Originally posted by kentishrev With my Pentax, I have the 18-55mm kit lens and the DA 50mm f1.8. I'm looking to build a full range and am considering (not all at once), the Sigma 10-20mm, the Pentax Limited 20-40mm, and the new Pentax WR 55-300mm. Eventually perhaps a Ltd 43mm also. I would be hoping at some time in the future to upgrade the K-30 body, but not for a while yet.
By my reckoning, this SHOULD give me all the coverage I might need, with the best glass in my favoured range. However, I recognise that the k-30 is not top of the range. Am I wasting money with the 20-40mm? Will I get the best out of it? Or should I stick to something cheaper?
Originally posted by Adam To answer your question, no, a lens can't be too good really. The best L lens on a Canon Rebel will beat the crap out of a 1D with a 28-300mm, just to give one example.
The 20-40mm will give you better image quality than the 18-55mm, but so would something like a Sigma 17-70mm, which I highly recommend.
To answer your fundamental question, it's as Adam said: NO, you're not wasting your money by getting top quality lenses on an entry-level body - especially with Pentax, which has the best entry-level cameras around.
I must have spent 5 to 10 times the price of a K-30 in lenses for my K-x. I finally upgraded to a K-5 and got little benefit in increased IQ. Top quality lenses were not only a good use of money, they're the main factor that made me enjoy my photography (and get better results).
I agree with Adam's statement that the DA20-40 might not be the best way to spend that money. I would instead look at a DA*16-50, or even an FA20-35 (both of which I have/had). The DA16-45 could also be a realistic choice. If you do go with the Sigma 17-70, I believe the latest version is the best one.
And I don't think the Sigma 10-20 (either version) is all that good. You'd be better off with the aforementioned DA*16-50/2.8, then adding a Sigma 8-16 later if you want to go really wide (or cross your fingers that the upcoming Samyang 10/2.8 will turn out good). The Sigma 8-16 is much stronger from 10 to 16mm than any 10-20ish lens I can think of.
Originally posted by Dice Look at images....at full size....find the flaws and determine whether they will inhibit your photography.
Absolutely - in the end, make sure you look at images from the lenses after (or even before) getting other's opinions. We mainly give you ideas on what to look at.
My favorite sources for Pentax images are:
PENTAX : Select a PENTAX interchangeable lens camera or a lens model Full-size sample photos from Pentax 16-45mm F/4 Pentax smc P-FA 20-35mm f/4 AL Lens Sample Photos and Specifications
Finally, would you mind sharing what Nikon lenses you had (and what body)? I'm guessing that you didn't have some of the better longer lenses, like the 85/1.8G or a 105. I think if you get a DA*50-135 or FA77 you'll change your mind about staying within the 20-40mm range.
At this point my recommendation would actually be to get a DA*50-135 and a DA16-45. The reason is the DA*50-135 is a standout choice in its range, whereas there are many more options (all of which are compromises) in the 16-50mm range. The DA16-45 is very good at a reasonable price. Then take some time and evaluate your options for other lenses like the Sigma 8-16, FA*24, DA35/2.4, and DA*16-50.