Scorpio Rising WideField.....

[Kokatha man]

Hi.....We stayed up last night shooting widies with both cameras, this a Scorpio widie with the modded 20d at 20mm using a 20-35mm Canon Ultrasonic lens.....the focus is a bit too soft really and I find it more difficult to get razor-sharp focus with the shorter f/l's lenses.....I am getting my 50d modded in a week or so and look forward to using liveview remote preview and a Bahtinov mask to sharpen the focus for widies, which I enjoy taking....! But despite the focus problems it still shows some nice dust lane delineations in and around the ol' Milky Way.....and I also had to crop it a bit to get rid of the trees that wouldn't get out of the composition....!

Speaking of dust, this was taken with Scorpio rising but still a bit low over my backyard just before 2am with some cloud "fingers" hanging around - the Moon was also just about to rise.....we enjoy reasonably dark skies at home here in the southernmost 'burb of Adelaide but am really looking forward to going out into really dark bush skies a hundred or so kliks from home to start a compilation of widies soon.....

3 X 6min subs @ ISO400 with darks and biases taken.....processed in DSSv3.2.3 beta10.....

Last night's endeavours were as much a chance to shoot widies as it was the start of setting up my darks etc library - so we had the old digital dual-thermometer out recording temps etc.....this is where sloppy beggars like me have to sharpen up our pc filing and start naming and storing our files etc with much more order....!:)

[Psychobilly]

Nice Image...

I'd focus in daylight and then switch to MF tape the lens focus ring to stop it moving or use a blob of blutack. lock the zoom ring as well as some lenses the focus changes slightly with the zoom setting...

Billy...

[Kokatha man]

.....well. you could go that way Bill, in fact I'd half-decided this morning to focus and then "tape" it set.....but a couple of problems with that approach is that, as you say, on some lenses the focus does shift slightly when you "zoom" and that would limit the choice for the session to say 20mm f/l which I suppose could be one way of going for a session.....the other re focussing in daylight I think is problematic as I've rarely found anything terrestial that gives identical focus as per star requirements except say the Moon.....and at 20mm you don't have the luxury of seeing the lunar landscape to verify sharp focus as you would with much greater focal length lenses.....

From my experience with this particular lens and setting I've found Venus and Jupiter give satisfactory AF responses when they're right in one of the AF sensor squares, but even Sirius is a bit iffy.....and I should've stated that this particular lens is not going to respond across its field like say my F4L which is essentially a mini-apo.....

Unlike the 50d's Liveview Remote mode where the use of a focussing mask or just the 10X screen view can make focussing much more reliable the 20d needs a more convoluted procedure.....I guess in the short term focussing on say Joop and taping the focussing ring for a fixed f/l imaging session the next night is the easiest.....my eyes seem to be a bit less reliable as I get older, one night I can crack it, the next....!

But I think ultimately modding the 50d and L/view remote focussing is the best solution, especially at low f/l widest field shots.....and spending megabucks on a top wide-angle lens isn't likely at the moment....!

[MartinB]

Very nice dusty detail

[Psychobilly]

The other option of course is to use the inherently larger DOF of the shorter focal length lenses and stop them down a bit...I find this gives much better stars at the edge of the field as well... I use a 10-20mmm zoom on the D200...

Thanks Kev for editing the ramblings of a totally knackered Billy....

I need to recharge the "billy batteries" today... this session has hit me for six...

Billy...

[Kokatha man]

Now that sounds like a worthwhile exercise Bill.....and you're right, with these lenses it's around the edges where their inadequacies really display themselves.....might be worth a try too!!!

Being knackered after an all-nighter (imaging etc I presume mate?!?) is a sign of advancing years.....well, it flaming well is in me....!

[markcol]

Nice shot KM!

I saw this the other week at about 2.30a.m. from South Island NZ and it was absolutely stunning, I'm sure you'll get some amazing shots in a few months time with it overhead.

Cheers

Mark

[Kokatha man]

Thanks Mark, I had to hastily set up a dovetail and paraphenalia to mount the 20d and 20-35mm lens next to my guidescope after removing the other camera and F4L.....I'd dismantled a little assembly made from a couple of "L" shaped pressed steel shelving brackets that allowed me to rotate the camera any which way to get whatever compositions I wanted.....found myself realizing I needed it again - darn!!! - and had to make do with this composition.

Not sure the time difference between 2.30am NZ time and Central Standard here in South Oz but it sounds about similar.....it's funny how in winter you wait for Orion et al down here and then in Summer after awhile you wait for Scorpio again etc etc.....

btw, very nice shots of Crux/Coalsack etc that you've posted recently....!

[Psychobilly]

Being knackered after an all-nighter (imaging etc I presume mate?!?) is a sign of advancing years.....well, it flaming well is in me....!

Until 3hours in bed this morning I had been about since 5am last Wednesday morning...grabbed the odd half hour on the settee or on the chair in the obs but no serious sleep...

What with imaging and processing and other things its been a hard (but worthwhile) few days so far... weather looks set to break tomorrow... so might get some shut eye for work Monday ...

Billy...