Larry Legg's Learner Projects
Project 1- Preparation for this course.

Watch out for these symbols in my projects!
 
A good idea
 
Use household stuff
 
The right way!
 
You can skip this if yer don't want details! 
 
 
A secret unlocked!

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The Brunel SP03 Basic Microscope  
If yer want to buy a microscope and follow these projects, the SP03 microscope is a good instrument for its low price. It can be purchased on-line from me Larry's Project Resources page in the Onview shop. There may be other microscopes in a similar price range available from other companies so you don't have to buy the SP03 to follow me projects... but if you did buy this one - at least we would all be getting comparable results. All lenses are glass. Beware if purchasing a microscope from department stores: some have inferior plastic lenses.  

Right, lets take a quick look at the specification here...  

1) 3 eyepieces: x5, x10, x12.5  
 2) Strong & robost die-cast metal body  
 3) Nosepiece turret holds 4 objectives  
 4) Supplied with 2 objectives: x10, x40  
 5) Stage can be fitted with optional (additional) mechanical stage  
 6) Abbe full sub-stage condenser (N.A.1.2) with iris diaphragm  
 7) Concave mirror for illumination. Sub-stage lamp (additional) available!  
 8) Cast metal horseshoe base for stability  
 9) Wooden Case (additional) available!  
10) Lens box for storing eyepieces and objectives  
11) Separate coarse focus control  
12) Separate fine focus control  
13) Viewing angle adjustable.  
14) Stage clips to hold specimen slide  
15) Filter carrier for polar disc or colour filters.  

So what kind of magnification will yer get from this basic model..? You can magnify from 50 to 500 times with the lenses supplied. At some time in the future if yer want to increase this range you can buy additional objectives and eyepieces and push that range wider from x20 to1500x.  

Beyond 1500x or 1600x - yer aint gonna see anymore. The limitations of light as the 'probing-medium' sets a barrier on resolution - er... that means  how much detail is definable. For most of our projects, 500x is plenty of magnification.  

Let there be light.   
Yeh... well...  yer need some of this. In fact - yer need lots of light. A concave mirror will help gather some rays, and the sub-stage condenser will get them focused and increase the amount of rays going up the ol' tube but you need a light source to start with. During the day, there's normally a very bright light that's free of charge:-  
it's called the Sun -  but don't ever go pointing that concave mirror at it directly: yer can't see much at all if yer burn the retina of your eye out!  

Pointing the mirror at the sky or towards 'daylight' from a window is okay as long as the sun isn't directly visible. Better still - is to use an artificial light source, such as a desk lamp. You can purchase a sub-stage light built for the purpose but if yer in a country that's using electricity different from 230 to 250 volts - the sub-stage lamp ain't gonna work properly. So here's a solution and one I use even though I'm on a 230-250volt supply:-  

Yup, it's an ordinary fluorescent desk lamp. Yer can pick this type up cheaply from most stores. Other lamps with  halogen or normal tungsten bulbs will do okay as well. I use this lamp as an aid with all my microscopes, and to light up me desk too so I get a lamp which has many different uses for my money.  

You can use the lamp, or one similar - possibly a little halogen spotlight - for both incident and transmitted lighting. You can either shine it on the mirror so the light goes up through the specimen slide from beneath or use it directly to shine down on to the top of the specimen. 

Is this type of light even? To the eye it aint bad. Most subjects look illuminated evenly. If yer using a microscope to take video or photos then this type of lamp may not be so good because film and Video ccds will detect the uneven bands of light coming from the lamp tubes. A halogen spotlight would work better but you will have to use at colour-correction to get the light to come out white on both video and photographic film. 

Dust-covers 
Nothing is work for microscopes than dust. Even a few specks can ruin a video or photo and can be annoying when just viewing by eye. Keep yer SP mic under a dust cover when not in use. I use those stronger plastic freezer bags. They're cheap, strong, and come in different sizes so you can normally find one the right size to slip over yer microscope! 
  
  
Important to have on yer basic microscope. 
If you look under the stage of the Brunel SP03 - or any of the SP range of microscopes, yer will see a condenser. This focuses and amplifies the light. As part of the condenser, there is also a tiny iris which - when almost shut to a pin-hole - can help improve contrast and crispness in the image seen through the scope. 

The condenser can be moved up and down (closer or further to the specimen) so as to optimize the illumination and resolution of the image seen. In the image below, you can also see a round filter holder swung away from the condenser. This is a 'nice' extra to have because it can be used to hold colour correction filters, polarisers, or a dark-field stop, If yer don't know what these things mean, don't worry about it yet: we will be covering all this on later projects! 

 

Now, I suppose I'd better show you what quality of image yer gonna (you are going to get) with the Brunel SP03. Let's turn the page and take a look... 
 

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