C9.25, DMK AU618.AS & Saturn, 2nd June

[Tim]

Still trying to get some decent results on Saturn, for this one I put my old faithful C9.25 on an EQ6 in the garden and grabbed a few avis. Saturn was only just clear of the roof and there seemed to be a lot of haze coming off it after a sunny day.

Even so, I think this is the best result I have had to date on a planet.

I'd be keen to hear suggestions regarding frame rate, gain, and exposure length please?

Thanks for looking

Tim

[Atlas]

I think it's great.

[SnakeyJ]

Tim - loads of detail here, though colour balance looks a little off giving a darker tinge. Some noise coming through, though I think push the gain as far as possible to get the highest achievable FPS to compensate for the seeing - the noise can be reduced with a gentle gaussian blur. If you've taken this with the 350D I think its an excellent result.

[Tim]

I'f i'd took it with the 350D i'd have laid an egg

DMK 618 camera. Is that the consensus? Push up gain to get 60fps?

[SnakeyJ]

I'f i'd took it with the 350D i'd have laid an egg

DMK 618 camera. Is that the consensus? Push up gain to get 60fps?

Sorry Tim, I missed the obvious in the subject line. I've been pushing 107FPS on a small 300x300 ROI on my QHY5L-II at 99.9% gain - I would imagine the 618 is a whole lot quieter even at full gain. I'd say push the frame rate as high as you can aiming for 2/3 histogram, but there may be more subtle approaches from the experienced DMK imagers.

Not so sure about egg laying - might be a tad uncomfortable and loud whoops of joy and a little dance may suffice

[Freddie]

With the DMK I'd set gain in the range 850-900. Adjust exposure to get a half full histo. This will obviously dictate the frame rate but you are best to then set the frame rate to match the exposure, assuming you use IC captute. IC does some strange things with frame rate as the cam has two internal operation modes. Matching the frame rate will ensure you get the maximum possible actual rate. You can check the actual rate on the live view.

I find the lower histo best, but be careful that Regi doesn't do an autostretch on your stack as if it does, it will over do it.

[DrRobin]

Very interesting Freddie.

I have two laptops both running Win 7 and the same version of IC Capture. The 32 bit laptop stays at 60fps all of the time and downloads the images as fast as it can even when not using 1/60th or less. However, my new 64 bit laptop downloads in fits and starts if I don't match the download rate to the camera rate.

I had never noticed this before, but if the exposure is set to say 1/30th second, I get a better frame rate with the transfer set to 30fps than set to 60fps.

I am also interested in your settings, going for half the histrogram and noted Jake's comments about using 2/3rds histogram. I always thought that you went for 75-90% to maximise the dynamic range. Apart from the faster exposure are there any other reasons for only going for 50 - 65% histogram?

Robin

[Freddie]

Robin, the cam has two operating modes. One it takes the pic and then downloads. The other it takes the pic and downloads at the same time. If the frame rate is set higher than the exposure rate will allow it operates in the first mode and is therefore slower.

In terms of setup, its all a bit of a balancing act obviously, but my experience is that you can sort out a slight loss of histo range during processing but you can't generate detail you have not captured. I therefore set the exposure short and have a lower histo to capture detail with the short exposure. This also has the advantage of increasing the frame rate and therefore capturing more images to control the noise. The short exposures are particularly important on Saturn with poor seeing at low alt, but I also apply the same technique to my Jupiter pics.

With a low histo, just watch that Regi doesn't do an autostretch on your stack as if it does, it will over do it.

All my shots are with a histo at 50% or slightly lower and I think they look reasonable. There will obviously be differences though with different setups and processing techniques.

Hope that is of some help.

[Tim]

Thanks guys!

Most of the detail, or at least the sharpest image is on the red channel, is that right? I'm just using my normal filters.

I didn't spot a histogram tool in IC capture, will look out for that too

[Freddie]

Yep, red will be best followed by green then blue. The histo icon is up towards the top left.

[DrRobin]

Very helpful Freddie, thanks. I am going to give that a try. I have been using gain around 950, 1/15th of a second to get about 85% on the histo with a C11 and DFK21AU618. I reckon with gain 900and 50% histo I should be able to get 1/30th or maybe faster which will certainly help with the seeing.

Thanks also for the tips on exposure/frame rate, I am going to ACTH out for that and always set an appropriate rate.

The sky didn't clear again tonight here, oh well try tomorrow night.

Robin

[Superdavo]

Awesome!

[Naemeth]

I really like the colour balance, although there does seem to be much more coming from the red channel. I think you captured good data considering the haze (which ruined the sharpness).