N E 1 run a Sigma 150-600 Contemporary for birds and WL?

WiscTim wrote in post #18214014
I own both the Canon 100-400mm L IS ver.1 and the Sigma 150-600 C and use them with my Canon 7d ver. 1. I photograph small animals, small birds, and butterflies, and am still on the early part the learning curve in my technique. There are example images in my POTN gallery. I have included some random observations below, but they may not apply if you are an advanced shooter after bear or moose.

To me, the Sigma is significantly larger. That is not a problem if I am specifically going to a location to get photos of something. But if I am going for a 3-5 mile hike and maybe I can get a photo during the hike, I prefer to carry the smaller, lighter 100-400. The Sigma requires a larger pack to carry, I use the Lowepro Flipside 400AW which is a small backpack. I can fit the 7d with the mounted 100-400 in a Think Tank TurnStyle 20 sling bag which is lighter and easier to carry.

For small birds flitting in trees or ducks winging past, I depend upon the zoom. Zoom wide to locate the bird, then zoom in once the bird is centered in the viewfinder. I find it very difficult to locate fast moving birds if am already at the maximum magnification.

For song birds and offshore ducks, the extra reach of the Sigma is a big difference. With the 100-400mm I can get good images, but they require cropping. With the 150-600mm I have a much easier time getting the bird to fill the image.

Probably not a common use, but for butterflies and insects the minimum focus difference of the Sigma is a drawback. It is easier to take two steps closer to an insect using the 100-400mm and getting the same size image but being able to use a slower shutter speed since the focal length is smaller.

I find I switch between the two lenses as needed. This spring I was photographing ducks swimming offshore and they rarely came close enough for the 100-400 but I was able to get good photos with the 150-600. This summer I wanted to get some pictures of hummingbirds feeding on flowers. I have a feeder and flowers outside my home office window, so I put some cloth over the window opening with a hole that I could put the lens through (the camera and lens were on a tripod with a gimbal). I tried the Sigma, but some of the flowers were closer than MFD and it was difficult to zoom fast enough before the bird moved on. The 100-400mm allowed me to get images when the bird was closer and to locate and quickly zoom in on the birds before they moved to another flower.

To summarize the random thoughts above, try to look at the lenses in person to check if weight and size will allow you to carry the lens to the places you want to use it. Also, evaluate what you want to photograph with the lens and at what distances you will be taking the photos.

Mel-S wrote in post #18613362
I have the same lenses as WiscTim. Only difference is I use mine on either a Canon 70D or 80D. I agree with all he has to say about them. I really enjoy my Sigma.

I'll be taking my first day trip of the year tomorrow into Yellowstone. Hopefully I'll have some good pics to post when I get home tomorrow evening.