The weather has been unusually warm throughout most of October with the last several days hitting the low 80s (Fahrenheit). It is even uncomfortable to the deer as this panting young buck demonstrates. At least it is raining today after about a month and a half without any significant precipitation.
Buck Panting-Canon 40-D 500mmF4 
Doe and Fawn Nursing-Canon 40-D 500mmF4 with 1.4 Extender
I successfully captured another nursing scene, this time using the 500mmF4 with 1.4 extender attached which is equal to a 700mm lens. On a Canon Digital SLR such as the 10-D through the 40-D and the digital Rebels this actually results in an effective focal length of 1120mm. These cameras have a 1.6 crop factor.
When one goes higher up the scale into models such as the 5D and the higher end professional DSLRS you are back to the lenses performing as they did on a film camera.,with full frame sensors. For that reason many professional wildlife photographers actually prefer cameras in the first group as they give them more effective range. If one wants better coverage of wide shots however then it is best to have a full frame sensor such as the second group of cameras offers. Most manufacturers have found a way around this by making special wide-angle zoom lenses that offer increased angle of view for the cameras in the first class.
Which will win out? Who knows! At this point many think that at some time the full frame sensor will dominate, but they are going to have to come down in price substantially for this to happen, and then one will lose the "crop factor" of the 1.6 sensor.
I am really getting technical now, but one position maintains that a full frame sensor camera with a high mega-pixel rating can be cropped in imaging programs to give the same size as the 1.6 crop factor cameras straight from the sensor and still equal or better their image quality. I don't know as I do not own a full frame DSLR, or know anyone who does so that I can make a
personal judgment.
As a side note, the picture of the panting buck is severely cropped and it maintains its quality well. So it is hard to find a definitive answer on this subject. The major criteria for being able to crop a photo to this extent are 1. Good Lighting 2. Shoot with a premium quality lens 3. Shoot with a fixed power lens also known as a "prime", but the better quality zooms such as the 70-200mm L will also do very well. 3. Only crop images that are in perfect focus.
