gorann

Thanks a lot Martin! I have actually previously used it with an ASI1600MM and filter slider for Ha and it does work, but doing mono with RGB filters would defenitively not be worth the effort.

Fortunately Adam I am at a quite dark place so would not know how well it works under light pollution, but a dual band filter like I used on this one could probably work quite well.

Yes, some nights I can get an SQM of 21.6, so Bortle 2-3, but last night was not as great with an SQM of 21.1 and poor seeing. But an FL of 400 mm is quite forgiving and f/2 helps a lot.

Thanks Carol! 2 hours and 15 min😉

After a month of constant clouds I managed to get 27 x 5 min (so 2.25 hours) of data on the Squid and Bat nebulae last night. As everyone (here) knows this is an extremely faint object so I had no expectations more than maybe to see if it would be worth while to do it properly with many hours. While being clouded in I have as usual been shopping, so the RASA 8 is now sitting on an iOptron CEM70. The ASI2600MC is attached to the scope with a new dedicated adapter from Artesky (less flimsy than the supplied Celestron one) that also has threading for a 2" filter. So in there I put a new filter, an IDAS NBX dual band (Ha + Oiii) filter that is made for fast systems like the f/2 RASA. Maybe the Artesky adapter is the reason I could not see any annoying amount of tilt this time. Here is the result. I aim/hope to get more data over the next few nights but I think this proves that the RASA 8 is a real light bucket, the ASI2600MC is a very sensitive camera, and that dual band filters work quite well on OSC cameras. And, yes it is very very faint - I think I got stretch marks from doing this one🥴 Time to buy an OSC Olly @ollypenrice? 😁 PS. That little blue and red baby squid down in the right corner is real and not a reflection in the optical train.

No reducer can work for a full frame chip (=43 mm diagonal) with the Esprits since they are already full frame (40 - 44 mm imaging circle with Esprit 100 - 150) so a reducer would only cause a dark ring along the edges with a full frame camera and loss of resolution, so utterly useless. For Esprit 150, the image circle with the new reducer would be 44mm x 0.77 = 34 mm, so it would just about fill the frame of an APS-C.

It is great that these reducers were finally made. They have been greatly missed and perfect for APS-C and smaller sensors. "Unfortunately" I have now invested in a full frame ASI6200 for my Esprit 150 so a reducer would be useless. I could use one for my Esprit 100 but as I understand it, it still does not exist.

I like the thick cloudy feeling you got in the central parts of the galaxy, but like Wim I suspect that some background correction procedure has created a too abrupt end to the galaxy, it actually stretches out quite a bit. To get some more colour you could try to change it temporarily to LabColor in PS and tweak the a and b curves in s-shapes after anchoring them in the center. There are other tricks too - maybe google astrophotography and colour boosting.

That is a really great and spoky image Dave! You have Gamma Cassiopeiae under control, clearly showing how it lits up the Ghost and its neighboring nebulosity.

Lovely image! Must be two great mirrors as I cannot spot much coma in the corners, or have you sneaked in a coma corrector without telling us?😉

I fully agree with everyone above - an outstanding image Martin with great star control for being a telephoto lens, which makes me curious. Which one of the Canon 200mm is it: https://en.wikipedia.org/wiki/Canon_EF_200mm_lens

Yes, and takes a bit of digestion! Thanks Vlaiv! Do I get it right that when we add Ha to the red channel of an RGB image, we really take a high intensity signal that is near the limit of what our red cones can detect (so it looks very dull to our eyes even if it is a high intensity signal picked up by our camera) and spread it evenly over the whole red channel, thereby really boosting the Ha signal in a way that we could never percieve with our eyes.

Is that RGB or HaRGB? Looks like HaRGB to me (which should exaggerate the red) but maybe HST picks up more Ha in the red channel than amateur equipment.

I would also recommend 2" filters. Then you also have the filters you need if you get a full frame APS. The Esprit 150 with ASI6200 images I posted above was through a 2" Baader IR/UV filter and vignetting was minimal. Also, using APS-C on a fast system you need 2" filters.

If it finally happens, it will for sure be a bestseller. I just wonder why the rumors about this have been going on for so long and so far it has not materialized. There is even this supplier saying that it is temporarily sold out..... https://cloudbreakoptics.com/products/268m

@Allinthehead @tooth_drWhere do you line up for these APS-C mono cameras? I cannot even find them on the ZWO, QHY or ATIK web pages. Are you sure they will ever be produced?

Lovely M31 Dave! Maybe I should collect Ha for mine one day, maybe even do that before I make that extra left panel with the dust hook that @ollypenrice goes on about😉

I think I agree Olly (even if I have not slept on them), the second one is an improvement. But I bet that if we showed these images to the general public and let them have a vote, the first more colourful one would win.

I gave up waiting for a mono APS-C CMOS so I ended up going for an ASI6200MM. Is there a mono APS-C that can be bought now? I expected that I would have to do quite a bit of cropping but I am happy to report that at least my Esprit 150 gives a flat enough field with that full frame sensor. This is what it looks like (with the Esprit flattener - no reducer):

Looks quite nice Olly and I also remember Vlaiv's @vlaiv suggestion that we tend to exaggerate the blue in galaxies. So you and Vlaiv now inspired me to tweak my 2.6 hours of RASA data on M31. The top image is the "original" and in the bottom one I have just brought down the blue and green curves a little bit. Made quite a difference. I have not slept on it yet so I have hard to judge which one I prefer🤔 The other question is if I should or should not collect Ha for the image. Adding Ha would certainly make it less true to what it really should look like to our eyes.

If you go to https://www.facebook.com/optolongusa/ you will find this post of the Squid taken with a OSC CMOS camera and a dual band filter. Quite amazing:

To me it has been kind of a random process especially with the ASI2600 and the flimpsy Celestron adapter - some nights are better than others dependent on how it happened to be positioned. I hope the Artesky will prove a bit better. At least it does not have the soft pads on the back side and it wobbles a bit less when it comes to center it. For my ASI1600MM I use the Baader filter slider and it is a bit more repeatable and then also the chip is smaller.

To me it has been kind of a random process especially with the ASI2600 and the flimpsy Celestron adapter - some nights are better than others dependent on how it happened to be positioned. I hope the Artesky will prove a bit better. At least it does not have the soft pads on the back side and it wobbles a bit less when it comes to center it. For my ASI1600MM I use the Baader filter slider and it is a bit more repeatable and then also the chip is smaller.

yes, and rotate it around until I get the right corner lifted and all stars round. If the thickness is not enough I just fold it a bit more. I hope it could be quick and simple, maybe have the handle inside a rubber band around the camera. That is my theory at least - cannot test it yet.

Yes the ASI2600 also has a tilt plate but I think it would be very difficult to reach the screw heads to adjust it while it is attached to the RASA. I think I may have just invented an alternative made by a folded thin aluminium-sheet cut out from a beer can. It can be pressed in between the holder-ring and adapter (Artesky or Celestron). Clouds prohibit me to test in right now.