geoflewis

Thanks Vlaiv, so I'm getting more and more confused and/oruncertain about my sampling with the C14 and ASI462MC camera. I've loaded a recent image into WinJupos which reads the image as 339.8 px and 0.1407"/px (see below image) Dawes' and Rayleigh limit calculators (see below) give the max resolution of my scope (C14 dia = 356mm) at between 0.33" to 0.39", so allowing for min 2px ideal sampling will be half of those so somewhere in the 0.16" to 0.20" range. If WinJupos is correct and I'm already sampling at 0.1407"/ px, then aren't I already oversampled? FWIW I checked one of my images from last year with the ASI290MM + x2 TV PM and WinJupos gave me 0.9" / px.....!! I'm really confused now, so please can anyone let me know what I am doing wrong with my maths?

How do you do that please, I've never done it?

Thanks Lee, can't argue with that 👍

Hi Lee, I'm not sure about Chris using F24, but maybe he is. This is from his website... All images were taken using a Celestron C14 mounted on an Astrophysics AP900GTO mount. A QHY 290M and a QHYIII462C cameras were used is these images. RGB is done using a set of Chroma Technology RGB filters on a Starlight Xpress Motorized filter wheel. Methane band images are done using a Chroma Methane Band filter (889nm 18nm bandpass). UV images are done using a Astrodon UV filter. Amplification is done using an Astrophysics Advance Convertible Barlow working at 2.0X. So his amplification is 2.0x and the nominal FR of the C14 Edge (FL3910mm) is F11, so I think more like F22, than F24 (depending on where he positioned the main mirror in his initial focusing), unless you have another source of info from him. It's still a lot more than the ~F12 that I've been using.....🤔 I now have the Baader x2.25 barlow with the removable x1.3 lens, to add to my image amplification toolkit, so lots of options to play around with.

It's an interesting topic John. I'm having to recalibrate my thinking with these very small pixel cameras. I know that Vlaiv has said that his analysis shows that we should optimise sampling which for the 462 sensor at 2.9mn pixels is in the ~F14/F15 range, but others here are suggesting that I should oversample a bit. At around F12, I'm currently undersampling, so it's a no brainer to increase my working FL. Time (and results) will tell of course..... I was previously using my x2 TV PM with the mono ASI290MM camera which has the same 2.9 mn size pixels, so I'm going to up the ante again, both by retrying the x2 PM, but also with the x1.3 lens of the Baader barlow that I've just ordered and will collect this afternoon. It's hard to argue with the maths that @vlaiv provided, but it's equally hard to ignore that reknowned imagers such as Damian Peach, Chris Go, Anthony Wesley, Neil MacNeill, etc., plus Lee @Magnum, Neil @neil phillips and others on SGL all slightly (or even more) oversample when planetary imaging, so my advise is to experiment and see what works for you.

No worries Lee, I just saw that Widescreen have it, so I'm going to drive over and collect it from them today, together with the Astronimik 642 IR BP filter that I've been hankering after, so all sorted thanks. No idea why I didn't check with them yesterday, as they're one of my nearest suppliers....🙄🤷‍♂️

Thanks Lee, I already checked it out, but it seems to be out of stock everywhere currently, so I'm not likely to get one in time for this year's apparitions. I'm going to play with the spacing of my existing TV barlows, to see if I can bring the mag down to nearer F17

Amazing work

Many thanks.

Neil, you spoke completely correctly for me 😉. I held back on the wavelets as my initial extra sharpening just looked wrong, hence why I valued your expert critique this afternoon. Kon also nailed it, it really didn't add much if anything. I've been getting excellent feedback from everyone on here - it's very inspiring. I sent it over to Richard McKim earlier this evening and he wanted more from UK imagers, regardless of quality, so this evening I've gradually been sending over what I've captured from earlier this aparition.

Thanks Kon, I think I agree, but I keep trying for that extra 1%.....🙄🤔

Wow, these are fantastic 👏👏

Thanks Nik, that's an excellent observation, I hadn't considered that 👍

Trying to extract a bit more detail from my later Mars data, I combined the final 3 stacks with de-rotation in WinJupos followed by a tad more wavelet sharpening in Registax. I shared a few version back and forth with @neil phillips this pm and had a long chat with him about a bunch of planetary imaging related stuff. As many already know, Neil is a great guy, very knowledgable and equally willing to share his knowledge and experience (thanks Neil). The edge rind on Mars is very problematic, proving especially so when combinging several stacks, so I had to use a healing brush, to disguise the worst of it. Anway, this is where I ended up, so will be interested to hear what others think.

Hi Lee, this has been a very helpful thread, thanks. I also had a long and very helpful chat with @neil phillips this afternoon in which we covered a bunch of topics around optimising planetary imaging. He also says that I'm wrong to be imaging whilst undersampled, due to loss of potential resolution, so really I would be better to go back to a being a bit oversampled. We discussed some solutions to get me there with my existing gear, so I'm definitely going to try that again, particulaly in the run up to Mars oppistion next month. I guess watch this space.....🤔

That's interesting Lee. I believe the rule of thumb is that FL should be x4-x6 pixel size in microns (@vlaiv has written the maths on this elsewhere), so as the 462 sensor is 2.9mn pixels, that gives a range of say, F12-F17. I only have x2 TV and x3 TV barlows, or x2 TV PM, so with the ADC in train those are going to push me well into the FL>20 range. I did experiment one night with the x2 PM, which magnification actually reduces (to about F20) when set back with the ADC, but I concluded that it was still too much. Maybe I should try that again. I have considered using the x3 barlow then binning the camera, but I'm not sure how that would turn out. I'm not aware of the Baader Q turret (well I am now 😉), but that does sound like a sweet solution, so I'll check that out, thanks.

Thanks Lee, I'm using the C14 at it's native F11, but the ADC pushes that up to between F12-F13, which is maybe a tad undersampled for the 2.9mn pixels of the ASI462, but I think introducing any barlow or powermate would be too much.

Thanks Kon

Thanks Stuart, she sounds a bit like my misses, though it's my volume that she always asking me to turn down - and I'm not talking about my computer.....🙄

Are you sure Mark, I only sent it to John Rogers today I think.....

You were too quick for me Neil 😉. I added a further note on my post to make the same point, but sorry no, that was the last image from my session, so inconclusive. However, your images do support the notion that it was a real feature rotating into view, with just a tiny hint of it in my image as a bright pimple on the polar limb.

Hi Kon, you maybe need to treat my Mars images of the polar region with a little caution, as I deliberately desaturate the blue in them as I'm not sure it's right. Here's one before I desaturated the polar region fyi.... Even then the bright region isn't showing as strongly as in @neil phillips images, so I'm not sure if this helps....🤷‍♂️ Neil's images are later in the night than mine, so maybe whatever it is rotated into view after I stopped imaging. There is a hint of brightening in my image in the correct location, if it is indeed just over the horizon.....

Thanks Neil, we all just need the seeing to play well for us the next month or so.....🤞. There's a lunar occultation of Mars on 8 Dec, so I'm hoping to try for that, but it's a late one if I stay up for that, or an early start if I decide I need some sleep first. It starts just before 5am, so Mars will already be heading west and getting low down, so I don't know if I'll be able to see it - only time will tell I guess.....

Thanks Neil, honestly the difference between the best from a single SER and the stack of best from 3 SERS was marginal for this set of data and barely worth it. I also tried running the SERS through PIPP, then derotating each SER in Jups, but that turned out slightly worse, so I chucked those. On balance the gain from the huge extra load of work is beneficial when seeing is excellent, but I just can't resist having a try. It's my birthday today, so I thought I'd treat myself with some extra processing....🤣🙄🤷‍♂️

Thanks Neil, it's just that your images have a real silky quality about them, not disimilar to DP's - mine never have that.....🤔