Over ten thousand people got their start in astrophotography with the first two editions, now The Deep-sky Imaging Primer has been fully revised and expanded in this new third edition. It has been updated to include the latest cameras, technology, and software. Everything you need to know about capturing and processing stunning images of deep-sky objects is covered:
- The fundamental principles of electronic cameras, optics, and mounts
- How to choose the best camera and telescope for you
- How to set up, choose exposure parameters, and take the images
- Where and when to find the best deep-sky objects
- How to process images—in addition to PixInsight® and Adobe Photoshop®, Affinity Photo® and AstroPixelProcessor® are now fully covered
Start-to-finish examples of image processing are included, with a focus on PixInsight. The book is 280 pages with 373 illustrations, printed in full-color.
There are two ways to purchase a copy:
- You can buy a printed copy at Amazon (affiliate link; I earn a few extra cents). List price is $54.99.
- By popular request, it is also now available as a personal pdf for $29.99. This includes a bonus chapter, and it’s best viewed on a laptop or full size tablet (not a mini or phone), as it retains the two-column layout of the printed book.
To purchase a personal pdf edition, you can use the Buy Now button below, or if you have PayPal, you can send $29.99 to me at deepskyprimer@gmail.com. By default, I will use the name and email address that come over with the payment. If you need me to customize it with a different name or send it to a different email address, just email me directly with your preferences, and I can send you a link to pay via credit card. I can usually turn your order around in a day or so.
If you haven’t received it in 48 hours, check your spam folder and make sure you are checking the email on record with Paypal. If it’s not there after 4 days, please email me. Note that I do not sell to groups; this is for an individual.
The complete Table of Contents is listed below.
Welcome to Astrophotography! 7
Section 1: Understanding Images
- Electronic sensors
- The challenges of deep-sky imaging 9
- How electronic sensors work 9
- Sensor architecture: CCD vs CMOS 10
- Well capacity and bit depth 11
- The trade-off between dynamic range and gain 11
- The importance of bit depth 13
- Linear data and response curves 13
- Creating color images 14
- Signal and Noise
- How signal varies 16
- Signal and noise at the pixel level 17
- Shot noise 18
- An example of shot noise 19
- A dimmer example 22
- Skyglow 22
- Why shot noise cannot be subtracted away 23
- Dark current 24
- Read noise 25
- Adding signals and noise 26
- Variation in two-dimensions 27
- Bringing it all together 27
Section 2: Acquiring Images
- Choosing and using a mount
- Types of mounts 31
- Choosing and using a GEM 33
- Meridian flip 33
- Polar alignment 34
- Drift alignment 35
- Impact of polar alignment error on tracking 35
- Tracking error 36
- Balancing a mount 37
- Choosing a camera
- DSLRs 38
- Dedicated astronomical cameras 38
- Parameters to consider in choosing a camera 39
- The CMOS revolution 39
- Sensor size and field of view 39
- Parameters of common sensors 40
- Connecting your camera to a telescope 42
- Image scale: matching sensor and optics
- Resolution and seeing 43
- Sampling 45
- Factors that limit resolution 46
- Equipment recommendations 48
- Focal reducers and field flatteners 48
- Finding the right flattener or reducer 49
- Understanding the ‘f-ratio myth’ debate 50
- Etendue and comparing optical systems 50
- Choosing a telescope
- Fundamental optical parameters 52
- Telescopes for visual vs. imaging use 52
- Optical aberrations 52
- The Strehl ratio 54
- Refractors 54
- Telephoto lenses 56
- Reflectors and compound telescopes 56
- Summary of telescope options 59
- Filters and narrowband imaging
- Filters for imaging 60
- Choosing the right filter size 60
- Narrowband filters 61
- Light pollution filters 63
- DSLR filters and modification 64
- Focusing and setting up
- Focusing 65
- Achieving critical focus 65
- Reducing setup time 66
- Dovetails, rings, and other mount accessories 67
- Threaded connections 67
- Power supplies 68
- Dew prevention 68
- USB cables and hubs 68
- Automating image acquisition
- Automating your imaging 69
- Connecting to the mount 70
- ASCOM, Alpaca, and INDI 70
- Choosing and setting up a control PC 71
- Autoguiding
- Autoguiding fundamentals 73
- Autoguiding software 74
- Guiding graphs and performance 76
- Setting exposure parameters
- Principles of choosing subexposure duration 78
- Subexposure duration: the histogram method 79
- Subexposure duration: the calculated method 79
- Setting gain 82
- Taking the exposures
- Planning for a night of imaging 84
- A basic image capture workflow 85
- A review of calibration frames 85
- Taking dark frames 87
- Taking flat frames 87
- How many flats should you take? 88
- Taking bias frames 88
- Do I really need to take calibration frames? 89
- Dithering light frames 89
- Choosing objects to image
- The size of deep-sky objects 90
- The deep-sky catalogs 90
- Object types and the seasons 91
- A survey of object sizes 94
- Giant Objects (2° or greater) 94
- Really Big Objects (1–2°) 94
- Objects from 30–60’ 94
- Objects from 15–30’ 95
- Objects from 5–15’ 95
- Objects from 1–5’ 95
- Objects smaller than 1’ 95
- The Sun, the Moon, and the atmosphere
- When is it dark enough? 96
- Light pollution 96
- Measuring sky brightness 98
- Impact of the moon 98
- Impact of object altitude 99
- Local turbulence 101
- Improving your results
- The astrophotography learning curve 102
- Getting more data 102
- Getting better SNR from your raw data 102
- Getting better resolution 103
- Getting more out of your data in processing 103
Section 3: Processing Images
- Color in digital images
- Raw data and image file formats 105
- How we perceive color 105
- Producing color on print and screen 105
- Color management and color spaces 107
- LAB color 108
- The HSL/HSV/HSB color model 108
- White balance and color temperature 108
- Deep-sky color accuracy 109
- Color calibration with stellar spectra 109
- Image processing applications
- The stages of image processing 110
- Choosing among image processing applications 110
- Using Pixinsight
- PixInsight’s learning curve 112
- The PixInsight user interface 112
- Working with images in PixInsight 114
- Working with processes in PixInsight 117
- Image and process containers 118
- ScreenTransferFunction 118
- Layers and selections in Photoshop and Affinity Photo
- Layers 120
- Layer blending modes 121
- Composite layers 121
- Working with filters non-destructively 122
- Selections and feathering 123
- Fundamentals of pre-processing
- Throwing out problem shots 124
- The types of calibration frames 124
- Pre-processing overview 125
- Creating master calibration frames 125
- Dark scaling 125
- Registration: aligning the calibrated subframes 127
- Normalization 127
- Integration methods 127
- Bad pixel maps 129
- The drizzle algorithm 129
- Pre-processing in PixInsight
- WBPP or manual processing? 131
- Before WBPP: Using CosmeticCorrection 131
- Using WBPP: Loading and viewing files 132
- WBPP: Parameters for bias, flats, and darks 134
- WBPP: Parameters for lights 134
- WBPP’s Calibration Panel 136
- WBPP’s Post-Calibration Panel 137
- Presets 137
- Running WBPP 138
- Manual pre-processing in PixInsight 138
- Pre-processing in AstroPixelProcessor
- APP’s User Interface 142
- The files panel 142
- The image viewer panel 143
- The pre-processing panel: Steps 1–6 144
- The TOOLS panel 148
- Pre-processing in DeepSkyStacker 150
- Pre-processing in Affinity Photo 153
- Diagnosing common image problems
- Misshapen Stars 155
- Diffraction patterns 157
- Stray light 158
- Halos 159
- Flat fielding problems 159
- Noise 160
- Principals and tools of post-processing
- Types of processing tools 162
- Selective adjustments 162
- PixInsight post-processing sequence 164
- Photoshop/Affinity post-processing sequence 165
- Masks and PixelMath
- Masks in PixInsight 166
- Creating a luminance mask: clip and convolve 167
- Creating a star mask with StarNet++ 167
- PixelMath 171
- Using a uniform mask 173
- Masks in Photoshop and Affinity Photo 173
- Creating a star mask in Photoshop or Affinity Photo 174
- Color synthesis
- Aligning color channel images in PixInsight 176
- Aligning color channel images in Affinity Photo 176
- Cropping out calibration artifacts 177
- Aligning histograms with LinearFit 177
- RGB color synthesis in PixInsight 178
- RGB color synthesis in Affinity Photo 178
- RGB color synthesis in Photoshop 178
- Narrowband mapped-color images 179
- Bi-color HOO narrowband color synthesis 180
- Creating HaRGB images 181
- Combining luminance and RGB data in PixInsight 182
- Combining luminance and RGB data in Photoshop or Affinity Photo 183
- Blending RGB star data into a narrowband image 183
- Creating a synthetic luminance image 184
- Combining color channels in AstroPixelProcessor 184
- Color calibration
- PixInsight’s PhotometricColorCalibration process 185
- Other calibration methods in PixInsight 186
- The PreviewAggregator Script 188
- Color calibration in AstroPixelProcessor 188
- Correcting gradients
- Gradient removal in PixInsight 190
- Gradient removal with AstroPixelProcessor 192
- Gradient removal in Affinity Photo 193
- Gradient removal in Photoshop 193
- Stretching the image
- What is stretching? 197
- Understanding the histogram 197
- How different curves affect the histogram 198
- Stretching in PixInsight 200
- Stretching in AstroPixelProcessor 201
- Stretching in Photoshop and Affinity Photo 203
- Posterization: the perils of over-stretching 204
- Stretching’s effect on color 205
- Noise reduction
- Visual noise, color, and scale 206
- Luminance masking for noise reduction 207
- An introduction to scale-based processing 207
- MultiscaleMedianTransform 209
- TGVDenoise 211
- One-step masking for TGVDenoise and MMT 212
- ACDNR 213
- MureDenoise 215
- Desaturating the background 215
- Noise reduction in Affinity Photo 215
- Noise reduction in Photoshop 216
- Adjusting color
- Enhancing color saturation in PixInsight 217
- Selecting Colors with PixInsight’s ColorMask script 217
- SCNR 218
- Enhancing color saturation in Photoshop and Affinity Photo 218
- Balancing Color in Photoshop and Affinity Photo 220
- AstroPixelProcessor’s HSL selective color tool 220
- Narrowband color adjustment in Photoshop 220
- Correcting magenta stars in PixInsight 220
- Correcting magenta stars in Photoshop or Affinity Photo 221
- Contrast enhancement and sharpening
- Creating contrast with S-curves 222
- Contrast enhancement with the soft light blend mode 224
- Local contrast enhancement in PixInsight 225
- Unsharp mask 227
- Affinity Photo’s Clarity filter 229
- The high pass filter 230
- Dynamic range compression with HDRMultiscaleTransform 231
- Deconvolution vs. sharpening 232
- Deconvolution in PixInsight 233
- Star reduction and removal
- Reducing star size 235
- PixInsight’s MorphologicalTransformation 235
- The minimum filter in Photoshop and Affinity Photo 238
- Starless image processing with StarNet++ 238
- Star reduction and removal in APP 241
- Star removal in Photoshop 242
- Reducing bright stars in Photoshop 243
- Large halo correction in PixInsight 244
- Large halo correction in Photoshop and Affinity Photo 245
- Cosmetic repairs
- Cosmetic repairs in Photoshop and Affinity Photo 247
- Cosmetic repairs in PixInsight 248
- Plate solving
- Plate solving 249
- Image annotation 250
- Mosaics
- Planning a mosiac 252
- Mosaics in AstroPixelProcessor 252
- Mosaics in PixInsight 253
- PhotometricMosaic 255
- Image composition
- Framing the scene 257
- Color 260
- Step away from the computer 261
- Images and reality 261
- Example: Nebula workflow (starless)
- Create the color image 262
- Separate the stars and nebula 263
- Process the starless image 263
- Process the stars 264
- Recombine the images and apply final tweaks 264
- Example: LRGB galaxy workflow
- Process the color image 266
- Process the luminance image 267
- Sharpen fine details and enhance contrast 268
- Noise reduction and finishing touches 269
- Example: Star cluster workflow 270
- What are we looking at? [Digital bonus chapter]
- Nebulae 273
- Star clusters 274
- Galaxies 275
- Appendix A: Deriving the stack efficiency equation 276
- Appendix B: Deep-sky highlights 277
- Index 280
- Further reading 283
Deep-sky Imaging 
How to buy this book in India. From Amazon, shipping charges are more than the cost of the book.
Hi Pranjal –
I’ll see if I can find a more cost effective way to get a copy to you. Send me a note at deepskyprimer@gmail.com with your shipping address, and I’ll send you a quote.
Thanks,
Charlie
Hi Charles, I live in Canada and discovered that Amazon.ca doesn’t carry your book, which I thought was odd… anyway, is there anywhere in Canada that can source it for me (bricks-and-mortar or online)? – Rod
Hi Rod –
Sorry for the book not being listed on Amazon.ca. I can have a copy sent to you (media mail) for US$32. That takes 1-3 weeks. (Priority Mail is ridiculously expensive, but available for $47.) If you are interested, email me at deepskyprimer*AT*gmail.com. You may also check Amazon.com’s rates to ship a copy to you in Canada, as they may actually be able to ship it cheaper than I can.
Thanks for your interest!
Charlie
Hi Charles,
I’d like to thank you for your book! I’am french, I was trying to find a book about deep sky imaging but in french there are only 2 or 3 books that are dealing with astrophotography in general. Then I find your book on Amazon by chance. I looked inside and found it very good, with simple explanations… I bought it and I’m not disappointed! I had read the first part of your book and I find the answers to many questions… Thanks again! I’am going to read the next parts 🙂
Thank you for your kind words about the book! I am happy to hear that the explanations are clear to you. I hope you enjoy reading the rest of it, and please send me a note if you have any thoughts or suggestions.
Best wishes,
Charlie
Charles,
You produced a wonderfully readable and information-rich book! I bought a copy about 4 months ago, and find I’m constantly referencing it for one thing or another. Yours is the first imaging book I’ve purchased, and I would eagerly recommend it to others. Excellent work!
Thank you very much, Sorin. I am glad that you are enjoying the book. And nice pics of Comet ISON on your blog, by the way!
Best,
Charlie
This was the x-mas gift from my wife. So far, it looks VERY good and informative .
Merry Christmas! I hope you enjoy the book, and feel free to shoot me an email if you have any questions or suggestions.
Best wishes,
Charlie
I think the book is great, however the font used is way too small. It is nice looking, but I have to make a real effort to read it. I would have much preferred a thicker book, but easy to read, after all books are meant to be read, not to be looked at. That is too bad, as the book deserves all the praises, and I do hope that a future edition considers this point of view. Thank you.
Thank you for your helpful comment, Angelo. I am working on the second edition, and I have indeed increased the font size by one point. I’d rather have a thicker book too, but the book’s cost is based on the number of pages, so increasing the font size can increase the final price of the book. To balance the increased font size, I’m planning to increase the size of the book itself from 8×10 inches to 8.5×11 inches.
Best wishes,
Charlie
Hello Charlie,
Thank you for your reply. I understand your concerns and am glad to read there will be a second edition with an increased font size. Do you know when it will be out? Thank you.
Best regards,
Angelo
Hi Angelo –
My goal is to have the second edition ready for NEAF in April.
Best,
Charlie
Have you considered releasing the book as an e-book? It’s great having a paper copy to read from cover to cover, but I find e-books much better for a quick reference. An e-book can go with me wherever I have my iPad. Eithe e-pub or pdf would be great.
Hi Brooks –
I am looking into it for the second edition, as I’ve gotten a lot of requests. How would you feel about Apple iBooks vs. epub?
Apple iBook is even better from my perspective.
Hi Charlie, would like to buy both your Primer and The Astrophotography Sky Atlas. But I’m just interested in ebooks, for several reasons. I travel a lot, like to look back on stuff I have read, and then save shipping duration, cost – and environment. Unless truly forced – a principle. Many great hi-res tablets these days. No idea why you would choose iBook platform lock-in. Kindle is at least everywhere. ePub is great, can even accept (Adobe) DRM. If you do, please let me know, and don’t forget adaption to be within the readable! (this guy, like plenty of others, forgot to check: http://www.cloudynights.com/topic/507308-the-astrophotography-manual/)
Thank you for the feedback. Now that the ePub and Kindle formats seem to be maturing, I will consider offering the second edition as an eBook. I’ve had several similar requests, and I completely understand the convenience of eBooks. I read most of my magazines now on the iPad. There are some challenges with the eBook formats that still make me hesitant due to the nature of my books: they are full-color with high resolution images. Neither book would be appropriate for monochromatic eReaders, as a lot of information is communicated with color in the figures, and one of the chapters is specifically about color. I fear the atlas is possibly too high resolution to work on an eReader. If I had a way to prevent those with monochrome devices from purchasing the books, I would be more comfortable. I don’t want anyone to be disappointed after downloading an expensive eBook!
I still have a long way to go with the second edition though, so perhaps things will be different by the time I’m ready to publish it. Or perhaps I need to create a specific version for tablets that is designed for the format. I’ll investigate my options, and appreciate any additional thoughts you have.
Best,
Charlie
Hi,
I am hesitant to buy this first edition if the second edition is being released soon. What are the plans for the second edition, still looking for ab April release date?
Thanks
Sorry, work commitments have delayed my ability to finish the second edition. I do not expect to have it ready until later in the year now.
Thanks,
Charlie
Hi, Any news about the second edition? I can’t wait 🙂
I’ve re-written sections 1 and 2 already, and I’m re-writing section 3 with a much greater focus on PixInsight this time. I have another book coming out next month (an astrophotography atlas), so work on that has delayed the second edition of this book. Thanks for your interest! When the second edition comes out will mostly depend on my work schedule, but I don’t think it will be ready before the end of this year.
Best,
Charlie
Hi,
I bought this about 18 months ago as a newbie. It’s one of the best you can buy on the subject. Covers most of the significant concepts in a relatively simple langauage that one can understand. Especially stuff like full well capacity, the coverage of the field of view and then processing tips as well. Well written with clean colour images. I still use it whenever I need to brush up. I bought several books before but this is the stand out for DSLR especially.
Nalin
Thank you, Nalin!
Charles:
I have the First Edition. I was working thru the exercises and came to Exercise 1.3 on page 33. The answer on p.185-186 confused me. How did you get 18.3 e- per second? From Ex 1.2, the thermal noise was 1.68e- per second at 20 deg C.
Michael
You are correct, this is an error in the book that carries over an old version of the question. The answer to 1.2 should read:
“An exposure of 20 minutes at 40 degrees Celsius would produce 20 min x 60 sec x 1.68 e- per second = ~2014 electrons. Dark current would fill 2014 / 25500 = ~8% of the full well capacity. The brightest capturable level would be 25500 – 2014 = 23486. The noise from the dark current is SQRT(2014) = ~45 electrons. The read noise is given in the problem as 10 electrons, thus maximum theoretical dynamic range is 23486 / (45 + 10) = 428, or 53 dB.
For the same exposure at -15C, following a similar set of calculations, the dynamic range would be 25468 / 15.6 = 1629, or 64 dB.
(Note that we are simplifying our calculation of total noise here by not using the proper summing in quadrature method, as that is not covered until the following chapter, but this simplification does not have a meaningful impact on the results.)”
Hi! I see there’s mention of a second edition of this book being prepared last year. Will that be released soon? I’d like to buy it.
I took a year off from writing the second edition to create The Astrophotography Sky Atlas. Now I’m working on the second edition again, but it’s still a long way from done. Sorry for the delay. It can be hard to squeeze in the time to write with a full-time job and family!
Hi from New Zealand. I wonder if your Astrophotography Star Atlas includes the Southern Hemisphere for all of us below the equator? I assume that you have probably spent most of your focus on only the Northern Hemisphere. thanks.
Hi Larry – The atlas covers the entire Southern Hemisphere in the same detail as the Northern Hemisphere. With so many great objects visible from “down” there, I couldn’t leave out the southern skies!
Best,
Charlie
Hi, I´m here to bug you, good Sir, for a digital version of your work. In my search for just that I see illegal downloadable copies in pdf-format out there. I simply refuse to go that way, it would not be fair to all that work you´ve put into your books.
SO many people have a full colour tablet these days, I really think your work would reach more people that way. Pictures could be enlarged for potentially better viewing than on paper.
E-books tend to come cheaper as well, no postage, no paper, instant delivery, has a lot of benefits. Please concider some sort of comercially available digital version of your work soon.
For my personal interest, the Deep-Sky Imaging Primer is my first wish. I´m rather impatient when I see something I need for my hobbies. I´ll probably acquire the printed version none the less, while I wait for my wish to come true (around Christmas? 😉 ).
Kind regards and hopes for clear skies
Bjorn, Denmark
Hi Bjorn – I appreciate your thoughtful note. As the e-reader market evolves (and I get feedback from potential readers like you), I am reconsidering my publication options. I still need to do some research on pricing structure, file formats (Kindle vs. ePub vs. iBooks), and resolution. All of my efforts right now are still on finishing the upcoming book, but once I’m done with that, I can see about releasing a digital version of The Deep Sky Imaging Primer.
Best,
Charlie
Thanks, Charlie. And best of luck with your current work.
I will order the hard copy asap. Can’t wait…
To promote the digital version you could stress the practicality of having it along in dark conditions (if the book should find it’s use in real-time-next-to-scope situations, idk.), some ebook-apps have night lighting, so one doesn’t spoil night vision.
I use both Blue Fire and iBooks, the former comes in both iOS and Android. Some inspiration: http://www.tomsguide.com/us/pictures-story/583-best-ereader-apps.html#s7
Clear skies (and clear types)
Bjorn
The Second Edition is available on Amazon today. Fantastic!
Hi Charlie, minor copy error you’re probably already aware of. On page 171, figure 230 covers up the text. It’s not a critical error as the intent is clear in the image, but I wanted to make you aware of it. Stu
Thank you Stu. The next printing will correct this error as well as a few typos.
I was wondering if your book shows information on filter wheels? I have two stellarvue refractors (80 & 105 triplets). What are the advantages of electronics over manual? Or is there any? I haven’t found anything that talks about filter wheels. Or what size filters are best 1-1/4” or 2”).
Thanks in advance.
Hi Stephen – Electronic filter wheels have enormous benefits. Mainly, it’s because you can set them to be controlled from your computer, allowing you to automate your imaging session with software like AstroPhotographyTool or Sequence Generator Pro. Otherwise, you’d have to sit by your scope all night and turn the filter wheel manually. Also, manual filter wheels won’t have the same accuracy in turning to the exact same spot, which is required for flat fielding.
As for filter sizes, there isn’t a “best”–it depends on the sensor size, how close the filters are to it, and the focal ratio. For most APS-sized sensors, 1.25″ are okay for focal ratios slower than f/4. SBIG cameras of this size don’t put the filter as close the sensor, they usually use 36 mm filters. Larger sensors require 2″ filters.
Hope that helps!
Charlie
Hello Charles, would it be possible to promote the information and image of the book in the next issue of the amateur astrophotography magazine please?
Looking forward to your reply
Steve
Hi Steve – Yes, that would be great! Please shoot me an email at deepskyprimer@gmail.com and let me know if you need a high-res image or anything like that. I also have a new book coming out next week that you might be interested in.
Thanks,
Charlie
Charles, I am enjoying your book. However, to get the most out of it you kind of need to be in front of the computer working through the examples you give. It would really be helpful if you could provide the images you use in your book to demonstrate PixInsight for download so that we could replicate your results as we work through the examples
Thanks,
Stuart
Hi Stuart – I’m so glad to hear you are enjoying the book! The files used in the examples were several gigabytes in size, and I’m not sure I have them all at this point. Is there is a specific example you’d like to try? I can see if I can find the original data and send your way.
Best,
Charlie
Hi Charles,
Thanks for this very interesting book. I’m trying to work out the solution for ex 2.2 in the second edition. If my reasoning is correct then reworking the formula would yield a = 1.22 times wavelength devided by sin(1/206265). I do not get 173mm. Even using 173 mm in the formula itself and calculating the angular resolution does not yield 1/206265. What is wrong with my reasoning?
Regards, Bart
Hi Bart –
I should have better explained in the text that the wavelength and aperture values are both in the same unit (meters). So the wavelength becomes 700 nm = 700*10^-9 meters. Your equation when you solve it should look something like:
sin(1/206265) = 1.22 * 700*10^-9 / a
with the value on the left in radians, it becomes
4.848*10^-6 = 854*10^-9 / a
a = 854*10^-9 / 4.848*10^-6
a = ~0.176 meters = ~176mm
Not only will I update the completed answer to show these steps better in the third edition, but I’ll also change Rayleigh’s criterion to drop the sin-1 function. I was being technically correct by including it, but for small angles, it doesn’t any material impact to the accuracy, so Rayleigh’s criterion just becomes resolution = 1.22 * wavelength/aperture. I think you’ll agree that equation is much easier to use! Reworking the problem with this approximation, it becomes:
1/206265 = 1.22 * 700*10^-9 / a
4.848*10^-6 = 854*10^-9 / a
a = 854*10^-9 / 4.848*10^-6
a = ~0.176 meters = ~176mm
Thanks for bringing this to my attention.
Clear skies,
Charlie
Hello Charlie;
What is the chance that you will be issuing a revised edition again? PI has advanced quite a bit in the 4 years since your last update.
Thank you!
Ken
Yes! I’m working on it now. Not only has PI advanced, APP and Affinity Photo have become a part of many people’s toolbox. I’m hoping to release the 3rd edition this fall to cover all of this.
Hi Charlie, I can’t wait for your new edition;) Can you give us a more specific date? I am looking forward to hearing from you…Best regards from Switzerland;)
I am working toward a launch at NEAF/NEAIC here in the US in April! I also plan to offer the book as an e-book this time.
Thanks!
Charlie
Are you still planning on releasing the 3rd edition of The Deep-sky Imaging Primer soon?
I just received my copies of the Deep-Sky Imaging Primer (3rd Ed.) and the Astrophotography Sky Atlas and I have to send you a big congratulations on the incredible work you have put together for our little community. The content is outstanding in both books, and I can anticipate that they’ll get a lot of use as I delve deeper and deeper into astrophotography from my little backyard observatory in New Zealand. What a great way to kick off a new year! Thank you very much!
So glad to hear that they have made it to you! Enjoy!