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Funny this should come up… yesterday I was in a sci-fi mood while having a smoke break, and I wondered what it would take to actually pull this off (hey, I’m just the visionary for this project, it’s up to someone with actual brains to collect the Nobel in physics for the lab work). So, someone needs to develop a material that has an Index of Refraction that varies with the angle of incidence of the incoming light. While they’re at it, they might want to come up with something that varies the IOR with frequency so we can have single-element APOs as well. 😆

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Rav, nice shot of moon and M45… I like the earthshine as well… at least you can see it and the stars…

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I tend to do that generally. I call it ‘the shotgun approach’ 😛

Speaking of… anyone have thoughts on a shot where the the stars are prevalent, but a backdrop to the moon? Loving an astro shot, but with my rig the stars all look like pin pricks in cardboard.

Pinprick stars is a good thing, actually. APers pull a lot of hair over making sure they come out that way. The hardest part of stars is getting their colors to show, like this guy managed to do:
Note the stars are not pinpricks, but that’s due to a smaller objective lens (101mm in this case). That’s from this guy’s site, BTW: http://www.dilbertobs.com/ccdimages.html …he just had a great example of color in a star cluster (/me weeps at own lack of optics to try this stuff with)

Getting the moon AND stars in the same shot is going to require some serious HDR… typical stars at mag 2, say, in the field with the moon at something like mag -10. It’s a huge difference in brightness.

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There is more to this contest’s rules than astrophotography (NTTAWWT), and I think the non-AP folks just need to get creative… lotsa room for the unexpected, here…

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Ohman… that’s some drool-worthy CCD action, right there. Some of the folks I’ve been learning AP from won’t even mount a DSLR to a scope, and after seeing their images I can understand why. Even the low-end peltier-cooled CCDs take amazingly clean subs, making the trade-off for lower resolution and acquisition time well worth it. They’ve got some of the more mechanically dextrous hobbyists suffering from cooling envy…to the point of modding DSLRs for cooling. One guy has managed 20C below ambient in what amounts to a refrigerator with a DSLR stuffed inside and mounted to the scope. That’s gotta be fun to balance.

I’ve got an old 300D here that’s itchin’ to be torn apart and stripped of it’s IR block. I’m wondering if the sensor can’t be distanced from the rest of the camera to allow it to be bonded to a peltier unit. I’m gonna need a bit more free time before I can think about that.

On the de-Bayering front, I’m finding bits and pieces and some software… I’ll post some links when/if they pan out into anything usable (keep in mind that I’m one of those open-source types, so what I find may be less than user-friendly).

[chupathingie]

Another technique that gets used is LRGB imaging… the normal R,G, and B filtered images plus one unfiltered for a Luminance channel. Normally this is done with a dedicated CCD imager, which is monochromatic (hence the need for filters and I think what Plamadude30k is speaking about), but I think if one has a DSLR the RAWs can be de-Bayered; leaving a luminance channel at twice the resolution of a color RAW… I need to dig into this yet, I’ve been wanting to try de-Bayering for a while now just for grins…

edit: debayering does not affect resolution (just found some info and trying to make sense of it…)

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Looking forward to seeing them… I might enter a couple of older shots I have filed away from way back if I even still have them.

The last time I opened a shutter for any appreciable length of time I used a 300D 😆

I’ve been wanting to find time to play with the low-ISO end of the 5DII just for star trails, but I guess I’ll never get to unless I quit answering the phone when work calls looking for help…

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I suppose there is quite a bit of noise in here – but without a stacked comparison next to it the noise isn’t too bothersome to my eye.

ISO 250, 25 minute exposure, Peleng Fisheye with manual aperture – I forget what I set it at. On a frozen river in Mopsy’s front yard. Appx 10 degrees F. Canon 5D Mk II.

http://www.ullepics.com/d/1920-4/Startrails_4273.jpg

more noticeable noise at 1400 x 1400 – http://www.ullepics.com/d/1925-3/Startrails_4273.jpg

I’ll use one from this series.

There’s not too much noise in that shot, but you can spot it easily in the larger version (hot pixels; show up as ‘stars’ that don’t move). Usually, resizing down takes care of them, and ‘long exposure noise reduction’ does wonders for an initial shot.

And damn–if you’re allowing stacking, I’m doomed. But I’ll roll with it.

Long-exposure noise increases with all of: ambient temperature, ISO, exposure duration. Some of you folks may be unfortunate enough to have a camera that suffers from amp glow, which will show up as a rather prominent gradient in longer (>5 min-ish) exposures. It gets worse until the camera gets as warm as it’s going to get. Only way to get rid of it is let the camera cool down or deal with it in post if it hasn’t saturated (either way you lose data…either by manipulation or lost acquisition time).

U-Man, that looks awesome…I’d imagine the noise is much more noticeable at full-rez, but still…25 minutes is a LONG exposure… I’m gonna have to try that myself and see how the 5DII fares at somewhat warmer temps.

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I managed some trails from within DFWs horrid light pollution by using shorter subs and stacking (short of an LP filter it’s the most viable weapon against LP). Shoot in RAW, blur the sub and subtract the blurred image from the original. This will drop most of the LP, and stretching the levels selectively will bring the stars out. This MUST be done in 16bit/channel, since in most cases you’ll be setting black point, stretching, and repeating (this kills an 8-bit image very quickly). This will work for a single image, but a long exposure under LP skies will usually saturate the red channel. I normally take a sample shot and try to keep the histogram from creeping up into the top third. Multiple exposures and stacking is almost a must, since the long exposures will generate a lot of thermal noise that becomes even more evident when you start to stretch levels.

If you’re using PS, there are a few noise-handling plugins available (Noise Ninja comes to mind) that I’ve seen used to great affect. PS and the plugins are something I miss from back before I went FOSS on the home PC. 🙁

[chupathingie]

Stacking… if we’re talking real stars (astrophotography), stacking is a necessity in the digital world. While it’s possible to expose for quite a long time on film if conditions allow, anything over 5 minutes on most digital cameras results in some seriously ugly thermal noise.

I need to come by more often, or stop working so much that I don’t have time to participate… or both.

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Thanks, Curious. I am pleased with the results.

Rav, The unemployment was awful, but as I look around, I realize others have had it much worse. We are still in our house, our relationship is solid, and we are not in debt up to our eyeballs (only to our shins). Our savings has taken a big hit but I feel pretty fortunate that we had savings to draw on. I am also really thankful that I have a solid job to keep us going. The lessons we have learned navigating this shitty time will be with us for a long time ? perhaps forever ? and that is not a bad thing.

It’s good to hear things are looking up… as you said, so many are still on the outs. My wife starts her new job tomorrow, after a year and a half working retail (which we both hated seeing her have to do… but you have to take what’s available sometimes). If it wasn’t for me having some stability on the job front, we’d have been in dire straights (that plus getting a lucky transfer to a cheap cost-of-living area just as the economy tanked). We’re looking forward to actually having time to spend together with weekends off. Now if I could only get her interested in photography…

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Awright, you guys… stop that this instant! I’ve already got plans for the income tax refund and you’re making it very difficult to not scrap them! 😆

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Anything in the foreground will suffer from parallax if the iris of the lens is not positioned on the pivot point of the mount. If you have nothing in the foreground, it’s a moot point.

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FTA: “However, when Tony took the lens apart he discovered that none of the elements were cemented but strangely, the separate elements were coated in oil.”

Amateur astronomers the world over are wailing and gnashing teeth over ruining an oil-spaced triplet… what once likely performed as an APO is now more akin to an achromat. Other than that, this is a cool project…

[chupathingie]

ooof…. I can see why they’d want to LOL I’m very surprised that made it past the editorial process.

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