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M31

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#1 Rushwind

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Posted 10 September 2004 - 11:02 PM

Got my mount back from the shop and took my autoguiding setup out for a test drive. This is from the first roll of film shot with the new setup.

Film: E200
Camera: Pentax K-1000
Lens: ED80 (600mm f/7.5)
Guiding: ST-4

This is a stack of 3 images of 20, 30, and 45 minutes, shot from my backyard night before last.

aligned and stacked in Photoshop, played with levels, black point.

It's so good to have a working autoguiding setup!

Jimbo

Attached Thumbnails

  • 193805-040909_M31_merged.jpg


#2 Guest_**DONOTDELETE**_*

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Posted 11 September 2004 - 12:51 AM

It's so good to have a working autoguiding setup!



Im jealous... :bawling: :cool:

Played with your image a bit, hope you don't mind.
Posted Image

#3 Rushwind

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Posted 11 September 2004 - 03:23 AM

Feel free to play. I can even send you a (much) higher res (and higher "fi"), if you like... :)

I have just enough Photoshop mojo to be dangerous.

Jimbo

#4 Suk Lee

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Posted 11 September 2004 - 04:10 AM

Jimbo:

Nice shot, it's SO great to have autoguiding isn't it?

Suk

#5 Blueshark928

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Posted 11 September 2004 - 09:23 AM

Attaboy Jimbo! Awsome job. Glad you have some guiding too. Now i dont feel so bad for selling you that Goto head.

Email me a hi res of each exposure. Id like to see how it would stack up with registar and images plus alignment routines. Plus i wanna play with your M31 images. I've nothing but clouds lately and expect more of the same.

#6 Rushwind

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Posted 11 September 2004 - 09:35 PM

Suk,

Don't leave home without it. :D

Shark,

What are you going to guide with once you sell off all your scopes? Are you going all widefield on us? :)

Jimbo

#7 Blueshark928

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Posted 11 September 2004 - 10:31 PM

Jimbo

I got a line on a Stellarvue 80/9d guidescope on Amart. I'm switching up from Orion to Stellarvue. I think im going to get myself a dob later so i can do something while imaging aside from watching TV.

BTW - Here is what i've done so far...Waddaya think?

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  • 194437-M31_JKrework.jpg


#8 Blueshark928

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Posted 11 September 2004 - 11:17 PM

This one might be better. Theres some rumor going around that there is no green in outer space. :)

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  • 194463-m31_3_SGBNR.jpg


#9 Rushwind

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Posted 12 September 2004 - 02:29 AM

I like the details in the dust lanes a lot!

I often see M31 color balanced in such a way that the center is brownish-purple and the outer edges are blue (sometimes a little brighter blue than I'd like).

I feel that my effort was a little overblue, and that your latest effort is a little overbrown. I like your first working better, although I agree that the greenish tinge should probably be stretched a little more into blue...

The second effort appears a little less "grainy"; probably some sort of artifact induced by getting under the 60K limit. Are these stacks of 4, 3, or 1?

I've got another 45 minute exposure of M31 cooking as I type. It's a bit of a "heroic effort"; for some strange reason, it always gets a little windier and cloudier right around the new moon. Stupid gravity. :mad: So I'm hoping for the best. I am planning on doing 5 or so more 45 minute exposures to build up this stack.

Thanks for playing with my image!

Jimbo

#10 Blueshark928

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Posted 12 September 2004 - 08:55 AM

The 45 min exposure was the best. I think if you had a stack of those and a stack of 20 min exposures layered. That would be the way to go. I am going to recombine them and throw out the 60 min. shot. It had guide error (the mickymouse ears) that were hard to elimiate. The other 3 were spot on. I registered all 4 with Registar and Median Mean combined them to eliminate the dust and scratches that are on the slides. It smoothed out the image pretty good. However, the 60min and the 20min slides were out of alignment with the 45 & 30, but thats no sweat for Registar as it automatically rotates and scales (sure wish IP did this). I then calibrated all the images to the 45 min image to even it all out some more. Then i did a stretch, DDP adjustments, and Brightness/Contrast log stretch in Images Plus. After that i took it into Paint Shop pro for Black/white point adjustments and levels and curves. Then back to IP for a little Lucy Richardson deconvolution to help tighten up the stars, then into PixInsight for SGBNR noise reduction and then back to Paint shop for a little unsharp masking and image resizeing.

The low noise is due to SGBNR. PixInsight is limited freeware so download it if you havnt already.

Im gonna burn a DVD with all this stuff on it and mail it to you so you can play with the registered and combined images yourself.



I rebalanced the first image. This may be a little better.

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  • 194642-M31_lr.jpg


#11 spaceydee

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Posted 12 September 2004 - 12:08 PM

Hi Jimbo! Good to see that your set up is working! Nice picture!

#12 Blueshark928

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Posted 12 September 2004 - 01:30 PM

JPG compression does seem to kill images. This is a 3 frame stack with the 45,30 and 20. I did everything like i described above except no 60min image. I like it a little better. The stars are a littel sharper since it doent show the guiding errors that were in the 60min image. However, I really should write things down as i do them so i can get reapeatable results. I managed to get a smoother image, but i lost some dark lane detail somewhere. :foreheadslap:

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  • 194824-040908_M31_ip_psp_rl_sgbnr.jpg


#13 spaceydee

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Posted 12 September 2004 - 03:59 PM

Hey, it is amazing what you can do with these images.. I am in awe.

#14 Rushwind

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Posted 13 September 2004 - 02:53 AM

J,
I hope that dark lane detail wasn't hiding in the 60... :lol: I like the color balance in the latest 2 workovers.

I've got the 5th 45 of M31 cooking as I type. Maybe I'll spend tomorrow doing 20s instead of 45s. Do you really think that it wasn't worth going to 60?

D,

It's a good feeling when it works. The promise of 35mm is finally making itself apparent to me. Not that I'd turn down a DigiReb if one dropped in my lap.. :)


Jimbo

#15 Blueshark928

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Posted 13 September 2004 - 07:52 AM

I dont think it was. I think i may have over did a step. And, no I think 60min is was fine. I only threw it out because of tracking errors and the weird rotation relative to the others. What you might want to do is to check to see if sky fog limit was reached between the 45 & 60 min frames. I think it was. Try (2) 60's, (2) 45's, (2) 30's and (2) 20's. You already have half of them done. If you see mouse ears on your stars, just move on and do it again. Tracking errors will muddy the nebulosity too. I think the last image without the 60sec frame is much sharper in detail because of this.

Personally, having a little experience with both, I like film. To me, payoff is greater. But then again so is the risk of failure. Lets, see if i change my tune when i get a cooled CCD camera with a color wheel. The one thing i find that is harder to deal with with processing film images is the vignetting and the gradients.

#16 Rushwind

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Posted 13 September 2004 - 02:36 PM

I was surprised and a little disappointed (I got over it :)) that there was slight vignetting in the corners of these. It's definitely a lot better with the 2" adapter than it was with the 1.25" one, though. I wouldn't turn down a cooled CCD + CFW, but I really like the wide expanses of sky that I can fit on my 24mmx36mm "chip".

Is there a good way to "see" the skyfog limit? Like, will it show up as a histogram that I just.. can't.. tweak the scan settions enough to "unpeg" it from the left, or something like that?

Is there a point at which more stacking is not really going to help? I'm beginning to look at this image like a stew; simmer for awhile, then add a handful of new stuff. :)

The ST-4 was really humming last night. I planned on doing a couple of 45's and quitting for the night, but it was *so* clear and steady that I couldn't help myself, and I popped another 20min on for the evening, and then another one.

I have 4x45 and 2x20 on this next roll, along with 6 other frames of happy that I'm just going to make you all wait fer.

The mouse ears was irritating. I knew it happened when I came out to check and the ST-4 was thrashing from E to -E. grr. I ended the exposure right away, but...

Maybe I'll do another 60 on this roll, just for the sake of knowing the skyfog limit.



Jimbo

#17 Suk Lee

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Posted 13 September 2004 - 04:32 PM

I was surprised and a little disappointed (I got over it :)) that there was slight vignetting in the corners of these. It's definitely a lot better with the 2" adapter than it was with the 1.25" one, though.


It's caused by the T-ring itself. Taks try to reduce the effect by having a 2.7" (or 4") focuser and a "wide" T-ring that reduces the constriction at the camera...

I wouldn't turn down a cooled CCD + CFW, but I really like the wide expanses of sky that I can fit on my 24mmx36mm "chip".


:jump: Yeah! That's what I love about film imaging, the beautiful wide expanses...

Is there a good way to "see" the skyfog limit? Like, will it show up as a histogram that I just.. can't.. tweak the scan settions enough to "unpeg" it from the left, or something like that?


Skyfog is the huge "hump" at the left side of the histogram. Also buried in there are faint stars and bit of nebulae...

Is there a point at which more stacking is not really going to help? I'm beginning to look at this image like a stew; simmer for awhile, then add a handful of new stuff. :)


Digital and silver noise are very different in spatial characteristics, I find that silver noise "knocks down" a lot faster than digital noise. I find that averaging 3 shots usually makes a dramatic difference and anything more than about 6 shots is just becoming masochistic.

The ST-4 was really humming last night. I planned on doing a couple of 45's and quitting for the night, but it was *so* clear and steady that I couldn't help myself, and I popped another 20min on for the evening, and then another one.


I know the feeling!!!

Maybe I'll do another 60 on this roll, just for the sake of knowing the skyfog limit.


Definitely worth knowing, since film is pretty nonlinear. It's strongly correlated with focal length - my experience is that you can shoot longer than you would expect, based on f-stop, with a longer focal length than short. i.e. you can shoot more than twice as long at 200mm @ f4 than 50mm @ f2.8 (where you would only expect to shoot twice as long because it's only 1 stop slower). I suspect it's because with longer focal lengths the sky fog is lower in the "toe" of the sensitivity curve of the film, so the stars and bright nebulae bits accumulate faster (because they're higher up the curve) than the skyglow.

Your shots have motivated me to take another stab at M31, but I'll do it with CCD!! (ST2000 and 180mm lens frames it nicely)

Cheers,
Suk

#18 Dennis

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Posted 13 September 2004 - 04:49 PM

Awesome images guys. Great depth. Still trying to get through my first roll with my OM-1. Autoguide just went on my list. Keep em coming.

#19 Rushwind

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Posted 13 September 2004 - 06:20 PM

Suk,

If it's the T-ring itself (I believe you, there; the 2" adapter is definitely "out of the way"), then I'm going to stop thinking about it. The vignetting was *very* slight (looked like those little stick-on corner tab thingies). This is me, breathing. :grin:

Re: histogram.
Often, when I do my inital preview scan (I get to look at the histogram in the TWAIN dialog before I import to PS), the histogram is jammed up against the left side of the box (so there's a ramp-down on the right, but it's still maxed out on the left). If I tweak the "exposure" settings in the TWAIN dialog, I can get the whole histogram to move to the right, some. I can tweak L, R, G, or B (or all of these). Once I do this, then usually, I can get the histogram to a place where there's a ramp-up on the left, a maxed out area, and a ramp-down on the right. When I'm then stretching the levels in PS, I move black to the bottom of the ramp-up curve, white to the bottom of the ramp-down curve, and the mid-range slider to about halfway up the ramp-down curve. Does that make sense? Is that about right?

How do I know if I've hit the skyfog "limit"? Is it the left-to-right position of the hump, or is it whether the hump goes to 100% in height, or is it the width of the hump? Or is it something else? :question:

Perhaps I'll cut my stack off at 5x45 and 5x20. I mean, "hurt me, but only a little, OK?" :D

Hey, get on that new M31 shot; I need another good image to color balance mine against.... :)

Dennis,

What targets are you chasing on your roll? What kind of film are you running? How many shots left before we can see something? We need answers, man! :)

Jimbo

#20 spaceydee

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Posted 13 September 2004 - 09:15 PM

Jimbo, did you change your avatar?? :)
Looks nice!

#21 raydar

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Posted 13 September 2004 - 09:37 PM

I know it has something to do with guiding (lol) but what exaclty does ST-4 mean.

Also, was the film pushed? If no, why not?

Great shot mate

#22 Dennis

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Posted 13 September 2004 - 09:57 PM

Dennis,What targets are you chasing on your roll? What kind of film are you running? How many shots left before we can see something? We need answers, man!


On my first roll of plain 400 asa. Piggy backing on my Celestron. Have a couple of adapter for afocal and through EP but want to see this roll first. Just shooting constellations. Shot the Big Dipper sitting in a notch of pines tonight. Been working on this roll for about 3 mohths. Never enough clear skies this summer to fit in viewing and filming. Viewing has won out. Hoping for a stretch of good viewing to start making progress. Am watching these threads though.

#23 Rushwind

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Posted 14 September 2004 - 03:44 AM

Dee,

You noticed! aw, shucks. :o Funny how the photo looks even better when you scrunch it down to 80x80...:grin:

raydar,

The autoguiding camera that I use is an SBIG ST-4. It's no longer in production (easily acquired on the used market, however), and has been sort of the "flagship" autoguider for quite some time (over a decade?). It's really easy to use (once you get the hang of it), and doesn't require a computer (all standalone), so it's just perfect for film imaging, because I can take my rig to someplace dark and run the whole thing off of a 12v powertank. Anyway, if you want an autoguider, you can't go wrong picking up a used ST-4. They're simply wonderful.

Dennis,
I'm a big fan of widefield stuff. I'm a little irritated that it looks like I may not get a shot of Sagittarius this year (my house is in the way), but I'm determined to pick up a widefield of Cygnus. I think that my next roll will be all piggyback.

I, too, started out (just 9 rolls ago!) with a random roll of 400 asa that was rolling around in my camera bag. Threw it on a fixed tripod, got a couple of star trails shots, and just kept rolling. Luckily, summer is pretty good for stars where I live, so it's been a productive time to learn on my new gear. I'm really looking forward, as I said, to getting back on the widefield train for awhile; the summer Milky Way is just too cool to miss.

I'm keeping my fingers crossed for clear skies in your future!

Jimbo

#24 Guest_**DONOTDELETE**_*

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Posted 14 September 2004 - 05:28 AM

After seeing the great results you guys are achieving as evidenced by the previous photos in this thread, it is with great humility that I post this piggy-backed shot of M31 (my first try). Hey, you have to crawl before you can walk!
The bright star directly below M31 is Nu Andromedae, and Mu Andromedae is lower right. The exposure time was about 2 1/2 minutes with 50 mm lens.

Bill in WI

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  • 196168-M31tracked.jpg


#25 Rushwind

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Posted 14 September 2004 - 12:04 PM

Good looking picture, Bill! What kind of film were you using?

Jimbo


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