Photography - 1

 Although point-and-shoot photography, provided by my smartphones, have served me well in the past, occasionally, I need to have more control and my study of biology has brought that forward, especially here in the desert where the intense light adds an extra factor and need for adjusting exposure.

So I decided to take Professor Marc Levoy's online digital photography course (Digital Photography). And I'm learning quite a lot.

Exposure, the amount of light reaching the photographic element affecting the brightness of the image, is a subtle balance of shutter speed, lens aperture, and ISO which is a measure of the sensors sensitivity to the light.

The trick is that each control involves a different trade off.

For instance, the longer the shutter remains open, the more motion you will catch and the more the subject will blur, which is an effect that you might want occasionally, but not usually.

These two scenes show what progressive shutter speeds will do to brightness.

If you expand the photos above, you can see that the dog is more blurred in the brighter (top) photo.

You can really see the trade off of motion blur and brightness in the photographs of the ceiling fan below  Only the shutter speeds were changed between photos.

Aperture width controls brightness but it also controls depth of field, the area a distance away from the lens where subjects are sharp. Only my Photon camera allows the virtual aperture to be changed and the differences aren't great, so that might be why the other apps don't provide the option.

Top right f/1 clockwise by steps to f/16. Expand each photo and you can see a difference in the sharpness of leaf veins 

ISO is the last element of exposure. It was originally a measure developed by the International Organization for Standards to describe how "fast" a photographic film was, that is, how sensitive it was to light. Since sensitivity was related to the graininess of the photographic emulsion used, it also was associated with the graininess of the image produced. That translated well into digital photography 

For a CCD, (photographic sensor) each pixel can be amplified to increase its sensitivity to light. That amplification also introduces noise. Enlarge the following photographs and note the "graininess" of the images.

An ISO of 100 is the image as it is produced by the sensor without any amplification. ProShot will adjust ISO from 100 to 19200 and those values are shown in steps above. The top left image has an ISO of 100 and the sequence gets brighter to the lower right. But enlarge the lower right image to see how grainy it looks, so there's a trade off. And you might want that graininess. I sorta like it 

Autofocus (automatic mode) adjusts everything for you and usually does a good job except for some special effects. You can even adjust depth of field in automatic mode on some cameras (like ProShot and Photon) by tapping on the part of a scene you want to have the focus.

Bracketing is a useful tool for planning a picture. It gives you a number of successive shots of the same scene with progressive exposures. The following shows three exposures differing by 2.2 stops.

So, before I go on to my second photography blog, let me tell you what Professor Levoy says about choosing a camera 

If you have the money, get an SLR (or DSLR) or MIL, not a point-and-shoot. 

Don't worry about megapixels, most cameras have too many.

Don't worry about brand or body 

Worry about lenses. Variable zooms are nice but consider the quality.

Avoid large focal ranges because they tend to be "soft".

Maximum aperture (lower f-stops) is good 

Some accessories you might want: 

50 mm f/1.8 "prime" (fixed focal length) lens for low light work

A good, light tripod isn't too expensive, and you might want a table tripod 

An external flash can be used to advantage. You can control where the light goes....and the shadows 

Video capability.

Now, that said:

Bryan Peterson's Understanding Photography Fieldguide is subtitled How to shoot great photographs with any camera, and for fieldwork I take it as gospel. For professional work, spend the money. 

I am a camera

Actually, I am not a camera. That was a quote from "Into the Lens", a song by Yes. You should find it on the Internet and listen to it while you read this blog.. or not.

Astrophotography is a fun hobby. To get great photos, you need to put out some substantial funds, but to get nice shots, like my shots of Venus...

You just need a phone camera, a way to connect it to a tripod, and an inexpensive telephoto lens.

You also have to have an intimate knowledge of your scope and your camera.

For any photographic work, you need to know your camera's field of view and resolution, and if you don't have this in your phone's specs, you can easily determine them like I did for my phone camera. Here's my setup.

I carried my portable podium onto the patio with a half meter ruler held up by optical bench stands (those are from an inexpensive set I bought from Home Science Tools. Great company. You could probably make your own.) Under the podium, I stretched out 20 feet of a tape measure.

On the bottom photograph above, there's a plumb bob I threw together using a random piece of plastic I had lying around. I hung it from my phone tripod clamp with a 1/4 20 wing nut and cord. I clamped that to my phone so I could tell how far away I was from the ruler using the tape measure.

To figure out the angular field of view, I stood back until the ruler filled the camera view from one side of the frame to the other. 

That was right at 2 feet (27 inches).

Next, to determine the camera's resolution, the distance at which two close objects at a specified separation can just be seen as two separate objects, I moved back until the millimeter markings on the ruler just blurred into indistinguishable marks.

That was at 28 inches.

So, why would I want an angular field of view? Many terrestrial scopes, including binoculars, give their field of view in terms of width in feet at 20 feet. That's okay when you're working at distances that can be expressed in feet, or even miles, but astronomers work in distances from astronomical units (1 AU is the average distance from Earth to the sun) to light years (a light year is about 6 billion miles) to billions of light years.

If you draw a great circle around the Earth, at any distance, it is composed of 360 degrees. The moon, as seen from Earth, has a diameter of about half a degree (we say it "subtends" an arc of 0.5 degree.) So does the sun, although the sun is much bigger. That's why the moon can block out the sun in a total eclipse. Astronomers work with arcminutes (an arcminutes is one sixtieth of a degree) and arcseconds (60 arcseconds make up an arcminute, 3600 arcseconds make up a degree). Binary stars, as seen from Earth have a separation of from 20 to less than one arcseconds.

Next...the math.

I have set up a right triangle here. The angle from one end of the ruler to the camera, back to the center of the ruler is half the angular field of view. I know the distance from the ruler to the camera (d), and I know that the half ruler is 250 millimeters long (it's a half meter ruler). I can use trigonometry to figure out the angle.

I need everything to be in millimeters, so 27 inches is 685.8 mm. The tangent of my angle is 250 mm/685.8 mm, so the half angular field of view works out to be 20° and the full field of view is 40°.

Mount Evans, pictured here, is 40 miles away. The tangent of half my view angle is the half width of my view field divided by the distance. That means the half width is equal to the tangent of half the angular field of view times the distance, or 14.6 miles. My full field of view at 40 miles is about 29.8 miles.

I figure that my measured distance to the ruler could have been off by 2 inches in either direction, so I can calculate my error by recalculating my field of view at 29 inches and 25 inches and that error turns out to be about ±3°.

I can calculate the resolution of my camera using the same method but, instead of using half the ruler, I use half a millimeter. The distance from the ruler where I can just make out millimeter markings is 31 inches or 787.4 millimeters. That gives me a resolution of 0.07° ± 0.005° . That's a far cry from being able to see binary stars as two stars, but, at least, I can see the sun and moon as a disk instead of just a point source of light.

My camera's electronic zoom does not increase resolution at all but my telephoto lens does. If I wanted to check the resolution of my camera with an optical system like a telephoto lens, binoculars, or a telescope, I wouldn't use trigonometry, I would just see if I could see a pair of stars with a known separation.

Angular field of view is a more flexible measure than width of view at a given distance, but now you know how to find your camera's angular field of view.

Can I trust my phone? Part 2

A while back, I downloaded an app that would do spectrometry. It would split light coming into the camera into its constituent "rainbow", which is cool since that is a way to analyze a substance. Each element has a rainbow fingerprint.

I was excited! I wondered if the representations of incandescent elements on the Internet would be true enough to create a faithful spectrum, so Zi pulled up a picture of a hydrogen lamp and looked at it with the spectrometer. Hydrogen has a very well known spectrum so I knew what it was supposed to look like. 

Wow! It looked great!...except…why was all that blue there? Hydrogen isn't supposed to have that big blue spike at the left end of it's rainbow.

I took my phone outside and looked at the sky through it's camera  Wow! Blue skies smilin' at me...way too blue skies, did I see. I was blue. I dumped the app.

It wasn't the app's fault. Phone cameras are made to produce pretty pictures and bluer skies are prettier. But they're not true blue and science looks for truth.

My son suggested that I use a yellow filter to remove some of the blue coming into the camera and then use the color balance on the camera to get back to true color, and it worked! On the hydrogen spectrum, it worked, but on everything else, it removed so much blue that I couldn't put any back in. blue again!

But recently I bought a packet of Selens Flight Flash Color Strobist Lighting Gel filters. Gels are plastic films. Less expensive than glass photographic filters, they're often used as compensation filters for different light sources. Slipping the ¼ CTO 6500 to 4500 K lightly yellow correction filter over the camera lens, between the phone and it's case did a great job. I used the SnailCamera Pro app, which gives me considerable color balance control to rebalance the picture and I "eyeballed" it until it looked right.

Here's what the camera saw without the picture.

Here's what the scene actually looked like.

Okay, a caveat. The colors were right but I lost some detail. The individual stones in the chimney lost some definition, but right now I'm more concerned with color values. I think some contrast adjustment could get some, if not all, of the definition back.

But I am impressed with the light capturing abilities of modern cell phones. Here are some early evening pictures I took.

A nice sunset

The same shot after the sun had gone away.

A star. Vega. I could not have seen that with my last cellphone camera.

Cell phones offer a lot of power to record your world but know your instrument. It's primary purposes are communication and entertainment. Accurate records require some finagling.

Astronomy tools

Again, I try to keep my equipment portable and inexpensive. You won't get clear, crisp photos of the crab nebula with my setup, but you might be surprised what you can do with it.

As always, my central and most expensive piece of equipment is my computer, currently a…..

Motorola Moto E5 Cruise phone

https://support.motorola.com/us/en/products/cell-phones/moto-e-family/moto-e5-cruise

In preparation for excursions into astronomy next year, my phone is packed with camera and astronomy apps and I have loaded my SD card with astronomy field guides.

This phone has 16 gigabytes of internal memory and an added SD card with another 31 gigabytes, plenty for my purposes. It's moderately priced (between $100 and $200 dollar) and it even serves as a phone!

The camera gives nice results with 8 megapixel resolution plus video and will magnify to 8 times (though the result at 8x is grainy).

Camera hardware

I supplement my phone's camera with a fanny pack full of hardware that I've collected over time including phone clamps, assorted tripods from  desk-size to an eight foot tall tripod. I also have an assortment of standard quarter inch screws, nuts, and bolts that I can use to attach the phone-camera to hardware that isn't particularly for cameras, like Erector set parts and pipe clamps.

I've also collected microscopic, telescopic, fish-eye, etc. lenses and eyepiece adapters for my assorted binoculars, monoculars, and rifle scopes. All this "stuff" is inexpensive at places like American Science and Surplus, Home Science Tools, and numerous other suppliers that cater to the backyard scientist.

The key...be a packrat.

Open Camera

Mark Harman

https://opencamera.sourceforge.io/#licence

The camera in my Android phone isn't all purpose but camera apps are inexpensive or free and they all have their special features. The camera that came with my phone is great for point-and-click photography, but there aren't many bells and whistles. 

The Open Camera app allow quick series of shots and allows for time/date/location stamped photos. It also provides slow motion and Bluetooth shutter release capabilities.

Snail Camera

https://apkhome.net/snail-camera-pro-0-44-01/

The Snail Camera app is very flexible with lots of color, contrast, etc. settings. Practically anything you can do with a DSLR camera except change lenses (but see the mention of my packrattery above.)

It even lets you take multiple and extended exposures. The timed exposure is important for astronomy because you will be trying to capture some dim images.

Note: astronomy requires a remote shutter release and stable mount. With telephotography, barely touching the camera will move it quite enough to lose the object you're photographing. The tripod should also have fine adjustments because aiming a phone camera with a telephoto lens is hard enough.

USB Camera app

Infinitegra Inc.

This app, plus a USB to microUSB plug converter lets me connect other cameras and webcams to my Android. This doesn't work with some smartphones (it requires the phone to be otg, On The Go, enabled) but it's had no problem with my Motorola. If you wonder if you're phone has the right software, there are free apps that you can download (if you have an Android phone, the Google Play store will have what you need) that will test for otg.

Heavens Above

Chris Peat and Jen's Tinz

https://www.reddit.com/r/heavensabove/comments/6pmhu7/app_faq/

This app will keep you up to date on things happening in the sky including satellites and their tricks, like Iridium flares.

Stellarium

https://stellarium.org/

My favorite astronomy app, the Stellarium is a planetarium you carry with you on your phone. There are also versions for laptops and desktop computers. It will orient you to where you should look in the sky and, like big planetariums, it's loaded with educational extras.

Night Sky Guide

Shiny Objects LLC

This is a no-frills table of observable objects and where to observe them, plus an observation log that you can save as a csv (comma separated values) file.

SkyWiki

http://www.kiranbagul.in/skywiki/

Sky map, calendar, astronomy news, image gallery, compass, and periscope all rolled into one package. (The periscope tells you where the sun, moon, and planets are right now, indoors or outside.)

Atmospheric

Check out this location on Astrospheric https://www.astrospheric.com/?Latitude=39.694538116455&Longitude=-104.9259262085

Atmospheric conditions are important for skywatching. Pollution, dust or light, can create a beautiful sunset, but they can also wreck an astronomical outing. This app provides a summary of weather and predictions for your area.

That's a lot of apps but they will all fit on one phone and are all free or inexpensive. They are programmed for an Android phone but many have versions for other kinds of phones, tablets, and laptops. If not, there are probably similar products that you can find with a little Internet search.

That's my lineup, Track down yours and join me for a year of sky watching and physics.

If you find references or equipment that you just can't do without, add a comment to the blog to let us know about it.

--- Useful things ---

2016

An advantage of walking is that you only need what you can carry, or, put another way, you only carry what you can carry. My years as a backpacker comes in handy. It's surprising how much you learn when you have to worry about size and weight.

I find that I don't have to worry too much. In the first place, I'm at that age where I can wear just about anything I want without drawing attention ("When I'm old, I shall wear purple...."). My main consideration is that I'm in Colorado which is a meteorologist's nightmare. I walked to the shopping center (less than a mile) a couple of days ago. When I left, it was warm and fair. I was chased home by a thunderstorm. That night, some folks around here was coerced into wearing sleeves. From September to June, if I go on a long hike, I have to plan to remove layers as the day goes on, and I'm never sure if I will need to. Luckily, I get hot in the upper 50s when I'm active.

It's been below freezing here and I've always worn overalls and coveralls hiking. A flannel shirt, sweater, and leather coat is the most I've ever needed for warmth. You, of course, need to plan for your weather and your body heat.

I wear regular clothes and inexpensive shoes. Socks make a difference. Shelling out for the microfibre wool and such is worthwhile if you don't like blisters and such, but I go the way of the bandaid and moleskin when I feel a hotspot developing. I've had a lifelong relationship with pain and it doesn't bother me much. Pain avoidance, I find, is a individualistic thing.

I have caps for short hikes and big, floppy expedition hats for long hikes. I've had cataracts removed from both eyes and Colorado's sun is not the same sun I knew in Alabama. It's closer and less filtered. I try to keep the sun out of my eyes and I find most sunglasses to be ineffective.

Secondly, hiking requires something to carry everything in. I'm a Rob Liefeld hiker. I like pockets and lots of them, which is one thing that draws me to overalls. I hate digging through a backpack to find a piece of equipment.

I have two backpacks, one for short, nontechnical hikes and just walking to the store - the other for long, technical hikes and for hauling back 60 pounds of groceries from the store.

I'll be distinguishing between technical hikes and nontechnical hikes. Technical hikes are project oriented, requires equipment, and usually involves the collection of quantitative data. Nontechnical hikes are more casual, requires little equipment, and usually involves observation.

My big backpack can handle a laptop and I have several laptop size inserts with pockets and straps, that can be used to outfit myself with a portable laboratory. American Science and Surplus (bless their little bitty comedic hearts) often carry those kinds of things at prices that a retiree can handle.

I also keep a couple of waist packs (or "fanny packs", if you must) for my photographic material. One of those I almost never carry on hikes because it carries equipment for the SLRD camera, which I only use for portrait photography. I would not want to have to carry that huge thing on a hike (although I wouldn't mind driving up to a ridge one afternoon with it.)

I carry two cameras. I use my regular digital camera for most of my photography. That saves batteries for my phone. That,  I use for much more than photographs. My phone camera is used for closeups, telephotos, and microphotos. It's much better and has much better stabilization than my regular camera.

The phone also carries a library of apps, guidebooks and maps that I use for technical hikes.

I like to be a model of what people on a limited income can do to enjoy their world so I try to avoid expensive equipment and activities. My most expensive piece of equipment is my laptop which, admittedly, is a little pricey, although not nearly so much as when I bought it. But I assume that, if you're reading this, you have access to a computer anyway. My computer is my home lab. I have many pieces of equipment that plugs into the USB port, things that, a few years ago, would have cost a laboratory enough that they would have to save up awhile to buy it. For instance, you can now buy a spectroscope for a computer or smartphone for less than ten dollars.

According to where you live, rain gear is important. In Colorado, definitely. In the southeast, it's a sometimes thing. And in Arizona, do you ever need it? A good, light rain jacket is inexpensive and easy to pack. I've never had any need at all for rain pants. As long as my shoes are relatively waterproof, I'm happy. Actually, I don't mind rain or being wet as long as I'm not also cold. Years working outside in the rain has made me rather blase about most weather conditions.

Werewolves don't get sick easily and heal quickly, but I carry a small first aid kit anyway, mostly for blisters. Plantar blisters plague me and I can slap a bandaid of swatch of moleskin on one and I'm good to go. I carry only what I think I might use. If I get a cut, I'll wipe it off with a moist towelette and smear on some Neosporin. I don't even cover it. If It's bleeding, I let it bleed. There's no better antiseptic/antibiotic in the world than blood. On long hikes, I carry suntan lotion (the spray on greaseless kind) because I'm light skinned and tend to burn easily, and I carry bug spray because biting insects find me tasty.

If I'm gone long, I carry a roll of toilet paper. There are many rest stops on Bear Creek - other places, maybe not so much.

I've taken to wearing a biker's mirror on my glasses, not so much for the bikers; in my area, they're very polite and warn you when they're coming up behind you, but for stalkers. We have a few furry ones who are not very much trouble but, I would want a photo. Briefly, I'm out there to observe my world and I want as much coverage as I can get.

Other than that, I choose the equipment I will need for the project I have at hand. I choose inexpensive and compact tools and I pack so that I can get to what I want when I want it.

Uh, I almost forgot one of the most important pieces of hiking equipment. I always carry an old, worn t-shirt tucked into my back pocket. I sweat a lot and that works much better than a handkerchief to keep the sweat out of my eyes. I can also twist it between the sleeves, flip it over my head so the tail falls over the back of my neck, and tie the twisted part around my forehead for a quick do-rag.