The Fujifilm LAS-3000 Imager is a versatile instrument for imaging anything from visible-light illuminated Coomassie stained gels to chemiluminescent Western blots, or even whole animals.
The main benefit of the LAS-3000 is the very sensitive, Fujifilm-designed optics and sensor. It was designed to compete directly with a standard X-ray film setup with which many laboratories are familiar and for this purpose, we have found it suitable. Although the system is sensitive and capable of imaging everything that X-ray film can image, we have found that it is not on par with X-ray film sensitivity in exposure times (i.e. we find we have to expose longer on the LAS-3000 than we did with X-ray film). Despite this, typical exposure times are not too long, as we have found 2 seconds to several minutes are sufficient for most common applications (SYBR™- and ethidium-stained DNA gels, chemiluminescent Western blots, etc). For other applications, the instrument is capable of exposures varying between 1/100 of a second right up to 30 hours.
To facilitate such long exposures, the imaging sensor is a high-sensitivity, peltier-cooled chip, recording a maximum of 3.2 MP, which is more than sufficient for large, publication-quality images. We have found the images produced by this camera to be excellent in terms of sharpness and resolution. Images can be captured normally, or by ‘pixel binning’ to effectively increase the sensitivity of the sensor, but this reduces the resolution. We have not required this level of sensitivity in the everyday imaging of chemiluminescent Western blots, DNA gels and so forth. Various settings allow the user to select the compromise between resolution and sensitivity that is optimal for the application and image required. The sensor collects 16 bits per pixel which provides a large dynamic range (4 orders of magnitude). This is much better than the many 8- or 12- bit imaging systems on the market.
The lens has a large aperture, going as large as f/0.85. The unit comes standard with a 43mm f/0.85 Fujinon lens for normal applications and a wide-angle 24mm f/2.0 Nikkor lens for imaging large gels (such as large format 2D gels etc). We have found these lenses to be adequately sharp even when used at maximum aperture. The focus is automatic on the Fujinon lens, but manual on the Nikkor lens. We have found this to be quite inconvenient, given that the only way to focus the manual lens is to open the unit and turn the focus dial on the lens barrel. This, in itself, is quite easy, but there is a delay in the live-capture preview which can make fine focusing slow and difficult. With the manual focus lens, the LAS-3000 can record images up to 25 x 25 cm in size, which we have found ideal for 2D SDS-PAGE gels. The tray height can be adjusted through the software to bring the sample closer or further from the lens as required. There are four tray positions.
Below the lens is a turret of five filters and they are interchangeable, allowing the use of as many filters as required. The filters are moved into place automatically by the software-controlled and motor-driven turret.
The LAS-3000 can use various light sources, including UV transillumination and visible white-light illumination in transmittance or reflectance mode. Various wavelengths can be utilized (in conjunction with the filters) from the built-in and interchangeable filtered LED illumination panels. Again, all light sources are controlled from the software. Further illumination sources can be purchased with the system or as attachments at a later date.
A chemiluminescent or fluorescent image can be captured, as well as a visible-light marker image, as a single task using the supplied software. These images are then easily overlaid, using the image analysis software package, to produce a composite image. We have found the image analysis software to be less intuitive than it could be, but it is easy to use with the help of the instruction manual.
A separate software application controls nearly every aspect of the system. The LAS-3000 can be attached to a Mac or a PC running Microsoft® Windows®. The device is attached via a standard USB port. We have found this setup to be, for the most part, reliable. However, occasionally the scanner loses connection to the PC for unknown reasons, requiring both the computer and scanner to be switched off and then on. This also means repeating a lengthy initiation sequence. This sequence occurs every time the unit is switched on and involves checks on the platform mechanism, filter turret rotation, camera connection and other tests on the system components. This can take a long time and, in addition to the time required for the camera sensor to cool, we have found that this causes a significant delay before the instrument can be used. For this reason, we have found it better to leave the unit switched on permanently.
In terms of space requirements, we have found that in comparison to many other imaging systems available, the unit is quite large both in footprint and height. It measures 51 x 48 cm and is 73 cm high. On top of the main dark-box is a camera head and cooling apparatus, which measures 180 x 250 mm and is 170 mm high. Therefore, a large bench space must be found to keep it and a computer system. Additionally, the whole system weighs nearly 55 kg and therefore, this unit is not at all portable. This is reasonable, however, in contrast to the space requirements for a darkroom and X-ray film processing equipment.
Scott Coutts
Research Scientist
Monash University
Department of Microbiology