Originally Posted by
Journeyman
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The reason for the 600 mention was that the focal length of 600 can be recreated on a crop frame using a 400 lens. I have always had trouble settling the comparison in my mind. I have seen beautiful pictures of birds with prey (large an grub sized) that are sharp and clear. I have photos of ospreys that are not cropped that fill the shot. Right place right time.
I think the last time I posted about a lens it was related to the use of a 400 type lens and the weight. I am working on a solution (I hope), as mentioned the 600 size lens would involve a lotto win at least.
Therefore I am wanting to stay in the range of most manufacturers 400, the Tamron has served me well. I believe it is about 10 to 15% shorter than advertised. Using an used shooting target, holding the position of target and tripod I was able to compare the magnified result. The measurement was 120mm on lens a. and 100 on the Tamron. An otherwise excellent lens by most measures.
After some reflection I think that my focus problems are due to my less than steady hands. As long as I have had hands they have never been steady. The obvious fix is to become good friends with a monopod at least and a tripod when needed.
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