iOptron SkyTracker + Examples

That is just beautiful!

You really did a great job.

andicus wrote in post #17995107
That is just beautiful!

You really did a great job.

Thanks!

This is a comparison of the stacking with and without the images taken with the Optolong UHC filter. I did two sets of exposures, one with the filter in and one without, each set is ISO 400 and f2.5, 2x 4 minutes, 2x 2 minutes, and 2x 1 minute exposures. Stacked with Deep Sky Stacker and edited with PixInsight and Photoshop. Shot from a Bortle 4/5 zone at Rockport Reservoir, Utah.

The image on the left is the set without the Optolong stacked, the image on the right is with and without the filter stacked together. I tried to edit them as similar as possible. I'm pretty excited about the improvement in the red channel data with a non-modified (and Nikon is notoriously stringent with filtering the red spectrum vs Canon) DSLR.

Tried an edit of my last Milky Way shot to see if I could bring out the nebulosity around the core region a bit more, turned out pretty nice:

pdxbenedetti wrote in post #17999117
Tried an edit of my last Milky Way shot to see if I could bring out the nebulosity around the core region a bit more, turned out pretty nice:

There was discussion earlier about light pollution, I took the shots for this image from a Green/Yellow transition zone (Bortle 4/5) marked with an arrow, about 35 miles from Salt Lake City, Utah (see the map below). When I took these shots the Milky Way was straight south so I was looking into light pollution from Park City and Heber. You can still get quality Milky Way shots from somewhat light polluted areas, not bad for only a 30 minute drive from home.

Great processing.

I need to try this some time. Are you just taking your 8 shots per panel and loading each into DSS as light frames? Any particular changes other than a normal stack session? I'm curious what your histograms looked like on those.

Very best,

MalVeauX wrote in post #17999139
Great processing.

I need to try this some time. Are you just taking your 8 shots per panel and loading each into DSS as light frames? Any particular changes other than a normal stack session? I'm curious what your histograms looked like on those.

Very best,

Ya, stacking the 8 shots as light frames in DSS, saving as a 32bit FTS file, opening in PixInsight and doing background + color calibration and basic histogram/curves stretching to get each panel to match in terms of brightness/contrast, exporting as 16bit TIFF files, open the 6 frames in PTGui and blend/merge, save as a photoshop document, then open in Photoshop and edit.

Out of DSS the stacked image is very dark, after background calibration and histogram/curve stretching the histogram is pretty much a single peak (since the colors are then calibrated/balanced) about 1/3 off the left side. Only in photoshop do I do the big time curve stretching and color saturation changes, sharpening, luminence, star shrinking, etc.

pdxbenedetti wrote in post #17999153
Ya, stacking the 8 shots as light frames in DSS, saving as a 32bit FTS file, opening in PixInsight and doing background + color calibration and basic histogram/curves stretching to get each panel to match in terms of brightness/contrast, exporting as 16bit TIFF files, open the 6 frames in PTGui and blend/merge, save as a photoshop document, then open in Photoshop and edit.

Out of DSS the stacked image is very dark, after background calibration and histogram/curve stretching the histogram is pretty much a single peak (since the colors are then calibrated/balanced) about 1/3 off the left side. Only in photoshop do I do the big time curve stretching and color saturation changes, sharpening, luminence, star shrinking, etc.

Interesting thanks.

I don't have PixInsight so I'm not familiar with all it's workings. Mainly just DSS & Photoshop (CS5). I'll have to play around soon if I can with some variable exposure times and stack them in DSS to see how it plays together versus just getting a few that have the most data in the histogram and stacking to reduce noise. I'm curious how DSS plays with the different exposures for areas that are over-exposed versus under-exposed since it mainly just reduces noise and doesn't do much else (maybe I'm wrong there).

Very best,

DSS does a fantastic job stacking different exposure lengths or ISO/f-stop settings, I find that for areas that have a big range of brightness (like the Milky Way core or even DSO's like the Orion Nebula with its super bright core) it allows you to bring out faint details with long exposure length while keeping the highlights in check. I'm shooting at ISO 400 or 800 for pretty much all my shots now so the noise only because an issue when I do crazy stretching like in the dusty regions of the Rho Ophiuchi complex. I'm going to give this another go from some darker skies and hopefully be able to push the exposure lengths to 5+ minutes to really get at that dusty part so I don't have to do such drastic stretching/processing to bring it out (and make it noisy in the process).

A couple recent ones of the core showing the effect clouds have on the shots:

Nikon D600 and Rokinon 85mm f1.4 on the iOptron Skytracker mount, 2 minute exposure, f2.0, ISO 800, whole sky was covered in high wispy thin clouds:

I bit the bullet and bought a Starwatcher Star Adventurer with the declination bracket and counter-weight setup hoping it'd allow me to use my 150-600mm lens for much longer exposures than what's possible with the iOptron (~1 minute max is the best I could do with the iOptron). It's a well constructed tracking mount, overall I think the quality of the Star Adventurer is significantly better than the iOptron, it's design does not have the flaws that the iOptron has (namely the body and polar scope getting in the way of the camera/long lens). It also has several tracking speeds and you can also do one axis guiding with a computer, plus it has fine adjustment controls for the dec and RA axis which is awesome. Overall it's a much better package than the Skytracker for about $100 more (including the EQ mount and counter-weight attachments).

Last night was the definition of frustrating and mixed bag, decided to head up to Rockport to do some testing with the Star Adventurer mount, got there and it was still a bit cloudy. So I set everything up, clouds cleared around Polaris enough to do an alignment, then clouds cleared enough to the east to do some shots of the Veil Nebula. Just as I set the intervalometer to take a series of shots it got cloudy again, so I only got a couple shots of the Veil, only 1 was decent but at least I managed a 3 minute exposure. It stayed cloudy almost until moonrise and because of the proximity of the moon to 52 Cyg I decided to can the Veil and take some test shots of the Lagoon Nebula. I just could not do better than 1 minute exposures without getting horrible star trailing, probably due to the location and having to put the Camera+lens so far off to the side of the mount (RA Axis), even though it seemed decently balanced.

On top of that there was a decent little 5mph breeze that kept gusting up to maybe 10mph and vibrations at 600mm (900mm effective with the D7000) focal length are a serious problem. If it stays clear tonight I'll try using the ballhead even though that will introduced another flex point (more vibration problems), I don't want to use it but it'll allow me to keep the camera+lens/counter-weight more vertical. Hopefully that helps.

Here's the shot of the Veil Nebula and Lagoon Nebula, only a single (uncalibrated) exposure of each so the editing is very harsh.

MalVeauX wrote in post #17309440
Heya,

I'm by no means a master of stacking. I just know that the point of stacking is to remove noise, it doesn't add detail or anything. It takes away information, oddly enough. So taking 40 light frames at 20 seconds each, like you have here, and doing 20 dark frames and 20 bias frames for a total of 80 frames (just to keep it less time consuming to process), would generate a master file that basically represents what is the constant light, and what is the noise or random light, and remove that. The result would be a cleaner image that has more of what is constantly there (the nebula) and less of what's just interfering (random stuff & ISO noise).

I like your method though, the result is quite good. Sure there's noise, but that's because you used a T3i. I'm sure if you were using your 6D, it would have been quite smooth.

I'm hoping to try Orion Nebula with a 650D and a 200 F2.8L prime on the iOptron. The weight is just enough, and I should be able to do it at a lower ISO with the tracker, to help keep the noise down. Gotta try that soon. Looks like best time for me is 11pm the next few nights, but the moon is also out, at least in my hemisphere.

Very best,

Nearly all my astro shots so far are stacked, as this is the only way to de-noise that preserves detail. Normal photographic de-noising techniques do not work, Topaz, Noisewre, et al, kill the stars.


I don't have a tracker yet, so I rely on high iso& shutter speed to combat trails, typically stacking 30 images + 30 darks in DSS.
200mm on a 5d3, sample shot of ETA Carinae. Notice the detail ? This is from stacking.

Photo from Pepster's gallery.
Image hosted by forum (770775)

Topaz, Noiseware, et al, kills stars. Stacking is the way to go to preserve detail.

Here is a 30x stack of the LMC + 30 darks, stacked in DSS.

No tracker (yet), but after seeing all the fabulous images in this thread, I think it is time to get one.

Photo from Pepster's gallery.
Image hosted by forum (767089)

I have the 100-400L II, and can tell you: GET THIS LENS !

It is the latest tech from Canon and the older lenses simply are not as good. I also have the revered 70-200L F2.8 II, and I can assure you that it is not nearly as good as the 100-400L II

Birds in flight ? Meh.. I have shot crispy clear dragon flys in flight with the 100-400L II + 1.4× III TC, AFs like a champ on my 5d3.

Lenses are like cars, older lenses are superceded by newer tech.

Pepster wrote in post #18025673
Nearly all my astro shots so far are stacked, as this is the only way to de-noise that preserves detail. Normal photographic de-noising techniques do not work, Topaz, Noisewre, et al, kill the stars.

You are correct , stacking multiple images is a big factor at reducing noise in night time images but Topaz DeNoise is the best on the market . I've had it for a few years now but I don't use it when stacking multiple images unless there is a small amount of noise I can't handle after all the stacking and editing . There is a lot of confusion over using a denoise program before or after editing . Myself if it's a night time shot that is multiple stacks I do so if needed after stacking , not before . If it's a daytime image I use it first before editing . One thing about any night time image is your going to have noise no matter what and if you use a denoise program your going to loose a certain amount of detail because of things being so small in images . But used properly a denoise program is one of your best friendly programs you can have . Any image that has a lot of stars it's best not to use a denoise program if you can get away with it because of hiding detail .

If you've got LOTS of images, then stacking is certainly the best way to eliminate the noise (or other unwanted anomalous artifacts) because the software can perform statistical analysis to clip out the noise (sigma clipping).

Some cameras, however, have pattern noise or stuck pixels and since those would appear in every frame, it can fool the software into thinking it's supposed to be there. A true computer controlled equatorial mount and guiding software can deal with that problem. Guiding software (such as PHD2) and image acquisition software (such as Backyard EOS, Backyard NIK, or Nebulosity) will "talk" to each other so that when the camera finishes taking one frame, it tells PHD2... which in-turn nudges the mount just a tiny amount, then tells the image acquisition software to grab the next frame (and this process of capturing a frame, nudging the mount a tiny amount in a random direction, capturing the next frame, nudging the mount, etc. repeats until all the frames are collected.) Now you have a set of images which are each slightly shifted. When the image registration software aligns the stars, the "noise" will no longer be aligned (including pattern noise and stuck pixels) and this allows the computer to easily identify that it should be removed and you get an even cleaner image. Unfortunately a tracking mount is too simple to be able to handle this... you need a full computerized equatorial mount. Still, the prices of lower-end computerized mounts (that would easily be sufficient for long exposure images with a camera & camera lens) start in the price range of the higher-end tracking mounts (a Celestron Advanced VX (aka "AVX") mount is roughly in the same price range as my Losmandy StarLapse tracking head.) but using an auto-guider requires a 2nd scope (a guide-scope) and a guide-camera. I use an Orion ST80 (short-tube refractor) for this. The Orion StarShoot AutoGuider (SSAG) is possibly the most popular auto-guiding camera. I use an LVI SmartGuider2 which is self-contained (doesn't need PHD2 software or a computer) and it also has a port that can control the image capture of the camera (it coordinates the dithering and image capture). You can get a dual-saddle mount to fit on a telescope mount which would allow you to hold a camera (or telescope) and the guide-scope & camera on the same mount.

As for not using a tracking mount and just taking many more very short exposures... that does work but it's MUCH easier to use a tracking mount because very short exposures end up with a terrible signal-to-noise ratio. Longer exposures allow for a much better signal to noise ratio.

As for noise software -- it's true that ANY amount of de-noising also sacrifices some detail. So it's best to not need it (or try to not need "much" of it anyway), I've tried a few and so far my favorite has been Imagenomic Noiseware Pro. What I can do with Noiseware that I could not do with the other methods was to set the frequency range and level of noise. Noise tends to show up in the darkest parts of the image. So I can tell it the noise is high in the dark areas and let it be a bit more aggressive ... and tell it to leave the brighter areas alone. Basically I can "tune" the behavior of the noise reduction so it's not just a global level of reduction across the entire image.

TCampbell wrote in post #18025847
...............

Some cameras, however, have pattern noise or stuck pixels and since those would appear in every frame, it can fool the software into thinking it's supposed to be there. ...............

And that is why you do dark frames so the software like DSS and subtract hot and coloured pixels ... problem solved

Dave