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Pixels v focal length (1 Viewer)

Marise

Well-known member
Hi all.

Help! I have spent ages pouring over as much info as I can lay my mitts on and subsequently am now more confused than ever.

I have a 300d with a 100-400 lens. I'm thinking of upgrading the camera and have been looking at the 350D, 20D and the ID MK11 all 8mp, I even looked at the 1DS 11mp. Am I right in thinking that with the latter the focal length on my 100 - 400 would remain at 400max but on the others would be either 1x6 or 1x3.

So for taking pictures of birds would I be better with more pixels to crop or the longer focal length in the 1st place?
 
Don't forget the 1Ds Mk 11 at 16.7Mp!

A 400 is a 400 is a 400 as far as I can see - the 1.3 or 1.6 crops of the two 8mps (don't bother with the 350D if you're considering the 1D models!) only enlarge the central section of the full image, they don't lengthen the focal-length of the lens in any way.

Hopefully, someone who has both 20D and 1D bodies will be able to say whether the difference between the two is noticeable in a practical situation (as opposed to theoretically)
 
Thanks Adey, I didn't realise that - told you I was confused - and no I'm not considering the IDs Mk11!
 
Marise said:
Help! I have spent ages pouring over as much info as I can lay my mitts on and subsequently am now more confused than ever.

I have a 300d with a 100-400 lens. I'm thinking of upgrading the camera and have been looking at the 350D, 20D and the ID MK11 all 8mp, I even looked at the 1DS 11mp. Am I right in thinking that with the latter the focal length on my 100 - 400 would remain at 400max but on the others would be either 1x6 or 1x3.

So for taking pictures of birds would I be better with more pixels to crop or the longer focal length in the 1st place?

The focal length is always the same. The multiplication factor refers to the field of view when the lens is mounted on your camera. The cameras with a smaller sensor (APS) like your 300D have the same field of view with your lens at 400mm as a 35mm camera has with a 560mm lens.

So for bird photography where it is usually important to get the bird relatively large in the frame, the smaller sensors have an advantage - assuming the lens makes full use of the sensor's resolving capability. The smaller sensors with smaller pixel pitches will also be more demanding of lens sharpness. Unless you are really good at getting close to the birds, the cameras with the larger sensors will probably be a net disadvantage for you.

Also, keep in mind that the difference between the resolution of a 20D or a 350D as compared to your 300D is about 15% linearly. That's a fairly minor improvement. If would give the equivalent extra detail that you would get if your 400mm was a 460mm lens (though the FOV doesn't change).

More resolution is better, and if you are constantly looking for that little bit more, then certainly consider the upgrade. But don't be surprised if the benefit is not overwhelming.

So before spending money, make sure you are solving the right problem. If the "problem" is reach, then maybe its new optics that your need more than a new camera?
 
Thank you very much Jay - much appreciated. I did wonder about the lens, but the price jump does seem very high and I wasn't sure which I would go for. At least with the 100-400 one does get flexibility and much as I would like a Canon 600mm neither budget or arm strength would really permit! Thank you again. Marise
 
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