I'm weighing options in a new camera. I've been using a Canon 400D (Xti) for years, but there have been so many advances that I think it's worth upgrading. A 550D (T3i) runs around $700. The 5D MkII is around $2500. I wouldn't pay the extra $ for a 70D compared to a 550D - there aren't any functions that I need on a 70D that aren't available on the 550D (I shoot almost exclusively in manual mode, occasionally in Av). If I go with a small sensor camera, I would just go with that 550.

The ?'s I  have are about the IQ difference between the 5D mkII and the 550D - 21mp on a 1x1.5" sensor vs. 18mp on a 22.3x14.9mm size sensor. I'm unsatisfied with the noise levels on my 400D. Most of my stock photography is done with strobe lights, but even with good exposures and ISO 100, there is a bit of noise in the shadows. I would also enjoy a larger file size and the ability to shoot outdoors with a higher ISO. I don't feel like I can shoot any stock on a higher ISO than 100 with my current camera.

Opinions on the IQ on the 5D vs. 550D (or cameras with same sensors) as related to microstock? Would the 550D be able to produce good quality files on any ISO's higher than 100 without having to use noise-reducing editing software? More editing means more time, which means less money / What is the highest ISO you've been able to use without getting problematic noise (without post processing or using multiple exposure techniques) on cameras with these two sized sensors?

Either camera will be a significant improvement over my current 400D, according to tests I've seen on review sites. But I wanted to get your views based on real-world experiences shooting stock.

So my main questions are how much quality improvement will I see with a 5D over a 550D, and how much faster of an ISO can I shoot with on the two cameras? Of course I would have to change a few lenses if I move up to the larger sensor size, but that isn't a real big concern for me.

If I'm lucky, a 5D mkIII will show up before I make a purchase - I'll probably be making a purchase in 2-4 months.

thanks in advance for your advice!!!

_Craig

Thanks for the words, tubed. I am thinking the same. I grew up on film, and always owned a Hasselblad, Mamiya, or Sinar - it's been difficult going from that aesthetic to the teensy-tiny viewfinder in these DSLR's. That is one of the reasons I want a new camera - I find it much nicer to compose images with the live-view on the display than through a itty bitty viewfinder. I've been a professional photographer for years, but have avoided putting the money into a real digital camera because of the resell factor. DSLR's just haven't seemed like lasting investments until recently. But I am beginning to realize that a few grand is a small investment compared to the time I spend cleaning up files. Probably should go ahead and bite the bullet - but still would love to hear more input.

if you are after viewfinder go the 5d (or sony a850/a900 - that's a brilliant viewfinder - but would be a whole system change to a system that may totally EVF from now on).

what do you shoot, primarily?

Well, I am an artist primarily - I have two sets of work that I focus on: social landscapes and abstract nudes (studio). But I pay the bills by shooting commercial stuff, mostly product, some editorial, a few portraits, and an occasional architectural gig. I am hoping to get away from shooting assignments and just concentrate on stock photography. The stock photography I do is almost all tabletop stuff - objects on white backgrounds w/strobes, etc., but I also like to break the monotony of that studio work and get out to photograph people, textures, or anything I come across that seems worthy. I would say that 80% of my stock work is tabletop in the studio and 20% is random out in the world stuff, if that makes any sense.

Ideally I would have something like a Hasselblad H4D, but that will have to wait until I get a lot more capital together. I took a big hit last summer and had to leave Phoenix AZ, where my studio and gallery were - now I'm back in SC living with family and shooting in an extra room that is half storage and about 50 sq ft for my "studio". I've yet to work on setting up any gigs here - I want to focus on building up my stock portfolio, which I haven't done anything with in almost 2 years.

The nice thing about it is that I'm really free right now to do whatever I want - I don't have much income, but don't have many bills either. I'm basically starting over. I want to be smart about it though. I'm lucky that I have a big collection of nice lenses, and all the studio gear I need. I just need a better camera and some more space. I am going to part with a couple/few lenses to get the $ for a camera. If I could get away with just using the 550D for now, it would make it easier - but if the 5D mkII will save me the ~$1900 difference in hours of work, fewer rejections, and better sales (I haven't looked, but I'm guessing that the 21mp file can sell at a larger size than the 18mp file) in the space of 1-2 years, then it makes financial sense to go ahead and get the right gear.

So it's the image quality that matters to you, not fps and focus accuracy. Therefore you won't be needing 7D (as you figured that on your own).
Well, IQ wise the only good choice you can make is the 5D2. The difference in image detail, contrast and tonal range it's huge compared to any APS-C sensor. Also, for high ISO work - I have shots at iso 2500 (maybe 3200 too?) accepted and selling on stock from my 5D2. It's all about correctly exposing the scene.
Also, for portraiture - 5D2 is the perfect tool in this price range of $3000 and below. Full frame sensor will give you shallower DOF as well if this matters to you - I frequently shoot at f/1.4 - f/2.8 outdoor and love the effect.
The only reason you would want an APS-C is when you're shooting sports, action or wildlife and you'll get better off with a 7D.

I ended up buying the 5DMKII and the 550D.  The 5DMKII is great but it's heavy to carry around all day.  I get dust spots on the sensor, so I can't really use it for video unless I keep cleaning it.  The 550D is a big improvement over the 400D.  Nose is well controlled at 100iso.  Get the exposure right at up to 400iso and you only need to use a bit of noise reduction in areas like blue sky.  The 5DMKII is superior for stills but I think the lens is the most important thing.  You really need the Canon "L" lenses or their equivalent.

I have ended up using the 550D most of the time and I use the 5DMKII mostly when I'm doing studio photos.  Either camera is great for stock photography, as long as you buy the right lenses.  I use the Canon EF 17-40 mm f/4.0 L most of the time, it cost almost as much as the 550D but it's worth it.

There's a 600D out now with an articulating screen, that's useful, especially for video.

This is great news since I have a fair amount invested in Canon glass.

I meant the T2i - there's no reason for me to pay more for the T3i, in relation to what I use a camera for, if I go that route.

But I'm pretty sure that I'm going to wait a little while and see what the 5D MKIII looks like. I'll either buy that or the MKII after the III comes out, depending on prices. Thanks for all the valuable input!