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Tony Hallas on Using a DSLR

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#51 Ivo Jager

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Posted 20 November 2014 - 06:26 PM

Ivo... thanks for looking at my images.  Imaging on Kitt Peak has its limitations.  No guiding for one thing.  Most of those images where taken for clients that rent a scope for the night at the Visitor Center.  I ran the scope and camera fo them. Even though they have the scope all night, they expect to see 30 or more objects and image at least half of those.  So there is not time to set up guiding with the equipment we had available.  That is why most exposures are around 2 minutes and there are often not more than 10 frames.   Some of the client images were from single 2 minute images.....no stacking.  See some examples here:  http://www.geoandpat...o_canon_6D.html   Maybe that is what the future hold!  No calibration and no stacking.  

 

George

You're doing great work - enthusing people for the night sky; that's where it all begins! :waytogo:

We clearly have the same goals here; I'm just really concerned with *keeping* people enthused as they start and progress in the hobby. With the right know-how, your guests can produce similar results from their (moderately) light polluted back yards with a cheap Canon T3 / 1100D. These are exciting times for AP and the barrier to entry has never been lower.


Edited by Ivo Jager, 20 November 2014 - 06:28 PM.


#52 Tonk

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Posted 20 November 2014 - 06:36 PM

Maybe that is what the future hold!  No calibration and no stacking

 

Yes - bit of a long wait though ..... the day when all camera sensors are 100% perfect and have have no hot pixels, no defects, no bias pattern and your optics are totally dust and defect free and have no vignetting and your electronics are noise free.

 

Why are people so afraid of calibrating and stacking????? Honestly its not hard to do.. I guess I'm just getting too old for the "instant" push button generation.



#53 Ranger Tim

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Posted 20 November 2014 - 07:20 PM

A very interesting discussion. I am glad that it did not turn into a "He said, she said" rant. This type of thread is why I read these forums religiously - there are nuggets of wisdom and technique that I can glean and try for myself.

 

At first glance this hobby seems pretty straightforward and that one need only to appropriate the requisite funding to achieve success. Yet I am continually surprised by people and their ingenious ability to make a silk purse out of a cow's ear. I don't understand one tenth of the technical language spouted in these forums and I take for granted many folks are better at it than I am; This is often proved by their posted images. It is enough for me to take what I can understand and implement it into my own workflow. 

 

It is important to me that I do the best I can with what I have, that is the allure that draws me into this "art." Being able to take a simple DSLR and shoot images that were impossible only a few decades ago fills me with wonder (and impresses the heck out of my friends at work). I am interested in capturing as much detail with as little noise as possible, yet I am (mostly) at the mercy of those persons that delve deeply into the theory and practice. From their efforts I gain, and from their failures I learn.

 

I appreciate the candor and zeal that Ivo expresses in his posts. When the light of scrutiny shines on a new or alternative process, it should expose any and all shortcomings. However, this should not take us into a cookie-cutter world where experimentation and ingenuity are considered heretical concepts. Mr. Hallas' methods will either stand the test of time or not, and I look forward to the discourse concerning them.

 

The end result of this entire process usually results in an image that is seen on a monitor or printed page (if one is so lucky as to be published). Few images are ever printed or displayed at full resolution, so that the detail and noise of an image can be examined in detail. If one is "lazy" you can post your latest and greatest attempt and continue unabashed down the road to bag another DSO. I see AP'ers as an eclectic group of artists/technichians that have varying levels of skill ranging from mediocrity to brilliance. I suspect some of us are so wrapped up in the acquisition and processing of our work that the end product results in some kind of "post-partum" reaction until the next opportunity to shoot arises.

 

What is my opinion? I'll continue to take calibration frames and work towards the lofty goal of maximizing the data as much as possible. But there may be times when a quick and dirty 9 frames might just be the only chance I get! Never hurts to have another tool in the drawer...

 

By the way, thanks for StarTools Ivo. It has made the hobby immensely more pleasurable for me.



#54 james7ca

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Posted 20 November 2014 - 09:28 PM

I don't use flats but I do use bias and DF. The reason I can get away with that is that I try to keep my sensors clean and I use well-corrected, flat-field refractors that have only small amounts of variation in their field illumination. I also use PixInsight's Dynamic Background Extraction process as the first step in my processing after stacking (so that helps too, although I suspect that if I did use flats my results would be even better).

 

As a rule, I also don't guide which means that I have to keep my individual exposures fairly short but with the side effect that I get a form of dithering without any direct effort on my part (since residual polar alignment errors, uncorrected mount errors, and atmospheric refraction cause my subs to "drift" over time). Truth be told, when I'm imaging at home I can't really use long, broad-band exposures anyway because of the light pollution.

 

Yes, I'm lazy and quite frankly I like to image without the use of a PC or any need for guiding. I also use off-the-shelf, consumer digital cameras. Thus, when I travel for astrophotography I only need my mount, my telescope, and my Sony APS-C cameras (no PC, no guide scope, no CCD camera or filters, etc.). I do, however, use my phone for SkySafari and to control the time-lapse settings for my subs. As for the latter (time-lapse and exposure control) I've just started using a very small Bluetooth/IR remote called the MaxStone. I just attach the MaxStone to the side of my telescope with a little bit of Velcro and it allows me to wireless control the time-lapse and exposure settings for my Sony camera. This means that I can have ZERO wires running from my imaging setup (another advantage, no worry about cable drag or routing).

 

That said, I know that my results are far from optimal but right now I'm okay with that. Eventually, I may progress to guided, long-exposure, LRGB, or narrow-band imaging but that will require more money and more effort. As it is, I've already spent a lot of money getting good equipment but at least I have a solid foundation to build upon.



#55 james7ca

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Posted 20 November 2014 - 10:29 PM

 

Maybe that is what the future hold!  No calibration and no stacking

 

Yes - bit of a long wait though ..... the day when all camera sensors are 100% perfect and have have no hot pixels, no defects, no bias pattern and your optics are totally dust and defect free and have no vignetting and your electronics are noise free.

...

 

Just remember that "digital" cameras and sensors are not really fully digital (they are analog/digital hybrids). But they are working on fully digital sensors that will actually count photons, so the days of needing to guide and other complications may be ending within the next several decades (if we're lucky).



#56 Tonk

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Posted 21 November 2014 - 05:07 AM

Just remember that "digital" cameras and sensors are not really fully digital (they are analog/digital hybrids). But they are working on fully digital sensors that will actually count photons, so the days of needing to guide and other complications may be ending within the next several decades (if we're lucky).

 

Yeah right :) 100% quantum efficiency in your camera, prefect fabrication of the sensor with no defects in the silicon, the fastest and biggest aperture scope that you can afford to get all those precious photons from a very dim object.

 

 

Meanwhile I'll continue to dark/flat calibrate via RAWS, use linear debayering AFTER stacking and THEN do the non-linear stretch. My "artistic" processing options are then maximised with the least issues.

 

 

 

the days of needing to guide ... may be ending

 

This is nothing to do with the camera - all to do with your mount and speed of your optics. The solution (today - future might be different)  is to get an absolute encoder mount. My 10Micron mount delivers 20 minutes+ unguided performance and I can use any camera ;)


Edited by Tonk, 21 November 2014 - 05:09 AM.


#57 james7ca

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Posted 21 November 2014 - 06:22 AM

 

Just remember that "digital" cameras and sensors are not really fully digital (they are analog/digital hybrids). But they are working on fully digital sensors that will actually count photons, so the days of needing to guide and other complications may be ending within the next several decades (if we're lucky).

 

Yeah right :) 100% quantum efficiency in your camera, prefect fabrication of the sensor with no defects in the silicon, the fastest and biggest aperture scope that you can afford to get all those precious photons from a very dim object.

 

 

Meanwhile I'll continue to dark/flat calibrate via RAWS, use linear debayering AFTER stacking and THEN do the non-linear stretch. My "artistic" processing options are then maximised with the least issues.

 

 

 

the days of needing to guide ... may be ending

 

This is nothing to do with the camera - all to do with your mount and speed of your optics. The solution (today - future might be different)  is to get an absolute encoder mount. My 10Micron mount delivers 20 minutes+ unguided performance and I can use any camera ;)

 

Frankly I would rather be guided by a lecture that I heard by one of the inventors of the original CMOS sensor. Physicist and engineers are working on purely digital detectors and when that happens it will be an absolute revolution in photography. Of course, as far as I know they still don't have a model or theory that will allow for such a design but they are working on it and as of a few years ago (when I watched the lecture) they were still very excited by the prospects. I also didn't say anything about silicon and there is really no reason to think that that process will lead the way for all time to come.

 

As for guiding, think of it this way. If you could actually count photons and you could accumulate those counts over time then in effect you might be able to divide those counts into periods of infinitely small duration. Then, "all" you would have to do is register and stack those small duration measurements to produce a final integrated image (it's a spin on what you can do today by stacking analog-derived subs). Of course, I can see that some form of the Heisenberg Uncertainly Principle could come into play here, but why limit your expectations on something as "little" as that (I'm kidding, sort of). I'm not saying that the initial process would be perfect or error free or even whether it will happen in my lifetime, but in a few more decades we could see orders of magnitude improvement in the quality of our detection skills.



#58 gdd

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Posted 21 November 2014 - 11:03 AM

 

 

Just remember that "digital" cameras and sensors are not really fully digital (they are analog/digital hybrids). But they are working on fully digital sensors that will actually count photons, so the days of needing to guide and other complications may be ending within the next several decades (if we're lucky).

 

Yeah right :) 100% quantum efficiency in your camera, prefect fabrication of the sensor with no defects in the silicon, the fastest and biggest aperture scope that you can afford to get all those precious photons from a very dim object.

 

 

Meanwhile I'll continue to dark/flat calibrate via RAWS, use linear debayering AFTER stacking and THEN do the non-linear stretch. My "artistic" processing options are then maximised with the least issues.

 

 

 

the days of needing to guide ... may be ending

 

This is nothing to do with the camera - all to do with your mount and speed of your optics. The solution (today - future might be different)  is to get an absolute encoder mount. My 10Micron mount delivers 20 minutes+ unguided performance and I can use any camera ;)

 

Frankly I would rather be guided by a lecture that I heard by one of the inventors of the original CMOS sensor. Physicist and engineers are working on purely digital detectors and when that happens it will be an absolute revolution in photography. Of course, as far as I know they still don't have a model or theory that will allow for such a design but they are working on it and as of a few years ago (when I watched the lecture) they were still very excited by the prospects. I also didn't say anything about silicon and there is really no reason to think that that process will lead the way for all time to come.

 

As for guiding, think of it this way. If you could actually count photons and you could accumulate those counts over time then in effect you might be able to divide those counts into periods of infinitely small duration. Then, "all" you would have to do is register and stack those small duration measurements to produce a final integrated image (it's a spin on what you can do today by stacking analog-derived subs). Of course, I can see that some form of the Heisenberg Uncertainly Principle could come into play here, but why limit your expectations on something as "little" as that (I'm kidding, sort of). I'm not saying that the initial process would be perfect or error free or even whether it will happen in my lifetime, but in a few more decades we could see orders of magnitude improvement in the quality of our detection skills.

 

The progressive scan CCD cameras stack as they go and adjust the scan so no guiding or tracking is required at all - just a fixed tripod. Only the size of the sensor limits how long of an exposure may be taken. All images would be the same width, but the longer the exposure the longer the image. Is "progressive scan" what you have in mind?

 

Gale



#59 james7ca

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Posted 21 November 2014 - 11:48 PM

The progressive scan CCD cameras stack as they go and adjust the scan so no guiding or tracking is required at all - just a fixed tripod. Only the size of the sensor limits how long of an exposure may be taken. All images would be the same width, but the longer the exposure the longer the image. Is "progressive scan" what you have in mind?

 

 

Gale

 

No, I don't think so. The "problem" with today's sensors is that their analog roots and A-to-D converters contribute a lot of noise and thus limit the signal-to-noise that is possible in a short exposure. A purely digital sensor SHOULD offer much better signal-to-noise and thus make short exposure captures even more usable. It's kind of mind boggling to think about a purely digital capture system. For one, it would practically eliminate the concept of ISO and gain settings and it would nearly eliminate the need for exposure control. If you recorded a deep enough digital signal (64 bit?) then it would be practically impossible to overexpose an image. Similarly, it would be a lot more difficult to completely underexpose an image (assuming that there was any amount of light on the subject to begin with). The net of this is that you'd have a huge dynamic range and given enough quantum efficiency (for lack of a better term) I don't think you'd even have to worry about exposure control when dealing with everyday situations (if you can see it at all then you can photograph it and then some).

 

Of course, as I mentioned before I'm not sure whether the physicist and engineers have even figured out how to make a fully digital detector, so this is pretty much out of reach given current technology.



#60 mike17

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Posted 23 November 2014 - 10:53 AM

Is Adobe Raw part of CS6 or do you have to download it seperately



#61 G. Hatfield

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Posted 23 November 2014 - 12:18 PM

It is part of CS5 for sure and certainly later editions.  In CS5 there are at least three ways to enter Camera Raw (and probably more).  Under files, you can go to "Browse in Bridge" and that will take you into Bridge where files can be opened in Raw (right click choice).  Or, also in file, you can use "open as", then pick camera raw as the file type, then your file and it will open in Camera Raw.  For this to work, the file you are trying to load into Camera Raw must be closed in PS.  Both of these methods allows one to open any file type in Camera Raw.  Or for raw or dng files, just open them in PS and they will open in Camera Raw automatically.   On my machine there is a delay of several seconds for Camera Raw to open when I use the latter.  

 

George


Edited by G. Hatfield, 23 November 2014 - 12:19 PM.


#62 Jerry Lodriguss

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Posted 23 November 2014 - 03:02 PM

Just remember that "digital" cameras and sensors are not really fully digital (they are analog/digital hybrids). But they are working on fully digital sensors that will actually count photons, so the days of needing to guide and other complications may be ending within the next several decades (if we're lucky).

 

 

You guys are behind on the news, Canon has already announced a QED (Quantum Entangled Detector) in the soon to be released 0D.

 

http://www.astropix....0d-zero-d-dslr/

 

Jerry



#63 Footbag

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Posted 23 November 2014 - 03:25 PM

 

Just remember that "digital" cameras and sensors are not really fully digital (they are analog/digital hybrids). But they are working on fully digital sensors that will actually count photons, so the days of needing to guide and other complications may be ending within the next several decades (if we're lucky).

 

 

You guys are behind on the news, Canon has already announced a QED (Quantum Entangled Detector) in the soon to be released 0D.

 

http://www.astropix....0d-zero-d-dslr/

 

Jerry

 

 

That source is always putting out bad info...  On April Fools! :p



#64 gdd

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Posted 23 November 2014 - 05:36 PM

 

 

Just remember that "digital" cameras and sensors are not really fully digital (they are analog/digital hybrids). But they are working on fully digital sensors that will actually count photons, so the days of needing to guide and other complications may be ending within the next several decades (if we're lucky).

 

 

You guys are behind on the news, Canon has already announced a QED (Quantum Entangled Detector) in the soon to be released 0D.

 

http://www.astropix....0d-zero-d-dslr/

 

Jerry

 

 

That source is always putting out bad info...  On April Fools! :p

The Canon 0D sounds no more fantastic than the Canon 6D would have when I was taking pictures with my Kodak Brownie.

 

Gale




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