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For those into photography and have SLR cameras
Topic Started: Mar 8 2009, 05:48 AM (619 Views)
Dwayne
Profanity deleted by Hoss
8247
Mar 9 2009, 07:53 PM
Dwayne, you aint the only one who can do panoramics. ;)

Posted Image

From 3 different photos.
That's a nice photo... Mine was done with 9 different photos and instead of spending hundreds on Adobe, I did it all with GIMP and other freely available software.
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Dwayne
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FYI: If anyone interested in photograph wants a nice little place to display their photos online, I really recommend Photosynth. It's a really cool way to display photos, particularly architectural photos and panorama's.
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somerled
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Admiral MacDonald RN
Dwayne
Mar 10 2009, 04:28 PM
FYI: If anyone interested in photograph wants a nice little place to display their photos online, I really recommend Photosynth. It's a really cool way to display photos, particularly architectural photos and panorama's.
I think CS3 and CS4 are way too expensive , seriously tempted to download CS4 demo and hack it's activation key if I decide I need CS that is. I am not convinced yet I do.

The software that came packaged with the 40D is not too and has some nice image editing capabilities, so does the software that came packaged with my wifes point and shoot camera , plus I have DEEPSKYSTACKER which is freeware and designed for astroimagers (allows stacking of subs , working on gradients and subtraction of darks and other nifty features).

Ooooo!!!! just spotted this on Ebay .... http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=140306537717 , that's a seriously nice piece of FAST ED APO glass and a very useful aperture (6") for wide field and deep astroimaging .... I AM TEMPTED !!!! SERIOUSLY TEMPTED !!!! .... I've put it my watchlist.
A 6" ED (or even better Fluorite Triplet) APO refractor with the same f no would be a seriously expensive bit of kit and then you'd need to adapt it to take a camera and add a field flattener lens.

Edited by somerled, Mar 11 2009, 12:44 AM.
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8247
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Apparently we look like this now
This is a mid dollar lens, but has anyone tried the Sigma 10-20mm 3.5? That is an AMAZING lens.
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~Luthien~
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Little Sister Of Sistertrek
hmm lemme try again
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Spanky
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Insanely Handsome Guy
Posted Image

The photo Luthien meant to post.
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somerled
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Admiral MacDonald RN
8247
Mar 11 2009, 06:55 AM
This is a mid dollar lens, but has anyone tried the Sigma 10-20mm 3.5? That is an AMAZING lens.
My kit EFS zoom lens has a short fl in that range .... is dambed wide !!!! have even , just for heck of it done some night tests with it .... it's apeture wide open at 18mm fl is a tad small for astroimaging, but may be useful for bright comets . I was pleasantly surprised by the results for some simple fixed camera "startrail" photos with the ISO set at 3200 , ICNR on , and exposures of up to 30 seconds.

Shows plenty of nebulosity in the Crux-Carina Milky Way region , and recorded the Large Magellanic Cloud despite the hazy conditions on the night and it's relatively low ALT above the SW horizon at the time....could easily make out the Coal Sack and Emu Nebulae, the Eta Carina Nebula , the starfields and considerable detail in the Large Magellanic Cloud.

It's a very nice fl range for landscapes and group photos as I found out when on safari and when my sister in law remarried. f2.8 or better on a similar would be much more useful I think.BUT since EFS lenses protrude into into the camera further , they preclude the use Astronomik CLS and Huteck LP clip in filters that fit inside the body between the reflex mirror and the lens. Bit if a bummer !!!

I quite like Sigma lenses .... I've not got one of their's yet , but I've read and heard very good things about their quality.
I'm a bit wary of Tokina and Tamron lenses ....

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somerled
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Admiral MacDonald RN
Spanky
Mar 11 2009, 04:13 PM
Posted Image

The photo Luthien meant to post.
Where was it taken ?
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8247
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Apparently we look like this now
Somerled, when you do a 30 second night exposure, and an airplane flys by, does the trail from the plane get overexposed? I've always wondered that.

This was 5 seconds, and you can see the over exposed part in the tunnel.

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somerled
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Admiral MacDonald RN
8247
Mar 11 2009, 10:36 PM
Somerled, when you do a 30 second night exposure, and an airplane flys by, does the trail from the plane get overexposed? I've always wondered that.

This was 5 seconds, and you can see the over exposed part in the tunnel.

Posted Image
Not had a airplane spoil an image yet .... not for a very long time , I used to take 60min and longer exposures with the old XD5 , I can't recall when the last time was that one of my long exposures was ruined that way .... neighbours turning on lights mid exposure were more frequent .... !!! hence I tend to image after midnight and until dawn twilight or moon rize to avoid that problem .... sky is calmer , stiller and darker then anyway.
The local airports (Williamtown and Sydney and Aeropelican have curfews in place).

I frequently found meteor trails , and satelite trails going across the image. The longer the exposure the higher the risk of this. Sometimes with deep images I'll capture asteriods and faint comets as trails against stars that are stationary in the images (where I've used one of my GEMs).

Typically the trails of moving objects are not overexposed in this situation.
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8247
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Apparently we look like this now
^^

That brings up another question...With the earth spinning on its axis, on a 60 minute exposure, wouldn't all the stars look like curved streaks...kind of like the lights on a 1/2 second exposure of a ferris wheel? I've wanted to try that, but llike I mentioned earlier, I'd have to go to a campsite at the top of a mountain.
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somerled
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Admiral MacDonald RN
^^^
Yes , and that is what you'll get with a fixed camera .... can be a very pretty effect BTW.

I'd suggest a reasonably wide lens , which is fast (a 50mm f1.4 is ideal) , and ISO set to about 400 (will fog up excessively in a suburban setting if you go higher) , probably helpful to set mirror lockup + internal camera noise reduction on (otherwise you'll get hot pixcels), and a must is either timer release (if you got to a suitably long exposure) or timer release cable ... critical not to touch the camera as the camera and tripod will shake and this will spoil the image will wobbly star trails .... been there and done that ....
A lens shade .... make one at least as long as the focal length (so long as it doesn't cut off the image) and paint the inside of that black (the no reflective black) .... will help reduce accidential light from cars etc from spoiling the image..... it's fun ....

If you want to do star images which show no trailing without an equatorial mount that is possible too (with very tight llmits based on the focal length of the lens .... I have a table I can send you , or extract a suitable exposure for you gear from .... let me know...

I use a German Equatorial Mount on top of a tripod (soon to be on top of a pemanent steel pier) to track the stars ....

To get really accurate tracking , no eggy stars , that's serious money , which I have spent , the Vixen Atlux , and less serious money for my older mounts which have dual axis drives which have drive correctors ....

My Atlux is rated to give a superb tracking precision which has an off the shelf error less than 5 arc seconds from perfect , which is tuneable with Periodic Error Correction Itakes into account very small machining errors in the drives) and other methods to under 2 arc second error (or better), add my autoguider and , my tracking error will be less than one pixcel on the autoguider CCD chip , if autoguiding using an off axis guider to pick off a suitable guidestar and engaged in prime focus imaging via the telescope , that's way under 1 arc second error ..... perfect tracking with a 2 m focal length .... hands free and automated.

Edited by somerled, Mar 12 2009, 02:06 AM.
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~Luthien~
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Little Sister Of Sistertrek
somerled
Mar 11 2009, 10:09 PM
Spanky
Mar 11 2009, 04:13 PM
Posted Image

The photo Luthien meant to post.
Where was it taken ?
Griffith Park in Los Angeles. At the observitory
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somerled
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Admiral MacDonald RN
Frimp :

Here's a rough guide if you want to use a fixed camera and get "tail-less" images of the night sky :

FL 50mm , max exposure 7.9sec , resolution 66 arcmin/mm at the chip
FL 85mm , max exposure 4.8sec , resolution 40 arcmin/mm
FL 100mm , max exposure 3.9sec , resolution 32 arcmin/mm
FL 135mm , max exposure 3sec , resolution 25 arcmin/mm
FL 200mm , max exposure 2.1sec , resolution 17 arcmin/mm
FL 300mm , max exposure 1.4sec , resolution 11 arcmin/mm

Longer exposures than these result in startrails in the image unless the camera is on an motorised equatorial mount and can track the stars.
Edited by somerled, Mar 12 2009, 08:28 AM.
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Admiralbill_gomec
UberAdmiral
somerled
Mar 11 2009, 10:09 PM
Spanky
Mar 11 2009, 04:13 PM
Posted Image

The photo Luthien meant to post.
Where was it taken ?
That's downtown LA viewed from the north or northwest. The small hill to the right looks like the Windsor Hills area.
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