Sounds like what you have heard above is good advice. I would go for both the 40mm and the 50mm. They both have their own uses ans you will soon see. For example, the Slit canyons in Arizona require a 40mm, though you will brain yourself if you go with a 50mm. I went with a 38mm and was quite pleased. Use Trix as long as you can get it. For all your work, please. It is simply the best, I used it at Monument Valley and it was perfect. 'Nuff said