General Full-Frame RF Ext. Tube Mod.

[Robert42]

Has anyone tried to ream out an ext. tube to make a 1.4 or 2x extender fit so the 100-500 mm could be dialed back to 100? If so what were the results? I have read that it could not be done because the contact traces were exposed before the opening was large enough for the extender to fit.

 

[David Berry]

Rob…

Welcome to the forum. It’s a gentle and helpful place.

Am I correct in assuming that you are referring to using an extension tube as a spacer to separate the 1.4x or 2x extender from the lens?

From a practical standpoint, my answer is “pointless”; but posed as a theoretical query (which, I think, you did), our members responses should be intriguing!

… David

 

[Robert42]

You have the jist of it.
Do you shoot macro? The tube would let the rf 100-500 start at 100 not 300mm with the extenders.I don't know why Canon made the extenders the way they did, but thats the way it is. The cheep 100-400mm works, but its not as sharp as the 100-500 and not as fast.

 

[Dean Wilson]

Google AI says:

No, you cannot use an RF teleconverter (often called an extender) and an RF extension tube together, as they are incompatible. While the RF 100-500mm lens works with the RF 1.4x or 2x teleconverters to increase focal length, adding an extension tube would remove the ability to focus on distant subjects, essentially limiting the lens to a macro-only or close-up purpose.

Why you can't combine them

• RF Teleconverters (Extenders):
  These attach between the camera and compatible telephoto lenses, like the RF 100-500mm, to increase the effective focal length.
  
  
• RF Extension Tubes:
  These add distance between the lens and the camera body, enabling closer focusing and higher magnification for macro photography, but they prevent focusing at infinity.
  
  
• Incompatibility:
  The optical design and physical connection of these two types of accessories are fundamentally different. You must choose one or the other for a specific photographic purpose.