Flame nebula, ASI120MM Halpha + Halpha as Red + Green + Blue

ndb

Five-layer processing for this image: three in Halpha (6nm) in 12 bits, one was re-used as red, plus two layers in green then blue (Astronomik LRGB filters) with binning 2x in 8 bits. I got rid of the red layer because the H-alpha was by far better. Color balance was easier to obtain, too. Only one dark per layer, acquired on the fly w/ FC.

The sensor naturally cooled down to 3.5°C (better conditions than when I was beta testing the ASI224MC in June !!!).

No guiding, no bias, no flat, no dark sky, the heating resistor rescued the images because of 2000% relative humidity :)

Now I'm thinking about a cooled ASI178 mono to improve results with short-focal telescopes and photolenses. Do you have some advice?

Nicolas

ngc2024_tair3s_halpha-37x120s+62x60s+45x60_rgb-25x10s_gain60_v2.jpg

Z0sF9b2n

ndb the link to the image does not work and is incomplete, how can I see it?

riklaunim

mono will allow using filters, like narrowband H-alpha which will make nebulosity visible better as well as limit lens chromatic aberrations. So there is potential to be used, as well as some cheap M42 that are actually good in terms of image quality.

ndb

Yes, that's exactly why I shot the nebula with a mono ASI120MM, Halpha and RGB filters with a vintage M42 telelens!

But I don't know if a cooled ASI could really bring the substantial improvements I'm waiting for. I've already shot Pickering's triangle with an uncooled ASI224MC in Halpha and very, very poor conditions, but I wonder if the comfort (that is, not permanently looking at the sensor temp to get new darks every 30 minutes) is worth the extra cost. Amp glow, remaining banding and likely detectivity alteration by non-disengageable FPN subtraction aboard the sensor (like DSLRs) cannot be fully fixed, after reports from beta testers of cooled ASI174. I added a unregulated (as for now) TEC on my ASI120MM and this brought some noticeable improvement while ZWO provides very serious cooling, therefore I'm extremely attracted by the ASI178MMC because I like DSO but I'm mainly a lunar photographer. The question is: eventually, is a cooled ASI really able to do the job of a cooled CCD (in addition, of course, of beeing a striking planetary camera)?

betacapricorni

Chapeau!!!

Inviato dal mio GT-I9301I utilizzando Tapatalk

riklaunim

ASI120MM has a bit of read noise and FPN. Cooled 174 would have less noise on start and easier processing due to smaller FPN. Keeping the exposures at some limit like 1-2min amp glow would still be low enough for easy removal. It should allow catching more fainter parts of nebulae, but also if you really try hard with ASI120 you could get some of that too, just harder ;)

Assuming you have dark sky high noise camera may not show as many nebulosity, check the image on the bottom on http://stefano-campani.net46.net/index.php?p=6_4 where you get a DSLR overlap on mouse hoover.

ndb

To Ricklaunim: 24-in Newton and Kaf 8300 ! :

This is no longer a hobby !

I'm not definitively sticked to the ASI120MM - especially after having tested the 224MC. I'm simply asking which cooled ASI could be best suited to short-focal telescopes and telelenses to get more extensions of galaxies and diffuse nebulae, the latter in narrow-band imaging (the latest ASI, cooled or not, proved to be excellent for planetary nebulae but that's not my main interest).

I was thinking about the ASI178MMC: affordable, 14-bit ADC, mono, regulated TEC, valuable well capacity, tiny photosites (counterbalanced by a better fill factor), little readout noise and plenty, plenty of pixels. The FOV is not an issue with small focal length. Unfortunately, despite the fact I didn't find any explanation about a possible detectivity threshold (but the on-board FPN cancellation), it seems that CMOS cameras are not suited to very long exposures to get faint DSO. Perhaps the lack of experience with these very new ASI cameras is deceptive: they possibly could conceal far better capacities to be explored. Are cooled CMOS limited to short exposures, excellent for planets and relatively bright DSO only? Did someone tried 10-mn exposures with a cooled 174 or 178?

Perhaps I'm too demanding and the best I have to do is to purchase a classic CCD for faint DSO, in addition to an uncooled ASI for the Moon and autoguiding. Unfortunately no uncooled ASI178MM is planned as for now. This is the only gap in ZWO's range in my opinion. But this could change in a not so distant future. I don't know.

To Betacapricorni: Merci !

betacapricorni

You are welcome! :)

Inviato dal mio GT-I9301I utilizzando Tapatalk