Suk Lee
Post Laureate
Reged: 10/07/03
Posts: 4534
Loc: Pleasanton, CA
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Well, while I don't actually LIKE the D70 for widefield astro-imaging compared to film  , it's too much fun to fool around with to stay away from... 
Here's the center of the Milky Way and the Galactic Horse. I took DaveC's suggestion and stacked 8 images and it cut down on the noise quite a bit. Because of the Bayer Matrix filter, when you examine the picture at full scale it get's pretty ugly (film doesn't do that...), but it's nice on a smaller scale.
Unguided EQ3, Nikkor 24mm f2.8 wide open, 8 x 150seconds each exposure @ ISO400. No darks.
Bigger at:
http://home.att.net/~lee.suk/root/widefield/080704_GalacticHorse.html
Note the TOTAL absence of emission nebulae courtesy of the patented NNNF  (Nikon No Nebula Filter  )
Cheers,
Suk
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DaveC
Pooh-Bah
Reged: 11/27/03
Posts: 1316
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"Nikon No Nebula Filter "
lol funny, but in a sad sorta way =) =(
at least your having fun messin round. gotta admit there is something to be said for the quick and dirty image when ya just dont feel like going thru all the hassle of the other equipment.
so i give this a thumbs up!
p.s. the mod only takes 30 minutes 
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Anonymous
Unregistered
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Nice shot Suk...looks good to me, but I don't know any better! 
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DaveC
Pooh-Bah
Reged: 11/27/03
Posts: 1316
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suk take a look here
http://www.pbase.com/terrylovejoy/erwins_modded_d70_gallery
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Suk Lee
Post Laureate
Reged: 10/07/03
Posts: 4534
Loc: Pleasanton, CA
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Must....not....dismantle....camera....must....not....dismantle....camera....
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Suk Lee
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Reged: 10/07/03
Posts: 4534
Loc: Pleasanton, CA
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I looked at the full size pictures - extremely nice. Do you know why he doesn't get the same nasty digital artifacts in the background that I do? Is he just stacking a lot more?
Here's an example of what I'm talking about at full scale, processed but not sharpened or smoothed. Lots of digital grunge which is very different in character from silver grunge.
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DaveC
Pooh-Bah
Reged: 11/27/03
Posts: 1316
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using my experience from the 300d...
in the jpeg you posted its a little hard to make out but it looks like there is a few different things going here. but just about everything boils down to how you process the images, what software you use, and the settings on the camera.
the blotchy quality you have looks very similar to a stretched dark frame. since you didnt use darks they are showing thru. here is a crop of a full size dark frame at iso400. ignore for a moment the hot pixels and just look at the background. next post ill explain why.
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DaveC
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Reged: 11/27/03
Posts: 1316
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you cant trust software these days =)
remember how i found a problem with photoshop CS causing black halos? well thats not the only thing it does. and for that matter the software that came with my camera is also doing weird stuff.
turns out the people pumping out the best images are using software that doesnt do anything sneaky behind the scenes when a raw file is converted. erwin and terry use iris. i am now using astro art with a raw file importer plug in (posted on astroarts web page). both of these programs convert the bayer matrix straight across. no fancy antialiasing. no fancy color noise reduction. you just get exactly what the camera captured. of course this means that it even ignores the white balance and color space settings too. so you have to manually color balance you images (trivial).
to illustrate exactly the differences between some programs ive used when converting raw files ill post a picture below.
note the first panel is canons own raw file converter. notice the hot pixels are elongated? this is an antialiasing routine doing that. then in photoshop CS it looks radically different. they are doing all sorts of weird stuff in the background. i actually find, after much studying of results, that photoshop is the worst of the bunch when handling raw files. the last pane is astroarts dumb importer. notice the hotpixels are nice and tight. the difference in size between the green and red pixels is due to the bayer matrix devoting twice as many pixels to green as red. therfor the spot size for red is greater because it has to interpolate over a greater distance from pixel to pixel. but the important part is that they are tight and clean.
here is the picture showing the EXACT SAME dark frame imported in three different programs.
Edited by DaveC (08/08/04 10:38 PM)
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DaveC
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Reged: 11/27/03
Posts: 1316
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so to wrap this up....
to get good results you have to take enough lights to average out the semi random low frequency color noise (this cannot be easily subracted out). you have to take enough darks to also average out the low freq color noise so when you subract your mainly subracting the hot pixels. ampglow subraction is a whole different beast that i wont even go into here.
and of course flat frames to even out the field.
the point is the same calibration steps you use for your sbig (although slidely different application) will vastly improve the results.
sorry this was so long =)
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Suk Lee
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Reged: 10/07/03
Posts: 4534
Loc: Pleasanton, CA
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Dave:
Thanks. I'll try processing my shots the same way I do with my ST2k.
But, naturally, I read your post *just* after I tossed all the raws for that shot...
Since I have AstroArt 2 I'll grab the RAW converter.
Thanks,
Suk
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DaveC
Pooh-Bah
Reged: 11/27/03
Posts: 1316
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check your recycle bin =)
hmm you may need astroart 3 to use that plugin. if that doesnt work suk you can download iris for free.
http://www.astrosurf.com/buil/us/iris/iris.htm
its really got a *bleep* interface though. much solution is to upgrade to astroart version 3.
if you find that dark frame subraction isnt working as well as you hoped (big gaping black holes or to weak a subraction leaving hot pixels) i can go into detail on the process im using to get clean subractions in astroart 3 dont know about 2.
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Suk Lee
Post Laureate
Reged: 10/07/03
Posts: 4534
Loc: Pleasanton, CA
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Nuts, more $$$ on software.
It sounds like IRIS hasn't gotten much easier to use - I downloaded it awhile ago but decided life was too short...
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Suk Lee
Post Laureate
Reged: 10/07/03
Posts: 4534
Loc: Pleasanton, CA
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By the way, instead of shooting RAWs, have you tried shooting high-res JPEGs? If so, does that bypass the color interpolation problem? Maybe I'll try that next time out...
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DaveC
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Reged: 11/27/03
Posts: 1316
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i did try that before i modded my camera. the jpegs didnt offer anything the raws didnt. but since they werent as flexible as raw i changed over to raw and never went back.
suk there is a certain mode in d70 that youll want to use. one of the modes just trashes the image. im sorry i dont know which one it is but if i come across it ill let ya know.
gotta run im shooting the bubble tonight. 
Edited by DaveC (08/09/04 01:12 AM)
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Blueshark928
Carpal Tunnel
Reged: 02/19/04
Posts: 2853
Loc: Crownsville, MD
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Mode IIIa is the one to use. Ia is the worst
Thats not bad! I wish i could get something that close with mine.
I can sympathise with you on the NNNF filter (when is SBIG releasing that new ST-237 replacement?). On a whim, i shot the Western Veil with mine last night. After playing around with different ISO settings and exposure lengths i got some decent RAWs to workwith at ISO800 @ 4min exposures. Thank goodness for autoguiding. I didnt use the IDAS filter last night, but tonight i think i will do it all over again with the filter just to see what the difference can be. I also did a couple of M31 test frames before i shut down for the night. My scope is too big to get it into one frame. D'oh! I think i have to shoot it with the 80mm f/11 guidescope. Or maybe i'll go to C7 and see if they have any ED80s left....Hmmm
When is SBIG releasing that new ST-237 replacement?
--------------------
John
SV-102APO
SV-80/9d
Losmandy G11
HX-916
Edited by Blueshark928 (08/09/04 09:48 AM)
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Suk Lee
Post Laureate
Reged: 10/07/03
Posts: 4534
Loc: Pleasanton, CA
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Ah! Thanks, I've been using mode II (that's the color space setting you're talking about, right?)
I'll switch to mode IIIa and try again, maybe tonight.
Thanks,
Suk
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Anonymous
Unregistered
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Suk,
Erwin's milky way shots are SINGLE 10 minute shots at ISO400.
However, like Dave says using raw files and 'Mode III' will make a major difference. Erwin says that Mode III is more necessary for wide angle shots, since star images tend to be much tighter and more effected by the median filter the in camera processing uses in the other modes.
His camera also has the benefit of having the blue IR block filter pulled from the camera.
Terry
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Suk Lee
Post Laureate
Reged: 10/07/03
Posts: 4534
Loc: Pleasanton, CA
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Quote:
Erwin's milky way shots are SINGLE 10 minute shots at ISO400
Good GAD. My skies aren't dark enough for 10 minutes, but I'm trying out Mode III tonight...
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Anonymous
Unregistered
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Hi Suk,
'Mode III' is the undocumented mode that Christian Buil discovered by putting the camera into noise reduction mode then turning off the power on the camera during the dark frame. The image held in the buffer is unprocessed and this is dumped to the CF card during powerdown. It is the only known way at the moment to avoid having a median filter applied to the image.
Terry.
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Blueshark928
Carpal Tunnel
Reged: 02/19/04
Posts: 2853
Loc: Crownsville, MD
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Oy! That can get to be a drag when doing lots of multiple exposures. The only way i can think of to make this work is to remove the battery from the camera when i have my AC adaptor plugged in and plug the AC adaptor into a switched outlet like a surge strip. I shudder to think that Christian actually touches the camera. Actually i shudder to think what would happen if I touched the camera. Bad things happen when i go near the rig during imaging operations.
BTW - you dont need to turn on NR to get the camera into mode IIIa. You can set it with NR off using Nikon Capture when the camera is plugged into a PC. Im sure theres a way to do it on camera, i just dont remember it.
--------------------
John
SV-102APO
SV-80/9d
Losmandy G11
HX-916
Edited by Blueshark928 (08/10/04 09:33 AM)
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