11 replies to this topic

[james7ca]

Here is the Lagoon Nebula as recorded by an Askar FMA180 Pro lens (40mm, f/4.5) and a ZWO ASI678MC uncooled planetary camera. You should click on the preview to see the full image size and to read more details on the capture that appear in the captions.

 

This was a test to see if I could image in one-shot-color within the worst part of the light dome of my Bortle 7 skies. The light pollution in this area is bad enough that it's quite difficult to see any of the stars that make up the so-called Tea Pot asterism of Sagittarius. I normally wouldn't attempt an RGB image this low toward my southern horizon (the Orion Nebula being my previous limit) but with it being galaxy season this was one of the few targets that I could try using the small FMA180.

 

That star cluster toward the lower left is NGC 6544, a 7.8 magnitude globular cluster that is being seen through much of the dust and gas that surrounds the Lagoon Nebula (making the stars look quite red). It may be more than twice as distant as the Lagoon nebula itself.

 

Given these results and later this summer I may try this target again in bi-color Ha and OIII with my larger format ZWO ASI183MM Pro camera.

 

Image capture with SharpCap Pro, processing with PixInsight (calibration, registration, integration, Spectrophotometric color calibration, histogram adjustments, StarXTerminator, BlurXTerminator) and Photoshop 2023 (recombined starless and stars layers, tweaks, photo frame).

 

Thanks for looking.

Attached Thumbnails

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Edited by james7ca, 04 May 2023 - 09:12 AM.

[John Miele]

Great image! I consider this pretty amazing...Bortle 7...one shot color...uncooled...  

[james7ca]

John, thanks for the comments.

 

Yes, it's surprising what you can do with a "cheap" scope and camera even under relatively poor conditions. However, it's interesting to note that the software used to process this image (PixInsight, Photoshop, StarXTerminator and BlurXTerminator) cost almost as much as both the scope and camera combined. However, I purchased PixInsight about ten years ago so its price has been well amortized over the years.

 

This is actually the first image that I've posted where I've used my recently purchased copies of StarXTerminator and BlurXTerminator. Those made a pretty significant difference in the final result, since I could "hit" the nebulosity pretty hard with noise reduction while keeping the stars small and sharp. I used BlurXTerminator to reduce the stars, I didn't do any sharpening on the nebula.

[calypsob]

Very nice James! I actually impulse purchased a 678 back in December and have not used it yet. The specs are impressive, you have demonstrated that this camera is easily capable of good data without any cooling. I bought mine with hopes to lucky image at f3 with my 12” newtonian. Do you mind sharing the integration time, gain, and exposure length? Im really amazed with your image from this tiny sensor.

 

Wait nm, I see you integration at the bottom right of the image now.

Very cool!

Edited by calypsob, 05 May 2023 - 10:54 AM.

[james7ca]

Very nice James! I actually impulse purchased a 678 back in December and have not used it yet. The specs are impressive, you have demonstrated that this camera is easily capable of good data without any cooling. I bought mine with hopes to lucky image at f3 with my 12” newtonian. Do you mind sharing the integration time, gain, and exposure length? Im really amazed with your image from this tiny sensor.

Wes, thanks. The gain, exposure time, and integration time are in the image captions along with other details.

 

Sony's IMX678 is a nice sensor for many purposes (as I've often said, mega pixels matter). However, without temperature regulation you're going to have some issues with calibration and you may find more pixel defects than you'd like in the finished integration. However, I typically do NOT dither and dithering would certainly help with this problem. 

Edited by james7ca, 05 May 2023 - 10:59 AM.

[erictheastrojunkie]

Very nice shot, I also picked up a 678mc to pair with my Rokinon 135mm as well as a 3D printed Newt project I've done just as an experiment. Have you noticed any walking noise/banding problems? I saw another post with it and the image had quite a bit of banding throughout, possibly as a result of the very tiny pixels and quantization error? Anyways, I'm excited to try using the tiny camera on some broadband targets, glad to see others getting good results with it. 

[james7ca]

I've had very few instances of significant walking noise on any of my cameras and the ASI678MC should be no different. Walking noise happens when you don't guide or track that well and when your calibration and cosmetic correction aren't working as they should (within a range of outcomes). That said, there will always be some walking noise but it really depends upon how much and how noticeable. It doesn't seem to be a huge issue with my images (sometimes visible if you look carefully, but there are ways to "hide" it with processing).

 

As for banding, it depends upon your definition. I don't see much color banding (i.e. wide bands with differences in color or noise). But, I do get color mottle and there is always some scanline pattern noise. However, there are ways to make these less visible in the finished image (but, probably NOT without some impact on the quality of the image).

 

All that said, I think some of the above problems are pretty much "swamped" by my light pollution and if I were at a darker site walking noise and banding would be a larger issue. Plus, the Lagoon Nebula is one of the brightest nebula visible from my location and that makes things a bit easier.

 

Probably the best way to deal with all of the above is to dither and to have darks taken during each imaging session (when using a camera without temperature regulation). But, I typically don't dither so I'm kind of breaking the "rules" fairly frequently. I also don't use bias files and you need to make certain that the calibration process doesn't try to "optimize" or scale your darks (and in any case, you need bias files for dark field optimization). I had assumed the latter prohibition was mainly concerned for cameras that had amp glow, but the ASI678MC doesn't really have any amp glow and yet for some reason dark field optimization still doesn't seem to work very well (in my hands).

 

By the way, here are links to two other images that I've taken with the Askar FMA180 Pro and the ZWO ASI678MC. I still plan on doing some more work on both of these since I think I can do better with the processing.

 

  https://www.cloudyni.../#entry12655731

 

  https://www.cloudyni.../#entry12647980

Edited by james7ca, 05 May 2023 - 03:29 PM.

[danny1976]

I am very interested in this telescope. Anything you can say about it, positive or negative. How is star quality in center and corners?

[james7ca]

Danny, I've only used the FMA180 Pro with the small ASI678MC sensor so I can't really give any good feedback on the "corner" performance. That said, both the center and corners look pretty much okay with the ASI678MC. However, I have noticed a slight amount of flare and "color" on one side of the field. It's minor but it adds a blue edge to bright stars and there appears to be an offset, oval flare on the stars on that side of the sensor. It looks somewhat like off-axis coma but the direction of the flare is exactly opposite to what you'd expect with coma.

 

But, it's fairly minor and you've got to remember that the ASI678MC has very small 2um pixels so it's going to show any kind of defect much more clearly than just about any other sensor.

 

It could be a spacing issue since I've not even tried to optimize that and I am still waiting until I can use a new ZWO EAF that I've just installed (using the Askar Autofocusing kit). So, changes to the spacing and perhaps a tilt adjustment might make the flare and slight color fringe go away. But, to fully answer your question I'd have to use the FMA180 Pro with something like an APS-C sensor and that's another thing that I plan to try when I get some clear skies (which have been absent for the last few weeks here in San Diego).

 

In any case, it's pretty minor and even if it can't be corrected with spacing if it gets NO worse even out to the edge of an APS-C sensor then I'd be very happy with the FMA180's performance.

[DavesGalaxy]

Hi James,

 

I just ordered the FMA180 Pro and I plan to use this with my QHY183C and QHY5III715C to see how it performs.  I am still trying to show that people don't account for pixel scale and seeing conditions affect the overall performance of optics.  I currently have been using a RASA 8" but living near Chicago, the weather has not been great and the smoke has ruined any change of imaging lately so I have missed a few clear nights as it take a while to setup and equalize the telescope temp.  So I am trying to put together a more portable rig that can be quickly setup anywhere.  I also have the ASI678MC but I wasn't too pleased with the performance but you did a great job with it.  I cant wait to see how this works and if I can break the law of the Dawes limit to capture resolution that normally you need a bigger aperture for!  Thanks to drizzling and deconvolution techniques I cant wait to see what I can produce.  You can also use 1x bayer drizzle to enhance your ASI678MC images as this removes the need for bayer interpolation that can cause blurriness and artifacts.  I look forward to to more image you are able to capture with this.  I hope I will be posting my own soon!

 

Clear Skies!

Dave

[james7ca]

Dave, thanks for the comments and good luck with your new setup.

 

I've used the ASI678MC quite a lot this summer but with the marine layer overcast we get at night here in San Diego I haven't been able to produce much total integration time (too few clear nights at all and those that start clear don't last very long).

 

The ASI678MC does seem to suffer somewhat from color mottle, but maybe that's just because it's an uncooled, one-shot-color camera (and quite cheap at that). It is, however, a good option if you want to increase or maximize your image scale.

 

Here are a few of my recent posts using the ASI678MC (but, only one more with the FMA180 Pro):

 

// M15 and Pease 1 with a Takahashi FC-100DZ

  https://www.cloudyni.../#entry12880586

 

// The Bow Tie Nebula with a Takahashi FC-100DZ

  https://www.cloudyni.../#entry12869961

 

// Rho Cassiopeiae with a Takahashi FC-100DZ

  https://www.cloudyni...post&p=12867961

 

// The Ring Nebula with a Takahashi FC-100DZ

  https://www.cloudyni.../#entry12861759

 

// Albireo with the FMA180 Pro

  https://www.cloudyni.../#entry12829349

Edited by james7ca, 20 August 2023 - 06:42 AM.

[DavesGalaxy]

Dave, thanks for the comments and good luck with your new setup.

 

I've used the ASI678MC quite a lot this summer but with the marine layer overcast we get at night here in San Diego I haven't been able to produce much total integration time (too few clear nights at all and those that start clear don't last very long).

 

The ASI678MC does seem to suffer somewhat from color mottle, but maybe that's just because it's an uncooled, one-shot-color camera (and quite cheap at that). It is, however, a good option if you want to increase or maximize your image scale.

 

Here are a few of my recent posts using the ASI678MC (but, only one more with the FMA180 Pro):

 

// M15 and Pease 1 with a Takahashi FC-100DZ

  https://www.cloudyni.../#entry12880586

 

// The Bow Tie Nebula with a Takahashi FC-100DZ

  https://www.cloudyni.../#entry12869961

 

// Rho Cassiopeiae with a Takahashi FC-100DZ

  https://www.cloudyni...post&p=12867961

 

// The Ring Nebula with a Takahashi FC-100DZ

  https://www.cloudyni.../#entry12861759

 

// Albireo with the FMA180 Pro

  https://www.cloudyni.../#entry12829349

Hey James!

 

These images are awesome!  I just posted a reply to this forum https://www.cloudyni...pro/?p=12935968

 

This is the image I produced with the FMA180Pro, QHY183C and the Askar Color Magic Duo 3nm 2" filter!

 

Clear Skies!

Dave