Frequently Asked Questions
What are the benefits of a live view interchangeable lens camera?
In addition to many superior specifications, interchangeable lens cameras can provide a less expensive alternative to those provided by the microscope manufacturer (called scientific cameras):
- No annoying and unproductive streaking since the live view ILC camera provides 24 fps video;
- Larger field of view with high pixel density because of the large sensor;
- Higher resolution for your lower power objectives (<40X) because there are 18 or more megapixels spread over most of the field observed through the eyepieces;
- Computer control capabilities are now available in consumer cameras, so it is no longer necessary to purchase a much more expensive scientific camera to have computer control;
- High sensitivity for capturing still fluorescent images;
- Automatic exposure control features;
- In addition to using the manufacturer’s software, a universal image editing program such as Photoshop maybe used with SLR type cameras as well as the new mirrorless digital cameras;
- The camera can be removed easily and quickly from the microscope and used for other purposes;
- A live view ILC camera can be purchased for less than $900;
- Most OSC adapters are available for under $600.
What are the procedures for microscope alignment?
The benefits of the large field of view offered by our adapters requires that the microscope be aligned in accordance with the Kohler illumination method. This assures that the illumination will be visually uniform over the field of view. The following link offers an explanation of Kohler illumination as well as an excellent alignment procedure:
http://zeiss-campus.magnet.fsu.edu/print/basics/kohler-print.html
How many pixels are enough?
The higher the magnification, the fewer pixels are required. Cameras like the ones we purchase are 18MP. This is perhaps a little less than you need for our large field adapters for a 2X objective and more than necessary for a 100X assuming a direct projection system. Scientific cameras generally have a much smaller field of view and therefore yield a satisfactory image quality with fewer megapixels.
What is a scientific camera?
These cameras are specifically sold to be used on microscopes. They typically couple to the microscope with a C-mount. All microscope manufacturers have C-mount adapters for TV cameras. These cameras evolved over time and assumed a kind of mushroom shape. Some or maybe most were repackaged security and consumer cameras. These cameras are augmented with frame grabbing software and computer control.
What are the exclusive benefits of scientific cameras?
- The first benefit is to be able to record an excellent image of a microscopic moving object. Also, with a cooled detector camera, an object that emits a very low light signal. These might include objects tagged with a fluorescent stain.
- A second benefit is special software specific for biological scientists.
- A possible third benefit is that not much ROM type memory is required.
- A possible fourth benefit is that the image can be adjusted before it is saved. So what you save is the same as what you saw.
The reason that a typical scientific camera doesn’t offer a bigger field of view is the bandwidth limitation of a USB connector. A consequence of this limitation is that the camera designers have to trade off between frames per second and the sensor size. That’s why some cameras will have as little as three frames per second. The result is streaking of the image when translating the stage and focusing.
Of course, these cameras can obtain still images by a process called frame grabbing. As the stream of images flow into the computer and are displayed on the monitor screen, a frame can be grabbed from the stream and stored as a still image. In fact, several frames of a still object can be grabbed and coupled together to reduce any noise in the background.
As technology moves forward, some statements about scientific cameras that are true today maybe obsolete tomorrow. Also, a statement made for one camera may not be true for another. However, generally speaking, some problems with some scientific cameras are image streaking when translating the stage or focusing. This requires moving the stage and focusing knob very slowly. Also, the limited field of view will present a difficulty for some applications.
Who can Benefit?
The scientific camera will have its best application for a research scientist who is studying the motion of microscopic objects.
What do you need to know about using a consumer camera?
To work best for a microscope camera, three conditions must be met:
- The camera must offer a TV image referred to as live view.
- It must have a removable lens in order to provide direct access to the sensor.
- It must have a USB receptacle and software driver to enable direct image storage on the computer hard drive and also camera control by the computer.
These cameras provide a live image with 24 fps (frames per second) temporal resolution. The resulting data maybe recorded to study the motion of microscopic objects, however, the resolution is limited to HD television. The advantage is to enable rapid stage motion and focusing without streaking.
These cameras are best at capturing images. With image capture, a shutter determines exposure time. Once the image is temporarily stored in the camera, an image can be transferred to the computer over a USB cable. There is no limit on the image size, because the image will be downloaded regardless of how long it takes. Therefore the bandwidth of the USB connection is irrelevant for capturing a still image.
By having a camera that works both like a TV camera and a still camera, most of the field of view observed through the eyepieces can be observed in real-time on a monitor screen and the image captured at much higher resolution. If the object moves slowly, then its motion may be studied at high resolution by taking multiple pictures. These can be presented in an array or as a slide show.
For dim static specimens, such as some fluorescent images or dense geological specimen, the ISO value can be adjusted upwards (with some noise introduced) and the exposure time increased.
A further consideration is that these cameras with an appropriate adapter are available for $1,500 more or less.
There is also commercial software such as Photoshop that can be used to adjust the images. This eliminates the need to learn a specialized software program provided with the scientific camera.
Who can benefit?
- Research scientists who are documenting static objects.
- Pathologists who make presentations and need images for their reports.
- Geologists and gemologists who need large field quality images.