Just want to share with you my Canon choices.
A few years ago I got the Canon 5D and it is a lovely camera, full frame yeah. My first lens was a 50mm f/1.4
I'm interested in railway photography and wide angle is the best there where you can take photos on railway platforms and things are cramped. So I got the 24-70mm f/2.8L after perusing the Fred Miranda forums. I did consider the 28-300 f/3.5-5.6L but decided that it was too heavy. (and expensive)
For the 24-70mm f/2.8L I bought the Tamrac 5629 bag which enables me to carry the camera with lens attached for my train trips. I call it the snoot bag.
After a a while I began to photograph other than railway stuff so I got the 70-300mm f/4.5-5.6 DO IS. Therefore I'd cover the 28-300 f/3.5-5.6L range with two lenses. (how does the cost compare?) I'm unlikely to need both on the one day. Took it to the Melbourne Showgrounds and took photos of the stunt motorbikes. Was wonderful stuff. It also fitted in the snoot bag.
After some thought and excitement at the start of 2009, I bought the 5D Mk II. The reasons were the Highlight Tone Priority and the self cleaning feature. There are numerous other improvements which I won't go into here.
I do like the auto ISO.
I don't know about the highlight tone priority feature. It's benefits are subtle. It prevents blowouts. One of my problems is photographing railway stations in bright daylight and I lose detail under the platform verandah. If I over expose by 1.5 f-stops, it may be over exposed. I haven't actually experimented with this feature. What I can also do is bracket them and HDR merge in Photoshop.
I didn't buy it for the live view or the movie feature. It is icing on the cake though.
I didn't get rid of the old 5D as it would have only got me $300 with the leasing arrangement I had. (leasing arrangements cost too much, don't do it unless you are a pro)
So I now have 2 5Ds, with full frame. Therefore there is no crop factor with all my lenses.
I still use the old 5D, sometimes I take it to work and use it after work, when I go on tram rides or train trips during daylight saving.
I pondered getting the 50mm f/1.2. The FM forums give it a mixed reviews but I think some of them don't understand that it has a very narrow DoF and AF doesn't work very well in low light and they blame the lens for back focus and related issues.
I also have two lenses which cover 50mm and I wonder if I would notice the difference in the photo later? One review I read said that there is a difference between the 50mm 1.4 and the 1.2. Not sure if he difference is discernible to me.
I do notice that when I'm photographing station buildings and old towns etc with the 28-70, I find myself at 50mm for more than half of the time. I marked it as low priority and eventually bought a 400mm 5.6L.
The 400mm 5.6L finally arrived last week after waiting two weeks. It was in Sydney but it took two weeks, I don't know what logistic issues they had?
I'm doing some bird photography with the 70-300mm f/4.5-5.6 DO IS at the 300mm end and the birds come out well with the cropping.
The 400mm 5.6 is said to be the best in birding as it can be hand held, best for birds in flight and has a good price and weight compared to the 400mm f/2.8 and the DO.
Still, I don't know how I'll go with the bird stuff as I'm just photographing anything that flies including aircraft near the park. I wonder if it's just an excuse to buy a telephoto lens, time will tell.
I'm also walking around for hours which is only good for a fat bastard like me.
The 400mm f/5.6 got good reviews in the FM forums and also in the bird photo forums.
Although I found a US bird forum where people buy 500mm or 400 2.8 and end up using the 400mm 5.6 or they bandy 400mms, 500mms and 600s as if money was no object.
Anyway, I'm quite happy with the bird photos so far but have been pondering things.
After last week's effort with the 300mm on auto settings, I decided to up the shutter speed to 1/1000s on the 400mm however this bumps up the ISO from 1600 to 2000 when photographing birds in foliage, this makes the photos look grainy when I enlarge to actual size. I like to freeze wing motion although some people prefer some artistic blur. My efforts last week had birds fly with no wings due to motion blur. Also birds against the sky are silhouettes. The 5DMkII has some custom positions on it's dial where 1.5 f-stop exposure compensation can be stored. However this setting will blow out foliage shots. I'm learning reflexes to capture birds in flight. The birding forums call this BIF.
The bokeh is nice with bright coloured lorikeets showing up in focus the middle of out of focus foliage. I'm happy, but I don't think it will win any awards. I'm just starting out. Seeing examples in the bird forums is interesting. Also interesting to note that I have mostly the same gear they have so I have no excuse. Great to see what's possible.
Anyway thanks for reading this wall of text, since I got my cameras I'm trying to photograph something every weekend and it gets me out and walking around (fat bastard). So I'm photographing railway interests, old towns scenery and more recently birds.