600mm PF with 1.4x TC versus 800mm PF

[Lance B]

I have encountered a "bad" copy of two lenses over the last 15 years but I did not expect this possibility to apply to the much less complex TCs. Now I am not so sure. I have both TC14 and TC20. I used them to look at 800 mm using the TC20 compared to stacked TCs. The reviews indicate the TC20 should a better choice. I took several RAW photos taken at 80 to 100 meters using a Z9 + 400 TC 2.8 on a Gitzo series 3 tripod. Examining the photos on a 27 inch UHD monitor at 200% there was certainly some softening, particularly in the corners. I could not see any difference between the TC20 and stacked TCs. Maybe my TC20 is not as good as some others.

Side note - I changed the camera and external TC without moving the lens and tripod. I could not see any difference in FOV. I suspect that 1.4 is just rounded off from the square root of 2 or the difference between 784 mm and 800 mm is pretty small.

A 1.4x TC is really a 1.414x TC. It is really the square root of 2 = 1.414. Thus 1.414 x 1.414 x 400mm = 800mm.

 

[macwalter]

I thought a 1.4tc would make a 400mm lens a 560mm

 

[ricardo00]

I thought a 1.4tc would make a 400mm lens a 560mm

He is talking about stacking two 1.4TCs, an internal and external one.

 

[ajrmd]

Again, I think the issue comes down to size and FL. Can you take and hold the larger 800 when traveling? Do you shoot at longer FL's. For my local WL, the 800 is a must have though when I travel, I rely more on the 186.