Finding overall magnification when using a tube lens and objective lens


I was using an actual microscope and realised that when understanding magnification, you have the objective lens and then the eyepiece lens which provide different magnifications so if the objective lens is x10 and the eyepiece lens is x10 then the total magnification is x100.

With my delta stage, I’m using a x10 objective lens and a achromatic doublet tube lens of focal length 50mm as suggested in the parts list but I can’t figure out what magnification it would provide when in use with the transmission optics module casing?

I assume there must be a relation somewhere to figure this out but I’m not sure I know enough to know where to look or how to start.

Could someone help?


Check this out and see if it can help.,that%20of%20a%2050x%20objective.


The page @dgrosen links to explains the factors determining the optical performance and magnification. Some of eth numbers for the Pi camera lens are for an older version of the microscope. In V6 and V7 the resolution and field of view of the simple Pi Camera optics module are now similar to a x20 objective lens.

The function of the tube lens in matching the field of view used on the camera to the designed field of view of the objective is also explained at Assembly Instructions.

Thanks for reply!! The links in the assembly instruction were really useful but I am struggling to understand, you say that the Pi camera optics module (I am assuming this is just the optics module casing, a pi camara and the tube lens) are similar to a x20 objective lens (therefore M = 20) but in the link you sent explaining the details, M = 0.261 which is demagnifying the image so I am a bit confused on what the actual magnification is.

Sorry if I’ve misunderstood your answer!!

I am sorry, I was not clear and I have confused you.

The demagnification that you have there is for the tube lens - camera system, working on the expected image 160mm behind an objective lens. It needs to be less than 1 because the field of view available from the objective is bigger than the camera sensor.

I was talking about the basic optics module, without an objective. This uses the original Pi camera lens to image the sample directly onto the sensor. In this case the actual magnification is not really relevant as you will not look directly at the sensor, you display the image in some way. By ‘similar to a x20 objective lens’ I mean that if I have the same sample in a conventional microscope and look through the eyepieces and compare the field of view and resolution to the images from the basic optics module, then they are broadly similar.

With the tube lens calculated for the Openflexure microscope optics for using objective lenses, again the field of view and resolution should be similar in the Openflexure system to the same lens used for looking into a conventional microscope.

Ah thank you! That explains it a lot!