Perfect on my 400 f/2.8L IS!!!! Easy on, easy off. Quick!
John

This was my third lens cap from DON Zeck. I have one and i bought for my two good friends another two. evyrything was perfect.

Wow!! My C2… (EF 300mm f2.8) cap arrived this morning, well ahead of schedule!!
It’s beautifully manufactured, and is of superb design!!
Thank you so much for your excellent product & service.

I could kick myself for not getting these earlier. Best product out there to replace those awkward leather socks. The fit is absolutely flawless.

Have come back for a second time for additional lens. Says something.

Great idea, felt that there should be some more protection for the front element of my Nikor 300mm,2.8. I feel secure with this cap.

Thank You

Bill

Installed one each on a Canon L 300, 400 and 600. The fit is excellent. The convenience is and simplicity of motion alone makes the caps worth the cost. Stronger protection for the large glass out front. I will keep the canvas covers in the truck as well for those days when the bottom falls out of the sky; an extra layer of flood control.
The owners were very pleasant to do business with.

I am very happy with the don zeck lens cap for mine canon ef 500.It fits top en easy to use. I put one bigger o ring on it to fit tighter.

Why did Nikon not think of this? Excellently made and thought out – the proverbial dot on the i. Arrived safely in Germany well short of the proposed date. Many thanks.

My order was delivered internationally well within the specified time frame, and fit perfectly on my Canon 500 mm f/4 II. No need for the oversize O-rings supplied.
For flying, I need to protect the front element of the lens when packed in a carry-on equipment bag.
It is so light and convenient that I also will use it to add that extra element of security while carrying the lens in the field under dusty or rainy conditions.