Astronomical Imaging : Tools of the Trade

Astronomical Imaging : Tools of the Trade

The following is a (non-exhaustive) list of digital cameras suitable for Astronomical Imaging. Quoted prices are believed to be correct at the time of writing, but will not remain correct for long.

The information presented is given in good faith and is believed to be correct, but I cannot accept any responsibility for its accuracy or otherwise.

·  Artemis

·  Philips

·  Starlight Xpress

·  Meade

·  Celestron

·  ATIK

·  SAC

·  Canon

·  Nikon

·  Useful Links

·  Glossary

Artemis

Competitively priced, self assembly cooled CCD cameras. All models are based on the same basic design, with the option to install different CCD chips according to your requirements and pocket. See http://www.artemisccd.co.uk/Artemis_Cameras.htm for up to date information.

Model

/

Chip Type

/

Size (mm)

/

Type

/

Pixels

/

Bits

/

Pixel Size (um)

/

Price

ART-254 / ICX254AL / 4.9x3.7 / Mono / 510x492 / 16 / 9.6x7.5 / £Call
ART-254C / ICX254AK / 4.9x3.7 / Colour / 510x492 / 16 / 9.6x7.5 / £Call
ART-255 / ICX255AL / 4.9x3.7 / Mono / 500x582 / 16 / 9.8x6.3 / £Call
ART-255C / ICX255AK / 4.9x3.7 / Colour / 500x582 / 16 / 9.8x6.3 / £Call
ART-424 / ICX424AL / 4.9x3.65 / Mono / 659x494 / 16 / 7.4x7.4 / £Call
ART-424C / ICX424AQ / 4.9x3.65 / Colour / 659x494 / 16 / 7.4x7.4 / £Call
ART-429 / ICX429ALL / 6.3x4.76 / Mono / 752x582 / 16 / 8.6x8.3 / £465
ART-429C / ICX429ALK / 6.3x4.76 / Colour / 752x582 / 16 / 8.6x8.3 / £Call
ART-285 / ICX285AL / 8.9x6.7 / Mono / 1392x1040 / 16 / 6.45x6.45 / £765
ART-285C / ICX285AQ / 8.9x6.7 / Colour / 1392x1040 / 16 / 6.45x6.45 / £775

Note that these cameras also require a separate power supply at £35 when purchased with kit.

I have a beta version of the ART-429. It works well with very low noise.

See ATIK below for pre-assembled alternatives.

Philips

The webcam of choice for planetary and lunar imaging. Philips make a number of different webcams. Only the top-end devices feature the more sensitive CCD chips.

ToucamPro 2 (PVC840K) / ICX098BQ / 3.6x2.7 / Colour / 640x480 / 8 / 5.6x5.6 / £55

You will usually require an IR/UV blocking filter when using a webcam. You will also need some means for mounting the webcam on the telescope. Suitable adapters can be sourced in a number of places including http://www.telescopehouse.co.uk.

The Toucam and several other webcams can be modified to do long exposures. This requires some dexterity and skill with a soldering iron. See for example http://homepage.ntlworld.com/molyned/web-cameras.htm for an excellent summary of web cameras and links to further information.

Starlight Xpress

Starlight Xpress offer a huge range of professionally built cooled CCD-based cameras. They are available from most astronomical suppliers. See http://www.starlight-xpress.co.uk.

SXV models support USB2.0, the older models support USB1.1 or parallel port.

Model

/

Chip Type

/

Size (mm)

/

Type

/

Pixels

/

Bits

/

Pixel Size (um)

/

Price

SXV-H5 / ICX424AL / 4.9x3.65 / Mono / 660x494 / 16 / 7.4x7.4 / £1000
SXV-M5 / ICX405AL / 4.9x3.65 / Colour / 500x580 / 16 / 9.8x6.3 / £700
SXV-M5C / ICX405AK / 4.9x3.65 / Colour / 500x580 / 16 / 9.8x6.3 / £720
SXV-M7 / ICX429AL / 6.3x4.76 / Mono / 752x580 / 16 / 8.2x8.4 (*) / £950
SXV-M7C / ICX429AK / 6.3x4.76 / Colour / 752x580 / 16 / 8.2x8.4 (*) / £1100
SXV-M9 / ICX423AL / 8.6x6.5 / Mono / 752x580 / 16 / 11.2x11.4 / £1350
SXV-H9 / ICX285AL? / 8.9x6.7 / Mono / 1392x1040 / 16 / 6.45x6.45 / £1850
SXV-H9C / ICX285AQ? / 8.9x6.7 / Colour / 1392x1040 / 16 / 6.45x6.45 / £1850
SXV-M8C / ICX406AQ / 7.225x5.375 / Colour / 2312x1720 / 16 / 3.125x3.125 / £1150
SXV-M25 / ICX413AQ / 23.4x15.6 / Colour / 3024x2016 / 16 / 7.8x7.8 / £3950
MX516 / ICX055BL / 4.9x3.6 / Mono / 500x290 / 16 / 9.8x12.6 / £550
MX5C / ICX055BK / 4.9x3.6 / Colour / 500x290 / 12 / 9.8x12.6 / £590
MX716 / ICX429AL / 6.3x4.76 / Mono / 752x580 / 16 / 8.2x8.4 (*) / £800
MX7C / ICX429AK / 6.3x4.76 / Colour / 752x580 / 16 / 8.2x8.4 (*) / £990

Starlight Xpress also produce a number of other products to assist with astronomical imaging including an Adaptive Optics Unit, Star2000 self-guider and a separate guide camera.

I have used the MX5C and MX716 cameras and have found them both to be reliable and good cameras. Terry Platt who set up Starlight Xpress is very responsive to user queries.

(*) as quoted on Starlight Xpress site. Size quoted in Sony datasheets and Artemis site disagree.

Meade

Model

/

Chip Type

/

Size (mm)

/

Type

/

Pixels

/

Bits

/

Pixel Size (um)

/

Price

LPI / CMOS / Colour / 640x480 / 8 / £125
DSI / ICX404AK? / 4.9x3.7 / Colour / 510x492 / 16 / 9.6x7.5 / £270
DSI PRO / ??? / 4.9x3.7 / Mono / 510x492 / 16 / 9.6x7.5 / £350/£450

DSI PRO model can be bought with a colour filter set to perform tri-colour imaging.

Celestron

Model

/

Chip Type

/

Size (mm)

/

Type

/

Pixels

/

Bits

/

Pixel Size (um)

/

Price

NexImage / ICX-098BQ? / 3.6x2.7 / Colour / 640x480 / 8 / 5.6x5.6

ATIK

ATIK instruments offer commercialised pre-assembled versions of some popular webcam modifications and ready-built versions of the Artemis cameras.

Model

/

Chip Type

/

Size (mm)

/

Type

/

Pixels

/

Bits

/

Pixel Size (um)

/

Price

ATK-2HS / ICX-424AL / 4.9x3.65 / Mono / 640x480 / 8 / 7.4x7.4 / £325
ATK-2C / ICX-424AQ / 4.9x3.65 / Colour / 640x480 / 8 / 7.4x7.4 / £325
ATK-1HS II / ICX-098BL / 3.6x2.7 / Mono / 640x480 / 8 / 5.6x5.6 / £269
ATK-1C / ICX-098BQ / 3.6x2.7 / Colour / 640x480 / 8 / 5.6x5.6 / £200
ATK-16 / ICX429ALL / 6.3x4.76 / Mono / 752x582 / 16 / 8.6x8.3 / £650
ATK-16HR / ICX285AL / 8.9x6.7 / Mono / 1392x1040 / 16 / 6.45x6.45 / £1250

Note the ATK-16 and ATK-16HR are pre-assembled versions of the ART-429 and ART-285 models from Artemis.

The other models are essentially webcams with forced air-cooling and long-exposure modifications.

Suppliers: www.modernastronomy.com, http://www.iankingimaging.com

SAC

This section is not complete.

SAC103.3MP ICX262AQ

SAC10 NGC11-429 ICX429ALL

SAC10 NGC12-422 ICX422AL

SAC10 NGC13-285 ICX285AL

Suppliers www.opticstar.co.uk

Canon

Conventional Digital cameras. Have the advantage you can use them for your holiday snaps as well.

300D £500 CMOS 6Mpixel 15.1 x 22.7mm

350D £660 CMOS 8Mpixel

Prices with lens. Canon produce an astronomical variant on these cameras the EOS 20Da, which has better H-alpha sensitivity and has been tweaked for astrophotography. I have not seen this in the UK.

www.ebuyer.co.uk

Nikon

TODO

Useful Links

http://www.cloudynights.com

http://www.wodaski.com/wodaski/pick_a_camera.htm

http://www.covingtoninnovations.com/dslr/EOS300Dastro.html

Glossary

Astronomical imaging has its own jargon words. The following are some that you will commonly encounter.

CMOS – complimentary metal oxide silicon. A technology used in the manufacture of silicon chips of all kinds. Light sensors made using the CMOS process tend to be noisier and less sensitive that CCD devices, but they are also cheaper.

CCD – charge coupled device. A silicon technology that converts photons of light into electrons which are stored in the chip until read-out.

QE – quantum efficiency. The proportion of photons that hit the sensor that are converted to electrons. QE often varies with frequency (colour) of the light.

Well depth – image sensors can only capture a finite number of photons before they saturate. Once saturated, no more information can be gathered by the pixel. The end result is that detail in bright areas is lost. The well-depth also affects how many brightness levels can be represented by each pixel.

ADC – analogue to digital conversion. This is the process whereby the charge stored in the sensor chip is converted to a digital count. The number of bits of resolution in the ADC determines how many brightness levels can be captured. An 8-bit ADC can produce 256 brightness levels. A 16-bit device produces 65536 levels. For planetary and lunar work, 8-bits is often sufficient. For deep sky work where very faint objects are being imaged, it is important to have more bits.

Noise – all sensors suffer from noise of various kinds. In particular, image sensors suffer from thermal noise and read-out noise. Noise introduces a random factor into the captured image, which is different at each pixel. When the signal is small (e.g. a very faint object), then the noise can dominate. Even with a strong signal, noise can be evidenced by images that are grainy looking.

Thermal noise – this kind of noise is introduced due to heat in the sensor chip. It can be reduced by cooling the chip.

Read-out noise – this kind of noise is generated during the transmission of data from the sensor chip to the computer. A well-designed camera will minimise read-out noise by careful placement and choice of components and by making sure that noise is eliminated from the power supplies.

Peltier – a semiconductor device that when a current passes through it, produces a temperature difference between its sides. If the hot side is cooled (e.g. by attaching it to a heat sink or the camera case, and perhaps fan assisted air cooling), then the temperature at the cold side can be as low as 20-30 degrees below ambient.