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Messages - marekc

Pages: 1 ... 10 11 [12]
Hi Vincent, Juan, and Ioannis,

Thank you all very much for helping me with this! I'm really grateful that you've taken the time to help me with what is basically an issue with my camera and my acquisition software.

When I first got the camera, I was acquiring with the evaluation version of Maxim that came with the camera. Around the time that software expired, Orion Telescopes posted an ASCOM driver, and I switched to acquiring with the ASCOM driver and Nebulosity. (Basically, I was being cheap; this avoided having to buy Maxim.)

Interestingly, both Maxim and Nebulosity seem have acquired bias frames with values around 3000. This might fit with Ioannis's idea that the drivers might be adding an offset to the bias.

In Maxim, I was able to select options like `dark', `bias', and `light'. In Nebulosity, I don't have those options, so my bias frame is just a light frame with a 0.0 sec exposure time. (I have a cap on the nosepiece of my camera, covered with black gaffer's tape, and I put the camera outside, at night, to help keep it cool when I shoot biases and darks. The camera also has an internal shutter - but maybe that's only automatically closed when `dark' or `bias' is selected, as in Maxim. At any rate, I'm confident that I've kept light off of my chip when shooting darks and biases, regardless of the software.)

Here are some single raw frames acquired in Maxim:

Here are some single raw frames acqured with Nebulosity and the camera's ASCOM driver:

Thanks again so much for helping me try to figure this out!

- Marek Cichanski

Many thanks again to Vincent for looking into the calibration issues that I've been having.

Now I've found something really weird in my camera... as Vincent noted, it has a giant bias value!

I just checked many of the bias frames I've shot during the time I've had the camera, and they all have pixel values around 3000 ADU (on a 16-bit unsigned integer scale, i.e. from 0 to approx. 65,000). Strange! That camera uses up about 5% of its full-well depth on the BIAS value. That is really weird.

A friend of mine just got a QSI monochrome camera, also based on the Kodak 8300 chip. His master bias has pixel values around 200 (on a 16-bit unsigned integer scale). Clearly, my camera (a `Parsec 8300M', from Orion Telescopes) has a really strange bias value.

I'll check with Orion and see if they think there's anything wrong with it. If not, then... that is a really strange way to build a CCD camera, it seems to me. Using up 5% of the dynamic range on the bias value, when a similar camera from a different company (but with the same chip) has a bias value 1/15th as big... not so good.

The big problem this presents for me is that I can't calibrate with Pixinsight. I really like the way PI allows me to just shoot a bunch of long-duration darks, which will cover any lights and flats that I shoot, as long as the lights and flats are the same temp and shorter exposure times thank my master dark. That's a really nice PI feature. But... with this crazy-big bias value, which is essentially the same as almost any dark frame I'm likely to shoot... that's messed-up. It seems to me that if I'm going to calibrate data from this camera, I have to shoot darks and `flatdarks' whose exposure times match my lights and flats. That's not impossible, of course - I can build a library of darks, but it's rather sub-optimal. Seems unnecessarily awkward. I'm feeling rather disappointed.

Thanks, Vincent, for helping me uncover this strange behavior. This is something for me to investigate further. Grr, argh...

- Marek Cichanski

Hi to Vincent and anyone else who's knowledgeable about correlation,

I'll second Jeff's request for some more guidance on how to use the Image Calibration tool. I have found the tutorial on `Master Calibration Frames: Acquisition and Processing' to be extremely helpful, but I could use more guidance on how to calibrate the light frames. As Jeff said, an image showing which items should be checked and which should not be checked would be great.

Also, in that tutorial, I'm wondering about something in Figure 1: Should `clip low range' and `clip high range' be checked? I was trying to combine some darks recently, and I found that my hot pixels were absent from part of the frame. What was strange about this was that the cut-off between the `with hots' and `without hots' was a straight horizontal line. Odd. When I unchecked `clip low range' and `clip high range' at the Figure 1 stage, the problem went away.

At any rate, I'm very grateful for the `Master...Calibration...' tutorial. If it were possible to extend it a bit to cover the calibration of light frames, or perhaps to write another tutorial about that process, I think it would be very helpful.


- Marek Cichanski

Hi Vincent,

Thank you very much for figuring this out!

Looking at my raw calibration frames in PI, here's what I see when I look at a bias frame: The `BITPIX' item in the FITS header says that the number of bits per pixel is -32. I assume this means that this raw bias frame is in 32-bit floating-point format.

Here's why it's that way: Basically, I saw an option for acquiring my frames in 32-bit float format, and I assumed that `more is better'. I'm using an Orion Parsec 8300M monochrome CCD camera, and I'm capturing my data using the camera's ASCOM driver and Craig Stark's `Nebulosity' software. In that program, there's an option to capture data in 32-bit float format, instead of the default 16-bit integer format. I figured `hey, sounds better!'... mostly because I don't know much about the file formats. `More' sounded like `better'.

It sounds like I should restrict my captures to the default 16-bit integer format, and all will probably be well.

I wonder if I could convert my 32-bit float frames to 16-bit integer format? I'll look around in PI (and the other software I have) and see if I can batch-convert like this. If so, I'll try converting the frames and then try again to calibrate. In the future, I'll just shoot at the default 16-bit depth.

Oh, I have a question about some settings in the `master calibration frames' tutorial, but I'll make that a new thread...

Thanks again!

- Marek Cichanski

Hi Vincent,

Thanks very much for your help with this issue. I've uploaded a light frame, as well as master dark, flat, and bias files to my Dropbox public folder. I hope that these links work correctly:

If anyone else wants to try calibrating these frames, that's fine with me, too.


- Marek Cichanski

Hi Vincent,

Thank you very much for your reply. Unfortunately, I'm afraid that your suggestion didn't work in my case. After I read your message, I ran Image Calibration on my light frames, both with and without the `calibrate' box checked (in the Master Dark section). Either way, I get the same `binarized-looking' result.

I wonder... is it possible that somehow PI isn't getting my `calibrate' command? In other words, maybe when I check the box, the Image Calibration module doesn't register that I've checked it?

-Marek Cichanski

General / Extra info for `Calibration Problem...'
« on: 2011 February 20 02:52:31 »
A quick follow-up:

My darks were all shot at a longer exposure time than any of my lights or flats, so that the darks could be scaled to match the lights and flats.

- Marek

Hi Everyone,

I just did a search on the phrase `no correlation', to see if anyone has been having the same problem that I have. This has been a pretty big problem for me during the last few weeks.

I'm trying to calibrate monochrome CCD images that I shot with an Orion Parsec 8300M camera. I shot lights, flats, darks, and biases. I have prepared the master bias, dark, and flat frames according to the standard Pixinsight tutorial:

After making these master frames, I've taken a quick look at each of them with an auto STF, and they look like images I've seen in books about CCD imaging, showing what the master frames `should' look like (e.g. Berry and Burnell, Wodaski).

I am applying these master frames to my light frames, using the Image Calibration module (The light frames also look normal with an auto STF).

However, when I try to calibrate my light frames, two strange things happen:

1) The processing console tells me that there is `no correlation' between my dark frame and my target frame.

2) I get a `calibrated' light frame that looks very strange... when I do an auto STF on it, it is perfectly gray, except for the brighter pixels, which are clipped to white. I call it a `binarized-looking' appearance. There is no useful data in the image. It's hardly even an image any more.

In the Image Calibration module, I've tried various combinations of checking and unchecking the `calibrate' and `optimize' boxes, in all of the places where they appear, without any luck.

I'm wondering if I'm just making a mistake, or if this might possibly be a bug? My darks, flats, biases, and lights were shot with the same camera, at the same temperature, and the same binning. They were saved at the same bit depth. (I get this problem both when I acquire everything at 16-bit and when I acquire everything at 32-bit depth).

There have been a couple of  recent threads that have mentioned this issue:

I'm using eng (x86), running under Mac OS X 10.6 (Snow Leopard) on a MacBook Pro.

Thanks, hopefully this is just some simple mistake that I'm making. I hope to be able to calibrate frames again sometime soon.

- Marek Cichanski

Off-topic / Re: ?'s for Vicent regarding Wavelets article
« on: 2011 February 12 23:29:41 »
I'll second Steve's request! I, too, really enjoyed reading about multi-scale processing in Pixinsight Magazine, and I'd love to read some `how-to' details. Steve's questions are great examples of the sorts of things I'd like to know more about.

- Marek Cichanski

Off-topic / S & T Interview that mentions Pixinsight (+ IRAF !)
« on: 2011 February 08 14:09:31 »
Hi Everyone,

There's an article (on the Sky and Telescope website) about the recent `Hidden Treasures' competition held by ESO:

I couldn't help noticing that Joe DePasquale (the 4th-place finisher), who is mentioned in the article, says that he uses Pixinsight! Nice bit of publicity for Juan and Co.  :D   As a perpetual PI Newbie, this was one more bit of encouragement to keep `fighting the good fight' as I learn PI.

I found one of Mr. DePasquale's comments very interesting... he said that he calibrated the data with IRAF, and then used PI.

Yes, Pixinsight is very challenging, but IRAF seems to be a much scratchier `hair shirt' to put on! I once attempted to learn how to use it, but I haven't progressed very far at all. It's a UNIX-based software package that the professional astronomers use for their processing and analysis, and there's not much reason for amateurs to use it. I doubt that it does anything that `our' software (PI, PS, Maxim, AIP4WIN, etc) can't do, at least in terms of making asthetically pleasing images. My only reason for wanting to `know IRAF' was purely for the satisfaction of having mastered such a difficult beast... but I haven't gotten very far  :-[  I really don't know UNIX, and so it would be a great deal of work for me to learn IRAF, and it probably wouldn't `buy' me anything.

But... I would be very curious to know why Joe DePasquale used IRAF for his calibration. I wonder why he didn't use PI? It seems likely that the files he used were FITS files (though I don't know this), so it would seem to me that PI could `eat' pretty much anything that ESO would have in their archives.

I don't know if he reads the PI Forum, but if so, I'd be curious to learn more about his IRAF/Pixinsight workflow someday.

- Marek Cichanski

General / Re: My first post: A question about printing
« on: 2011 January 31 10:21:41 »
Hi Everybody,

Thank you very much for your replies! It sounds like the printing capabilities in OS X will be dealt with in the future - I'll keep an eye out for that. In the meantime, I'll follow Juan's suggestions for saving as a TIFF and printing from PS. Since I'm using a fairly inexpensive, low-end printer, and I'm not printing very many images, I think this will be fine. I'm not sure when I'll get a `good' printer, so I can certainly wait to see how the printing routines get incorporated into the OS X version of PI.


- Marek Cichanski

General / My first post: A question about printing
« on: 2011 January 30 19:48:23 »
Hi Everyone,

This is my first post to the Pixinsight Forum. I've been using PI for a few months now, and I'm enjoying the challenge of trying to get the most out of my data!

I'm fairly new to astro-imaging, I'm still not sure that I've made anything yet that's worth showing to the world... but hopefully soon!

I live in the San Francisco Bay area of the U.S., so naturally I've been greatly inspired by RBA, and the other talented and diligent imagers in this part of the world.

My equipment is fairly rudimentary, it's basically all from `Orion', the U.S. importer of astronomy gear. I'm using their `ED80' f/7.5 refractor, their Parsec 8300 monochrome camera, and their LRGB filters. I'm running Pixinsight 32-bit on a MacBook Pro using Mac OS X 10.6 (`Snow Leopard'). I just calibrated this laptop's display with a DataColor Spyder 3 Pro colorimeter.

My first question for the forum is related to *printing*. Although I don't feel like I've made any world-beating images yet, I thought I'd try printing a few images in small sizes. I'm using an Epson Stylus C88+ printer - it's a rather basic small desktop printer, the kind that they give away at the Apple Store when you buy a computer.

Here's my problem: When I try to print from PI, the Processing Console says:

Adobe PDF 9.0
Sending data to printer...
<* failed *>

I also get a pop-up window that says `Unexpected error during printer initialization'.

I am able to print with this printer using Photoshop CS4, Acrobat CS4 (=9.4.1), and other applications, like my LaTeX front end (TeXShop), OpenOffice, and TextEdit.

I was wondering if anyone else has encountered a `printer initialization' error like this?

I suppose it's to early to ask this next question, but... if it ends up not being possible to use this printer with PI, I wonder what would be the best workflow for producing a file in PI, and then opening in PS and printing from there? I suppose that's best left as a case of `we'll cross that bridge when we come to it'.

Thanks for the great software and for the very helpful forum!

- Marek Cichanski
San Francisco Bay area, U.S.A.

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