1st reasonable jupiter this year

[Ian]

25th January, 22:58 seeing 60%

Before you ask, this is a composite

Approximately 700 frames for jupiter, 45 for moons, stacked in Registax and composed in Photoshop.


Io was behind Jupiter

[ This Message was edited by: Ian on 2003-01-28 13:58 ]

[Ian]

and this is Jupiter on it's own. Not sure about the processing, I'll probably try again.

[Ian]

is this one better? I'm not sure, but it looks more realistic...

[Mike]

Fantastic images Ian - Your making me jealous. I had a go at both Jupiter and SAturn the other night when the seeing was great, but I am wasting my time. The mount just isnt up to it. Its a nightmare to find the bloody object im photgraphig to start with and then keeping it in frame once I have it is just as hard. I really do give up. I think ill not bother with astrophotography more complicated than the moon until I can get a scope with a good sturdy driven mount.

I agree the last image looks far more like how it should look.

[Whitters]

WOW
Superb images. love the composite

[Whitters]

I agree that the second images looks more like the telescopic image, however it depends what you want to show from the image. If you wanted to enhance the cloud belt structure then the first does that job better.

Again superb picture.

[Rick]

I wonder a bit whether some of the apparent detail in the first image isn't actually an artefact of the processing. I suspect the second image gives a more accurate representation, nearer to what is actually there on Jupiter.

[Ian]

thats always the biggie when processing images. But as there is very little noise left in the images after stacking, the contrast differences are more likely to be structure. One thing I have noticed is that patterns and details introduced by processing often appear to be unnatural. Although not necessarily unfortunately...

[Whitters]

True that processing of an image will enhance artifacts in the origional image. To be confident of what the image shows then the camera should be calibrated. To calibrate the image requires the use of dark frames and flat fields, nb flat fields should also be dark framed. Remembering that it is the origional individual frames that should be calibrated, not the result.

[Ian]

true, but does that not really only hold true for measurements (Astrometrics/photometrics) rather than apparent subtle details of structure whose interpretation is largely subjective?

[Rick]

With subjective detail, it's worth being aware what forms the artefacts of the image-processing algorithms take...

The limb-brightening on the first image seemed to me like the effects of an over-active edge-detection algorithm, and I figured that, if the limb showed the effect, then the detail would probably be affected by it too. That led me to distrust the apparent detail in the image somewhat. With the secon image, while I have to look at it harder to see the detail, I'm more inclined to trust that detail because I don't see effects that look like they might be artefacts of an enhancement algorithm.

[Mike]

I agree with Rick there. The second picture look smore natural and is probably closer to the truth. Nice to see the three moons as nice distinct orbs. How about trying even higher magnification and trying to capture some detail on the moons ? It has been done many times before by amateurs quite well - Might be an interesting project !?

p.s. I have finally cracked down to the effort of making my website. WOn't be giving any details away until it is finished as it is quite ambitious - I'll keep you posted. I may be asking some of you permission to reproduce some of your pics

[Ian]

limb brightening is something of a side effect, however it does not necessarily discount other details as false. That brightening is caused by the high contrast boundary at the edge, for kicks I may try to apply the same processing to an image with a white background...

The original images of the composite were processed separately and then combined.

[Rick]

Yeah, the high contrast of the boundary means that it's most likely the first place algorithm artefacts are going to show up. If there are no apparent artefacts on a high contrast boundary then the rest of the image is less likely to have them as well.

[Ian]

On 2003-01-31 11:46, Rick wrote:
Yeah, the high contrast of the boundary means that it's most likely the first place algorithm artefacts are going to show up. If there are no apparent artefacts on a high contrast boundary then the rest of the image is less likely to have them as well.

The high contrast boundary is due to the fact that the planet is there and suddenly not. This has no relevance when discussing details on the disc itself. But, what happens than, to make the low contrast details more apparent, you apply the same algorithm across the whole image. If you do this then you are faced with a compromise, make the detail more apparent with strong application of a filter and accept the artifacts at the object boundary, or be more aesthetic and perhaps make low contrast details barely apparent. The pics I posted illustrate the point.
The question is, do you want to see a nice picture of a planet, or emphasise, artifically, details of it's structure that are not easily apparent in the eyepiece?

[Rick]

Both, of course.

[Ian]

good answer