Embedded Files
Post date: Dec 09, 2016 6:23:16 AM
BackgroundThe camera obscura uses a lens and a screen to form an image. One of the main advantages over a pinhole camera is that the aperture can be much larger to allow light in, which is one of the main drawback of pinhole cameras.
However, as the camera obscura uses a lens it is important to make sure the image is in focus. To achieve this using one lens, the screen must be positioned an appropriate distance away. For landscapes that are far away, this was not a problem as the image distance doesn't change; however, for portraits (as pictured) the position of the object plays an important role on the image distance.
This investigation aims to explore how the image distance changes as we change the object distance.
Equipment
Equipment
12V powerpack
12V light bulb
Wires
Convex lens and lens holder
Meter rule
Vertical white screen
Method
Method
Setup the light bulb, convex lens, and screen as shown in the diagram above.
Set the bulb 30cm away from the lens, which will act as our first object distance (lens to filament distance).
Adjust the distance of the screen until the filament of the light bulb (the object) comes sharply into focus. It may be useful to dim or black-out other sources of light in the room to see the image more clearly.
Record the image distance (lens to screen distance).
Repeat steps 2-4 for different object distances up to 80cm in steps of 10cm.
Risk Assessment
Risk Assessment
The bulb will become hot during use and could cause burns if touched directly. To avoid this always move the bulb by the base and do not touch the bulb.
When working in a darkened room, it is harder to see trip hazards which could cause injury: therefore all stools will be tucked under desks.
Page updated
Google Sites
Report abuse