For your enjoyment!

Hi everyone,

I don't post here very often but I do read the threads from time to time. Just by chance I stumbled upon this one. It's an interesting discussion and one that would probably have been sorted if the image that appeared on LPOD had been this one...

www.digitalsky.org.uk/occultations/occul...osite-single_800.jpg

There was never any intention to make out that this was a single shot (in fact the LPOD text explains this).

It is an interesting question to ask what constitutes a false image. In my view any image captured by a camera is false as soon as the exposure stops because what's been captured is what the camera sees not what a human being would see.

I was well aware that it was impossible to capture both the Moon and Saturn in a way that would do justice to both. Hence my decision to make a composite using imaged gathered from that night.

This, rather large image, may explain things more...

www.digitalsky.org.uk/occultations/20070...ultation-summary.jpg

As for capturing fine detail on Saturn, well that comes with equipment and experience...

www.digitalsky.org.uk/saturn/2007-03-01_...41_RGB-v3-titled.jpg

I'm glad that the LPOD image has created such a healthy discussion point and it's been interesting reading the replies to this thread.

Thanks for coming aboard Pete. This topic (the thread as a whole) does make for some great debating! Advocates for and against, and each with their own opinions as to where any lines are to be drawn. It's also a matter of simply changing with the times!

Hi Seanie,

Yes it is very interesting and an area where it's easy to get tied into knots. Let me give you an example.

The modern way to image, for example, Saturn is with a high frame rate device such as a webcam or one of the new breed of industrial strength webcams such as the DMKs or the Lumeneras.

The images captured by the webcam are then processed by a registration and stacking application (e.g. Registax) and a nice crisp enhanced result obtained. However, that's not what the planet looks like to the human eye. Looking through the eyepiece, the planet will be a mass of wobbles and distortions.

Ok - perhaps a purer way would be to take a still shot of Saturn with a normal camera. In this way the image captured wouldn't be sharp but would be much more representative of what the planet actually looked like.

Hold on though because that's not what the planet looks like at all. That's what the planet looks like when its light has passed through the turbulent atmosphere above your telescope - conditions which may actually be localised to you.

The closest image to what Saturn really looks like is actually the webcam processed image because that tries to take out the effects of the atmosphere.

Another interesting topic is whether this is art or science. In the case of the occultation where there is little science to be had (save for positional data to permit further refinement of say the profile of the edge of the Moon) then the resulting image is more art then science. In this respect the effect I wanted to achieve was a wow shot rather than a shot which tried to simulate the view through an eyepiece with the naked eye.

In the bottom right hand corner of the larger image I gave a link to, I've shown the positional images that I took during the session. These represent the science of the capture in my mind. However, the images are exposed for Saturn not the Moon which is burnt out. The human eye of course doesn't see the Moon this as it's flexible enough to accommodate the brightness of the Moon's surface and the dimness of Saturn at the same time.

I'd love a camera that could do that

I'd love a camera that could do that

Wouldn't we all Pete, wouldn't we all!!

Hi Phil,
Thanks for getting into this discussion. We had a quick discussion among a number of us at the SAC meeting last night and some really think that some imaging techniques are cheating, such as combining a number of images to make a single image, I dont mean stacking, I mean copying and paste to fix exposure problems

I put to them do they think that hypering film back in the film age was cheating?, images were also spliced back then also, or how about when film came out in the first place, maybe astronomers back then felt that the best "images" were drawings made by pencil as these were true interpretations of what the human eye sees.
I know of some who think that using a goto scope is cheating, dont get me wrong, I own both manual and goto scopes, but I wouldn't consider either method of observing as invalid.

In my book the golden rule is that data should not be altered to show something that isn't there. For, example a white spot on Saturn or detail on Mars that just couldn't be seen. I've seen composites that have been put together showing things like the Moon placed against a random star field that wasn't anywhere near the Moon. In my opinion, although such results can be aesthetically pleasing, they step over the mark and into the world of fantasy.

Combining images to reveal what was there is, in my opinion acceptable and it's the mainstay of modern astrophotography. Deepsky masters like Rob Gendler, Nik Syzmanek, Russ Crowman, etc. couldn't show us what they show us without cutting pasting, blending, masking and ehancing bits of an image that would otherwise be lost. Take M42 imaging for example where multiple images are often combined, masked and enhanced to allow additional detail to be revealed in a single composite.

I have an image of the occultation exposed correctly for Saturn with the Moon washed out. I could have published that (and the whole sequence is shown on my large summary image) but it's not a particularly beautiful image. It's scientifically correct but it just doesn't grab the imagination. All of the components for my occultation image were grabbed during the same session and do represent what was genuinely up for grabs.