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rogerj
01-25-2005, 01:51 PM
I am considering buying a Sigma 28-105 (f2.8-4) as my basic lens. I plan to use it inside with dim light from time to time. Is this lens suitable for this. I would expect that the f2.8 would be good for this. Am I correct? Has anyone had any experience with this lens?

eagle17
01-26-2005, 11:02 AM
I do not have any experiance with that lens but I bet you would get better results from something like the 24-70 macro f2.8 ex lens from sigma... I was looking at this lens but It was not really wide enough for me.

jamison55
01-27-2005, 03:16 AM
I can highly recommend the Tamron 28-75 2.8. It is SHARP all the way through it's range (even wide open). Before you buy any lens check out the reviews at: http://www.fredmiranda.com/reviews

ktixx
01-29-2005, 12:19 AM
I have the 20D and I have the Sigma 18-125. The lens is excellent and because it is a lense made for digital cameras the crop factor is already built into the lense, therefore you actually get 18-125. I have not had a lot of time to use the lens, but from what I can tell it is a great all around lens. I know a few people who peruse this forum have the lense and they swear by it as their walk around lens. I am sure there are lenses (such as primes and L's ) which will be much better for shooting low light shots, however for the price and the flexibility this lens offers I consider it worthwile to own.
Ken

D70FAN
01-29-2005, 06:51 AM
I have the 20D and I have the Sigma 18-125. The lens is excellent and because it is a lense made for digital cameras the crop factor is already built into the lense, therefore you actually get 18-125. I have not had a lot of time to use the lens, but from what I can tell it is a great all around lens. I know a few people who peruse this forum have the lense and they swear by it as their walk around lens. I am sure there are lenses (such as primes and L's ) which will be much better for shooting low light shots, however for the price and the flexibility this lens offers I consider it worthwile to own.
Ken

Ktixx, sorry but this is not the case. Even lenses made specifically for dSLRs must use the crop factor.

ktixx
01-31-2005, 02:46 PM
Ktixx, sorry but this is not the case. Even lenses made specifically for dSLRs must use the crop factor.

Forgive me for the incorrect information I am still in the learning process. :) I have had a couple of questions about this specific topic (which I posted on different thread) but maybe someone here can answer it for me. If I were looking through the viewfinder of my 20d and had a 100mm lens attached would I see (through the viewfinder) as if a 160mm lens were attached? To my understanding I would not because the "crop factor" is attributed to the fact that the CMOS is too small and only part of the image is captured. The reson why I thought the DC lenses were "immune" to the crop is because I took a picture and mentally marked the edges of the objects I was photographing (specifcally a can of soda). I aligned the edge of the soda can with the edge of my viewfinder. When I looked at the images on my computer the edge of the soda can wasn't cropped out of the picture. Can anyone give me some insight on this topic?
Thank you for all your help
Ken

pmnapier
01-31-2005, 07:56 PM
If I were looking through the viewfinder of my 20d and had a 100mm lens attached would I see (through the viewfinder) as if a 160mm lens were attached?
I believe the answer is yes. The viewfinder will show the image as if you were looking through a 160mm. Can you imagine the difficulty if the photographer had to mentally (visually) figure in the 1.5 or 1.6 factor to determine what area of the viewfinder frame would be cropped? If you want that soda can at the edge of the image in the viewfinder, it should be there on the final recorded image. That's why most people put such a premium on viewfinder accuracy.

D70FAN
02-01-2005, 09:06 AM
Forgive me for the incorrect information I am still in the learning process. :) I have had a couple of questions about this specific topic (which I posted on different thread) but maybe someone here can answer it for me. If I were looking through the viewfinder of my 20d and had a 100mm lens attached would I see (through the viewfinder) as if a 160mm lens were attached? To my understanding I would not because the "crop factor" is attributed to the fact that the CMOS is too small and only part of the image is captured. The reson why I thought the DC lenses were "immune" to the crop is because I took a picture and mentally marked the edges of the objects I was photographing (specifcally a can of soda). I aligned the edge of the soda can with the edge of my viewfinder. When I looked at the images on my computer the edge of the soda can wasn't cropped out of the picture. Can anyone give me some insight on this topic?
Thank you for all your help
Ken

Not a problem, and a frequent misunderstanding generally perpetuated by people selling cameras who don't know this either.

The error you see between the viewfinder and the final image is because the viewfinders on most cameras (dSLR or otherwise) only show 92% to 97% of the final image. My D70 shows 95%, and most others are about the same.

Sometime ago I read an artical on why this is, but can't remember the story, and honestly don't care. If I get unwanted objects on the periphery I just crop them out in Photoshop. Not a big deal. ;) With film it's a different story.