Friday, June 16, 2006

Canon PowerShot "Pro1 IR"

The Canon PowerShot Pro1 is an 8-megapixel "compact" camera with a feature set I've found to be particularly well-suited to an infrared camera.

  • It has a high-quality lens (rated by Canon as an 'L' lens) with a zoom range
    equivalent to a 28-200mm lens (in the 135-format terms which everyone understands). Many cameras with non-interchangeable lenses only go as wide as 35mm or so.
  • The camera produces RAW files which are supported by Adobe Camera Raw (the core of my photo processing workflow). The image quality is excellent: I can easily produce 11x14-inch prints from Pro1 images that stand up to close examination, and depending on the image even larger prints can work well also. Stitched panoramas are correspondingly larger still.
  • Unlike an SLR, the metering mechanism uses the imaging sensor (as used for the final image). See this page for an outline of the complications caused when using an SLR for infrared photography.
  • As well as having a flip-out LCD which can make waist- and ground-level photography convenient, the Pro1 has an "EVF" electronic viewfinder which is designed to have your eye mashed up against it.
  • A customised L-plate is available for the Pro1 from Really Right Stuff. This plate provides an Arca-Swiss quick-release mount which matches my tripods and monopod, making it interchangeable with the bigger cameras and lenses I use for my visible-light photography, including working with a mount that provides for distortion-free composite panoramas.
  • Lastly, it uses the same CompactFlash cards and BP-511 batteries as my EOS cameras.
Note that my Pro1 has had its firmware updated (to version 1.0.1) which fixed a number of early issues with autofocus and zooming.

Not good for IR? Ha!

Despite initial Internet reports of the Pro1 lens performing poorly with IR filters (resulting in flare and a "hot spot") I can confirm that the camera and lens perform wonderfully when the internal IR-cut filter is removed.

There are some caveats though. Those early testers were using unmodified cameras, and the internal IR filter does seem to cause IR reflections inside the lens. Also there is some flare in the centre area in some conditions with some wavelengths of light (only so far seen with R72-style filters, not with darker "monochromatic" filters).

The Pro1's autofocus system uses the same contrast-detection algorithms as most other small-sensor digital cameras (analysing the image being captured by the main sensor) but at low light levels combines this with an external "AF sensor" (a similar mechanism is used by the Olympus C-8080).
This sensor is essentially a crude rangefinder, letting the camera set an approximate focus distance and hope that the small sensor's large depth of field will bring the appropriate areas of the image into focus. In the end this doesn't present any complications for IR photography.

EVF

Some photographers say they hate these, preferring optical viewfinders. I can see their arguments working for a visible-light camera: the image in the EVF is very coarse and pixellated in comparison to the image you get in the viewfinder of an SLR. But in an infrared camera where the image being captured by the camera does not match the image you can see with your eyes, the electronic viewfinder is extremely useful.

Not only does the EVF allow you to hold the camera in a stable grip against your face (holding a camera at arms length to use an LCD viewfinder is usually not a recipe for sharp images) but it also allows you to see the images even in bright sunlight. For those times you don't want to use the EVF, simply flip open the LCD and it takes over as the viewfinder.

Image quality

At its base ISO of 50 the Pro1 produces a very clean and noise-free result, but as with all cameras the noise levels increase as you move to higher sensitivities. Early reviews of the Pro1 often mentioned the noise levels at high ISOs as being a problem, and while it's true that the Pro1 can't produce images as noise-free as 8Mp DSLRs such as the EOS 20D/30D/350D, the problem isn't quite as bad as some of those reviewers reported.

When a camera produces JPEG files, each image goes through a series of processing steps. First the white balance, contrast, and saturation settings are used in producing a colour image. The camera may apply some noise reduction processing, and then some image sharpening is applied. Finally the result is compressed into a JPEG. Unfortunately the image sharpening and JPEG compression can exacerbate any image noise that wasn't removed in the noise reduction.

When a camera produces a RAW file none of that processing has been applied, and when processing the RAW file you have much more flexibility in applying things like noise reduction and sharpening. I find that in general the images produced by Camera Raw exhibit less noise than the equivalent JPEG files produced by the camera. Incidentally, this advantage of shooting RAW also applies to other "noisy" cameras such as Panasonic's DMC-LX1. It turns out that most reviews of digital cameras examine the image quality produced by the camera's JPEGs...

I've been quite happy with the quality of my Pro1 images. Where I've boosted the ISO levels the noise is higher, but Noise Ninja deals with that quite nicely. At short focal lengths at some apertures there is some slight darkening of the image corners (is usually only a concern when stitching composite panoramas) but Camera Raw's vignetting controls deal with that.

Better than a DSLR

Because of the advantages of an electronic viewfinder (either the one behind the eyepiece, or the flip-out LCD) and with the reasonable image quality that the camera can deliver, the Pro1 has become my main IR camera (on major outings I usually have a 30D and a 350D for visible-light work, and the Pro1 for IR).

Working with DSLR for IR photography, there's a continual need to "chimp" (check the histogram and image on the LCD after the shot): the camera's exposure meter cannot calculate the appropriate IR exposure (see this page for details). With the Pro1 the camera's meter tends to nail the exposure every time, even when metering flash exposures with E-TTL.

Note that the camera doesn't have the same responsiveness as an SLR, and the viewfinder blacks out after taking a photo. For studio use and slow-paced work (e.g. some landscape imagery) the better image quality of a DSLR would be advantageous, and it's not a camera I'd really want to use for sports photography but as a general-purpose IR camera I think it's a winning combination!

Camera faults

The camera does have a few faults: most noticeably the mounting for the lens cap, the hood, and 58mm filters. The supplied lens cap is very awkward to fit while the hood is on, requiring you to have long fingernails. The hood and the filter adapter use the same bayonet fitting, so either one or the other can be used.

Some Pro1 photographers use 58mm filters in conjunction with screw-in hoods. Either collapsible rubber hoods, or a screw-in "petal" hood such as from FotoDiox. Unfortunately finding one that doesn't cause vignetting at wide angles can be a problem.

I have taken the path of using the Canon hood without any protective filters, combined with the LensMate Pro1 lens cap (no longer available) which fits within the hood. During use the front element is exposed to dust and moisture, and although I'm happy to live with this I wish that Canon had made the filter-mount part of the lens sit within the hood bayonet mount, as they do with most of their EF lenses. However, with the LensMate cap in place the lens is well-protected: on a recent trip to Tanzania I was often covered in dust but the Pro1 ran flawlessly.

I hear many people on web forums moaning that the Pro1 doesn't have Image Stabilisation (IS). While having this might give you more flexibility in your shutter speeds (especially at the 200mm end of the zoom) I don't find its absence a problem. This may partially be because of the ability to hold the camera stably using the EVF. Several of my SLR lenses are IS models, and I know how useful it can be. But not having it in the Pro1 is not the end of the world!

Another small annoyance is that the camera will not turn on properly when the camera is tilted to the left (the normal orientation for me when shooting panoramas). The lens starts to extend but the camera decides to get upset and reports an error. This has been reported by many Pro1 users, and it's easily worked around: tilt the camera slightly when turning it on and the problem is avoided. After that the lens will extend/retract correctly in any position.

There's a range of other camera types and models I also convert to IR, and each has its own compromises. I've found those of the Pro1 suit my own photography well, and for now it's my IR "workhorse".

The future of the Pro1

The Powershot Pro1 was introduced in February 2004, and surprisingly two years later no replacement has been seen. Regardless the Pro1 remains an excellent camera. Unfortunately it seems that Canon may be moving away from having compact digital cameras with RAW support and the Pro1, G6, and S70 have been the last RAW-capable models for a while. I'm hoping there'll be more, but until then my Pro1 will keep ticking on.

If you have a Pro1 already but are missing accessories such as the LH-DC10 hood, FA-DC58A filter adaptor, or the lens cap, I can supply replacements.
Continue reading "Canon PowerShot "Pro1 IR""...

Nexto ND-2500 image storage

I use all my cameras in RAW mode, and the files they produce range from 8 to 16 MB each. When photographing static subjects such as landscapes the number of images I take are a lot less than the number I take when photographing wildlife, where the compositions constantly change, and the opportunities are fleeting. On my home system I have a setup with multiple Firewire and USB hard disks, with copies of everything on offline disks. But how do you manage all those files when away from home?


If you're on a day-trip from home you can often avoid the problem by having enough card storage that you can last a day without downloading, but on longer and busier trips you need somewhere to offload the files to. "PSD"s (Portable Storage Devices) containing a 2.5" laptop hard disk, a card reader, a battery, and a USB interface to connect to a computer for later download are a familiar site these days. There are lots of choices in the market, each with different features. For example the Epson P-2000 (and 4000/4500) have a large screen for reviewing images.

The Nexto PSD

The device I use is a Nexto CF ND-2500, which has a very simple interface. A small text LCD displays download status, and single button (with long and short presses having different meanings depending on the screen menu). It only has a CompactFlash card slot, so to read other card formats an adaptor is required. To read SD cards I use a Mittoni adaptor, which is the size of a CF-II card and thus isn't as unwieldy as some of the "5-in-1" adaptors on the market. One of the attractive features of the Nexto for me is the fact that it is fast: a full 2GB SanDisk Extreme III card can be downloaded in about 3 minutes. Faster downloads mean less time with the disk spinning, which means both less risk of bumps damaging the drive and less power being consumed (and thus longer battery life). It has both USB2 and Firewire interfaces (and when connected by Firewire it doesn't have to use the internal battery). It can be charged from a 12V lead either from a car or an AC adaptor (or by Firewire if the unit is not running). Together, these features made it a compelling choice when looking to upgrade my previous CompactDrive PD7X.

The Nexto has an internal 600 mAh Lithium-polymer battery, and although this can't be swapped with a spare, the unit does have a connection for a secondary Li-Ion battery (seen here attached to the side of the unit). There are at least two versions of this going around: 1800 mAh and 2200 mAh. With the battery attached the unit runs off both batteries, and this is enough power to cope with most outings.

However on a recent trip through Kenya and Tanzania I was using several cameras, and between them had three 2GB CF cards, one 1GB, and one 512MB, while my wife had two 1GB Ultra II SD cards for her camera. With lots of wildlife opportunities, it wasn't unusual for us to be filling all those cards in a day. This was fine, but a complication came in the form of us being away from recharging facilities for 4 days at a time. Also, not all of these CF and SD cards were as fast as the Extreme III CF: some of them were almost twice as slow. With the constant downloading, and the daily connection to a laptop to mirror the new files to a backup drive (which in the end sometimes had to be done using USB due to a cable fault!) this
stretched the Nexto's battery capacity. We came through OK with all our files intact, but on my return home I decided to implement a solution I'd been considering for a while.

Extra power for the Nexto

The Li-Ion battery of the Nexto is the same voltage (7.4V) as the batteries used by many of today's digital cameras. The BP-511 batteries used by most of my Canon cameras range in rated capacity from 1100 to 1400 mAh, and last a long time. For instance on that African trip my EOS 30D would typically go for two days on a single BP-511A, with lots of photos being taken, with lenses drawing extra power for the IS function. I had plenty of spare camera batteries, but in the end they were overkill. Finding a way to connect them to the Nexto would provide a very flexible solution.

Here you can see a common third-party Li-Ion charger, with interchangeable plates to allow the charging of many different battery models. I considered modifying the charger itself to allow the use of various adaptor plates unmodified, but then I would have to cope with the plates/batteries that have different voltages, and the cost (and size) would be greater. Given the number of BP-511-style batteries I have, I bought a spare BP-511 plate at my local camera store.

Then I opened up the plate (simply two screws on the underside) and removed the internal wiring (including the contacts on the base to attach to the charger) and cut off the protruding plastic clips on the underside. The addition of some wire and a DC power connector (1.3mm internal diameter, 3.5mm external, 9.5mm shaft length) and a bit of soldering, and I had my solution.

As you can see it's a quite small setup, easily kept in the bottom of a camera bag as a backup. It doesn't have quite the mAh rating of the Nexto's secondary battery, but it's easy to pop in a spare battery. There's little risk I'll ever run out of power for my image downloads!

All up it cost me about AU$12 ($10 of which was for the charger plate).


August 2008: I've got a new article about a replacement for the ND-2500. The 2500 is still a great device but if you need more space, more speed, and SDHC backups you can do even
better. Check it out.
Continue reading "Nexto ND-2500 image storage"...