I know lens-buying advice threads are all over the place, but this is different, I swear! Okay, so, before two weeks ago, my general-purpose lenses were an 18-55 mm f/3.5-5.6 (Canon) and 70-300 mm f/4.0-5.6 (Quantaray). I just got a 35 mm f/1.4L prime that I can use for people (see next paragraph) and my wide-field astrophotography. I also have a 600-1000 mm but that's special-purpose for lunar and solar photography. I have almost certainly just been hired to do some model work that should give me a fair amount of "playing around" money, and every-other $1k I get I'd like to put back into a new lens since this is not my day job. But, I can claim them as tax-deductible (at least the 35 mm and the wider zoom below) since they'll be used a lot for the model shooting (don't worry, I won't claim them as used for it 100%, I'll be fair and legal ). I've been doing some research and I would like to, over the next 1-2 years, purchase the following lenses (in no particular order): - Sigma Zoom 12-24 mm f/4.5-5.6. - Canon Zoom 24-70 mm f/2.8L (USM). - Canon Zoom 70-200 mm f/2.8L (USM). - Canon Normal 50 mm f/1.4 (USM) prime. Why? First, I don't want an EF-S lens because I plan on upgrading bodies in a few years to a more full-frame sensor. Specific to the lenses above, in order: - I do landscapes a lot and find that 18 mm is not wide enough in many cases, and I'd really like a true very wide-angle lens so I'm not always doing panoramae. - I want to replace my 18-55 mm kit lens with a high-quality lens that gives me a range up to the next lens. - I want to replace my crappy Quantaray lens with a good Canon and I don't think the 200-300 mm range gives me anything too important that I can't get just by cropping (I think it's around 30% less field of view on the APS-C sensors). And that's not worth sacrificing the f/2.8L for a f/4.0-5.6 to get the extra 100 mm. Especially in an astrophotography context, that's a difference of 4x in speed at the long end. - Not completely certain on this one, I'll really have to see how close I need to get to the models with the 35 mm to decide whether or not I actually want a 50 mm prime. So, that in mind, I'm torn on the order in which to buy these lenses. I believe I want the 24-70 and 70-200 "first," the 12-24 third, and still not sure on the 50 mm. I just don't know which one will be first and which second. I also realize that I'll need to buy new 77 mm filters which will be fairly expensive (since I want an IR filter in there), so that might actually count as my second "lens" purchase and I'd hold off on getting the second lens for the third round of cash. So the lenses in first and second place will be general-purpose and replacements for what I currently have. The 24-70 I could use for the model shoots. But the 70-200 I could use in astrophotography to try to snap some smaller but fairly large objects (like the Andromeda Galaxy or the constellation Dolphinus). And, I'm going to Hawaii in November and I'm pretty sure I'll have one of these lenses but not both at that time, so I'm not sure which will be better. Okay, if you're still reading, congratulations! You get a prize: You get to tell me your advice. I'd really like this not to come down to a coin toss between the two, so please let me know what you think.