These are simplified answers to some of the commonly asked questions concerning photographs of the sky...whether it's of the sun, moons, comets, stars, or whatever else is up there, these photographic principles remain true.


FAQ: Camera's, photography, astro-photography, etc

Q: How does a camera work?
A: Cameras work by focusing light through a series of lenses onto either film or a tiny bank of light sensing mechanical "eyes". The most rudimentary form of camera, though, doesn’t have a lens, it has a pinprick in a sheet of foil which projects the light into the back of the camera box onto the film (called a pinhole camera, you can make one yourself with a box, some aluminum foil, and some black-and-white photo paper)

Q: How do photographers get clear pictures of the night sky?
A: This is a tricky one, because there's almost as many ways to do it as there are photographers doing it. There are certain things that you must have though:
- A sturdy tripod. This is a 3-legged stand, which the camera attaches to with a large screw. Turn over your camera, if it has a threaded hole, that's for a tripod. If you have nothing else on this list, you must have a tripod.
- A "cable release". This is a cable that goes from the camera picture-taking button (shutter release) to a little button you push and makes it so you don’t actually have to touch the camera to take the picture. If you've seen the old cowboy movies where they photographer is standing under the hood of a big camera, and he's got the flash in one hand, and a black trigger thing in the other, the trigger thing is a cable release.
- Bracket exposures. This means you don’t just take one snap-shot of the sky. You take several pictures of the same thing using different settings on the camera, like the time the lens is open. What this does is makes sure you have at least one good picture, even if the camera's light meter system is fooled by the dark sky. The amount of pictures someone brackets directly relates to the amount of experience they have taking night-sky pictures. It can be as few as 3, or as many as the entire roll of film, or more.
- Fast film. This means film that is sensitive to light. The way you can tell how fast a film is (how fast it can record light) is by the ISO or ASA number on it. ISO 200 film isn’t very fast, it's used for daylight or flash photography. ISO 1600, the fastest color film on the market right now, is extremely fast and should not be used for daylight pictures at all. The problem is, the faster a film is, the more the little grains of color can be seen, so many astro-photographers actually use slow film which has been chemically treated with a gas to make it react faster to light, which gives the film a "hyper" designation.
- Time and patience. The longer the shutter on a camera is open, the more light gets captured by the film. The spectacular shots you've seen of galaxies are usually exposures of 30 minutes or more. For exposures that long, the photographers have special motorized tripods, which can follow the sky in order to keep the stars from blurring with motion.

Q: How does a photographer take a picture through a telescope?
A: There are several methods of doing this as well, but I'll talk about the one that is the most reliable. The first things you need are: a camera with changeable lenses and a device called a T-Ring adapter. The T-Ring adapter fits onto your camera where the lenses normally would. The next thing you need is an adapter tube for your brand of telescope, or a generic one that matches the measurements of the lens opening in the telescope. The adapter tube screws onto the T-Ring adapter, then the other end of the adapter tube fits into the lens opening on the viewing end of your telescope. Now, you can look through the camera right through the telescope as if the telescope were a giant zoom lens. After that, it's just a matter of experience learning how to find and focus on objects this way. More advanced camera tubes allow you to put magnifying lenses between the telescope and the camera, which enlarges the images, but also makes it much more difficult to find and focus on those objects. (You could also go to your telescope dealer and get a device called a CCD, which is a digital imaging device, and it fits directly on the telescope's lens opening. CCD's feed digital images directly into a computer, making it so you don’t need a camera, film, developing, etc, but they are also very expensive.)

Q: What causes <insert strange photographic anomaly here>?
A: I'll tackle this by categories:
- Circular blobs with very faint centers but very defined edge outlines (like a circular line with fog inside it): usually only on film cameras. This is caused by a bubble getting on the negative when it was in the developing process. As that bubble sat on the negative, it prevented the developing chemicals from reaching the film properly, causing the ring with the smoky center.
- Streaks that look like sparks: Coming from pictures that don’t have very bright objects in them, in film cameras, these are caused by static electricity striking the film while it was in the camera or being handled for development. Most cameras have a metal plate, which touches the film in order to absorb any static, but it doesn’t always work. If the streaks come from a bright object, and are in the form of a cross, or a 6-point star, they are called Diffraction Spikes and are caused by irregularities in the lens surface (like dirt, scratches, fingerprints, or the way the lens was ground into shape when it was manufactured).
- Small splotches or dots on digital images: These are either a) one of the sensor "eyes" in the camera got overloaded by light and reported a false color or brightness or b) some little bit of data got messed up when the picture was being recorded by the camera or being transferred from the camera to a computer. You can tell these glitches by the way they are regular colored (no shading like a 3D object would have) and they don’t seem to match up with what you saw with your eyes.
- Circular blobs with even color and without defined edge outlines: These are lens flares. They can appear circular, or as hexagons. They can be almost any color, but are usually between yellow and red. There can be as few as 1, or as many as 20, depending on how many pieces of glass are in the lens (most cameras have 3 lenses, but telephoto zoom lenses can have 7 to 15 or more pieces of glass inside them). They are caused by the camera being pointed at or near a bright light and are the most commonly mistaken camera artifact that I know of.

Q: What causes a lens flare?
A: Lens flare is caused by a few factors:
- Bright light enters the front lens of the camera
- A portion of that bright light is reflected off an internal part of the camera
- That little piece of light is reflected again off the inside of the lens
- The light ends up as a small, faint circle on the picture, quite often shaped like a hexagon
As you can see, it takes all 4 of these things to make the lens flare appear on the picture. Usually, the only way for all the reflections to line up the right way, the source of bright light has to be either right in front of the lens, or almost 90 degrees to the side of it. If the source is right in front, there is only 1 flare spot. If the source is to the side, there can be as many spots as there are pieces of glass in the camera lens.


Above is a diagram I did showing a very simplified view of a lens flare happening. The yellow area is the entire field of view, the red and blue lines are light from a very bright object. The blue line is the light from that object as it travels to the film, the red line is a portion of that light that gets reflected and becomes a lens flare.


Here is an illustration I did, similar to the one above, which deals specifically with webcam reflections within Plexiglas housings. Recently there were several questions about how a reflection of a bright object can be reflected in duplicate on the same picture. The blue line is a bright object, such as the moon, the red line is the reflection off the lens, the enclosure, and back to the film at an offset location.

Notice their similar causes? They are beasts of the same breed, so-to-speak. (Pictures not to scale nor technically accurate concerning the path light takes through a lens...merely representative)

Q: How do I get rid of lens flares?
A: A photographer who knows he/she is going to be in a situation with harsh light sources takes precautions. They make sure they have lenses which come with coated optics. That means the pieces of glass in the lens have chemical coatings on them which don’t let light bounce off of them. The photographer also has a variety of hoods to use, which are attachments for the lens, and act like the brim of a hat does when you wear it to block sun from your eyes. Lately, a lot of outdoor photographers are trying to make use of lens flare as a dynamic effect that makes your eyes follow through a picture. You can even add false lens flare, with programs like PhotoShop, to pictures that don’t have one.

Q: Why did I get lens flare on my picture when I didnt see it in the viewfinder with my point-and-shoot camera?
A: Your camera has a viewfinder that does not "look" through the same lens that puts an image on the film. The viewfinders of point-and-shoot (PaS cameras are the kind that dont have the ability to remove the lens) cameras only have two lenses, one sets your field of view to the maximum that your camera can use, the other focuses the first lens. These two lenses are too far apart for lens flare to occur, and are also usually just a little bit recessed into the camera body which protects them further from lens flares. The focus lens system is also offset from the main lens by sometimes more than an inch. That offset is often enough to make one set have a flare and the other not. Even on cameras with zoom capabilities, where your viewfinder zooms to match what you see on the film, this is the usually the case.

Q: Why is it so hard to get a picture of the Moon that shows the "face"?
A: Well, most cameras are set up to automatically measure the amount of light entering them so that they can properly open the shutter for the perfect amount of time. This meter inside the camera takes a measurement of everything you can see through the lens, then averages that measurement, which is usually fine for daytime or flash photography. When you're shooting the Moon, though, the meter is fooled into an average that is too low for the Moon (making it over-exposed, or just a white blob) or too high for the surrounding sky (washing out the sky and making it look gray instead of black). Cameras with a "Spot Meter" system are more appropriate for shooting bright objects against a dark background because they don’t average the entire scene, they only measure what is in the middle of the picture. If you don’t have the ability to spot meter, then you have to manually adjust for the camera's mistake by taking several pictures of different exposure settings (like shoot one at the camera's automatic reading, then another with a faster shutter speed, then another with an even faster speed, and so on) this is called bracketing.

Q: How do you get the 1 hour folks at Wal-Mart to actually develop all your shots?
A: Ideally, you should take your film to a professional developer with some experience with astro-photography developing. You should also take a few reference shots at the beginning of the roll of film, 1 or 2 shots of the box the film came in, using normal light or a flash. That allows the developer to have a starting point. If you must take your film to the 1 hour developers, then it's a bit more of a hit-or-miss proposition. I generally tell the teenagers working there this basic speech "Ok, this roll of film has some astro-photography on it. That means I took pictures of stars. Your machine is going to think that the black frames with a white dot in them are mis-shot pictures where the flash didnt fire or the lens cap was on. I want you to override the machine and force it to print every frame even if it's just pure black." And then I hope for something good. At least, even if they dont make a good print, it's difficult to mess up the negatives. So if they cant print something right, I just take the negative to my local camera shop, rent a dark room, and print my own.

Q: This sounds fun, what camera should I buy to get started?
A: I cant really answer this question for you. The best thing to do is actually go to camera stores and handle the cameras they have for display. Find one that has these minimum functions:
- Tripod attachment hole
- Spot metering capability
- Ability to attach a cable release
- A manual function that includes a "Bulb" setting, which is what you will use for exposures over the maximum available on your camera. You can lock the cable release in the shutter-open position and set a stopwatch, then unlock it when your exposure is complete.
- The ability to switch lenses, and for those lenses to be set to manual focus
There are many $150-300 cameras that meet these minimum requirements, and you should choose the one that meets your budget and comfort levels. I use a professional quality Canon Elan 7E for all my work, of which astro-photography is only a fraction. I also have an old Canon AE-1, which I use to teach my teenage step-sons about photography. (good suggestion g99)

Post questions and I will try and answer them, as long as they are about taking pictures of the sky...

edit 1: added film developing and camera choice questions
edit 2: added flare on picture vs. no flare in viewfinder question

__________________
~Brad - Astropaparazzo
http://signaturedigitalimages.com

...Bravo!.....<loud applause>.......
...My only experiences with night-time photography consisted of one successful and interesting use of a Canon AE-1 Program (set to manual shutter speed), high-speed film and the lighted ferris-wheel at the local 'county fair' for my high-school annual.......
....and a completely UNsuccessful use of an 'el cheapo' digital camera and the last lunar eclipse........
....Got some *great* shots of 'dark' though..... ops:
....Now, if I could just convince my wife that I need a coupla' thousand for a telescope, new camera or CCD, etc. and your fine work here, I'd be set for the next one.......
.....Thanks for the time it took to write this up......I'm sure there are many who know all of this already, but I didn't.......

I recently made the switch from from an old Pentaz zx-m to a ccd. The pentax actually broke the mount on my telescope while I was tracking. I also decided to go with a ccd because I am tired of shooting rolls of film and paying for development and only ending up with 3 or 4 good shots. My greatest problem with the film was lens flare. I do have several nice colored lens flare shots of the moon, but for the most part that, or scratches on the film made the "old" way of astrophotography too time consuming. Of course I have only had one clear sky since my new telescope and camera arrived, so I don't know if the CCD way is any better. Great write up though, thanks a lot.

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We've got a five dollar fine, for whining: Chris Ledoux

Great!!! (youi might want to add this to general Astronomy too (or just a link) . :-)


O.K. how about add a list of good cheap cameras a beginner can use to take pictures with?

Added: also a thing about developing film and how to not let the camera shop throw away the pics. :-)

Excellant Comixx


I copied it to Word for my own files , hope that is OK.

I appreciate the feedback

Use this as you see fit. I'd much rather people had their own copies of this than see so much truly bad photography out there passing around. Bad pictures dilute the market, making it harder to sell any pictures at all...but good pictures means good competition, which means better pictures, and 'round she goes

__________________
~Brad - Astropaparazzo
http://signaturedigitalimages.com

I always used a development studio that would do what I asked. Because I used various shutter speeds I always told them not to cut negatives, and to develop every photo, regardless of if there was nothing on it. This helped me when I took notes.
Anyway, that is just my opinion.

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We've got a five dollar fine, for whining: Chris Ledoux

I've added those 2 questions g99 to the bottom of the FAQ.

I'll keep editing to add answers, if I have the answers to add, that is

edit: Also, pertaining to professional developing: A lot of astro-photographers use hypered film or they push regular film to different speeds than it's rated for. ISO 3200 black and white kodak can be pushed to ISO 6400 or 9600, but that kind of handling of the film requires professional developers only, using special chemicals and developing processes. Pushing film that high increases it's grain size tremendously, so most pushing is something like ISO 100 to ISO 800, which is a very fine-grained film pushed to much higher speeds than it was meant for. It's also a very tricky process which is why I didnt mention it in the FAQ body.

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~Brad - Astropaparazzo
http://signaturedigitalimages.com

thanks comixx. :-)

I didn't know a lot about photography (and almost nothing about lens flares) and found your FAQ very informative and easy to understand. Thanks Comixx! Good diagrams too.

Film camera recommendation for the beginner = Pentax K1000. See ebay.

__________________
"If a tree is cut down in the rainforest, and is used to make paper to print a book, and the book is really bad, and there's nobody that will read it, do you still hear a sucking sound?"
Charlie in Dayton, A.AsC.

I have had my Pentax K1000 for about 18 years and have taken the most awesome pictures, including some great ones of stained glass windows in several English cathedrals. There is nothing like manual controls for those badly lit places.

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"Somewhere, something incredible is waiting to be known." Carl Sagan

Thanks Comixx! A great piece of work. It's a definite keeper.

Comixx - have turned the FAQ's into a word document with pics that I intend to save. May pm you and ask for your real name if I spread this around - there are a few folks around here who are interested.

Bravo, sir! A true tour de force on the subject.

I think we could use an expanded section on lens flares. Most probable shapes, streak effects off the corners, locations on a line thru the lens optic center to the sun, etc. That one would get cited a whoooooooooooooole lot on here...

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"If a tree is cut down in the rainforest, and is used to make paper to print a book, and the book is really bad, and there's nobody that will read it, do you still hear a sucking sound?"
Charlie in Dayton, A.AsC.

Thanks very much for the words of support I didnt think this would be so popular...

Anyways, I'm working on an expanded "Advanced" section that I intend to add tonight or tomorrow dealing with hypered film, de-rotators, wedges, infra-red film, nebula filters, and a few other things...I'll have it up as soon as I'm happy with it.

PS. I sign all my posts with my real name.

edits: ascii is a lost art for me...sigh...
edit: Charlie, the reason I didnt include the line from center-optics to flare-center was because many people cant distinguish a flare from an external reflection (like the infamous 2-moons webcam shot) and reflections dont follow that rule, but are based on the more complex geometries of the camera + housing + other factors...I also didnt tackle spiking because it has so many causes as well. I may add them to the advanced section, though.

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~Brad - Astropaparazzo
http://signaturedigitalimages.com

Three things:

1) Diffraction spikes. 4 or 6 point spikes are usually caused by the secondary mirror holder in a reflecting telescope.

2) Add my reccomendation of the Pentax K1000. Great basic camera.

3) Beware of all electronic cameras. If the shutter is held open electrically, time exposures will quickly drain the battery and the camera won't work until you change the battery.

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Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

where did you copy and paste that from brad?

__________________
New Brilliant Astronomy Site:
http://evilspace.cjb.net
Join Their Please.

I don't believe this. You must be involved in the conspiracy! I can't believe that you're trying to keep the truth about Planet X from us. Indeed! Lenses in cameras! (j/k)

Glen, I just thought that you might want to know... when I click on your link in your sig, I get sent to http://pop.mircx.com/pop/cjb/script/105481517383697 and then I get a URL could not be retrieved error. That's with Netscape. When I use IE, I have no problem.

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Don't put off till tomorrow what you can avoid altogether.

Ran a few phrases through Altavista and never got a single hit. Looks like its the real thing, baby! A true Comixx original.

Why do you assume it is not original? :-?

__________________
Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

Now i am torn between a good manual camera and a very good Digital camera (4 megapixel.). (sort of)

I do not have a Telescope, What are the chances i will get really good night shots from just a tripod with the manual?

I am currently leaning heavily towards digital. But i might get a regular manual camera in the future. Will it be worth it without a telescope, or should i wait to get a scope too?


p.s. the reason why i want the digital is becuase photography is a good hobby of mine (very amature hobby, all self taught) and i love working with the digital cameras ( i currently have a 2.0 megapixel that my dad wants to get from me). It ends up being cheaper in the end ($10 or so a roll for film adds up) and i think the quality is just as good as a regular camera if you have a good printer (i print up full page shots, to the usual picture sizes). Most of my shots are day or dusk shots and my digital works great for that. I have also taken some very good fireworks shots with my digital. :-)

I know i can't take good bight shots of stars with my digital. The moon i might with your idea of spot meter (that is good, thanks! :-))

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GIYUL :-)
"It takes Thousands to fight a battle for a mile, Millions to hold an election for a nation, but it only takes One to change the world." - Dan Sandler 2002

Well, I'm a bit peeved at this...If I had copied and pasted from someplace, I would have given credit. The only place this information was copied and pasted from was my Word program. It's completely original and comes from my experience and training as a photographer.

The Diffraction spikes I'm talking about are with camera-only pictures of bright objects such as the sun. The 4 or 6 point spikes caused by secondary optics-holding vanes in telescopes do exist, but only if you're taking pictures through a telescope which has such vanes...

I hesitate to endorse any specific camera, although the one you mention may well be a good basic camera, it may be beyond a beginner's abilities to figure out the manual-only functions.

Your warning about electronic cameras is well-founded though. I had this same problem with my AE-1 last winter...cold + battery-operated shutter + time exposure = dead battery. I always keep spare batteries in my camera pack since I dont own a mechanical-shutter camera.

I'm having to research a little bit of the information in my "Advanced" section for this FAQ...I'll have it up as soon as I can.

__________________
~Brad - Astropaparazzo
http://signaturedigitalimages.com

Well, for just star-field shots and sunset or sunrise skies, digital on a tripod is fine. The problem with digital cameras is you have to get into the rather expensive range in order to get ones with interchangeable lenses. I would never buy a camera that would not allow me to change lenses, but you may not have that as one of your needs. If you go digital, make sure it allows you to: Spot meter, set manual exposure, set time exposures of more than 30 seconds. One with aperture priority and shutter priority settings is really nice too for sunset shots, but that's a bit into the advanced photography stuff...if you have a digital that does not allow you to change lenses, you will not be able to attach it to a telescope, so that answers your questions about getting a scope.

__________________
~Brad - Astropaparazzo
http://signaturedigitalimages.com

I will look for those things. The intgterchangable lenses is not that big of a deal for me, but i will keep the idea open. Most digital cameras i have seen have the ability to set the exposure a few seconds longer or shorter. I have not seen 30 seconds, but i will look at real camera shops. All i have looked at so far is best buy and other stores like that. The only problem i have is price. I am looking in the $450-$490 range. The cameras i have seen that i like are in that range now.



How about a reguar manual 35 mm camera? Will it be worth it to get it on its own, or wait for a telescope too?

added: by the way, i really apreciate the help. :-) Thanks.

Well, let me clarify: Any camera that takes good pictures will also take good pictures of the night skies. Digital cameras often have a fixed lens with some zoom abilities (never use the digital zoom, its a fake zoom created with software within the camera) so they have a pretty good range of field-of-view. Almost any manual 35mm camera will also let you take good night shots, as long as it allows you to attach it to a tripod and set a reasonably long exposure. (edit: what makes good pictures of the night sky is patience, a tripod, and time-exposures, not the camera...it's the photographer's dedication to making a good shot that counts.)

Pick up an issue of Popular Photography and Imaging from your local book store, this month's issue has an entire article dedicated to beginner camera's on a budget. My favorite cameras are Canons...but Pentax, and Minolta have really good offerings too.

__________________
~Brad - Astropaparazzo
http://signaturedigitalimages.com

Thanks Comixx.

I always thought that digital cameras could not take good night shots because of their design. I guess i was wrong. I have the patience to take a night shot. It is just that i have never had the technology to. I will really look for a camera that will have the ability to set exposure steeings and spot metering mainly. Then interchangable lenses. But i think i will not have much luck with that (lenses) in my price range for digital.

I found out about the digital doom the hard way. I took many pictures in Washington D.C. and some of the longer shots were with the digital zoom. They became very grainy and pixeated. Uhhggg...


Well i think you have decided it for me. Digital it is. Thnaks alot!!! :-)

Later.

You should be aware that with longer exposures on a digital camera you will have to contend with noise. This produces a kind of speckling effect in the darker regions of the image.

Here's a link to a paper that describes a little about astrophotography with a digital.

That is great Hamlet! thanks alot. :-)

ok. i have done some reaserch and have found a good digital camera i like: (it has 15 second shutter delay, spot metering option. But a fixed lens.) Canon PowerShot S400 Digital ELPH Camera
That site gives everything about it. From what you described, it has most of the functions. Even a ability to reduce noise at the longer exposures. Not to mention the camera i have now is a earlier version of the same camera (S100) and this camera was my first choice before i asked you guys. Thanks again guys for your help in what i should look for. I will continue to look. But this is #1 so far.


Added: i am not asking you if the above camera is good, just telling you what i am probobly getting. :-)
Question:

1. what is ISO? as in "Sensitivity equivalents include 50, 100, 200, and 400 ISO settings, as well as an Auto adjustment."

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GIYUL :-)
"It takes Thousands to fight a battle for a mile, Millions to hold an election for a nation, but it only takes One to change the world." - Dan Sandler 2002

ISO or ASA is the light sensitivity rating. The higher that number, the more sensitive to light the film (or digital camera) will be. It's also referred to as the speed of the film. For example, a fast film would be ISO 800 or higher, meaning it responds to light pretty fast.

The higher the ISO, the higher the amount of grain or noise in a picture though, so faster isnt always better. Sometimes it's a lot better to take a slow film and expose it for longer, so you have a finer grain in the picture (think of picture grain like sandpaper grain, the finer it is, the smaller the grains). But, when you're doing that you get into the reciprocity problems, which I wont go into here...

__________________
~Brad - Astropaparazzo
http://signaturedigitalimages.com