Minimum Focusing Distance Question about Canon RF 600 mm F11 IS STM

[DPS]

Hi, I am shooting with a Canon RP. I bought the RF 600 mm F11 IS STM lens because I do a lot of wild photography.

I have found that the minimum focal distance for the lens is rather large an I have difficulty shooting small birds. If I go close to the small bird, the lens will not be able to focus. If I for far enough from the subject, so that the camera can focus, the subject appears too small and the focus is not so good. Yes, I see photographers using 600 mm lenses (prime, the L series) a lot. Is it possible to use the RF 600 mm F11 for small objects, or is it only for bigger objects because the the minimal focusing distance issues? I am well aware of the price difference and of the difference in the minimal focus distance that brings along with it. I am asking, because I am thinking of selling the lens in and buying an RF 100-400 mm instead, which allows me to get much closer to the subject.

Thank you

[jrhoffman75]

The minimum focusing distance for your lens is 14.8 ft. The $13000 EF 600mm f/4L has a minimum focusing distance of 13.8 ft.

There is a limit to what a focusing system can do. You may be at that limit.

[rs-eos]

I'll try to do some math later, but if moving to a 100-400mm, the angle of view (even at 400mm) will be greater than what you have with the 600mm.  I don't know if the shorter focusing distance would full compensate for that.

i.e. at the end of the day, how much of the sensor can you fill with an object when both lenses are at their minimum focusing distance.

[rs-eos]

No math to share, but I just did a simulation in my 3D software.  Positioned 400mm and 600mm cameras at their minimum focusing distance away from a 10 cm cube using a full-frame camera.  The 400mm was able to fill the frame substantially more than the 600mm due to the much shorter minimum focusing distance.

[DPS]

Oh, thank you SO much! That is really helpful. I was suspecting that this would be the case. Thank you for doing this! 

[DPS]

Ricky, thank you for doing some math and 3D stimulation. The technical aspect of photography is not my forte, so I appreciate it doubl-y....I love that the family of photographers is so amazing and supportive!

[MikeSowsun]

Here are a couple of charts from The-Digital-Picture showing the Maximum Magnification of various tele lenses. The RF 600mm f/11 is the worst of the bunch. The RF 100-400 is the best of the bunch. 

[DPS]

Thank you so much Mike. Yes, I will go ahead and sell it and get the 100-400mm. I was happy when it first came out but the lens has so many limitations!

[FloridaDrafter]

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@DPS wrote:

"I am thinking of selling the lens in and buying an RF 100-400 mm instead, which allows me to get much closer to the subject."

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My wife and I shoot a lot of small birds, flowers, and insects. I do like a little reach, so I use an RF 100-500mm L on my R5, but it has close focusing abilities, roughly 4' at 500mm. My wife uses the RF 100-400 on her R6 and it works well from 3.5' to 60' on the 20mp R6 when shooting smaller birds like warblers. The RF 100-400 has excellent IQ, but the R6 is a really nice camera, so it may contribute to the quality images.

Here are some examples from the RF 100-400mm f/5.6-8 IS USM on the EOS R6 taken by my wife. They were shot Raw, edited in DPP 4, cropped and reduced for the forum. All at 400mm.

1/320th, f/14, ISO 3200, distance = 4'.

Black and Red Paper Wasp.

1/400th, f/8, ISO 1600, distance - 7'.

Carolina Wren.

1/500th, f/8, ISO 2500, distance 60'.

Fish Crow.

1/500th, f/8, ISO 2500, distance =  30'.

Juvenile Red-shouldered Hawk.

1/400th, f/8, ISO 2000, distance 6'.

Ruby-throated Hummingbird.

Newton

[DPS]

Thank you so much for the thoughtful answer and the examples. Yes, I am sure that my RP camera has its own limitations added to those of the lens. Thanks again. I love the family of photographers. People are so helpful.