Lens Projection Tests 9/10/2024

Richard P. Hill

9/10/2024

This lab was written quite a while after the original test. As of this writing, it is 9/27/2024. I will do my best to recall all of the information I can. 

This lab involved doing a simple test of lens projection. I'd like to start with a brief overview of taking pictures through a Schmidt-Cassegrain telescope. The simple way is to hook a camera up directly to the back of the scope using a t-mount screw adapter. This results in the camera using the telescope as just a big lens. This means the magnification would be similar to a 2-meter lens, specifically when using the C8 scope I am talking about today.

Now, I must explain how this works with just a normal eyepiece. This, again, is a simple overview and could be a much deeper topic. The magnification when using an eyepiece can be calculated by dividing the effective length of the scope (in this case, 2 meters) by the eyepiece length (let's say a 6mm lens). This means that if I use my examples, the magnification would be around 333 times. This is hard to quantify by numbers, or at least I don't know how to compare this with the directly attached camera, so I'll resort to good ol' pictures. 

But wait, you may be saying. Why are we comparing pictures? Well, well, well, there is this thing called lens projection. To put it simply, I bought a telescope camera extension tube kit. There are many different names for this type of equipment, but the gist is that it puts an eyepiece between the scope and the camera sensor. Included below are some pictures of this in action.

The first thing I want to note is the missing information from the camera on the last two images. I have no idea what caused this, but it could be some issue with corrupted data, as I did have an SD card give some fits around this time.

Anyway, these show the technique quite well. I will explore some of the issues more in other observations and tests, but this is quite a useful tool to add to my arsenal.