ugh I hate to ask... new lense or 30d

ok, I have a 10d thats like new, im very happy with it, but i have a decision to make... when i get paid form my magazine, im going to either buy a 50-1.8 and a 85 1.8 or .... maybe sell the 10d and add that cash i get to get a 30d. my main concern is better low light shots.

i shot today indoors with a 17-40 f4 @ 1600... im pretty happy with the shutter speeds at around 1/125 sec, but they have a lil more noise than i care for and i dont like running it thru neat image as i cant keep the dirt detailed and looks fake.

so what would improve these shots more? 1.8 glass and lower iso on the 10d
or i really like the 17-40 inside, but maybe on a 30d with better iso..???

I vote for the 30D...

Or pick up a used 20D, same low light performance as the 30D, and get one of the lenses for the money saved.
The 20D comes cheap these days.

I would go for the 30d for better low light noise performance.

You could also give the 30D a few more months to depreciate a little more...

I say the 1.8 It'll make much more of a difference, get a used 50mm f1.8 and if you don't like it, sell it for what you brought it for.

im getting the fiddy either way, if i can find one before it sold lol...

ok maybe help me with the "stop" math...
those were taken 1/125 @ 1600.. with f4
if i dropped to 1.8 and kept the 1/125 ss, could i use iso 800? or maybe even 800 and a lil faster shutter?

is 800 to 1600 "1 stop"?

hmmm the more i think about it, a 30d and a nifty, should suffice, id love a 85 1.8 but for all intensive purposes the 50 should be fine...

gravy graffix wrote in post #4165178
im getting the fiddy either way, if i can find one before it sold lol...

ok maybe help me with the "stop" math...
those were taken 1/125 @ 1600.. with f4
if i dropped to 1.8 and kept the 1/125 ss, could i use iso 800? or maybe even 800 and a lil faster shutter?

is 800 to 1600 "1 stop"?

f/2 is 2 stops faster than f/4. So, you could drop to ISO 400, and shot at 1/160th. (f/1.8 is 2 1/3 stops faster than f/4)

gravy graffix wrote in post #4165178
ok maybe help me with the "stop" math...
those were taken 1/125 @ 1600.. with f4
if i dropped to 1.8 and kept the 1/125 ss, could i use iso 800? or maybe even 800 and a lil faster shutter?
is 800 to 1600 "1 stop"?

Here's how it works: one stop difference is twice (or 1/2) the amount of light.

If you're changing shutter speeds or ISOs, the relationship is linear: from 800 to 1600 is one stop, or twice the light sensitivity. From 1/250 to 1/500 second is one stop, or half the light.

The amount of light coming through the lens depends on the area of the lens opening. Twice the area = twice the light = one stop.

But the area changes as the square of the diameter, and the f stop is a measure of diameter. This means that light varies as the square of the f stop number.

So changing from f/4 to f/2 is two stops, and to f/1.8 is another half stop.

F stop numbers go like this:
1, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22

Notice that each step is 1.414 times the previous one (the square root of 2) so the change in light from one stop to the next one is 2.

HTH.

-js

Number six,

Thanks for putting that in a post. It give a handy way of pasting that definition into a note that I can remind myself of and to email to others!

Tony

I shoot fast moving things in low light. I've been using a 30D for about a year(10D before that), and got a 40D when they first came out. The difference is quite pronounced in the 40's ability to use servo focus and have very low noise at Hi ISO. I'd go for a 40D over the 30D for those reasons if you're really looking for high ISO, high frames per second, and great servo focus performance. If you can't afford one at this time, get the 85 1.8 lens and you'll see a big improvement from that too. Save up and get the 40D later, it is well worth if for the performance you get over the 30D based on my experience with both.

man your killing me with the 40d... i do want one for all the reasons mentions, but 800 on top of my 10d is a streatch... i did just find a 50. 1.8 so... look like ill be on a mission to up grade bodies...

pm me what you want for that 20d... and ill think about it.

Don't forget to consider an XTi.