BGazing

On 27/08/2022 at 22:17, Simon128D said:

Took me longer to get around to doing this than I expected but I finally got in the mood to do it when setting up for an observing session. 

It's crude, all done on my phone, so is lacking in any professionalism and was all done on the fly in one take. 

Hopefully it's helpful to anyone else wanting to know more about these scopes as a possible next purchase. 

 

Very nice scope. Not sure that the laser compliments it. It could be collimated, though...

My back would not handle that mirror box, for sure.

9 minutes ago, paul mc c said:

What gear did you use for this..... cracking image by the way.

Still have a C11, borrowed from my mate, Rowan AZ100 and 678MC with ADC.

Thank you.

I've been geting the view of the 'boring' side consistently, but managed to catch a GRS transit finally.

Seeing was iffy, this was eked out of 6 min video derotation, exp 7m, stacked the best 19 percent.

14 hours ago, Maurizio83 said:

Beautiful image!  Have you used the C8? The idea of video derotation is interesting and worth trying! 👍

It was again C11. I will dig out and reprocess my best C8 data at some point.

I find video derotation, once you get a hang of it, a bit less tricky than image derotation - for Jupiter (emphasis added). But I would not go past 6 minutes for color camera, too much rotation. There's a good instruction about this in the FAQ portion of the relevant CN subforum.

2 hours ago, Kon said:

Very nice image. Very nice fine details. Do you find video derotation better than the tiff derotation?

Thank you. I am never sure about tiff derotation if there are no moons to anchor to. Video derotation is time consuming, but it is done by the computer, once you set the parameters.

OTOH, Saturn is relatively easy to do image derotation because of the rings.

Sorry guys (and girls), no GRS or moons or transits this time.

Turned out better than I expected, seeing was iffy and transparency also not that great, had to up exposure to compensate. This is 6 minutes of video derotation, 15K frames stacked.

14 hours ago, Kon said:

Thanks for the processing. Looks nice. Good tips on capture but with the 462 I haven't been too worried about noise. Even close to maxing the gain on methane or UV captures I can manage the noise ok. I may have been a bit conservative here.

Regarding metaguide I have read about it but I am not sure how easy it will be with my manual dob. I will give it a try. I always check collimation by star test before capture and I think it is more of focusing in this case. I have just upgraded to a dual focuser.

I have forgotten you are doing this on a manual dob...you have done a fantastic job, indeed.

I guess Paracorr would help if you are capturing it while it is drifting accross the field?

Indeed a very nice capture, I played around with it a bit, result attached.

I'd say 5ms is really short in good seeing. 7.5ms would get a much better S/N for you. Also, although readout noise is not that important, when stacking many frames it makes sense to up the gain over HGC threshold, check it out.

Also, try metaguide for collimation. Your images have that little bit of softness mine had before collimation tweak.

1 hour ago, Space Hopper said:

Stunningly good capture and processing 👍🏼

I think its safe to say the seeing and other conditions are rather better in Serbia than they are here........

Thank you.

As for conditions, well...we have planets 6 or so degrees higher and I'd say that I've never seen clouds run accross the sky as quickly as they do over England. But some of the best planetary images have indeed been shot from the UK...gentle rolling hills and laminary flow can work magic.

I shoot from the city and from a tiny balcony in the city center. Paradoxically, sometimes it is really a fairly good spot - city pollution (we have plenty) dampens heat exchange, and balcony is lifted above ground turbulences.

Second image was done from our dark site at approx 1000m above sea level.

Sadly, if pollution is at its worst you know the seeing will be great. Coatings may suffer, but YOLO 😄

This is very very nice, you may try a touch more of vibrance and/or saturation, if that suits your taste. Settings look good to me, but IMHO perhaps resizing to 150 percent is too much unless we are talking about excellent seeing, even then might be too much on Jupiter. I usually do not resize over 130 percent of the original, even on C8, seems to me that it is a diminishing return.

5 hours ago, morimarty said:

Thats a great capture of Jupiter and it's satellite. The detail on Ganymede is superb. Was Ganymede deroted or did you do a composite image.

5 hours ago, johnturley said:

Looks like, due to Jupiter's varying inclination (only 3 degrees though), Ganymede is only just touching the Jovian disc, I assume Callisto will be missing it completely. 

John 

Thank you, everyone. This was indeed derotation of video, and to my surprise it turned out good. Perhaps it was because Ganymede is slow.

I thought this derotation (click for time and date) had better seeing, but for some reason details in the disc look the same, Ganymede...well, not sure there.

Seeing looked rough and I was tweaking focus between captures endlessly...so was kinda surprised to see this result. Video derotation 6 minutes, 12K best frames (about 25 percent of the total). C11 again, still have not returned it.

Comments and suggestions welcome, on processing especially, always looking to improve.

Probably my first buy when getting into the hobby, 127Mak. Not that it was bad, but I could have skipped that and should have started either with a 100mm refractor or a C8. Both of which I have purchased later. 5 inch mak is neither here nor there, and it was very hard finding a decent diagonal for it. Sold it the moment I bought C8.

Bought my 678 last September with the FLO, flat cable, zero problems.

1 hour ago, Kon said:

Thanks. I am making my life difficult , don't I?🤣. An ADC would be nice but with manual is another challenge to battle.

Wow, this without ADC and tracking is truly superb.

Move on to tracking and ADC...ASAP.

Excellent result, especially given that you do it manually and without Paracorr. 

20 minutes ago, vlaiv said:

I've been reading explanations on AstroBin - and this is essentially what he did - except he did it manually

He did create "reference" image and then stacked mars from previous video and blended the two in Photoshop.

My proposal above was to let stacking software do the composition - but general idea is the same.

 

And there is probably a reason why he chose the pedestrian way. I suspect that letting AS do it would inevitably create artefacts and/or overlaps...

1 hour ago, vlaiv said:

I just measured in Stellarium.

It takes 30 seconds from first to "second" contact - or to fully occluded mars.

At the time Mars had 17" of apparent diameter. This makes it roughly 0.5"/s. If image was sampled at say 0.2"/px - this makes 2px per second drift. You can easily create reference image in one second.

Good Mars image requires good SNR - it does not have to be 6 minute video for that. Only if you sample at critical sampling frequency, but you can use larger telescope that gathers more light and you will shorten your imaging time that way.

Seeing and local conditions play a part as well, however - for above technique, it does not matter how long the video is.

AS!3 has interesting feature - it can use local quality estimator instead of whole frame.

It also allows you to choose how to build reference frame - and even use external reference frame (previous stack as reference).

Local / AP quality estimator means that only those APs that are of sufficiently high quality will get stacked.

If you take part of video prior to reference point - whole mars will be seen, but only APs on whole mars that can be matched against reference (where half of mars is occluded) will get stacked. Similarly - same goes for the moon.

Moon is not that much brighter than the Mars and they can be easily captured in single exposure. Exposure difference is not even x10 or so and with 12bit depth - you can easily capture both.

Well, something does not add up.

https://www.astrobin.com/1pnfjk/D/

Apparently 100 frames of Mars could be used originally, so the image was dim and noisy .At 18ms exposures. So that is why he made a composite image.

Here's the original https://www.astrobin.com/r5196p/E/

Whilst the description on the website says

Equipment used: Celestron EdgeHD 14 telescope, iOptron CEM70 mount, Astro-Physics BARADV lens, ZWO ASI462MC camera, 7,120 mm f/20, multiple 15-millisecond exposures 

So the 'real' window was 100 frames (without any selection), e.g. 1800 ms. Too short for anything as crisp on Mars as you see on the final photo.

IIRC, images like these are composite, combining separate shots of the Moon and of a planet involved. I recall watching a 'how to' tutorial.

A good Mars image requires for a color camera a 6 minute video in at least a fair seeing, and then relatively strict selection of frames (normally under 30 percent). In 6 minutes your Moon is gone. These objects are of different brightness, and, frankly, I am not sure how it would be possible for AS to handle them together.

1 hour ago, vlaiv said:

Not sure what you mean by this?

this is Stellarium simulation on the date the image was taken.

 

How much would be their apparent movement against each other in 6 minutes? How do you process it in AS - surface or planet?

Now browsing through planets, and the winner is a false color combination of UV and IR on venus. The sort of combination that takes informaton out of both sets of images...sigh.

Jupiter shot is simply amazing.

14 hours ago, vlaiv said:

Jupiter was taken with 21" telescope. and Mars is in line with about 10" of aperture. Fact that it is behind the Moon is just good timing.

But the apparent motion of Mars vs Moon would prohibit it.

Puzzled by the h-alpha winner, image is overprocessed

Just EXCELLENT. I really like your processing...

Shot through a borrowed C11, from L to R Rhea, Enceladus, Dione, Tethys. September 10, 20:25 UTC

25K frames in total, derotated 2 images of 6 min stacks.

Tried to process rings separately and to bring out moons gently. Suggestions for improvement welcome. 

C11 is a beast, in every sense of the word.

By the way, always save your pngs and jpegs in srgb format if you are using PS.