of my favourites teh Whirlpool,so will ook forward to your next image of it =D>
Can i ask what set up you have Jim?

Err. Guess what this thread is about!

BugBear

Err,astrology is it??

 

[bugbear]

Another great image Jim,thats one of my favourites teh Whirlpool,so will ook forward to your next image of it =D>
Can i ask what set up you have Jim?

Err. Guess what this thread is about!

BugBear

Err,astrology is it??

Actually, I've just re-read the thread, and looked (again) at Jim's nice images.

I rather suspect he's bought quite a few toys that haven't been mentioned here.

BugBear

 

[Paul.J]

I thought i had read all the posts on this thread so far,but seem to have missed the one where Jim says he bought the Skywatcher Evostar 100ED DS-Pro :roll:

 

[jimi43]

Ok Paul...that Andromeda shot...it kind of demonstrates what Jen was seeing...a single shot I would expect from the cigar shaped stars on the periphery.

It's a JPG image so I can't do much with it as most of the hidden data is dumped when you compress it but I did a bit of data extraction on it and revealed a bit more of the spiral...

If you can take RAW images with your camera...do about 15x 30s shots on "bulb" at 800ASA and save them in a folder called "subs". Take exactly the same number of shots with exactly the same settings at the same temperature (time)...but with the lens cap on and save them in a folder called "darks". Then take 15x shots at the fastest speed your camera can do again at 800ASA and Manual and save them in a folder called "flats". Finally... next day...point the lens up to the sky with a white T shirt over the lens and take a few shots on AV or auto at 100ASA and save them in a folder called "bias".

When you have done that let me know and I will help you make an image out of them.

Just an update on the equipment front...

I changed the mount because it wasn't quite man enough...then I added a guide scope (the black one)...and a guide camera which I have yet to use in anger (bleedin' clouds!)...the Nikon is there for wide field shots...so not many changes.

For observing...(don't show this shot to Annie!!!)....

...a little reflector...now upgraded with a better focuser...

...and this one for you John...

...just a tiny ( :wink: ) mirror and cell from way back when...soon to be recoated with hi spec mirroring...and used to form the basis of my own Newtonian...out of wood?

Oh...and I do it all from my lounge watching TV....

CLICK FOR YOUTUBE VIDEOS

Cheers

Jimi

 

[jimi43]

Hey John....

I thought you might be interested to see the underside of the mirror which I took out of its cell to clean tonight...

I'm quite willing to explain the significance of the name of the maker...the great Mr. Henry Wildey, but thought you might like that honour!

I am made up at finding this...astounded might be the word! I wonder if the grinding is accurate enough to be 1/10 PV?

Needless to say this lump of "Pyrex" will be heading off to Orion Optics for analysis and then recoating if it proves to be one of Henry's usual paraboloids!

(we need a "jumping up and down and running around the lounge" smiley!!!)

Jim

 

[bugbear]

Holy "shoot". This thread title is coming true...

Hope your pension holds out!

BugBear

 

[jimi43]

Holy "shoot". This thread title is coming true...

Hope your pension holds out!

BugBear

Hey BB...with these two hobbies I'm actually spending far less than I did on crack cocaine and gambling which were my real passions a few years back! :mrgreen: :mrgreen: :mrgreen: :wink:

Jim

 

[mickthetree]

haha, so is that mirror out of the black scope you showed? Or another?.....