8 replies to this topic

[james7ca]

I took these frames back in mid-December and just finished my first pass on the processing. This is a two frame mosaic that was captured with an uncooled ZWO ASI174MM camera and a Tele Vue NP127is (528mm e.f.l. with 0.8X reducer, f/4.2). Each half of the mosaic had 84 x 96 seconds of exposure through a Baader 7nm H-alpha filter (134 minutes of total integration time for each panel).

 

Processing was done in PixInsight and Photoshop CC2015.

 

There are a few banding artifacts (from the camera) which I may work to remove and I didn't apply any noise or star reduction in PI since I thought I could wait until it had been exported to Photoshop to do those kinds of tweaks. But, with more work on those areas and a 2X drizzle in PI I think I could get a better result (maybe in the next day or two, the drizzle is needed as the stars were undersampled).

 

This is a 1276 x 1200 image, reduced significantly to meeting the CN posting guidelines (the final matrix was about 2K x 2K).

Attached Thumbnails

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Edited by james7ca, 19 January 2016 - 04:27 AM.

[pedxing]

Beautiful, great depth and detail, hard to believe it's only about 2 hours of integration.

 

Good job!

[james7ca]

Well, the Rosette is crazy bright and in fact it is the only emission nebula other than M42 that I've been able to image successfully in both RGB and Ha from my red/orange zone location. I may even try to combine this image with some RGB data that I took a few years ago with an unmodified Sony NEX-5 APS-C camera.

[entilza]

Great image!  I know that scope is something special though!  I wonder how this camera would work with my setup.  I have some rosette data but the backyard is difficult.

[james7ca]

Great image!  I know that scope is something special though!  I wonder how this camera would work with my setup.  I have some rosette data but the backyard is difficult.

I've had some problems with the NP127is when imaging in Ha, the scope wants to produce lopsided stars unless I defocus the image (you can see a small amount of this problem here, since even when defocused the stars aren't round). However, it's a fast system at only f/4.2 so that definitely helps with these relatively short exposures.

 

This was taken under red/orange zone light pollution and like I said before I've even been able to photograph the Rosette in RGB under this same sky.

 

Thanks for the notice.

[josh smith]

Very nice work on this! Did I read right in the other thread that you got the 178?

[SergeC]

Amazing camera. Well done.

[Goofi]

Fantastic image ... you keep producing these stunners with that camera, well done!

[james7ca]

Josh, Serge, and Goofi, thanks for the notice.

 

Yes, I also have the cooled version of ZWO's ASI178MM and I've already posted a few images from that camera. The ASI178 is kind of on the "bleeding edge" for DSO photography (I suspect) and some very preliminary results suggest that the cooling MAY not really give you that much over what you could do with a good set of calibration frames on the uncooled version of the camera. However, I'm hoping more for thermal stability which may allow me to skip taking DF and bias frames with every session.

 

Note also that with the smaller field of the ASI178MM you'd need at least 6 overlapping frames to cover the field that is shown in this 2 frame mosaic that was taken with the larger ASI174MM. But, that would also produce a result with about 30 mega pixels of resolution whereas with the ASI174MM you only get about 4 mega pixels (for the entire mosaic).

Edited by james7ca, 19 January 2016 - 09:10 PM.