teddyweverka

https://www.amazon.com/gp/product/B01J8WRZBC/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

I got this lens cap to fit the 600mm f8 solid cat by wrapping a few layers of tape to the lens.

I've been able to reach out to really long focal lengths with the reflex lenses (including a Celestron 1250mm) and a NIkon TC-1 or a Vivitar (2X, original co.) telextender.

 

Results are amazingly good (LINK)

 

It has somewhat dampened (I am glad to say) the urge to buy ever longer and longer mirror lenses.

I topped out with the Celestron Edge 9.25 inch (2350mm focal length). This thing makes the 600mm solid cat feel like a hand held lens.