First image - Jupiter

[Jakstaar17]

Hi everyone. Just tested out the parts that i bought for imaging for the first time. (SPC900NC, Baader Neo filter)

Tried to get my first image with it using SharpCap and Registax, but i can't seem to get the detail out of the image like in the tutorials.

Does anyone have any tips please?

Thanks

[Clayton]

Hmmm! Looks like it is well under exposed or less likely darkened in post processing?

Whilst a fullish histogram (= desirable exposure) won't directly make your image sharper, it is one of the many things which will help you along the road.

You haven't divulged much info regarding your setup or exposures, so it is harder to give relevent advice.

I have adjusted the levels for your image.

It shows a lot of promise and may benefit from more scale when imaging, close attention to focus and collomation, Maybe the # frames.

All this is subject to seeing conditions of course which can ruin images from even the best setups

[Jakstaar17]

im not sure of the exact exposure as Sharpcap doesn't give numbers, just a slider. But i had it quite low as i thought that i read that it was better to under expose than over expose. Have i got that the wrong way around?

Seeing was very good. And settings were pretty much default,i think, apart from shutter speed and gain, which were quite low.

[Jakstaar17]

Just tried it again with one of the videos with more exposure, and this is the best i can get;

Maybe i am doing something wrong in Registax

[Space Cowboy]

The first image is too low on gain I would say. Are these taken with your Dobsonian scope? How many frames did you take? I've found the best results for Jupiter are around 60% Gain with Gamma set very low.

[Jakstaar17]

Yep, they are taken with the scope in my sig.

I took 896 frames for the 2nd image that i posted.

Gain was probably about 25%.

I used the following tutorial;

Webcam Astrophotography Tutorial for Planets

[black5f]

Having similar challanges! Playing with registax a bit but my single shot with a dlsr is looking better! Tried a web cam last night (it's a cheap one!) to see what happens. A little prog called ninox is useful for centreing and croping all the images first.

Jupiter | Flickr - Photo Sharing!

Although the seeing looked very good, when I did a time exposure of about 10 secs, the sky showed up misty red!

Good luck.

Tom

[Clayton]

im not sure of the exact exposure as Sharpcap doesn't give numbers, just a slider. But i had it quite low as i thought that i read that it was better to under expose than over expose. Have i got that the wrong way around?

Seeing was very good. And settings were pretty much default,i think, apart from shutter speed and gain, which were quite low.

If you under expose then you will limit the number of shades available for each colour. A fully exposed 8 bit colour channel has 256 shades to represent brightness (0-255), if the Histo is only half filled then only 128 shades are available this may not affect you too much as you can "stretch" the Histo to compensate, but if you grossly under expose it will become obvious.

On the other hand if you over expose and saturate the image then the levels of detail that are brighter than those that just fill the Histo will be truncated to a Digital Number = 255, in other words anything brighter will appear to be the same brightness and recorded as the same brightness, so the detail at the brighter end will be lost forever.

So neither extreme is desireable.

The last image looks to be in the ball park. RGB align may help?

How long are the video's, and what are the details of the telescope Diameter and focal length, and did you use a barlow?

Just noticed some of the Q's A'd.

Below with RGB align and levels

[Jakstaar17]

The video for the 2nd image is 1:29. I used a 2x barlow, and the telescope details are;

Diameter of Primary Mirror: 203mm

Telescope Focal Length: 1200mm (f/5.91)

[Clayton]

With this setup you should be able to achieve much better. If the seeing was very good as you stated, then you may have a problem with your optics eg. collomation or inferior figure on one or more surfaces, rubbish barlow, etc., though it's more likely to be a focus problem. Try taking your time, and refocusing between avi's (experience or practise does make a difference here). You could easilly double the length of your avi's which will allow you to push the gain up a bit without noise becoming an issue, and maybe even move to the next shortest shutter speed.

Having said all that, this form of imaging is much more demanding of seeing than visual, and what looks OK through the eyepiece may not be good on "film"

I think most here would agree that the single biggest factor is practise and more practise. I don't even know what I am doing different now to what I was doing 12 Months ago, but my images are vastly improved and my best Jupiter images from last year were well past opposition when most imagers had given up. They were streets ahead of my shots at opposition.

[Jakstaar17]

Thanks very much for the tips.

The seeing probably isn't perfect, as you have said, and i have taken some 2-3 minute AVI's gradually increasing gain on one, and slightly decreasing shutter speed on the other.

I will try to put them through Registax tomorrow to see if i come up with anything better this time.

Thanks again.

[michael.h.f.wilkinson]

My guess would be that the focus is simply out. Getting good focus is critical (and tricky). I fiddle around a lot with the focus before starting capture.

[Jakstaar17]

i will try to see if i can get the focus any better next time.

also, when i am processing it, should i be getting rid of any invidual frames where the image is poor? as when it is aligning, jupiter seems to be missed by the box quite often.

[Jakstaar17]

Had another go at imaging Jupiter last night upping the gain on some of the videos, dropping the gamma, and playing around with the shutter speed on others.

I still seem to have the same problem, and the best that i can come up with at the moment are below.

I have made sure that they are focussed as much as possible, so i am nut sure if i am also not processing the videos properly.

[michael.h.f.wilkinson]

Can you show a few single, unprocessed frames? That makes it easier to rule out focusing and collimation problems.

[Space Cowboy]

The focus looks ok on those last images. How many frames did you stack on each image? I see you talk about the alignment box missing Jupiter in registax, have you tried the "manual alignment" option? I would imagine your tracking is not smooth enough to utilise the auto alignment feature therefore registax will be missing out a lot of your frames.

[michael.h.f.wilkinson]

I do not think the focus looks spot on. I get better results with my C8, which has the same aperture.

[Jakstaar17]

I tried to focus it as best as i could and that is what i got.

I will give the manual alignment a try, but that looks like it will take ages as i have to align each individual frame.

[michael.h.f.wilkinson]

Can you show us a single frame?

[Jakstaar17]

Here is a single frame

[michael.h.f.wilkinson]

Focus looks reasonable, but perhaps some improvement is possible (depending heavily on seeing). There is a residual shift between the R, G and B channels. This can be seen by the difference in colour of the upper and lower edges of the planet. This is usually the case when Jupiter is low in the sky, due to atmospheric dispersion, not any optical problem with the scope. This can be corrected in registax (RGB align button). One other option in Registax you can try is realigning the video with the processed image. Normally you should select the best frame as reference, and align on that. The noise in this frame can degrade the alignment. By using the result of the first attempt as a reference image, you get rid of the influence of noise. A button "Realign with processed" is available.

Finally, you could try more aggressive wavelet processing. This simply requires experimentation. Play around with the settings to see what they do.

Having said this, I have struggled with focus a lot, and do not get it right even now. Seeing is of course also a problem.

[Cloudwatcher]

I'm sure Michael is right about the atmospherics bit and very annoying it is to!

Still,you have quite a nice image to work with that can be improved in PS with a little brightening,sharpening and saturation etc......... not too much mind or you end up with a Beachball.

[Jakstaar17]

Thanks very much guys.

At the moment, Jupiter is normally in the same direction as a streetlight that shines over into the garden and it is around 2am before it is far enough away.

Hopefully it is also this (along with the lack of perfect imaging conditions) rather than my scope or settings

Thanks again. I will give it another go on Friday or Saturday night hopefully.

Also, i have just received some colour filters from Astroboot. Will these make any difference whatsoever to imaging? I assume that they won't and are just for viewing purposes?