The Tamron lens that you are talking about (18-270) got a very poor review in Popular Photography, especially at the long end. The Canon lenses have an ultrasonic motor (USM). They focus a little faster than the lenses that do not have this motor. This has to do with the autofocus. I would check the lens reviews in Popular Photography and determine the lens that I buy by sharpness more so than how fast it focuses. If you are a sports photographer I would be concerned with this but think about this. What did photographers do when they had to focus manually? One thing that I have found is that the greater the difference between the long end of the lens and the short end, the more distortion you will see with this particular lens.

With lenses you usually get what you pay for. All I can tell you is that you normally don't see a great difference in lenses until you make some really big enlargements. When you look at Canon's "L" lenses you better be prepared to pay at least $1,000 on up. They are defenitely worth it but it depends if this amount of sharpness and quality build is worth it to you. The late Herbert Keppler, one of the editors for Popular Photography, said in one of his articles that the sharpness of the lens is dictated by your budget and what you are going to use the lens for. Many professional photographers do not use prime lenses or constant aperture zooms because of the expense of these lenses. If you are making $100,000 a year doing photography or just happen to have that kind of money to spend on good lenses, by all means, go for it. What Mr. Keppler said in his article was that most of the people you see using the high quality lenses have these lenses bought by the company that these photographers work for or they are very high end photographers making 6 figure incomes from their photography. He also said that you can do adequate work with mid range lenses with floating apertures such as 3.5, 4.5 apertures. The Canon kit lenses are adequate for most shooting situations. I have blown many 8 x 10's up from my 18-55 Canon lens and it was very sharp. Needless to say your view of a good print and mine might be totally different. Also there is software in programs such as Photoshop CS5 and Lightroom 3 that can sharpen images.

You can use a faster shutter speed or a tripod. Tripods, because of image stabilization, are not used as much as they should be. Also try shooting at a smaller F stop like F 11, or F 16. These will make your images a little sharper if they are in focus. Make sure your image stabilization is turned on. I keep mine on all the time. Don't shoot in automatic or program modes. On Canon the camera always chooses slow shutter speeds and wide open apertures such as 3.5 or 5.6. Good shooting!!

These are some beautiful images. That's a pretty little girl that is the model too. She seems to be having a lot of fun. Those are great photographs because they convey the fun she is having.

The ASA used to be the film speed but now that has been replaced with ISO which is the sensitivity to light of the sensor.

I think the 40mm 2.8 lens would be the best. I think the main concern would be the renditon of the colors and texture of the painting. The colors accuracy will be decided by the white balance set in the camera. This will be determined by the color temperature of the light which the pictures are being taken at. The best thing would be to shoot the pictures raw under available light with the camera on a tripod. This may sound a little complicated but if you take your time and process the pictures in a raw file you will be able to get some great images. See if you can find someone that will help you with the assignment. I would use the in camera meter and it will give you some good exposures.

I don't know but I think if you wrote to Popular Photography or go to them on line they will be able to tell you. I have seen them give other people similar answers.

I love the picture. Beautiful colors and good texture in the tree. What lens and what ISO did you shoot it at?

There is a article on this forum titled "A Tedious Explanation of F-stops" by Matthew Cole. I read it recently and learned a lot. He explains apertures and how F-stops are determined. He can explain this far better than I can. This is a must read for any new or old photographer. I knew how F-stops worked but had forgotten how they were determined. Please read this article several times and you will have a better grasp of what others have been saying on this forum. I say read this several times because it is fairly technical.

The numbers 9 and 13 are thirds of a stop. If you look in the numbers of your manual sometimes they will explain the stops in 1/3rds. They are 8, 9, 10, 11. Then you go to 11, 13, 14, and 16. I know this because I constantly set my exposure manually in 1/3rd of a stop. For critical exposure this is important.

If it was plenty bright go with the largest number F 16, 22 that you can at ISO 400 and see what shutter speed you get. Try to get at least 1/60th. The larger the number the smaller the aperture (F-stop). After you take the picture look on your LCD and blow the picture up so you can see how sharp the people in the back rows are.

Raw files have to be converted to do anything with them. If you are a Canon shooter they give you software called Digital Professional where you can convert your images into JPEGS once you have edited them. You can also do this in Lightroom, Photoshop, and other image editing programs. I cannot tell you the exact process because I rarely shoot in raw, although many professionals recommend shooting in RAW. I know you have to set your camera for Raw and then download it to your computer in one in one of the above mentioned programs.

I always erase the images from my card and then I reformat the card. I was told to do this when I first started doing digital about 7 years ago. If you just erase the images they are still on the card. I noticed that I used a card once to do a job that I had just erased the images and the images from another job came up on my computer screen. I download the images on the computer and burn a CD with the images on them. I always reformat the card in the camera.

Automatic focusing normally takes the closest object and focuses on that. I normally take the center focus point and let that be my focus point. You can go into your menu and there is normally a way to set your focus points. I set my focus point to the center point and then press the shutter button half way down and then recompose the shot. I have been doing this for about 20 years and it has always worked for me.

If the people in the first row were in focus I think that your problem was definitely the F stop that you used. The camera that you used, which is excellent by the way, has nothing to do with the depth of field. If you had people four rows back you should shoot at least at F 16 if at all possible. This will give you what you need. The next time you have a shot like that set your camera for AV or aperture value and let the camera decide the shutter speed. If it is below 1/60th of a second knock the ISO up to get at least F 16 at a 1/60. You should get an excellent shot. If it is bright daylight you should be able to shoot at ISO 400 and get the shot. Don't feel bad because we all had to learn. I've been in photography for over 50 years and I still have a lot to learn. Get a good book on photography or better yet take a course at a junior college and get some hands on instruction. Good Luck. Keep shooting!!!