Carina at 85mm and HDR

avandonk · #1 06-12-2007, 11:27 AM

Finally no cloud .

Large image 2.5MB The FOV is 24x16 degrees.
http://members.optusnet.com.au/~fmlee/CAR_85mm.jpg

Details
Canon 5DH. Canon 85mm F1.8, Hutech LPS filter, all at ISO500.

At f/2.8, 5X(2min, 4min)
At f/4 , 5x( 30s, 1min, 2min)

Converted from RAW to TIFF and corrected for flats with ImagesPlus. Stacked and aligned wiith Registar. Used EasyHDR to produce a LDR image from these five images. The potential dynamic range displayed is better than sixteen bits. Note how the dark dust clouds show contrast detail and the bright stars and nebulae are not burnt or washed out. The fine detail is also all there.

Seems like HDR works very well for widefields.

Bert

iceman (Mike) · #2 06-12-2007, 11:30 AM

Beautiful image, Bert. Those dust lanes are very pretty. I'd love to see what you could do under a dark sky.

avandonk · #3 06-12-2007, 11:59 AM

Thanks Mike. The other thing to notice is the "seagulls" at the corners that are on the 4 min f/2.8 exposures almost dissapear with the f/4 data from the shorter exposures. Below is a crop from the top left corner of the 4min exposure stack at f/2.8 and next to it the exact same area from the large image. To get dark skies I may have to camp in Kens backyard but it could lower the tone of the neighborhood!

Bert

iceman (Mike) · #4 06-12-2007, 12:25 PM

It would bring down property prices for sure!

h0ughy (David) · #5 06-12-2007, 01:11 PM

Quote:

Originally Posted by avandonk

Thanks Mike. The other thing to notice is the "seagulls" at the corners that are on the 4 min f/2.8 exposures almost dissapear with the f/4 data from the shorter exposures. Below is a crop from the top left corner of the 4min exposure stack at f/2.8 and next to it the exact same area from the large image. To get dark skies I may have to camp in Kens backyard but it could lower the tone of the neighborhood!

Bert

he might let you stay if you supply a white cue ball

Lovely image Bert

Garyh · #6 06-12-2007, 02:58 PM

Nice Bert! you always get the nebs a lovely red!
Yeah go bush Bert!

cheers Gary

tornado33 · #7 06-12-2007, 04:04 PM

Yes nice shot there Bert
I find that playing with the focus, movign the ring only a millimetre at a time and taking short test shots at F1.8, then checking the corners as well as the centre for focus, and settling on a best compromise between corner and centre sharpness might reduce the seagull effect. Mind you most of my 50mm shots have been with a baader UHCS filter on front, it may reduce the seagull effect because of the light being filtered out.
Scott

jase (Jason) · #8 06-12-2007, 04:13 PM

Nicely done Bert. You'd be getting around 20 arcsec/pixel I'm guessing. HDR does appear to work well for wide fields as you indicate. Though it maybe limited by the type of objects in the FOV. I recall your longer focal length Carina resulting in subtly pink hue stars. These certainly aren't present in this super wide field vista - perhaps due to the overall lack of dominating red nebulosity. Really like the subtle dark lanes. What's the nebula is the lower right corner of the frame? That lens performs nicely. Well done.

avandonk · #9 07-12-2007, 10:26 AM

Thanks all. Jase the dark neb in the bottom right hand corner is the 'thingo' in Musca. I have superimposed a map from StarAtlasPro on the image with Registar.
Scott I use a stepper motor to focus lenses. This stepper has a 1350:1 gearbox with almost no backlash so it holds focus without the motor being energised. I can also swap filters and the focus is not disturbed. I have not yet done it for the 85mm lens but obtaining focus if you swap filters it is just a matter of changing focus by the correct number of steps. Different manufacturers have different optical path lengths.

Bert

avandonk · #10 07-12-2007, 11:57 AM

I have put up a slightly better? version same place same name. It is amazing what a good nights sleep will do.

large image 2.7MB
http://members.optusnet.com.au/~fmlee/CAR_85mm.jpg

Bert

Ric · #11 07-12-2007, 12:57 PM

Lovely images Bert, I like the clarity and detail in the large images.

Cheers

avandonk · #12 19-01-2008, 11:54 AM

Here is a better version where all the colour was present before going from HDR to LDR. I have found it is better to adjust in HDR then only tweak a little bit in PS later. It is then far more simple to reduce saturation in PS rather than increasing it to attempt to get colour that is not there.

Large image 2.3MB
http://members.optusnet.com.au/~fmlee/CAR_85mm.jpg

Bert