geoflewis

4 minutes ago, vlaiv said:

Quite simple procedure.

Take your Jupiter image as recorded (no drizzle, no binning, no rescaling) - but it can be stacked and sharpened (and it really should be for measurement precision).

Measure diameter of Jupiter disk on equator (there is actually quite bit of difference as I recently found out between measuring at equator and at an angle) and check current or rather at the date of recording, apparent angular diameter of Jupiter.

Divide the two to get pixel scale - and from that and pixel size - derive actual focal length.

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?

10 minutes ago, Magnum said:

im sure hes measured jupiters disc in pixels to get a true value before telling me. as I do that with mine each time i change anything

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

1 minute ago, Magnum said:

Chris told my personally that hes working at f24, this was a few weeks ago.

Barlows never give the exact multiplication factor they claim and the adc spacing to the barlow will add a bit more, im sure hes measured jupiters disc in pixels to get a true value before telling me. as I do that with mine each time i change anything.

Lee

Thanks Lee, can't argue with that 👍

4 hours ago, Magnum said:

So all of his images are taken at F24 with the C14 at 8.5m FL

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.

26 minutes ago, johnturley said:

That's interesting Lee that you get good results with the ASI 462 at f21-25, I usually use a 2.5 x Powermate which gives f17.5 when imaging planets through my Esprit 150 with my ASI 462, which gives reasonably good results.

However, some people suggested that I should be aiming for just 3x the pixel size of the ASI 462, which would be around f9, but with the focal length of the Esprit being just 1050 mm, f9 would result in too small an image size, and led me to believe that the ASI 462 was not the ideal camera to use with the Esprit 150, and that I would have got better results with the cheaper ASI 224, with its larger pixel size, tempting me to buy one of these.

John

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.

Just now, Magnum said:

I saw a used one the other day but can't remember where

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....🙄🤷‍♂️

5 minutes ago, Magnum said:

https://www.firstlightoptics.com/barlow-eyepieces/baader-classic-q-225x-barlow.html

this is the Barlow I was talking about, gives 1.3x or 2.25x. but you can also adjust that further by altering the spacing

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

1 hour ago, Sunshine said:

Amazing images!

Many thanks.

1 hour ago, neil phillips said:

Also he held back on sharpening somewhat to prevent a unnatural balance which also probably is playing its part Can't speak for Geof of course

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.

1 hour ago, Kon said:

You are in good hands with Neil. I really value his advice as well. To be perfectly honest and in my eyes, adding all the data together has not brought out more features. Your original last image has as many details as this one I reckon. That's with my limited experience.

The new workflow on the edge rind, has made it look very nice and smooth.

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

Wow, these are fantastic 👏👏

4 minutes ago, Nik271 said:

Bear in mind that for colour cameras because of the bayer matrix you are sampling at lower resolution: 2 times less for red and blue and about 1.5 times less for green. So in case of colour camera it is better to use at least 1.5 times extra focal ratio than what the theory says about mono. 

In excellent seeing F20 with 2.9micron pizels in a colour camera should be OK.

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.

8 hours ago, Magnum said:

Yes I’ve read many debates on the 5x pixel size but others say 7x. But following Damian Peach’s example he’s normally working his c14 at around 7-8metres depending on the pixel size and likes to cover Jupiters disc with 5-600 pixels so that’s what I’ve been doing and have had good results. If it’s a poor night then I drop down to 6 metres, if it’s a good night then I go up to 7 metres.

Lee

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.....🤔

6 minutes ago, Magnum said:

im not so sure Geof, depending on the seeing im using my 12" LX200 at between f21 & f25 with the 462. on most nights I find f23 gives the best detail for me, so thats around 7000mm FL, on poorer nights I go down to f21 which is just over 6000mm FL. 

I have just bought a Baader Q turret 2.25x barlow ( only about £45 ) which seems as good quality as my GSO2.5 App barlow, but has the benefit that the end can be removed and screwed straight into an ADC giving a more modest  1.3x mag so that could be a nice option for you to get just a little more if you don't want to go as crazy on the mag as I am. 

I think it would get you to about f17 & 6000mm FL which is about the same FL as mine at f21.

Lee

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.

1 minute ago, Magnum said:

Nice set Geof, what f number are you working at approx? 

Lee

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.

3 minutes ago, Kon said:

Great set of images.

Thanks Kon

1 hour ago, Space Cowboy said:

Lots of detail on those Geof though a little dark on my screen?

Edit : Its my monitor, sorry Geof, my missus turned down the brightness.

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.....🙄

28 minutes ago, MarkRadice said:

Beautiful images, Geof - and I was interested to note the 2122 image is included in the latest Jupiter section report from the BAA . 

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

4 minutes ago, neil phillips said:

Also, a time difference Geof as can be seen by the more prominent volcano? what time was this? do you have any later? so we can rule out, it is rotating into view somewhat later 

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.

17 minutes ago, Kon said:

The images from @geoflewisseem to have it as well but more subtle; less colour saturation than yours. In my eyes it makes that area uneven, as if it is popping upwards a bit.

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.....

5 minutes ago, neil phillips said:

Appreciated Geoff. Mars is getting interesting. I have a feeling in the next two or three weeks you're going to be setting the forum alight with your Mars images. Already i was taken aback at what you got recently. still a couple of arcsecs to go yet. And good seeing hopefully. Fun times.

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.....

14 minutes ago, neil phillips said:

Nice captures and processing Geof. I really need to start experimenting more. I often can't be bothered to cherry pick from the top frames from each 6 min ser. And combine. I am sure it does sharpen the image a bit. As more quality frames are going into the mix. But it certainly does take quite a bit longer to be that thorough.

Saving the data does mean it could be attempted when the planets are gone prior to next year. On those cold rainy nights. So, it's always in the back of my mind. Especially when i see your results working so well. Proof is in the pudding as the English say. And your work has been showing me these techniques are worth pursuing. We discussed this didn't we. 

Great results again Geof. Don't know about you. But been finding it harder and harder out there lately on Jupiter. I sometimes think your location is exceptional as far as stability is concerned. Your results often exceeding what's around the country generally. But i realize if true?  that's only part of the picture. After all there is a human in control of the whole capture and process thing. And I don't underestimate your skill and input either.

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....🤣🙄🤷‍♂️

2 minutes ago, neil phillips said:

One thing i love about you Geof is your modesty. Your processing skills are top notch. You could teach me a thing or too i am sure. 

Cheers for the sentiment

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