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i have several photos of the folks i work with (some shot for the “hands” contest) but the lighting is so crappy there they aren’t very good.

If these were shot with your new camera, you can change the color temperature with it’s software (GREAT for florescent lighting issues.) You may be able to do so even with pics taken before then–my Canon software will let me do so, at least.

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The only way to make sure it’s uniform across all the exposures is to have the center of your front element at the center of rotation.

Through the scope, the center will be whatever the point the telescope is centered upon. But this hasn’t helped any in the alignment front. Something about the rotation algorithms seems to throw things off, or perhaps some other optical technicality that I haven’t mastered mathematically to compensate for (and likely won’t, which is unfortunate.)

In *brighter* news, there is Comet Hartley II this month, and it’ll be around Cassiopeia and Perseus this month; a good 30 second exposure might capture a nice view of it, given the field of rotation that near the North pole is minimal over so short a span.

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That’s actually a question I can address, Orionid, but not really answer. The axis point from which to rotate is likely out-of-frame, technically. Take Orion as an example, it’s far from the north pole, so the axis point would be some 45+ degrees out of view. There’s probably a formula out there that would tell you how far to tweek the image, but it’s not as easy as ’15 degrees for every hour’. The amount would vary depending on the centering of the image and the distance to the north pole.

Thus far, my manual field rotation attempts to compensate have been far lacking. I’ve tried triangulation to two stars in the FOV, but haven’t figured out how to get it right as of yet (you’d think it’s as easy as x^2 +y^2=z^2, but it hasn’t proven to be–despite shooting at the same focal length, the images never quite work out correctly across the image when I’ve done so–I can get two-star alignment, but other stars somehow do not line up when I do so. If someone could solve this quandry for me, I’d be most appreciative.)

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Photograph some people while they’re hard at work.

‘Hard’ at work. Literal, or metaphorical? I have a shot where there’s work being done, but nobody’s sweating or anything. As an example–someone making a pizza pie, or knitting. Yeay? Nay?

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chupaWow. Amazing detail. As I said, I ain’t no expert. Shame on me for believing what I read without looking further into the matter.

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Most modern lenses will focus slightly past infinity to allow autofocus algorithms to pass proper focus from both directions.

Yep, I get that, but I mean that in ‘autofocus’, it’s a tad off–the factory marked ‘infinity’ tic is a wee bit closer than it should be. I get a sharper image by going about 1 degree beyond it, determined by trial-and-error and marked with a scratch into the lens body.

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I have that very same Tamron lens. See Orion Nebula pic in the recent Tips ‘Astrophotography’ thread. Have fun with it!

p.s., with my Tamron, the focus is a little bit off in the infinity range. I’ve marked a ‘tic’ into the lens to mark proper focus at infinity. Don’t know if it’s the lens or my Canon that causes it, though.

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There are several ways to stack, but the simplest method is to is to stack multiple exposures on top of each other in layers. The bottom layer gets 100% opacity, second gets 50%, third gets 33%, 4th gets 25% etc. This gives a straight average of image data, which reinforces the actual data while minimizing noise. Stacking 30+ images knocks the noise floor *WAY* down, and allows you to aggressively stretch levels (always do this in 16bits/channel) to increase the contrast of the faint fuzzies in the sky. This even works with 8-bit channel images, stacking can give you a 16-bit image that can be stretched far more than if averaged into an 8-bit image. It’s not as good as starting with 16-bit RAW-to-tiff, but it’s an improvement over the base 8-bit.

So you take, say, 32 images at the same exposure, and arrange them in layers in Your Favorite Image Hacking Program? Am I understanding this correctly?

32 is overkill. Take 32 of the same exposure, but let the stacking software use the best 9 of them. I was reading in this month’s Astronomy magazine that the noise reduction ‘rules’ offer diminished returns for more pictures in the stack. 4 pictures is 1/2 the noise, 9 is 1/3, 16 1/4, 25 1/5, 36 1/6th, etch. The article writer suggests 9.

Of course, I’ve never figured out how to make registax do a good job of it myself, so I’m just quoting an expert. My experience in this area is lacking.

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Here’s a shot of Orion’s nebula, 2.4 seconds, 300mm focal length. Noise in an xTi is bad. No processing, just the raw shot.

It’s at lease discernible. I could do better–but we drinks the day after my birthday, ya know.

Stacking would greatly improve the image. Since this isn’t piggy backed, I’m kinda stuck with the shot as is.

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Telephoto is great for reducing CA (if the subject is well centered), though movement makes things difficult to capture. Lens characteristics and a few physical laws prohibit the elimination of CA entirely. If light passes through glass, there will be diffraction–it’s why the best telescopes use front-surface mirrors.

Even the earth’s atmosphere creates CA. Here’s Venus about a week ago. Note the prominent CA (well, it’s more prominent if you zoom in). And excepting the aforementioned mirror, there was nothing between the sensor and the planet. It’s just it was near to the horizon, maximizing the effect.

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I have a few. Nothing I am super excited about.

Found this one during the archive search. I don’t think I’ll use it (but, who knows, the Fark crowd might like it). It was my oldest girl’s 7th birthday. She was blowing out the candles and put up the sneaky cupped-left-hand defense so that her little sister could blow too.

http://photos.imageevent.com/ulle17/fark/Blocked_2082.jpg

I love candid shots.

I actually am sorta excited for this one. After a retake session, I think I’ve done well with at least one picture. The other two will at least be unique. I think.

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I hadn’t gotten the Weaver’s Needle shot at the time the contest opened.

http://www.arizonahighways.com/photocontest/viewpoll/index.cfm?action=viewpoll&contestID=10&startrow=197&PAGESIZE=36

First photo, second row from the bottom – the orange sunset lightning strike.

Dang. I’m kinda thinking of doing this one from macrobugs:

http://fossilspringsaz.com/pics/2010/jun/02/6632.html

I don’t like the interloping leaf, but I do love the spider. But I have other bug shots I’m considering, and I keep getting better, so I’m holding off for the moment. I plan on waiting till at least December, just so I don’t take something the day after I submit and regret having submitted something the day before.

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It’s a family magazine. And by family, I don’t mean gay.

But that is a so totally most awesome shot, I’m complaining to the editors!!

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If you have that 300mm lens, give Orion’s nebula a shot–you should be able to get it.

I ran a couple passes at it two years back. At 1600 ISO, 300mm f/5.6 and five seconds exposure, I got a purple streak with two white lines in the middle. Of course, I was working with sub-urban new york skies, so you may have better luck out in BFE.

Camera shake due to mirror movement, I’d bet. Lock the mirror, use a remote shutter release; it should be doable (though 2 seconds at 3200 would be better–wish my cannon had ISO above 1600; but I got a save with piggybacking the camera onto the telescope.

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I do have a 300mm and a remote shutter fob. Thanks for the suggestions. I live in northern MN and the sky at night is amazing and no light pollution either.

Ditto on caradoc‘s tripod comment. You’ll do fine under MN skies. I understand October is good for the Aurora (you’d have to ask soosh about that, though.)

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