-
-
Post a Thank You. - 1 Thanks
-
Stunning. I'm anxious to see the "improved" version, after you get more time to work it.
-
Holy Dooley Grasshopper! This is wonderful. Are those colours really out (up) there?
-
Thanks guys!
There are amazing colors in deep sky objects, but it's hard to know how best to process them. You'll see many variations of color in them. I had on a light pollution filter which cuts out the artificial light haze that's found at many "good" dark sky sites. It gives a cyan cast, and I didn't get it fully neutralized. Doing so would bring out even more magenta/red. Some cameras have a filter that captures more of the reds (hydrogen emission from some nebula) which are "true" but not well recorded by normal cameras. Other filters can capture other emission lines. But these two nebula do have both red and blue colors, so I'm in the ballpark. I was actually surprised at the color I did capture.
I'll do some research and try to find a reasonably accurate balance.
What impressed me most was the sharpness of that lens for stars.
-
This is Very Impressive Diane..!! I look forward to the upgraded version too..
DON
-
Dianne, I am speechless. This is stunning. How many exposures did you stack this with? Dang, this is super awesome. I do wonder how does the lens perform on the edges? Does it have any coma? I will not be too worried about WB unless you would like to present this in a peer-reviewed archived publications. *wink* For the life of me, I am just not patient enough to figure out all this star tracker and stuff. I am gonna shut up and keep on looking at this picture.
-
Thanks guys! It may take me another year to get far enough with PixInsight. This is just a single 3 min exposure, with a very small area of 30 sec exposure masked into the very bright center region, clumsily processed in LR/PS. Right now I have about 40 frames at each of three different exposures to stack, with 3 kinds of matching calibration frames. All that to deal with different kinds of noise. (There are several kinds to deal with in astro work.) And I really should shoot several more hours of each target and combine the data. After that step, which is largely mechanical, the hard work begins....
I haven't tried the lens on the full-frame 5D3 with stars, but will test it soon. Don't need awesome skies for that. The 7D2 and 6D generation from Canon has significant improvements in fixed pattern noise and low on-sensor dark current suppression that make it preferable to older models for astro work, where you are teasing out very subtle detail and need the best signal to noise ratio. I only use the 5D3 for the Milky Way, with wide angle lenses. That's where you get into coma and other corner distortion, and it's a huge problem for many lenses that are supposed to great for daylight work. I wouldn't expect any trace of corner issues with the 400 DO II but I'll be checking it out, as 400mm on the 7D2 is a bit tight for a few objects. I'm hoping the 1DX II will continue or improve on the 7D2/6D for this kind of work.
-
Macro and Flora Moderator
Amazing Diane, looking forward to seeing more.
-
This is really stunning Diane. The techs of astro photography are all a little beyond me, but I like what I see.
-
Landscapes Moderator
Diane...now this is COOL!!! Perfect as presented :)
-
-
Just wonderful Diane! Fascinating image. I'm still amazed that it is possible to shoot these kind of images with relatively normal photography equipment. This raises a few technical questions I hope you are able to answer.
You say that this is a stack of images, which I can imagine you need to get enough light from a weak object in the sky. But does 'stack' in this case also mean that this is a composite image, i.e. are we looking at several stitched images here also? Or is this just a very big crop? The reason I'm asking is that the nebula roughly equals the size of the full moon at 400mm in this frame, while I experience the size of the nebula much smaller to the naked eye.
Second question is related to how you positioned the nebula. On a Dutch photo forum I saw a post of the same nebula, but then as a 90 degree CCW rotation of this image. Is this due to a difference in angle on the two continents, or has one of you positioned the nebula in the wrong projection? A Google image search didsn't help, the projections shown there are all over the place. In my recollection, the smaller nebula is indeed on top of the larger one, like in your post.
Sorry if any of these questions is silly, but I'm totally unfamiliar with space photography, but images like this make me eager to learn!
-
Hi Jerry - thanks, and always glad to (try to) answer questions. This is a stack of 2-3 exposures because the central core is very bright compared to the very dim dust nebula surrounding it, which is illuminated by starlight. It's not a big crop -- maybe 50-60% of the original frame. It was shot with 400mm and an APS-C sensor, no TC. Here is one of the uncropped raw frames from the 3 minute exposure set. The Running Man (the smaller nebula) is indeed right there. There are some fascinating regions of the sky that I'm just starting to explore. Makes the nature photographer's desire for ever-longer glass look trivial. The night before I made this there was a guy at the same dark sky site who had a telescope that I literally could have stood inside, volume-wise -- a reflector with a 24" mirror and a tube that was 7-8 ft long. I was admiring it and he said, "This isn't my first telescope."
I shot about 40 frames at each of 3 different exposures that will each be stacked for noise reduction. Very low noise will be needed when I stretch the tonalities to bring out even more detail. Then the 3 finished images (at different exposures) will be composited with an HDR treatment. I will use PixInsight, which will also use 3 kinds of calibration frames (also stacks, of 100-200 each) to reduce different kinds of noise and vignetting. It will let me bring out much better detail at much lower noise than one frame does, but I'm still trying to learn it.
The object is much larger in the frame than it would appear to the eye, even with a telescope, because the long exposure shows dim nebulosity that we can't see. It is actually a little bigger than the full moon. Here's the moon with the 100-400 at 400, with the same camera, no crop. So you could say this object is low-hanging fruit.
As Orion moves across the sky through the night, it rotates clockwise (as does the moon). In addition, astro photographs are made with a variety of cameras and trackers that can need different camera orientation to keep things from bumping into one another as the rig rotates to follow the object, so you'll see all sorts of orientations, and some just for aesthetics.
From the pictures I see, latitude (especially Northern vs Southern hemisphere) makes a difference in the visual orientation of the core (galactic center) of the Milky Way, but I'm not really sure about Orion. (Off to a dark closet to think about it...) Longitude wouldn't make a difference.
-
BPN Member
One word for this Diane Beautiful
-
Thanks Don! Jerry got me tracking down the elusive-seeming appearance of the Milky Way as seasons progress -- it doesn't seem to rotate across the sky in the simple way "stars" or the moon and planets do. Here's a somewhat-understandable explanation. It's complicated because the Milky Way circles the earth's orbit around the sun.
https://andrewrhodesphoto.wordpress....the-milky-way/
In the first line drawing, you can see that our angle of view of the interesting and structured core region changes as our orbit around the sun gives us a different angle. Of course the drawing isn't to scale, but that core region is visible at different seasons in the N and S hemisphere, as we are on different sides of our orbital circle, and that is apparently enough to change the view.
But the orientation of things like the Orion nebula wouldn't be simpler. Your latitude would affect how high in the sky things are. Go far enough south and Polaris isn't visible but Orion is much more overhead or in the north sky. But from wherever we can see an object, our angle at different positions on the globe only changes by a miniscule amount. Our longitude (east and west) only changes where in a 24 hour period it is in the sky.
Last edited by Diane Miller; 02-15-2016 at 11:25 PM.
-
Thanks For the good explanation Diane, I learned a lot. Locations of objects in the night sky have always been puzzling to me, because in many cases several things move along their own orbit, kcluding the place you're standing on. Luckily there are many good sites nowaday that tell you what is where at what time.
I can remember noticing that the moon looked odd to me when I was in Australia. I'll try to find my images to check if it indeed was upside down (from my Northern hemisphere perspective of course!). Can't rember how it was with the constellations.
-
Hmm -- you got me thinking again. If you go from pole to pole, you're standing upside down, relatively. Even with a lesser journey, you are viewing the sky from a different angle. Picture shooting the moon from your location and then rotating the camera upside down -- the crater pattern (the man-in-the-moon face) would be in a different orientation, as though the moon had rotated.
So a large feature, such as a constellation, would appear similarly rotated. Of course, the farther south you go, the more our familiar constellations are low or below the horizon and a whole new world (or set of worlds) opens up. There is a wonderful planetaruim program called Stellarium that shows the appearance of the night sky from anywhere at any time. (And it's free!) It's a little like riding a bike -- it's easy once you figure it out. I'll try it later and see how much something like Orion's or Scorpio's rotational orientation changes with latitude. Will report back...
-
Here's a good illustration of the different appearance of the Milky Way from N and S hemispheres: http://intothenightphoto.blogspot.com/
The first photographs and screenshots are from the N hemisphere. In the first actual photograph (below the screenshot) note the two dark strands 1/5 in from the left that extend up and toward the right. But scroll down to the three photographs by Greg Gibbs and you see it from the S hemisphere. Those filaments now extend to the left. But if you compare the two panorama images, you can see that if you just rotate the Milky Way then they come into the same orientation. That's because it is viewed at opposite seasons in the 2 hemispheres.
Thanks for making me figure this out -- it was simple in the end but took a while to get there.
-
-
There is a difference in rotation with the time of year and it rotates during the night from rising to setting. And of course you have different phases here. Would be interesting to see shots made at the same time from very far north and south, since one of the photographers is standing on his head!
Reply With Quote
