saturn 8th april jet stream blues

[neil phillips]

As mentioned a fast moving jet stream killed any hope of real quality. but its the best so far out of 3 recent trys

150%

Higher focal length 150%

[RogerTheDodger]

pfft, thou dost protest too much methinks... a lovely image of Saturn there, I wish I could get as halsf as good

[neil phillips]

Thanks Roger, but if i get good seeing without a fast moving jet stream. I think you will understand where im coming from. images were disturbed badly. No question

[Space Cowboy]

Bit noiser than usual Neil just shows what conditions do to the image quality.What shutter speed did you use? I've been doing 1/33 but the best shot from my last session was at 1/25 even though seeing was so wobbly.

[bigal1]

Great attempt Neil considering the conditions , had the same problem with unstable seeing myself over the last few days .

[neil phillips]

Yeah i just threw them together Stuart, rubbish data. im at 1/30 secs exposure. Its a dogged belief that speed will prevail over noise and poor histo. maybe im wrong. but i dont think i am. seeing will not allow slower shutter speeds here

Thanks All

[brianb]

Good result for average / poor conditions.

1/30 sec exposure at 30 fps maximizes photon capture; 1/60 sec at 60 fps just doesn't work for Saturn because there's not enough light even with the gain turned right up.

[neil phillips]

Thanks Brian, pretty much would agree. Though i have no experiance of 60fps. (other than lunar ) would have thought with say a flea 3 and LARGE scopes. It might be possible. But for us mortals. Not even close. 1/30 secs is pushing it for a 245mm primary Brian. Hoping theres no jet stream tonight ? waiting for my new laser collimator. I may refit the old cell, as this is with the 51 mm flat still. im undecided yet ? i have drilled holes all over the back of the Europa Plate to aid ventilation. if and when i decide to go back.

[beamish]

hey Neil at least you were getting colour data -just in case it it was a good night;)

The ups & downs of planetary imaging, don't you just love it ?

[brianb]

1/30 secs is pushing it for a 245mm primary

It's working focal ratio that's the determining factor, not aperture - more aperture just gives a bigger image at the same focal ratio.

1/30 sec works for me with a C11 but only barely so with the blue filter & not at all with a IR pass filter. The IR image I posted a couple of days ago was taken at 1/15 sec. Fortunately the seeing is usually steadier in longer wavelengths!

Hoping theres no jet stream tonight ?

Moot for me - solid high cloud, last night was NBG here with very hazy skies (cirrostratus sheet, looked as though it was contrail derived)

[astroman001]

Nice image scale there. I shoot at only 15 fps 1/15th sec with a DMK21 and C11. I am thinking of having my DMK chipped with the IX618 CCD. This will boost sensitivity by 3-4x so I am told. £120 at Astronomiser.

regards

Peter

[neil phillips]

Just wish conditions would change for the better Peter, nothing has gone right for a while now. I thought about getting the 618ccd mod too. But imaging source are apparently going to release a camera at some point, that likely will have at least 60 fps without artifacts. useful for lunar and jupiter. by selling both my cameras i may get that when it arrives. But its def, a worthwhile mod no question. second best thing maybe

But apeture affects the relationship between gain, focal length, and histogram strength Brian. More apeture = either less gain, more focal length ( with the same amount of gain as possibly a smaller scope) or a better histogram strength. thats what i meant by pushing it. high gain, low histo. which of course would be improved with more apeture at the same focal lengths

[Nick Smith]

Quote from BrianB: 'It's working focal ratio that's the determining factor, not aperture - more aperture just gives a bigger image at the same focal ratio.'

Sorry Brian, just need to correct you here for the sake of newcomers. More aperture gives a BRIGHTER image at the same focal ratio. The longer the focal length, the dimmer things get.

Cheers

Nick

[brianb]

More aperture gives a BRIGHTER image at the same focal ratio

More (linear) aperture gives a BRIGHTER image at the same focal length - same shutter speed & f stop (with the same ISO) irrespective of the focal length of the lens.

Of course the light is more spread out as the focal length increases but if the aperture increases in proportion (which is what the same focal ratio means) then the image brightness remains constant. (For extended objects)

[JonTT]

I was able to use 60fps with just the IR cut with the histogram sensitive to around 80% of maximum. I had to use 30fps for R and 15fps for G&B though.

[Kokatha man]

.....still quite reasonable results under the conditions Neil.

It's too early on Sunday morning here in Oz (11:24am Adelaide:eek:) and I can't even work out the differences between Nick's, Brian's and Neil's assertions.....this is my "thick" day!

About the only things sensible I can say today is that there is a bit of a trend lately towards shorter f/l newts over the long f/l SCT's that are such great planetary workhorses (eg, like my C11) which has influenced my new scope selection.

From my perspective the OO f4 16" will still allow me to configure plenty of image scale, but it is in the areas of framerate and reduced gain required that I expect to see very marked advantages over the C11...

Also, I raised a topic over on CN the other day and was most interested to hear from one of the regular planetary chaps (WayneJ) where he espoused and exampled the advantage of binning, particularly for the blue channel - which I'd like to trial myself, along with another "pet idea" of mine, camera cooling re dark noise/current. (the Flea3 gets quite warm in operation.....going from an "idle" temperature below 20C up to around 28C during capture.....this is with night-time air temps of around 10C:eek:)

[johnh]

Those images are not bad Neil but not good for a perfectionist I know, Jetstream has been around for me and have spent 20 hours over few days recently with nothing to show so thinking of getting back to deep space.

Last night showed promise but no good in the end. Registax6 is great for the Encke as it puts alignment points over whole of saturn and rings with by better images. Storm on Saturn seems fainter these days as it spreads out but that may be down to seeing.

John.

[neil phillips]

Hi Everyone, Just want a killer night, but saturn is resisting all my attempts at getting what i felt was possible at my location, and equipment. still im enjoying doing it. And seeing the features from different sessions.

You know what im like john, if i dont start with the words quite pleased with this, i have to have a whing lol. But really its been bad lately, these were postable, the other two occassions recently just ALL went in the bin.

Will be interesting to see what you do with that OO scope Darryl, im just waiting for the IS to release there new camera ( will they ever ??? ) i read a lot about hot cameras needing cooling, anything positive you discover, always interested in hearing about. was better last night ( seeing ) but sadly trans was the pits, so just dim noisy images. but maybe i prefer them i think. as they are a little tighter. if with very poor histo problems at 1/30 secs