Under Construction LMC Mosaic

[avandonk]

Here is a preliminary mosaic of the LMC.I have more images to collect.The nights are too short this time of year.This image is only a rough attempt at processing
as it depends on more images what the final mosaic will look like.

2.6M image
http://users.bigpond.net.au/avandonk/LMC_Mosaic1.jpg

Bert

[iceman]

Incredible Bert, it looks great. How many images make up what's there so far?

I wish there was more of this kind of image, I love them!

[Itchy]

Nice work Bert. Can't wait to see the finished product.

Details Please :prey:

Do you know the designation of any of the objects in the nebulous region near the top of the frame?


Cheers

[avandonk]

OK.There are three different fields of five frames each.Exposure for each frame 330sec ISO 1600 300mm F2.8.Hutech Nebula Filter.The in camera (20D) noise reduction ON.
All frames from RAW to TIFF (24M).All frames run through Noiseware Professional
then stacked with Registar.The usuals adjusted with Photoshop.
Final image was 80+M tiff which reduced to a 8.4M JPG (6385x4430) with least compression.This image was reduced in size to 2.6M 3000x2081. This is the image
you can see LMC_Mosaic1.jpg.

I don't know offhand any of them without looking it up.I am sure there are people here who do know.
I hope the final mosaic to be at least 3x3 in size for a total of nine ie this image so far is only three.Also more frames with different camera orientations to smooth out any camera sensitivity variations.

Bert

[Mombat]

Thats amazing!!

Above the Tarantula nebula and a little to the left there is a spreical nebulous region does anyone know what this is?

[avandonk]

Its a planetary nebula, which one I dont know.There are a few around this region.

Bert

[davidpretorius]

great stuff. i want to do something similiar down the track. what exposure time would you limit yourself to do a large mosaic?

it must be a fine balance to get structure, but not billions of stars burning out the image!!!

[davidpretorius]

imagine using this with ipix where you could wrap it around 360 degrees and in a dome!!!!!!

now that would be something. again you would want it resembling what your naked eye sees, but also some of the structures!

[Striker]

I love your work bert...even though you should sell that cheap 300mm F2.8 lense to me cheap...you should get a better one....lol

look forward to your complete final image.

When can we expect it.?????

[avandonk]

This is something that is poorly understood.The brightness of an image of a point source (a star) depends on the size of the aperture independant of F number.The brightness of an image of an extended object such as a nebula,comet aurora depends on the F number.So the smaller the F number ie F2.8 is four times brighter than F5.6 for extended objects but if both lenses or optic have the same aperture the stars are the same brightness.Obviously the greater the aperture the better the resolution due to diffraction limits.

For photography small F number is better.If i put a 30mm eyepiece on my 300mm F2.8 the resultant exit pupil would be about 11mm in diameter!So more than 50% of the light would not even enter the average eye (7mm at best).

For visual observing low F numbers are not all that important for this reason.Aperture is all that matters.The Dob enthusiasts are correct!A bit over zealous but still correct.The trick is to match the magnification to the aperture so the exit pupil of the eyepiece is about 7mm for young people and 6mm to 5mm for us oldies.

So to get back to your query,why this lens works so well it has an aperture of 107mm and is F2.8 and it has as good a quality as man can produce at this time.I am not in competition with the Hubble or any other pro telescope.Just like all you visual observers I want to look/take pictures in real time.That is when we can depending on weather etc. but we are involved.Excuse the pun,Astronomy is not a spectator sport!

Bert

[Striker]

I still reckon you should go for the Canon 400mm F2.8....Bert

Move on...lol

[avandonk]

There is one at Camera Exchange in Melbourne for Aus 7K.When I saw it I left straight away.It was used but looked to be in good condition.When a pro photographer hangs on to a lens,it is very good.Beware of near new expensive glass it is most probably not up to specs.

I calculated the theoretical diffraction limit (Airy Disk) of my lens at F2.8 if it was perfect,and came up with four micron at a wavelength of 500nM (green).If you look carefully at dim stars they are about 3 to 4 pixels.This corresponds to 15 to 20 micron.Not bad for a multi element real lens in the real world.

Bert

[CometGuy]

Bert,

There is a very interesting article regarding the performance of the Canon Long Telephoto's here:

http://www.astropix.com/HTML/M_DAP/M004/M004.HTM

PS Can't wait to see your full mosaic.

Terry

[CometGuy]

Bert,

I was going to add your 300 f2.8 clearly performs better than the example Jerry uses. Is yours the non IS?

Terry

[Striker]

See Bert.....sell it cheap before it starts performing badly.....lol

I have also heard that Canon IS lenses dont perform aswell as NON IS for astrophotography

[ving]

good stuff :D

[avandonk]

Yes my Canon 300mm F2.8L is the non IS version.It does seem to perform better than than the 300mm F2.8L IS on Jerry Lodriguss site.Focus is absolutely critical.The symtom shown on Jerrys site leads me to believe the IS optical train is 'parking' slightly misaligned when the IS is turned off.
This is another example of one of the immutable rules of the Universe:-

You can't have everything at once or each time you improve one parameter another goes awry.
Or said another way,there is no free lunch in this Universe!

Here is a single jpg straight out of the camera.It has only been processed with Noiseware Professional (this reduces size without affecting anything else).
http://users.bigpond.net.au/avandonk/Image_4870_filtered.jpg
The colour is due to the Hutech Nebula Filter and the light pollution from high pressure Sodium street lamps which have emissions at green that get past the filter .Note that the stars are just as good whether centre or any edge or corner.I have yet to see the performance of this lens with a full frame.I suspect it would not be as good if you look at the MTF diagrams of this lens.One (left)is for the 300mm F2.8L the other the 400mm F2.8L.There is only one lens that has a better MTF diagram and that is the Canon 200mm F1.8L.

Bert

[avandonk]

Mosaic updated,Same name
http://users.bigpond.net.au/avandonk/LMC_Mosaic1.jpg

Bert

[Itchy]

Looking better all the time Bert. Congratulations

[CometGuy]

Regarding the 300 2.8 + full frame I came across this:

http://www.pbase.com/jayseejay/image/38455497

Terry

[avandonk]

Thanks to Itchy we have added his Tarantula picture to the current LMC mosaic.This has filled in what was a too bright part with little detail.

2.7M
http://users.bigpond.net.au/avandonk/LMC_Mosaic1.jpg

Bert

[Striker]

Thats just amazing Bert...so much detail.

[iceman]

Just beautiful!

[avandonk]

All we need now is for Itchy, Tornado33 and others to start and get all the other bright extensive fuzzies and then we would have a stunning image!

If anyone would like a large version 9M just ask will email it.

Bert