Saturday, March 8, 2008

Digiscoping: Cameras - Features

Cameras Today's consumer is inundated with tons of new cameras that hit the market every year. Digiscoping got its start from the use of a compact digital camera (or Point &Shoot) with a 3X optical zoom. Now, mega-zoom cameras up to 24X are available, and most folks think that bigger is better. Not so! Reason? Vignetting! That dreaded black circle or shadow observed along the outside of your camera's viewfinder. A 3X optical zoom camera may show some vignetting at its lowest zoom (1X) with most scopes, but one can get rid of it by zooming in a click or two with their camera's zoom. A mega-zoom camera shows vignetting at all magnifications because the lens cannot get close enough to the eyepiece to align focal planes, so it quickly becomes apparent that they are (generally) considered unacceptable for digiscoping. That said.... Is there an ideal digiscoping camera available? – NO!

Today's camera's provide many features that did not exist in the old classics. More megapixels, brighter and larger viewfinders, more features, etc.. However, it appears that as the new models are released they tend to start losing many of the features that are desired among digiscopers. When looking for a new digiscoping camera it should have the following features: 

3-4X magnification The CP990 that made digiscoping famous had a simple 3X optical zoom. Any more than that results in potential vignetting problems, increased CA at higher magnifications, and an exponential loss in image quality. Many of today's cameras come w/ 3.5 - 6X optical zooms that should not be discounted, but bring your scope when you test these cameras. Never digiscope using 'digital' zoom. 

Internal zoom The early Coolpix cameras had a fixed outer lens and internal lens elements that zoomed in and out. Those days are gone, as all cameras now have inner and outer lens barrels that move in and out as you zoom through optical magnifications. This makes mounting the camera to the scope eyepiece, at a fixed distance, impossible. Cameras with variable-zoom lenses need to be constantly adjusted to maintain proper lens-eyepiece distance. 

Threaded lens The early Coolpix (and others) had a threaded lens mount that allowed for the attachment of such things as step rings, filters, and optical magnifiers. The early digiscoping adapters took advantage of these threaded elements to connect the camera directly to the scope via tube adapters. Now, cameras with a threaded are increasingly rare, so bracket-type adapters may be needed to fix camera to scope. 

Swivel viewfinder Early digital cameras had a viewfinder that swiveled independently of the camera body and lens. This made it possible to view through the scope at more angles to reduce glare. Current cameras that have this feature are the Canon Powershot "A" Series cameras. Surprisingly, today's cameras are bringing back the swivel viewfinder, so keep an eye out for the newer choices.

Large, bright viewfinder The early Coolpix cameras suffered from dull, dark viewfinders. Today's camera viewfinders are increasingly larger, brighter, and have more pixels. This makes it easier to focus on the subject and get sharper images. Glare from the sun may still be a problem so viewfinder shades, such as a jeweler's loup or a Hoodman Loup are recommended. Electronic viewfinders (EVF) are becoming more popular and can provide critical viewing / focusing even on sunny days.

Megapixels Most digiscopers believe that more pixels are better. It's true, but at a cost. It takes longer for the camera to write bigger files and this can slow down camera speed, especially if you shoot continuously. Wonderful images have been taken with the early 2-4 Mp cameras, and this still true, today. Camera sensors have not increased in size, so cramming more pixels into the same size sensor generally leads to more noise. 

Low noise @ high ISO This is huge, especially when digiscoping on cloudy days or low light. Many cameras suffer from extreme noise at ISO's greater than 200. The Fuji F30 was considered the best camera in this department with low noise at ISO's greater than 800. 

Cable release thread Digital camera manufacturers have left this feature off cameras, which means that vibration can be a problem even on a tripod-mounted system. Many digiscopers have resorted to making a bracket for a cable release to reduce camera vibration when taking pictures. An alternative to cable release is the camera's self-timer function. But these tend to require standing in front of the camera and do not provide continuous shooting functions. I myself have never used a cable release and find hand-holding to work just fine (shoot continuously while using long-lens techniques). 

CF or SD memory card Compact Flash (CF) or Secure Digital (SD) cards read and write at very high speeds. Look for a camera with these options. The Fuji F30 uses xD cards, and they are painfully slow. Sony cameras uses Memory Sticks which were incompatible with most card readers.  Today most cameras are opting for the SDHD cards, which are blazingly fast. So its important to be able to use a format that can be read by external card readers and computers. SD cards are common in today's cameras and are an extremely reliable medium for storing images at an inexpensive price. I use Scandisk Extreme Pro 16 GB cards and am quite happy w/ them! 

Fast read/write It can seem like hours when you've found that Ivory-billed Woodpecker and can't take that perfect shot because the camera is writing your last set of House Sparrow images to disk. The Canon Powershot A620 allowed continuous shooting without having to pause to write to disk. The F30 allows only 3 frames continuous shooting, so there is a 5-10 second delay between bursts. The Nikon P5000 and P5100 are considered two of the best digiscoping cameras today, but only allow 0.8 fps shooting.  Buy the fastest cards you can find - Best Buy tends to sell the slower versions, so look online for cards that write up 90 MB/sec 

Customizable menus The Canon Powershot cameras allowed you to set up your own menus that are stored in the camera. Turn on the camera and shoot. The Nikon Coolpix CP990 and F30 were frustrating to use because all settings are lost when the camera is turned off, or switched to a different shooting mode. Setting up shooting menus in the field is not a good idea, especially when that IBWP has just appeared. The newer camera models now allow customizable menus to be saved when the camera is turned off. 

Continuous shooting The Canon Powershot cameras allowed Continuous shooting as long as you had memory. The F30 only allows 3 Frames (top three or final 3). It's not necessarily a bad thing, as you end up with fewer images to review (and potentially process), but there are times when you don't want to have to wait for the camera to write images to disk. Today's Micro 4/3  or "Mirrorless" cameras can provide continuous shooting up to 10 fps in normal shooting or 30-60 fps in limiting modes.

Instant firing The Coolpix cameras were frustratingly slow when it came time to snap a picture. Press the button, wait 3-5 seconds for the camera to lock in focus, set exposures, take a diagnostic, have a cup of coffee, etc., then fire. Today's cameras are much, much faster, and operate much like the more expensive DSLR's. A tip: depress the shutter half-way to lock in focus, then fire when your moment is upon you.

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