i dont pride myself in being blunt. i just realize that since photoj is taking some time off the board someone's gotta take his place being the guy telling people what's up.
the photos really are nice, however the models look waaayy too smooth.
, well giving constructive criticism doesn't have to be blunt. But it's good to see that you're trying your hand at it and justifying your thoughts. I still keep an eye out on the forum, but I'm avoiding involvement in many threads. Let's say I'm here on a selective basis from time-to-time.
Returning to the matter in hand:
Positives - well, they're all smiling.
Maybe it's a stylistic thing or a problem with your monitor, but these photos are incredibly vibrant and saturated - too much for my liking. That aside, the lighting (though natural) is not dynamic; they're all flatly lit subjects. The DoF is suspect (and correct me if I'm wrong) but I see traces of handiwork with the gaussian blur in #2 and 4.
General comments aside, here's detailed feedback:
#1 - Lacks contrast and is cropped too tight on the right. Having one shoulder cropped is fine, but on both sides, no. Less a stylistic thing, more erroneous composition. The contrast is lacking down to a combination of flat lighting and the overly vibrant colours. You can barely tell the background from the subject with the relatively broad DoF. A hairlight or backlight might have helped - I'd like to have seen this with some cross-lighting. The problem isn't with the model who holds a fair pose.
#2 - Colour. Green and blue... Need I say more? Colour clashing works n some cases, and in others it's just distracting. I feel it's the latter here. Apparently better DoF control than in #1, but I see suggestions that it might not be natural. If it happens to be natural DoF, then maybe you ought to have considered an even shallower one to lessen the immediate colour clash with a softer background. Lighting, as mentioned on the whole, is flat. A strobe with a snoot/grid for a hairlight might just have added a bit of dynamism and separation - failing that a reflector might just squeeze the same effect, but in the shade as you are, that wouldn't have been an option. Model's pose just about passes muster, but I'm unsure of that left hand of hers.
#3 - It's not the background that's distracting in this one, but it's the prop. It's not the most pretty of props and is quite ill-fitting in light of the wardrobe. If you were still going to go ahead with the umbrella, get the model to push it far behind her shoulder so that it's not resting right behind her head. It's too close to her so it'll be retained in the DoF you choose (as you're going to get her head in focus and sharp). Pushing it back will also allow a little more light under the umbrella. You've compensated (quite rightly) with fill-flash. However it's not powerful enough and the face is still lacking light relative to the rest of her in the frame. The close proximity of the umbrella to her head also casts the shadow of the hotshoe flash, which can be seen drifting to the model's left because of the portrait orientation. Remedy? As I've said, move the umbrella further back in relation to the model, or get rid of it entirely. I'd have gone for the latter. I won't say anything particular about composition as it's going to be repetition to the above with cropping on both sides...also a bit central for my liking.
#4 - Colour matched to the background, which really poses a question on how to get the best dynamism possible. You won't get that with the lighting you have, and it's not a simple case of more fill light. The light hits her shoulder first and you're lucky that the highlights there are minimal. That really makes the shoulder more a focal point that the face because of the contrast with the darker background right behind that part of her anatomy. There's also a shadow under her chin. The simple solution would be to get the model to handhold a reflector with her free right hand out of frame to lift that shadow and some harshness from the poor positioning in relation to the sun. A hairlight (again) would have added some interest and separation. Composition is too central and here I'd have rather wanted to see you frame it with more space on the model's left and her distractly bright shoulder partly cropped out of frame. Then she'd be off centre and the composition would be stronger.
The pose is the least natural of the 4 with the most forced smile.
Obviously these are my opinions, but I think they're closer to the truth than: "Excellent work! The photos look well composed and exposed. "
I guess thanks are in order for sharing your images.