Why are you supposed to use the low power objective before using the high power objective?

Question

Why are we supposed to start viewing something using LPO before HPO? Does it affect the image if you use HPO before LPO?

Answer 1

It's good practice to get the object your viewing in the center of the field before going to a higher power (it's easier to find things). Also, it's less chance that you'll mash the LPO into the slide and damage it or destroy your specimen.

Doug

Answer 2

The area of specimen covered by the LPO is bigger than the area covered by the HPO. If you are looking for a specific feature in the sample using the HPO you will take much longer to find it as if you use LPO first. Once you locate the feature you were looking for using the LPO then you can switch to HPO. Now the feature should be already centered in the eyepiece providing it was centered when you found it using the LPO. In order to get a well focused image with HPO the distance between the sample and the HPO is much smaller than the distance between the sample and the LPO. It is very likely that the sample could get cracked or damaged while you attempt to focus the image with HPO as sometimes the HPO must be actually touching the sample. Depending on the power of the HPO you might have to use a drop of oil (higher different refraction index compared to air) between the sample and the HPO in order to effectively gather the light coming from the sample and in order to increase the effective resolution of the microscope. If you use HPO with oil before the LPO, then you will have to clean and wipe the oil off the sample before you use the LPO. This is another reason why you should start with LPO and then move to HPO.

Answer 3

if u use a LPO and u can see the things that ur suppose to see in ur specimen... then there no need to use the HPO...

but if u cant... then u have to use the HPO... to see/view/inspect the specimen clearly