Birds Ideal Planetary / Deep-Sky Camera
Anthony Wesley, May 22 2005
I've been doing a lot of research on the web lately, trying to locate a suitable replacement for my current planetary camera (a Unibrain fire-i mono camera) but without any real success. The "ideal" planetary camera simply does not exist, or if it does then it's buried somewhere that I can't find it...
I've written a companion article that goes into the requirements for planetary imaging with modern CCD cameras in more detail - it might be worth a read if you're new to this part of astronomy or just interested to see how the "other half" lives. The article is here.
As an act of desperation I've decided to make this page, describing what this mythical "ideal" planetary camera should look like and how it ought to behave. The purpose of this page is to attract enough support that we might (as a group) convince a manufacturer to build this device, make their fortune and retire to the Bahamas.
(Well, ok, maybe not, but at least sell enough to make it a worthwhile proposition).
Now before you object that there can be no such thing as an "ideal" astronomy camera because everyone will want something slightly different, let me start by saying that such a camera would be modular in design, allowing the fitting of different CCDs using a carrier board that slides or slots in and locks onto the main board. There would be different modular (carrier) boards for planetary use vs deep-sky use etc.
And, as an additional benefit, this camera should be useful for moderately serious deep-sky photography as well by including peltier cooling and extended shutter controls. It would probably not compare with the "expensive" deep-sky cameras (i.e. in the $4k+ price bracket) but should be able to hold its own in the lower end of the market, say challenging those deep-sky cameras currently in the $1k to $4k price range.
But I get ahead of myself... Here's the full specs for this camera as I envision it:
If this sounds like something interesting, please email me. I've set up a special email address (email@example.com) which automatically archives emails sent to it. Feel free to comment on these features, suggest different features etc. (Note that you'll have to get past my anti-spam defence, so expect to get a challenge. Just reply to this and your email will be delivered).
- Housed in a lightweight, black aluminium or plastic body. Target mass around 150g so it's light enough for almost any scope.
- Fitted with a standard thread (maybe female SCT) so the user can screw on the appropriate adapter - 1.25" nosepiece etc.
- No LED's or other thermal nasties inside the camera, maybe not on the exterior either. LED's emit light, and almost always screw up long exposures.
- Firewire 400 (or 800) interface back to host PC for delivering uncompressed high speed frames. Firewire is designed for video data and has a standard API that is widely supported by all major platforms (Windows, Linux, Mac etc). USB1.1 simply isn't fast enough and USB2 doesn't have a standard video API - this leaves firewire as the obvious choice. A side benefit is that firewire can also deliver the power (+12vDC) to the camera, meaning one less cable.
- Onboard eeprom/firmware that is field upgradeable so the unit can be completely updated or reprogrammed to keep it future-proof. This may be through a serial port provided as a 3.5mm socket on the camera body (+5v,Gnd,Data). This is standard procedure for many low-cost microcontrollers on the market.
- No built-in CCD. Instead, there is a holder on the camera board that takes a small form factor "carrier board" that either slides in or clicks in, and holds a CCD and some of its support electronics (maybe the timing & AFE circuitry). This carrier board would be about the same size and form factor as current "memory cards" for PDA's, and use a low-profile connector to make contact with the camera mainboard.
The carrier board might be held securely in place by a spring-loaded mechanism so there is no change of it moving while the camera is being used or handled.
- There must be a variety of carrier boards available with CCD's for different purposes. The CCD's will come in different flavours (monochrome vs colour), different cell sizes (3.4, 4.4, 5.6, 7.4, 9.9 micron etc), different sensitivities and physical sizes (1/3, 1/2 inch etc). This makes the camera suitable for many purposes - occultation, planetary, deep sky etc.
(For practicality, maybe this could be restricted to one CCD manufacturer (like Sony) whose CCDs are mostly interchangeable).
- The camera must provide full control over shutter, gain, brightness, gamma, framerate etc so that it can be used in various disciplines. e.g. planetary people want framerates between 60fps and 10fps (or 5 fps) with the shutter open for the full duration of each frame. Deep-sky people want long exposures up to 30 mins (or more), the ability to read out alternate fields for guiding etc. (Some of this functionality might be implemented on the carrier board, so a DSO carrier board might offer the alternate field readout, but not a planetary carrier board).
- An optional add-on for peltier or fan cooling should be available. This might be done as an alternate camera body or as an add-on to the standard body.
- Internal electronics organised to keep noisy components such as amplifier circuitry etc away from the CCD. If this circuitry is on the carrier board then it opens the possibility for purchasing replacement boards as newer and better electronics come available.
I'll be sending this link to major CCD camera manufacturers for their comment. Maybe we can get one of them interested.
regards, Anthony Wesley (Bird)
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