https://www.youtube.com/watch?v=4LsiM9H8w_o Samyang 800mm f/8 Mirror, & 2x telecoverter (with samples). Wide lens. Mirror lenses are cost effective (10x) vs telephoto lenses.
https://www.youtube.com/watch?v=wQCppYxR1U0 ultra wide cannon lens. Ultra Wide Canon Lenses on a Sony Camera - Rokinon 14mm F2.8 + WonderPana. WonderPana is extra large filters mounted on to lens. https://www.fotodioxpro.com/collections/wonderpana
https://www.youtube.com/watch?v=RX9RKQFJukQ 3d printed I got a Opteca 650-1300mm telephoto lens. I purchased this for astrophotography with this, but I had hard time to focus. So, I decided to make a motor focuser for this lens.
https://www.youtube.com/watch?v=U3vNur71xfY a6500 1000mm lens , $80
diy hack Edit
https://www.youtube.com/watch?v=Zi1DCPi-oow This Mobile phonne telescope with DIY mount of EPS board is fitted with Samsung Galaxy Grand, which has very powerful camera -1:4x and the Binoclular -20x, thus the total magnification is around 80x, It has captured some of very good still shots of far away object..... attached with the clip. The total cost of the entire assembly would be less than 5 Dollar in Nepal... excluding the phone.
https://www.banggood.com/Universal-12x50-Hiking-Concert-Camera-Lens-Telescope-MonocularPhone-Holder-For-Smartphone-p-1060019.html or use binoculars for suitable zoom size(50x). Zoom focus adjustment is done with stepper motor actuation. See https://www.youtube.com/watch?v=fWBnDZzzuvs This tutorial will show you how to make your own DIY zoom lens! Now you can get those shots of faraway subjects that you've always dreamed of! You can also get some great shallow depth of field (blurry backgrounds) which is otherwise not possible with a fixed focus camera. This lens is completely removable and will not damage your camera or binoculars in any way.
https://www.youtube.com/watch?v=qBKDgpI5ano How to build a $40 USB spy telescope
https://www.youtube.com/watch?v=iarXeMkIJ2E How to adapt an HD-4110 webcam to a telescope for astrophotography.
https://www.youtube.com/watch?v=qwM0EBNGo2o Remove the IR lens. Its not as difficult as you'd think. To do so, carefully disassemble the camera until you have the lens assembly visible, depending on the camera model you may or may not be able to remove the IR filter which will look like a red tinted piece of glass. Use tweezers to remove it. This should fix it. Here's a surprisingly powerful and effective spy camera and camcorder. Depending on what you already have at your disposal this could only cost you around $40. Most Night Vision Viewers cost around $99 and don't record or take pictures. They also have very cheap low power LED that don't illuminate very much. This is one of the best ways to make a Night Vision Spy Camera - 200 MW Triple Infrared LED http://lnk.nu/shop.ebay.com/1pdj.html -3 Inch LCD viewfinder x2.8 for Camera & Camcorder http://lnk.nu/shop.ebay.com/1pdk.html
https://www.youtube.com/watch?v=0a-f4EIxBc4 remove ir filter from digital camera for nightvision.