902 replies to this topic

[maadscientist]

Processed a 10x barlowed Saturn with the Esprit 120.

 

From May 9, 2015

 

Dan Llewellyn 

 

[dr.who]

Brian-

 

That is a great shot!

[james7ca]

There are a few things I'm noticing about the image quality of these small-bore shots. Firstly, there is sometimes a faint darkening near the outer edge of the rings (major axis, between Cassini's division and the outer edge of the ring). I think this may actually be a sharpening artifact and not a true feature of the ring system. Secondly, there appears to be a darkening on both sides of the planet's disk on the backside of the rings. The larger and more prominent of these darkening is the planet's shadow on the ring, however, I'm not sure what is causing the smaller darkening on the other side of the planet/ring. I think this may also be an artifact from the processing (or largely so) since it doesn't seem to be as nearly prominent or even visible in shots done with larger scopes.

 

Now for the "good" news. Some of these shots show evidence of the planet's disk as seen through Cassini's division. This causes an apparent "break" or decrease in contrast within the division. At one time I wondered whether this was an artifact from the foreshortening of the rings, but if you look carefully on the better shots you can see you are actually seeing the bright surface of the planet behind the rings (or in this case behind Cassini's division).

 

Lastly, on some of these images it almost seems like you can detect that the northern polar cap feature isn't perfectly round. Maybe this is wishful thinking on my part, but it looks like you can almost detect the hexagonal structure of this polar cap (or at least it looks like the edges are somewhat straight, not smoothly curved).

[BKBrown]

Brian-

 

That is a great shot!

Thanks!

 

This is a fun thread, and with lots of good pix to see . A few stand out for me: Darin, James, and kakadush all have images very close to my personal aesthetic: sharp, with clearly defined color bands and detail, and no effort in the best shots to push the scale too hard    One of the hardest things about Saturn in a smaller scope is being able to accept the limitations of scale and being willing to not push resizing and sharpening (wavelets or any other kind) too hard. I recommend keeping a light hand during processing, once we try to enlarge beyond a reasonable limit the lack of resolution will just result in a larger, blurry image with no additional coolness to be seen, and what is there to be corrupted...

 

Clear Skies,

Brian

[BKBrown]

5" Dobsonian reflector, 1200 frames captured with Logitech Quickcam Pro 4000 through 2x Barlow.

 

Question for the experts here.  I'm skeptical of 5X barlows (though some of the images here could change that), but I seem to be able to get plenty of light onto the CCD sensor for planetary images.  If I were to increase magnification (either by using a higher power barlow or stacking on another 2X) would I end up with a net loss or gain in detail?

 

 

That's a terrific effort with a 5" Dob and 2x magnification. Well done

 

Clear Skies,

Brian

[dr.planet]

Saturn through a Skywatcher 100ED w/ ASI120MM, Astronomik RGB filters, and 2x Barlow.  Processed with Autostakkert and GIMP, drizzle enlarged 1.5x.

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[KiwiRay]

Trying something different for last night's capture (May 15).  Here I've increased the sharpness and saturation beyond my usual taste.  Increasing saturation certainly highlights the bands, which were very hard to see with more natural colours.  Greater sharpness helps with that too, but also widens the Cassini division.  Used a Neximage 5 camera on a Celestron Nexstar 6SE with 2x Barlow.  Three 6-minute avis stacked in Autostakkert, processed in Registax, combined in WinJUPOS and further processed in Photoshop.

 

Edited by KiwiRay, 16 May 2015 - 08:20 AM.

[james7ca]

KiwiRay, your last image looks good to me, not too much color saturation (IMO) and you picked up a hint of the planet's surface behind (or through) Cassini's division.

[BKBrown]

Saturn through a Skywatcher 100ED w/ ASI120MM, Astronomik RGB filters, and 2x Barlow.  Processed with Autostakkert and GIMP, drizzle enlarged 1.5x.

 

Good job dr.planet, and I just love my SW100ED

 

Clear Skies,

Brian

[BKBrown]

KiwiRay, your last image looks good to me, not too much color saturation (IMO) and you picked up a hint of the planet's surface behind (or through) Cassini's division.

 

+1

Good job KiwiRay!

 

Clear Skies,

Brian

[eehar]

This is from last year.  Nexstar 6 SE and Neximage 5 camera.

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[Stargazer3236]

My first images of Saturn taken 5/23 @ 2:30 Am. Nexstar 6SE and Neximage 5. Took a dozen avi's and processed with Registax 6.

 

 

 

 

 

 

[kqn]

Hi All. Nice thread. I'm really enjoying the images and thought I'd throw my latest into the ring along with a question.  I've been trying planetary imaging with my 120mm Sky-Watcher doublet and have been using Scope -> 3xBarlow -> ASI120MC as the optical train but the resulting image fills a small area of the camera sensor.  So next I tried Scope -> 2XPowerMate -> 2xBarlow -> ASI120MC, ... but not much improvement.  So now I'm trying eyepiece projection using Scope -> 2XPowerMate -> 12mmPlossl -> ASI120MC.  This last arrangement definitely creates a much bigger image but is very hard to focus, which may be because of the crappy seeing we've had in New York lately.  But, I don't see a lot eyepiece project images here. Is there a reason? Is this is a bad idea?

 

Thanks,
Karl

 

[james7ca]

Karl, I'm not sure which model of the Sky-Watcher 120 you have (f/7.5 or f/5 or ...) but you've probably heard of the term "empty magnification" and because of that I'm not sure whether you can really gain much by trying to create a larger image. In any case, if you have the f/7.5 model and have already tried a 3X barlow then you may be just about at the limit of what you can do at capture time. The relatively small pixel size on the ASI120MC means that once you are working at about f/18 you can't really gain much from further magnification. You might be able to bump it up to f/24, but beyond that and you're probably just wasting photons (by requiring increased exposure times and having to work with dimmer images). You could try drizzle to create a larger image, but by the time you are working at those pixel scales (with your 120mm refractor) you probably aren't getting anything that couldn't be had from just a regular enlargement after capture.

 

One thing to check, with a typical barlow the effective magnification changes as you alter the spacing between the barlow and the camera/sensor. So, you want to make certain that the spacing you are using is giving you the specified magnifications (i.e. a "3X" barlow giving an actual 3X magnification factor, etc.).

 

If we take 18.5 arc seconds as the current, apparent diameter of Saturn's disk (the rings are obviously larger) then you should be able to work out the approximate pixel scale and magnification that you are currently getting. When I measured the image that you posted I got a scale of 0.28 arc seconds per pixel which means that for the ASI120MC you are capturing at an effective focal length of approximately 2800mm (f/23). But, of course, I don't know whether the image you posted has been enlarged or whether it is at a 1:1 reproduction from the original capture. In any case, if you have the f/7.5 version of the Sky-Watcher a 3X barlow should give you 3 x f/7.5 = f/22.5 which is in good agreement with my calculation.

 

As for eyepiece projection, as few years ago that was the only way I had to take high-magnification shots of the moon and planets and it seemed to work fine. However, when using that technique with a Powermate you're adding a lot of "glass" between you and the subject which is never the best of ideas. So, I'd say that there is really nothing wrong with eyepiece projection but that it may not be the most optimum way to achieve larger image scales (but, if that is what you have to do because you have no other alternatives then it's obviously the right thing to try).

 

By the way, that's a pretty good shot of Saturn given your 120mm of aperture. I would, however, try to brighten the image a bit and see if you can remove some of the overall green in rings and the planet's disk. Here is something that I did to your image with a fairly quick round in Photoshop.

 

[NOTE]This is a re-post of Karl's original image that was done with his Sky-Watcher 120[/NOTE]

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Edited by james7ca, 24 May 2015 - 03:44 PM.

[Herr Ointment]

All these make my attempts with my C11HD look ridiculous.

 

I'm utterly without practice and the seeing is awful.

 

Obviously from the work posted here there is hope for me yet!

 

Pretty and impressive!

[kqn]

james7ca, thanks for the info and the modified image which is definitely an improvement especially around the polar region. I'll have to fuss more with Paint Shop Pro to see if I can boost color and contrast a bit and duplicate the improvement. 

 

My scope is the 120mm Pro ED f7.5. With the 3x barlow I'm out of focuser travel and have to extent the barlow tube to achieve focus. Good thing the ASI120MC is a light-weight camera. I noticed in a previous post of yours that you're using a 4X PowerMate. I did not buy the 4X because of my focuser travel issue with the 3x barlow. Is that a valid concern?

 

The Saturn picture was taken using the ASI120MC 640x480 setting and cropped down to 400x300.  But the ASI120MC can shoot at 1280x960 so I feel like I'm wasting a lot of sensor real estate, thus the attempt at eyepiece projection.  There's probably going to be a sweet spot with the right eyepiece and right distance of the camera from the eyepiece, but you're correct in that too much magnification leads to a very dim image to the point of exceeding what the camera settings can mitigate.  Note the attached "Ghost of Saturn" image using eyepiece projection to nearly double the size of the planet, also cropped to 400x300 and no PSP processing. This was with the camera gain set to 100% and exposure length set to something that produced a discernible (maybe usable) image. Seeing was horrible.

 

BTW your modified version of my image gave me an idea for a new CN Thread (or Astronomy Reality Show): "Can This Image Be Saved?" wherein somebody submits a planetary video and everyone else tries to process it.  Votes are tallied and the submitter must send the winner a T-Shirt (any old T-shirt will do). 

 

Karl K.

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[james7ca]

Karl, you should be selecting a smaller region of interest to reduce the field size on the ASI120MC rather than trying to increase magnification to fill the entire 640 x 480 (or 1280 x 960) frame. By going to higher magnifications you aren't saving yourself from "wasting a lot of sensor real estate" but rather you are asking for more problems and poorer results.

 

I'd stick with the 3X barlow and reduce the region of interest until Saturn is framed with just a small border around the rings (that is, if your tracking is accurate enough to keep Saturn within that same field).

 

I'm using a 4X Powermate because I'm using an f/5.2 system, so I'm already sampling at less magnification than you are with the 3X barlow. Note, I'm working at around f/21 while you are apparently already up to something near f/23.

[PaulEK]

I took this one last year with a 5-inch Orion Apex Mak and a 2x Barlow. The camera was a Zwo ASI120MC.

 

[PaulEK]

I may have remembered the Barlow wrong. The other one I have is a 5x Powermate. The image of Mars in my avatar was taken with the same setup.

[KiwiRay]

My sharpest Saturn of the season from May 28.  We've had beautiful weather in Seattle this week, with seeing conditions to match - Saturn looks stunning in an 8mm eyepiece in my Nexstar 6SE.  As a bonus, I no longer have to get up at awful hours of the morning or sit in near-freezing temperatures to see it.  Capture and processing as in my May 16 post above. 

 

[kqn]

KiwiRay: Great image.  Good detail and very nice color balance.  Obviously, less clouds in Seattle means more clouds on Saturn.

[Gintasss]

2015 06 04 Saturn. Bresser Messier 127/1200 refractor + ASI 120 MC + 2X TSshorty Barlow.

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[Hesiod]

http://astrob.in/185191/B/

 

I processed the pic "halfway" between rings and disk, and left it rather soft to avoid "unnatural" contrasts. Seeing was rather good (Antoniadi III), so more version will come, to see if some details in A ring could be glimpsed (the pic on the left is here just to have a "term of reference")

[easybob95]

Hello,

 

here is my best Saturn with a SCT 6", barlow 2x and QHY5L-IIc. I don't have an other one left.

 

 

Clear skies.

 

Alain

[azure1961p]

Hi Folks,

 

Seeing was challenging this night when out of a dozen avi runs really only one was fair . Setup was my C6 at F18 using a dbk21au.04 at Y800- 60fps at 1/30 of a second, gain was 850 and Gamma was 98. BG algorithm.

 

I'm not happy with the granular look which I think is a result of the sharpening needed to overcome the lousy pickering value.  Still I nailed cassinis if imperfectly around the rings and I just began to get evidence of the thin thin belt bisecting the EZ.

 

I forgot if I drizzled or resized but its up 150%.

 

I'm a student so all advice and critiques welcome.

 

pete

 

 

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