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 Post subject: Comet Holmes with FZ18
PostPosted: Thu Nov 15, 2007 6:28 pm 
Panasonic FZ18,
wide angle (FocalLength - 4.60 mm), 60sec, ISO100, f2.8
2007:11:14 01:28:56

yep, ISO100 ! the camera was so new to me that I had not yet found my way to the ISO settings to change it from the default !
I have tweaked the brightness a bit to save everyone having to adjust their monitors.
The original 700kb(dialup users beware :-!) ) file produced by the camera can be seen at http://www.ptarmigan.fsnet.co.uk/holmes/cometholmes.jpg
No tracking, no tripod, just a chair and a small block of wood to prop up the camera.
Image

and a guide to what can be seen :-
Image


Last edited by MalcolmP on Fri Dec 28, 2007 3:41 am, edited 1 time in total.

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 Post subject:
PostPosted: Thu Nov 15, 2007 7:00 pm 
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Nice one, Malcolm, and pretty amazing given you were at ISO 100. You have shown that it's possible to do astrophotography with just a camera and a tripod. It will be interesting to see how it goes with ISO 200 or even 400. That would allow you to see more stars or to shorten the exposure and hence the star trails.

By the way, I've edited your post in order to make the main image "clickable" with a link to your full sized image - click the Edit button in your post to see how I did it. And forgive me if you knew how to do it but had decided not to!

Bob.

_________________
Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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 Post subject:
PostPosted: Thu Nov 15, 2007 7:20 pm 
Thanks Bob
no prob.
What I had intended to do was
"by the camera can be seen here"
where "here" becomes a link.
I used to know how but it has ben a long time since I used phpBB and I forgot !
Also I ran out of time to figure it cos I realised that it was dark and clear and a crescent moon was inviting ,,,, but the bad news is I just had my first failure, the battery needed charging :( !! grrrr

Here is a crop to show the degree ( and direction) of trailing etc
Image


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 Post subject:
PostPosted: Thu Nov 15, 2007 9:29 pm 
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Hi Malcolm, nice work!

If your FZ18 ever has trouble focusing in these situations, just set it to infinity in manual focus mode.

You'll find that at an equivalent focal length of 28mm, the longest exposure you'll be able to have without trailing will be approx 30 seconds, plus or minus a few seconds depending on how far you're pointing from the pole.

So I'd suggest some 30 second exposures at different sensitivities, although beware that light polution from streetlamps can and will creep in, making your sky appear orange!


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 Post subject:
PostPosted: Fri Nov 16, 2007 2:12 am 
Bob > I was happy to explore (for now) the capabilities of the FZ18 at ISO100 given that all the reviews comment on the noise problem of this little chip at higher ISOs.
Trying out higher ISOs was on my roundtuit list :)

However, it seems that ISO 100 is the only setting available in the long exposure (15, 30, 60s) modes :(
Unless I am getting confused somewhere.

Gordon> Yes, shorter exposures would minimise the trail length and I have got some at 30 and 15s which show the comet, but they are noticably lacking in the fainter background stars.
It seems that on these average nights it is managing mag. 6.5 or thereabouts at 60s
visual limiting mag. is about 4 to 4.5 these past few nights, I dont class the sky as very good if I cant reach 5.5m unaided eye

Do you still have your review FZ18 ? cos I cant find an ISO setting menu for the long exposure modes. I can set up to 1600 in other modes.

This evening I tried some longer fl. shots and in all of them I missed the target !
So, on my growing rountuit list is
(1) a tracking platform,, either a Poncet or a barn door(Scotch mount), maybe.
and (2) a telrad or similar aiming device .

Latest news :
I managed to record the Andromeda galaxy as a faint smudge this evening.


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 Post subject:
PostPosted: Fri Nov 16, 2007 2:55 am 
I've been playing a bit more :)
I have combined, in GIMP, a bit of the crop that I posted earlier with a similar crop tonight nearly 48hr later :
Image

The bright star at slightly below right of centre is alpha Per.


Last edited by MalcolmP on Fri Dec 28, 2007 3:48 am, edited 1 time in total.

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 Post subject:
PostPosted: Fri Nov 16, 2007 7:47 am 
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Hi Malcolm, nice work! It's cool to see how the comet moves from night to night...

As for the FZ18, have you tried putting it in Manual mode and setting the aperture, shutter and ISO from there?

Gordon


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 Post subject:
PostPosted: Fri Nov 16, 2007 11:24 pm 
Gordon Laing wrote:
As for the FZ18, have you tried putting it in Manual mode and setting the aperture, shutter and ISO from there?
Ah! Thanks Gordon, you're a hero !!
For some reason I had it fixed in my brain cell that manual gave a range of 1s to 1/2000 and that to get the longer exposures we needed to go into the so called 'starry sky' scene mode
but not so, it is all there in the manual settings as you say.

If it please m'lud, I claim in my defence mental aberration from sleep deprivation staying awake all night photographing stars with my new toy !
Oh ,, and also mental instability from trying to get RegiStax and/or Iris to perform :-(

It is cloudy tonight, so I'll get back to reading the destructions ;)


Last edited by MalcolmP on Sat Nov 17, 2007 2:55 am, edited 1 time in total.

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 Post subject:
PostPosted: Fri Nov 16, 2007 11:53 pm 
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Hi Malcolm,

I haven't tried RegiStax yet but I share your frustration with IRIS. I still feel I have hardly tapped its potential. My normal "bible" is ash's "Diamonds from the Rough" Page.

By the way, I really like the idea of combining a couple of images to illustrate the comet's movement.

Bob.

_________________
Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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 Post subject:
PostPosted: Sat Nov 17, 2007 2:49 am 
Gordon>It's cool to see how the comet moves from night to night.
Bob>I really like the idea of combining a couple of images to illustrate the comet's movement.

Yes, I must admit that I enjoyed the results of that wee experiment :)
GIMP is a little 'nerdish' in its user interface but it is free !
And so a small shift and bit of rotation to match up the 'fixed' stars, two layers added, and bingo ! :)
The prob. is that the background not-quite-blackness also added, but I ran out of time and energy to reduce it back to a reasonable darkness ;-!)

Also, getting a little pixelpeeking nerdishness here, in the stacked pic there is the hint of two more stars that I had not noted before in the original individual pics :
Between alpha perseus and, to the left of it, Flamsteed Per.34 are two smudges of mag6.94 and mag7.11 stars
so, at 60s the FZ18 is getting deeper than the mag6(ish) that I had previously thought.

Well, it isnt exactly Hubble Space Telescope stuff, but it is a lot cheaper and it is keeping me off the streets, LOL !!


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 Post subject:
PostPosted: Sat Nov 17, 2007 3:08 am 
Hi Bob,
yes, Ash's page was one of the ones that I was working thro' and which spurred me to go back to the IRIS tutorial pages,
but, !
I am at a very elementary starter level and although I have managed to load a couple of frames of BMP and get them converted and written as both FITs and PICs and identified a star as ref., when I try to do any further processing the program tells me "file format not recognised", despite the fact that the prog. just generated that file !!
Grrrr, need another beer ,,,, >>>


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 Post subject:
PostPosted: Sat Nov 17, 2007 3:53 am 
I wrote:
Also, getting a little pixelpeeking nerdishness here, in the stacked pic there is the hint of two more stars that I had not noted before in the original individual pics :
An extract from "Cartes du Ciel"*, lower right, is shown again above with added lines to my stacked image.
The two red lines identify the 6.94 & 7.11 stars and their 'smudges' in my stacked x2image.
Image
I'm probably boring the pants of everyone ! but if I ever get IRIS figured out then stacking images from consumer-cams could be quite entertaining :) !

* http://www.stargazing.net/astropc/


Last edited by MalcolmP on Fri Dec 28, 2007 3:54 am, edited 1 time in total.

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 Post subject:
PostPosted: Sat Nov 17, 2007 11:14 am 
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Hi Malcolm,

Well, you aren't boring the pants off everyone but I may just be about to!

IRIS sometimes feels as though it's been cobbled together from a random selection of beautifully machined components which somehow still don't quite fit together. Here are a few thoughts which you have probably already had yourself but, if I'm lucky, something might help.

The first suggestion is to use the FZ18's RAW mode. I don't believe that IRIS can read and convert Panasonic's RAW files, which is a shame, but if you have, or can find, software that can convert your RAW files into 16-bit TIFF files that can be read by IRIS then that is definitely the way to go in my opinion.

Before I start IRIS I copy all the images I need to use into a temporary folder and make sure that this folder is the IRIS working path (Settings dialog from the File menu).

Open each of the TIFF files in IRIS and then save them as PIC files. For a sequence you want to stack together the last character in the name has to be numeric - I use names like "holmes_1" (IRIS will add the PIC extension).

For simple processing I also expose a single "dark frame" while still outside with the same ISO and exposure length as the proper image files. With that frame saved in PIC format I open each of the image files and then subtract the dark frame (Subtract... from the Processing menu) and save the result (e.g. "holmes_md_1").

As an aside, if you start from 16-bit TIF files it's possible that you may be seeing very little of your images in the main window. The Threshold dialog allows you to fix this but remember that until you save a file in an 8-bit format (such as JPEG) the Threshold dialog settings don't actually alter the image files - they just map the 16-bit depths into a range that your monitor can display sensibly.

Let's say I have two files, "holmes_md_1" and "holmes_md_2" which I want to stack. The first thing is to align them. I have had variable results using the IRIS Stellar Registration dialog (accessed from the Processing menu). I prefer to align manually using the QR2 command described here. Open a command window (the icon to the left of the "camera" icon on the toolbar) and type QR2 holmes_md_1 holmes_md_2 and hit the Enter key. IRIS prompts you to select three stars and displays holmes_md_1. I like to pick a star in the top left, bottom middle and top right in that order. The star should be nice and small and preferably not too close to other stars - if the star has "trailed" then pick, for example, the top left extremity of the trail. After you have selected the third star IRIS will display "holmes_md_2" and prompt you to select the same three stars. You need to do this in the same order and IRIS helpfully displays a small circle around the original position of the first three stars to help you find the corresponding stars in the second image. With that done IRIS chunters away for a while. When it has finished remember to save the aligned image as, say, "holmes_mdal_2". If needed this process can be repeated as many times as needed (e.g. QR2 holmes_md_01 holmes_md_27). The last step is to open "holmes_md_1" and immediately save it as "holmes_mdal_1".

Phew! Now for the fun bit. From the IRIS Processing menu select "Add a sequence...". The generic name you need is "holmes_mdal_" (number left off). Type in the total number of images and select the method of addition to use. Because we are working with 16-bit files it is probably a good idea to select "Normalize if overflow" and I usually go with "Adaptive weighting" and 2 or 3 iterations because I don't know any better. After you hit the OK button IRIS can take quite some time to do the processing but eventually it stops and you should see an image (the Threshold dialog may be useful here). The first thing to do next is to save the result (e.g. "holmes_st") as, almost unforgivably, IRIS doesn't have an Undo function.

After that you can spend hours (and hours and hours...) tweaking the image. With the final result saved as a PIC file you can then either export a 16-bit TIFF file for further tweaks elsewhere or set the final Thresholds and convert to JPEG. 8)

I hope something in the above helps sort your problem. Let us know how you get on.

Bob.

P.S. For those who are tempted to download IRIS it's available here.

_________________
Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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 Post subject:
PostPosted: Sun Nov 18, 2007 11:01 am 
It works !!!
Thank you very very much for your tutorial Bob, it would have taken me a month of sundays (if ever) to get that figured out.
Nothing dramatic yet, just a stack of 4 pics of part of Cygnus, starting with JPG converted to TIF, just to practice on.

Now I need to sort out the RAW format,
the camera's CD has SilkyPix bundled which is reputed to handle RAWs, but first I need to do some serious clearing of space on my drive. ( 40G drive now down to my last few Mbs !! )

Malcolm.


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 Post subject:
PostPosted: Sun Nov 18, 2007 11:19 am 
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MalcolmP wrote:
It works !!!
Thank you very very much for your tutorial Bob
.
first I need to do some serious clearing of space on my drive..

My very great pleasure. The storage space issue is certainly a pain with each IRIS PIC file running into tens of megabytes. Hard disk prices are a lot cheaper these days (both internal and external USB) but often that's money we would rather spend on other things. :(

Bob.

_________________
Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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