Category Archives: Digital Photography

Is a Kit Lens Better for Infrared Photography?

Okay, I have a digital camera converted to capture infrared light. I’m ready to go out and shoot pictures, right? My camera is ready–Is my lens?

Light is bent when it passes through transparent materials such as air, water, and glass. However, different colors (wavelengths of light) may not bend at the same degree so water droplets and prisms make rainbows by spreading out the mix of frequencies of light at different degrees. A lens bends this composite of colored light towards its focal plane, our camera sensor or film. It is shaped and coated with materials that eliminate the spreading out by different colors of light.

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A premium Sigma 17mm-50mm f/2.8 lens at f16 produces a hot spot which I have exaggerated with a curves adjustment.
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A Nikon 18mm-55mm f/3.5-5.6 kit lens at f/8 did not produce a hot spot. I have applied a similar curves adjustment which would have revealed an appreciable hot spot if it had been there.

My subject is in focus–what’s the big deal about infrared light? Camera lenses focus the visible spectrum. Some lenses also bring infrared to the same focus as visible light. Others don’t do as well and may produce a hot spot on the image.

Compared to pro lenses, a kit lens may not be able to produce as sharp an image in the visible spectrum, but may focus infrared frequencies more accurately. Look here to read a list of some lenses which have been tested for infrared photography.

Inspiration by Association

I’ve learned not to think when I run out with my camera to take some pictures. I may have a feeling about a place, a time of day, a sense of perfection or ruin in mind, but I am looking in my camera for something that just feels right. When I began as a photographer I had to think until I mastered operating my camera controls, which were all manual. Unfortunately, that habit of thinking about every shot really inhibited my shooting; and I took forever to expose a roll of film.

 

2015startonthestreetI was over my hesitancy when my enthusiasm for photography was reignited in 2000 or so when I accepted warm invitations from Randi Laak, then an instructor at the Worcester Center for Crafts, to enroll in his Friday evening photography class. I freely experimented with exposures, films, darkroom chemistry and processes as I had not when I started out.

 

Together with the freedom in the darkroom (And now in Photoshop), the history of photography of which I had learned as a beginning photographer and witnessed in publications and exhibitions as time passed, and my love of many paintings, prints, sculptures, etc. at the Worcester Art Museum and elsewhere, I am endowed with feelings associated with these beautiful or provocative objects that are evoked, I believe, as I walk through the world. I think those feelings and associations are part of my feeling of “rightness” when something captures my eye.

 

The universe seems to notice that I take the time to stop and see things then  once in a while shouts at me to stop and look at this!

 

Here’s one example of a landscape photograph of a scene of light penetrating a shadowy wild place for which I felt similarly to when I look at an 18th century painting by Alessandro Magnasco:In painting and photograph the light seems to stab into a shadowy wild place.

 

“Good” and Cheap

wetland-reflection-1-PA260181I believe digital cameras, their sensors, lenses, and image processors have evolved and multiplied enough that I can buy equipment to make “fine art” for not a lot of bucks. However, I don’t think full frame cameras, professional lenses and the like are without value. They’re tools in talented hands for making extraordinary images.

 

My point is that I don’t need spend like crazy on high end gear to make photographs that please me and whatever audience I can gather.

 

After one or two newer model generations have gone to market, leftover inventories may be steeply discounted. I look at specifications. A pro-grade camera may share technology with a lower priced model. Hey, if I can control aperture, ISO, and exposure time, then I’m happy.

 

I think of this approach as buying trailing edge technology. Maybe it’s just my Yankee stinginess. Whatever it is, I save by buying things that give me raw files, high resolution, low noise, and that satisfy my fussy eye without breaking the bank.

 

What is enough? I must be happy with the work that I create. If doing photography doesn’t give me joy and satisfaction, it won’t matter what I spend.

Numbers, part three (Conclusion)

Sensitivity is defined by the International Organization for Standards (ISO) in its abstract thus:

“ISO 12232:2006 specifies the method for assigning and reporting ISO speed ratings, ISO speed latitude ratings, standard output sensitivity values, and recommended exposure index values, for digital still cameras. ISO 12232:2006 is applicable to both monochrome and colour digital still cameras.”

ISO 200 (low noise)
ISO 200 (low noise)

Long ago we used to call this the ASA, which was the similar method for determining film sensitivity from the American Standards Association.

The lower the ISO number is set the longer it takes to record an image; and the less noise appears in the image files; higher ISO’s make faster recordings of images with more noise. Camera image processors have improved noise reduction so I may select higher ISO settings with little noise in my image with recent digital camera models.

Click on images to view at full size for better comparison of noise levels in the two images.

ISO 16000 (high noise)
ISO 16000 (high noise)

Methods of noise reduction include blurring or smearing small artifacts, subtracting pixels based on another exposure, and so on. Perhaps some small details get lost in the process. Although, details may be recovered using the algorithms used in the camera image processor or post processing. Some pixels in the resulting image thus may be made by firmware or editing software rather than light.

In summary, I can apply three basic camera settings: aperture, time, and sensitivity to make creative choices such as sharpness, and blurred or frozen motion. I can compensate for the lighting; I can select high sensitivity for low light exposures, and low ISO settings for cleaner, more detailed images.

Making choices with these settings lets me capture how I see a thing and share it in a photograph.

Numbers, part two

Today, I want to talk about time. The duration of an exposure can be very short, very long or anywhere in-between. Cameras can be set for exposures of one thousandth of a second or less, or of many seconds or minutes.

OLYMPUS DIGITAL CAMERA
1/800 Second Exposure Freezes Motion

Time, how long the shutter is open, or how long the sensor is recording can be set for a capture that is shorter, which will freeze action, and is handy for sports and fast moving subjects like children and race cars.

I can choose a longer exposure to blur objects as they move across the frame for an impression of speed, or to smooth moving surfaces like river rapids in which the water is a smooth clear or milky flowing substance over rocks.

With very long exposure times, electronic noise can get recorded in my image file as the camera circuitry builds up heat, and, especially if it had been low at the start, the battery could run out of charge.

1/25 Second Exposure Blurs Motion
1/25 Second Exposure Blurs Motion

There may be technical consequences to very short and very long shutter speeds that I want to bear in mind. Higher sensitivity (which I’ll write about in my next post) may be required to capture an image completely when I wish or need to make a very fast exposure.

Numbers, part one.

Sometimes I understand the way one person says things better than others. So here in my words are a few comments about camera settings that may help us know our cameras better. Photo editing software may allow me to compensate for less than ideal exposures, but better results come with good initial captures.

Loosely defined, these settings are:

  1. Aperture: The size of the lens opening relative to the distance from the sensor.
  2. Time: How long the lens is open for light to pass, how long the sensor is recording.
  3. Sensitivity: How long it will take for the sensor to record enough data for an image.

Today, I’ll discuss number one, the aperture. Aperture, the diameter of the opening for light, is expressed as an f-stop. The higher the f-number is; the smaller the opening. The f-number is equal to the distance from the aperture opening to the sensor divided by the diameter of the opening. If I had a gigantic camera with a one mile diameter opening that was sixteen miles from my gigantic sensor, my aperture would be f/16. Sixteen miles distance divided by one mile diameter is f/16. Fortunately, my camera is smaller, but because f-stops are ratios they work at any scale.

f/64
f/64
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f/5.6

One impact of my choice of aperture is how much of my photo is sharply in focus. The smaller the aperture (higher f-stop), the greater percentage of the distance in my capture from foreground to background is sharply in focus. The larger the light opening (lower f-stop), the less depth of field is in focus. High f-stops are ideal for lots of sharp detail in my image, maybe for a landscape or architectural shot. Low f-stops allow for selective focus, so I can, for instance, take a portrait shot of someone where they are in focus, but the background is softly focussed.

Next time, I’ll take a look at time and sensitivity.

Fixed Lens Cameras & Camera Raw

Camera-Raw-EditorHaving your camera configured to save in camera raw file format is like having a negative from which to work. All the data from light that reached the sensor is recorded in your file. JPEGs are smaller, but some data and development or editing latitude are lost in the process of compressing the files.
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Here are some fixed lens cameras that can be found online for under $500 with the capability of saving in raw format.
  • Canon PowerShot G16
  • Canon PowerShot S120
  • Canon PowerShot S110Olympus SH-2
  • Fujifilm FinePix HS50XR
  • Fujifilm XQ2
  • FujifilmXQ1
  • FujifilmXS1
  • Nikon COOLPIX P340
  • Olympus SH-2
  • Panasonic LUMIX DMC-LX7
  • Panasonic LUMIX DMC-ZS40
  • Panasonic LUMIX DMC-FZ70
  • Sony Cyber-shot RX100
There are higher priced fixed lens cameras out there if you need more from your gear. Interchangeable lens mirrorless cameras or DSLRs, will as a rule offer raw file format capability also at higher prices.
Want features at lower prices? Look for earlier model versions, but check specifications for any feature changes. Discontinued new, like-new, and refurbished cameras can often be found, sometimes with significant savings.

Film & Sensor Sizes

The naming scheme for digital camera sensors is derived from old television camera sizes expressed as the diameter of the tube through which light enters to strike the sensor at the end of the tube. The sensor’s diagonal measurement is about one third less than that of the tv camera tube so camera sensor diagonal measurements are smaller than you might expect from their names.
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Camera with a Four Thirds Sensor: Micro Four Thirds cameras are mirrorless.
Here are a few film and sensor dimensions, and their relative sizes compared to 35mm film and full frame digital sensors.
Type Format Dimensions (mm) Surface Ratio to 35mm
Width Height mm²
film 4×5 121 97 11737 1358%
film 645 56 42 2352 272%
Sensor 645 43.8 32.8 1436.6 166%
Sensor Full Frame 36 24 864 100%
Sensor APS-C 22.3 14.9 332.27 38%
Sensor four thirds sensor 17.3 13 224.9 26%
Sensor 2/3″ 8.8 6.6 58.08 7%
Sensor 1/1.6″ 8 6 48 6%
Sensor 1/1.8″ 7.2 5.3 38.16 4%
Sensor 1/2.7″ 5.3 4 21.2 2%

 

Nothing’s Changed?–Digital/Film Analogues

As I said in an earlier post, several years ago I resumed shooting and printing a lot. With some review at the Worcester Craft Center I went back out with my cameras and into the darkroom with less pain and more joy than ever. I changed formats from 35mm to 645 medium format when I bought a used Bronica ETRS.

There are parallels in digital photography. Point and shoots in general make nice images fairly automatically; that’s a big selling point for them. However, trying to edit nice looking images for fine art prints is not always successful.

second-growth-P3060086A combination of factors may account for this. if we say a pixel on a camera sensor and a grain of silver on a negative are equivalent, 20MP or more is approximately equivalent to the resolution of a 35mm film negative. The size of a small camera sensor in a low price camera might be 1/2.5″ or smaller; that is about 2 percent as big as a 35mm negative. The electronic noise that leaks from all those pixels on a small surface area can be thought to be equivalent to grainy film.

Film as a rule records a wider dynamic range of tones than a camera sensor. More contrasty imagery with detail and texture in both shadow and bright zones was possible in a single click of the shutter with film. Electronic noise has been suppressed or reduced in successive generations of digital cameras; and dynamic range has improved–greatly improved in HDR captures which combine multiple exposures for dark and bright regions in the frame.

Another consideration is the file format in which a digital camera saves its image capture. Many point and shoot and fixed lens cameras save in a lossy compressed format called JPEG. In simplified terms, the file is saved in a smaller space by first applying all the optional and automatic camera settings, and then tossing out other data that the sensor recorded but is not required for the picture. It’s like we made a print, and threw out the negative. We can still make some editing choices, but not as many.

The situation may be remedied in the digital world with the right choices. Get a larger format camera. Cameras have been manufactured to utilize many sizes and formats of film from 8mm x 10.5mm frames on disc camera film to 8″ x 10″ large format cameras and even bigger ultra-large formats. In the digital market, point and shoot and fixed lens camera sensor sizes range from say 2 percent to 100 percent the size of one frame on a roll of 35mm film. Their prices range around $80 to $2700 roughly in parallel with sensor size. Lower priced, higher sales volume cameras benefit from economies of scale; higher priced, lower sales volume cameras benefit from better build quality, more durable components, and superior optics.

We get the equivalent to a film negative in cameras that are capable of saving images in camera raw format. Everything the camera sensor recorded gets saved in raw. Some fixed lens cameras have this feature, but many only save in a compressed format such as JPEG. I’ll work up a selected list of camera sensor sizes and post it next time; and another list of selected fixed lens cameras that feature raw capability after that.

Metal Prints

My friend, Tom Wyatt, has exhibited some lovely color photographs of reflections on various kinds of natural and human made surfaces. His metal prints of these subject materials are amazing to see, if you get the chance.

I recently received a Groupon deal by email for $5 metal prints that includes a limited time offer to share it for additional savings. If you’d like to take advantage, you can find the offer here.

Here is one of the images I uploaded for printing:

OLYMPUS DIGITAL CAMERA
OLYMPUS DIGITAL CAMERA

Here’s another uploaded image, an unusual effort for me, solarized color infrared:

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Because I have no experiences with the seller, I can’t personally endorse them; but I have had positive experiences with other Groupon deals in the past. Be sure to let me know, if you take advantage, what you think when you see your prints; now that I’ve got some metal prints in the pipeline I will do the same once they arrive.