Adam J

New revision pushed a little harder, again maybe too far. The main aim here to be to bring out more of the background nebulocity. Adam

Got to admit that seeing the weight you have on the rig and the fact that the counter weight it located right at the end of its travel, I have difficulty believing that your RA is in balance. Adam

Yes you are out of colimation although you wont get much finess on that looking at Venus you need to use a star really. Its important that the star is in the centre of the field BTW. Adam

flatness and colour correction look ok for the size of the sensor at least. Would be nice to see it on a larger sensor camera.

I think it would be an interesting experiment to put a 400mm triplet refactor mono camera combination next to a RASA 8 with a OSC and the same pixel size and perform a comparison against a bright detailed target. Its very difficult looking at astrobin as as there is such a wider variation in processing ability. Ultimately Bayer interpolation is little better if at all than any up sampling algorithm as might be applied to any image in Photoshop. I would also point out that only the Red and Blue pixels resolve to a single larger pixel, the green is different as it has higher sampling. In terms of OCS broadband RGB imaging the algorithm will perform better as it uses the green channel to improve B and R as a kind of luminescence. But if using a duel band filter and extracting the Ha and OIII channels that methodology does not apply, in fact debeyering of that type doesn't occur at all and cant without mixing the Ha and OIII channel data (don't want to do that). In this instance you will and do end up with Ha super pixels that are then up-scaled to the original resolution using a bi-linear interpolation, OIII being a little more interesting than this. Its is in the use of duel band filters that you see the most significant reduction in resolution vs mono narrow-band. I suspect that back in your Atik 4000 imaging days duel band filters where not available, but in the end without trying a duel band on the ATIK4000s you are unlikely to see as significant a reduction in resolution. Using a RASA OSC vs mono is unlikely to make a big difference to resolution based on specification, that being because resolved detail will not be limited based on pixel size. The reason for this is that the spot size is much larger than the 3.75um pixels on the 2600, to the point that its larger than even the RGGB super pixel grouping. The same reasoning is behind the false belief that the ASI183mm or the ASI294mm pro in its bin 1 mode will gain you resolution. I have looked at many spot diagrams and not a single one when the spot size is at 2.3um or less. Top end performance is normally 3-4um more often 6um significantly larger than 2.3um pixels. Below is the spot diagram for the RASA 8, while in green its a lovely 3.6um, I will interpolate that for Ha (between the 600-700nm spots), it will have at least have doubled to 7um spots and thats on axis, that is about the same size as a Ha super pixel on the 2600mc pro. All in all the leaves you with a resolving power in Ha of about 3.6arc seconds. To put that into context the Daws limit is about 0.6 arc-seconds for an unobstructed aperture. The interesting thing is that a 80mm aperture quad refactor with a mono camera would be expected to perform at closer to 2 arc-seconds per pixel. In a nut shell I am one of the people that you will hear saying the RGGB resolves less than Mono, but as above that is also dependent on how you use it, the scope its paired with and the filter type being used, what it isn't is a blanket untrue statement. However, all of the above is a diversion and in the end we have the cameras available to use with a limited veraity of sensor sizes and pixel sizes. Hence, my advice to the OP stands, the 2600mc is a good camera so although its interesting to discuss the details above from an intellectual perspective I think you need to stop overthinking it as viable alternatives to the 2600mc are thin on the ground and I have seen excellent images across a wide range of focal length and diverse setups. Tine taken thinking about this stuff is imaging time lost. Adam

The FRA300 looks like a great little scope, there is allot of miss information about in respect to optimal sampling and pixel scale, my own thinking is the the optimal in the UK is between 2 and 3 arc seconds per pixel for mono cameras. If I wanted something between the FMA180 and the Esprit 100 then I think I would go with the FRA300 although I am cautious of flat feild astrographs at the cheaper end of the market. Wil be inteterested to see how it performs for you. Adam

Cant really tell from that but it is highly unlikely that you will produce spot sizes below 6um from a F4 Newtonian from what I have seen in other scopes. Quad flat field refractors can get down to 3-4um but fast Newtonians just don't perform as well as that due to the central obstruction and compromises within the coma corrector design. So basically what I am saying is that you are not going to be resolving images to the pixel level with that scope and a 3.75um pixel camera and so the camera pixel size is not going to be the limiting factor. In the end the 2600mc is going to work fine with either of those scopes certainly the Bayer Matrix is not going to be limiting you, your over thinking it...just get the camera. Adam

A mini PC running NINA is in my opinion the best option of all. Been using one for years, if your not processing on it don't be tempted to over spec the actual requirements are very low for image capture. I paid less for my mini pc then the cost or the original ASI Air. Adam

A link to my latest image for my fellow fma180 fans! Adam J

Firstly thanks for taking a look! I don’t have much time to image these days due to real life commitments and it’s been quite a while since I have done a longer integration as opposed to just pottering around. So I figured it was about time that I posted something in the DSO imaging section. Original: New V2: Looking through Astrobin content the question mark nebula as a whole is not one of the most imaged targets, most people focusing on the bright core as opposed to the whole object. This is most likely due to the short focal lengths required for all but the largest sensors normally meaning a lens as opposed to a telescope. This was shot at only 180mm with an Askar FMA180 40mm triplet refractor (the original version not the V2). I am a big fan of this little scope, its good for LRGB imaging but produces especially sharp images for its image scale in SHO. Also F4.5 is fast for a refractor and fast enough for me. I have tried to control the pallet in such a way as to show the three separate channels as three dominant colours within the final processed image as opposed to pushing it towards a duel gold and blue that most seem to favour in SHO. I have said it before but I am a big believer in three filters = three colours, or why did you bother shooting SII. One of the things I like about this little scope is just how nice and flat the field is to the corners of my ASI1600MM Pro sensor making for an idea portable / grab and go imaging setup. That’s something that is important to me these days as since I moved house and lost the observatory in the process I have not had time to setup my Esprit 100 and heavy AZEQ6 GTI, this rig being much more practical in my current situation, I can pick it up in one hand. This is also the first completed image that I have shot using my StarAdventurer GTI that I got back in August 2022. The biggest advantage over my previous AZ GTI setup being the ability to dither the mount without causing issues due to excessive backlash. This is ideal for a light weight travel setup and makes for a system that can just consistently produce excellent quality subs all night long without much supervision once properly setup. This image consists of a total integration of 29 hours pretty evenly spread across each of my 5nm Astrodon SHO filters in 300second subs at gain 200 offset 50. Calibrated by Darks, Flats and Dark Flats. Stars have been removed using Starnet V2 and reintroduced in a HOO pallet to approximate RGB coloration. Care has to be taken with this process as Starnet is given to taking some of the brighter or rounder nebula elements along with the stars and so these have to be reintegrated selectively with each SHO channel to prevent details from being lost. This is especially true of the very small and very round planetary nebula PK119+6.1 that is absent from virtually all images of this target that I have seen recently, most likely as people are inadvertently letting their star removal software of choice cut it away during processing. I am also pretty happy with the amount of detail that I got in some of the smaller objects present within the feild especially the Little Rosetta and so have provided some focused crops below to show them off. Some I think might say that I could have reduced the stars further (and I could have done) but I am of the thinking that stars should not be processed totally out of images as they tell their own little story, in this case the presence of two open clusters one primarily of blue stars and one dominated by older red giant stars. I also enjoy how the star density increases down towards the bottom of the image. Stacking took place in APP, Star removal in Starnet++ v2, processing in Photoshop CS2, Noise reduction in Topaz Labs DeNoise AI (with the lightest touch possible using the Low Light Algorithm). This is the first imagin to incorporate a few new processing techniques I have been thinking about for a while. Hopefully not pushed it too far. Image is at about 4 arc seconds per pixel with a FWHM of 1.4 pixels and I think it stands up quite well to actual size / full resolution viewing, something that is always a goal for me in my imaging. Below: NGC7822 Below: PK119+6.1, easily removed by Starnet++ v2 or Star Exterminator. Below: SH2-170, the little rosetta, and planetary nebula PK118+2.1, also easily removed by Starnet++ v2 or Star Exterminator. Below: Open cluser NGC7762. Below: Can't find a designation for this but would have thought it warrents one, any help? Hope you enjoy and once again thanks for looking. All feedback welcome. Adam J P.s With luck my next significant image will be less than 12 months away this time and taken from the top of Mt Teide using the same setup.

Interesting choice of filter what made you use it rather than a UV/IR cut?

If you can get hold of a spot diagram then spot size is also an important factor in understanding resolution. Of the spot size is significantly larger than the pixels then you won't achieve the theoretical resolution even in perfect seeing. The other thing with the CCD suitability guide is that it makes no account of OSC sampling due to the Bayer matrix and so only really works at all for mono cameras. Adam

So in Bortle 5 you will want a UV/IR cut and a Duel narrow band filter. Honestly with the requirement to use such filters with a DSLR and or a 533mc pro I would personally be looking at a flat feild scope to make changing between cameras and backfocus a none issue. I would go with something like this as you can image smaller targets at 600mm without the reducer. https://www.firstlightoptics.com/askar-telescopes/askar-80-phq-f75-quadruplet-astrograph.html or You can use the reducer and image at 456mm for the wider targets. https://www.firstlightoptics.com/askar-telescopes/askar-80phq-076x-full-frame-reducer.html But you say wide feild in at the same time as wanting more apperture..that doent really make sense. For true wide feild I would looke at the smaller 65mm https://www.firstlightoptics.com/askar-telescopes/askar-65-phq-quintuplet-flatfield-astrograph.html Its a better choice for things the size of M31. Adam

So your main issue is that the black level is really far too high. I normally aim for a black level of around 25-30 on the 0-255 scale. I dont use wither of the X's I use Topaz Denoise and only on its mildest settings as if you push any of these too high then its going to result in the image quickly starting to look atrificial and details being extracted from the noise. This looks to me like oversharpening. I cant help on the setting you should be trying though as I simply dont use those programs. Adam

I see no advantage to doing that and some potentially huge issues if you have a problem with the camera. If you want to go down that line then Rising Cam is sufficiently cheaper than ZWO to make the cost difference worth the risk. Adam

Its more like miss use of things with X in their title. Adam

Its a reflection from a curved surface from the sensor or the filter. You can tell as its distorted and offset from the star. The reducer would be the primary culprit for me. Adam

Great image, only comment is that I think you have pushed the blue channel too far and that you need a touch more green, but only a touch. Adam

Honestly 30-60seconds is all you need at unity gain more likely 30s, just lots of exposures. If not the the core will be blown out. Adam

Lincoln is very bright you won't reach a dark site in 15 mins drive.

You can still buy the original FMA180 but there is now a V2 called the FMA180 pro that has some tweaks and improvements. The Borg is much more expensive and faster, personally i like the FMA180 enough that i would not pay more.

The other classic one is spider silk threads. Adam

When I started (not that long ago really) if you wanted filters you had some choices: Baader - Good Budget IDAS / Astronomik- Mid Range Chroma / Astrodon - High End But now you also have: ZWO, OPTOLONG, ASKAR, ANTLIA I would say that ANTLIA and ASKAR are trying to position themselves as mid - High end, Optolong Budget / Mid range and ZWO Budget. But the reality is that very little has changed for me despite the new players on the market, if you want the best filters, with assurance that they will hit their specification or better then you should be going for Chroma / Astrodon. I still cant imagine that I will be swapping out my 5nm Astrodons for a 3nm from any of the newer, companies for many reasons. If you want to take a chance and roll the dice then you might get a fine filter at a third the cost of Chroma or Astrodon, but you might also get something with (at the extreme) 50% peak on band transmission and 4nm as opposed to 3nm and never know which sample you got. Its also the reason I shudder at the thought of imaging at F2 because you see so much variation in the apparent signal collected in OIII mostly but sometimes also Ha using these high speed duel narrowband OSC setups that I can only conclude that the delta in signal between one image and another is caused by how well the filter is meeting its specifications. I have seen some people with long integrations at F2 and images that don't live up to what you could do with an F5 refactor. Ignorance is Bliss.... Adam

Yes exactly you can bin the 694 2x2 in hardware. Adam

True but the spot diagram has changed. Make of that what you will. Although still only goes down to 430 nm OLD NEW Crossings are different too. Adam