p.15 #4 · Nightscapes using AstroTrac Tracking Mount
I just got my Astrotrac. Looking forward to using it once the rain stops! This thread has me excited to bring out a new avenue to pursue. I am mainly interested in incorporating the night sky into my landscape photography, so that will be an interesting challenge. The images here are very impressive.
I started simple with a Manfrotto 410 Jr geared head to mount the Astrotrac to the tripod. and using my current Arca Swiss Z1 to mount the camera. No guiding, just tracking. Should be fun.
p.15 #5 · Nightscapes using AstroTrac Tracking Mount
astro-ep wrote:
Wow, those are really great images, Todd. Are these single exposures or stacks? Really impressive shots with a DSLR.
Eric
Hi Eric,
Thanks for the comments. These are indeed single exposures. The current Nikon bodies have low noise and great dynamic range compared to canon. I have never had to stack images. I'm very happy with my Nikon D800/E bodies.
p.15 #6 · Nightscapes using AstroTrac Tracking Mount
Todd wrote:
Hi Eric,
Thanks for the comments. These are indeed single exposures. The current Nikon bodies have low noise and great dynamic range compared to canon. I have never had to stack images. I'm very happy with my Nikon D800/E bodies.
Todd
Todd, I can't disagree with anything you said, but you may be pleasantly surprised what just a few lights and darks can do to your already impressive photos.
p.15 #7 · Nightscapes using AstroTrac Tracking Mount
Here's my latest attempt. I started taking this at about 4:00am after I spent hours fighting with drift alignment. I ended up just giving up and sticking with regular polar alignment. I wanted to try autoguiding but I was having equipment issues with a clamp so I went without it, but I am very happy with the result.
About 31 minutes of exposures, due to the time constraints I shot sets of 3 exposures ranging from 30 to 180 seconds, and only one dark frame for each exposure. The shots were stacked in in Deep Sky Stacker and the final iamge was processed the image in Lightroom 4. Any tips on adjusting the white balance?
p.15 #8 · Nightscapes using AstroTrac Tracking Mount
Excellent shot there. Very nice detail.
The galaxy has a bit too much magenta I think. But I see many different colored versions of this, so do what you like.
Your black point is probably too dark.
Good job.
I was camping out this am for the meteor shower but was hammered by clouds and bugs. Glad I made it out alive.
p.15 #9 · Nightscapes using AstroTrac Tracking Mount
Interesting thread!
One of the reasons I haven't posted here for some time is that I got distracted into astrophotography. Is there a case for a Fred Miranda Astro board ??
Here is an image I took a few days (nights!) ago, of an object in the Southern sky rejoicing in the name NGC6188/93. It is an emission nebula/ reflection nebula/ open star cluster abot 4000light years away.
Total exposure time was 90 minutes
The tracking mount is by ASA (Austrian) and it can track with extraordinary precision (<1arcsec for at least 2-3 hours)
For anyone interested the telescope lens is 250mm aperture, f/3.6, and the camera is a cooled CCD astro camera.
p.15 #10 · Nightscapes using AstroTrac Tracking Mount
These are phenomenal and the conversation very interesting and enlightening. I wish I had the budget for even the basic setup.
I read all 15 pages and did not see any mention of heads like the video fluid heads and the 3-way pan heads. Are either of these workable for this kind of work (attaching the AstroTrac to it)?
p.15 #11 · Nightscapes using AstroTrac Tracking Mount
kwoodard wrote:
These are phenomenal and the conversation very interesting and enlightening. I wish I had the budget for even the basic setup.
I read all 15 pages and did not see any mention of heads like the video fluid heads and the 3-way pan heads. Are either of these workable for this kind of work (attaching the AstroTrac to it)?
I purchased a monfrotto geared head (410) for it and it's really the best way to go. Once you try it, you won't go back.
p.15 #14 · Nightscapes using AstroTrac Tracking Mount
dasams wrote:
Shooting at 800 or 1600 is preferred over 100 for several reasons. First of all, the higher ISO means a shorter exposure time which allows for more shots in a given session. Secondly, stacking images improves the S/N ratio as hot and variable pixels are removed. Shooting multiple darks also gives a reference for subtraction of high ISO noise. Finally, shorter exposures also reduces tracking errors. I'm sure there are other reasons I've missed so please chime in. Dave
Can someone help me with understanding what shooting multiple darks is? I've seen reference to it a lot but not an explanation. Is it shooting some images in the same framing at a shutter speed and exposure that results in completely black images that are used in post processing to reduce ISO noise?
p.15 #15 · Nightscapes using AstroTrac Tracking Mount
Jim,
sounds like you got the gist of it. A dark frame is taken:
1. at the same duration, iso, and temperature** as the light image.
2. The lens or sensor is covered from all light so that all that is recorded by the sensor is the noise.
Subtracting a dark from from an image helps reduce the noise. While a single dark frame may contain some other sources of noise such as cosmic ray hits and such, averaging a bunch of dark frames gives you a better representation of the fixed pattern noise.
One would then use the "master" averaged dark file to subtract from your light images.
**Noise changes with temperature, colder is better. Dedicated astro camera have regulated cooling to keep the sensor at precise temperature. Thus, dark and light frames are all taken at the same temperature. This is not possible with DSLR's but taking dark files on the same night as the images are taken is close enough (and better than nothing).
p.15 #16 · Nightscapes using AstroTrac Tracking Mount
Socalastro wrote:
Jim,
sounds like you got the gist of it. A dark frame is taken:
1. at the same duration, iso, and temperature** as the light image.
2. The lens or sensor is covered from all light so that all that is recorded by the sensor is the noise.
Subtracting a dark from from an image helps reduce the noise. While a single dark frame may contain some other sources of noise such as cosmic ray hits and such, averaging a bunch of dark frames gives you a better representation of the fixed pattern noise.
One would then use the "master" averaged dark file to subtract from your light images.
**Noise changes with temperature, colder is better. Dedicated astro camera have regulated cooling to keep the sensor at precise temperature. Thus, dark and light frames are all taken at the same temperature. This is not possible with DSLR's but taking dark files on the same night as the images are taken is close enough (and better than nothing).
p.15 #17 · Nightscapes using AstroTrac Tracking Mount
Deep sky stacker is great. I tried processing my recent images in DSS for luminance and saturation which initially looked ok, but examining the TIFF closely I noticed that the brighter stars had a central black 'crunchy blotch'. Looked like some black hole scab. Even small stars had them but it was not noticeable zoomed out. So, I saved the tiff "without applying edits" and the blotches went away. Net effect was the stars looked less crunchy especially the milky way core. Why go through all that effort by yourself in the cold at night with bears possibly watching you if it looks awful when you get home? Maybe I did something wrong, but I did cruise through a couple tutorials. For Canon cr2 raw files (recommend raw) I have to convert them to TIFF files first, o/w DSS won't work properly. You can do most editing in Lightroom except for overlaying the foreground with the sky portion (if you do a composite image).
p.15 #20 · Nightscapes using AstroTrac Tracking Mount
It's a great wedge. The manual isn't much.
You can find a copy of it in the Files section of the Astrotrac Yahoo group. Looking for the file link, I see you just joined the group and posted there.
The greater challenge will be collimation of the polar scope (keeping the center on axis as you rotate it). It was pure misery likely for something I must have done wrong in the past, and I suspect some others have needed counseling afterwards. I gave up and had an adapter made for my Vixen Polarie Polar scope. Enjoy your new toy!
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