Taking moon picture

[Sanjaydesai]

I have Canon 6D camera. I am trying to take picture of full moon using EF 70 300 lens. Even at 300mm the picture of moon appreas to be very small. I know I need to use higher focal length but at 300mm the size of moon should be relatively large.

I do not know why this happens. can anyone tell me what is required to be done.

[kvbarkley]

It has an APS-C "mode"

https://www.usa.canon.com/internet/portal/us/home/products/details/cameras/eos-dslr-and-mirrorless-c...

"Whether you're purchasing your first EOS camera or your fifth, the EOS R camera is designed to integrate smoothly into existing EOS systems. Engineered to work seamlessly with RF lenses, it maintains complete compatibility with EF and EF-S lenses by using one of three optional Mount Adapters. When using EF-S lenses, the EOS R even crops automatically to reflect the APS-C sized sensor the lenses are designed for."

I don't know whether something in this bizarre setup forced APS-C, or whether he chose it.

[TCampbell]

Thanks ... I can see how that would make sense.  

An APS-C mode would mean you can use EF-S lenses without vignetting.  Since there's no issues with mirrors having enough clearance when using EF-S lenses... this mode likely exists to support EF-S lenses on a full-frame body.

[kvbarkley]

I think the takeaway from this silly exercise is that the EOS-R could actually autofocus at f/18.

[RobertTheFat]

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@TCampbell wrote:

Thanks ... I can see how that would make sense.  

An APS-C mode would mean you can use EF-S lenses without vignetting.  Since there's no issues with mirrors having enough clearance when using EF-S lenses... this mode likely exists to support EF-S lenses on a full-frame body. 

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"Without vignetting" seems a bit optimistic, since vignetting is inevitable if you focus an APS-C lens on a FF sensor. A better phrase might be "controlled vignetting via automatic cropping".