DSLR's - Rethinking the ISO question

[MrPogo]

I think I'll have to be getting myself a new lens then. I'm just not sure whether I'd be best to go for the Nikon 50mm 1.8 or 1.4 (I have a D50) and live with the lack of zoom/wideangle when shooting, or try for a 2.8mm zoom in the 18-50mm sort of range...

JimC wrote:

MrPogo wrote:

f/2.8 is exactly twice as bright as f/4, allowing shutter speeds twice as fast for the same lighting and ISO speed.

[TDN]

schatham wrote:

My question still is - how do you tell a fast lens from a not-so-fast one (without relying on the guy trying to sell you one)?

SC

The f-number on the lens specifies that.

The f-number actually represents the maximum aperture of you lens. The bigger the aperture, the more light can come trough the lens.
The smaller the f-number, the bigger the aperture.

Anything from f2.8 and lower f-numbers is considered "fast".

On zooms the f-number is noted differently, for example f2.8-4
That means at the wide end of the zoom the max aperture is 2.8, at the tele end it'll be 4.

an f2.8 lens is more than 1 full "stop" faster than an f4 lens, which means that it will let more than twice as much light in. (1 "stop" doubles the exposure)


I hope this made sense to you

TDN

[steve]

bernabeu wrote:

KM 7D with IS on

28-100mm 'kit' lens @ 100mm

ISO-400, spot metered

1/60 sec, f5.6

Damn, is Rod still alive :lol:

[schatham]

Is there a good website (or other source of reviews such as the camera ones here) for lenses?

Also, regarding online purchases of cameras - any ones to stay away from (or otherwise recommend)? I'm a little reluctant to drop over $1000 via an online site instead of a local store.

[kenbalbari]

I've been using these sites for researcing lens reviews and surveys. Don't miss the user performance surveys at the bottom on the photozone page. I find it's very useful when a lens has been rated by a couple dozen users or more.

http://www.slrgear.com/reviews/index.php

http://www.photozone.de/8Reviews/index.html

[JimC]

The best place for mtf charts is http://old.photodo.com (on the downside, a lot of newer lenses are not included).

The site was recently purchased and the new site is at http://www.photodo.com

As already mentioned, you can also go to http://www.photozone.de. I use it mostly for user opinions (go to the "User Performance Surveys" section, select a Lens category and browse the database to see opinions).

Make sure to visit the camera specfic lens forums here, too. You'll find lots of tips about low light shooting. But, the answer is relatively simple. :-)

Buy a good f/2.8 zoom (one that can maintain f/2.8 throughout it's focal range) if you want to try to get by using f/2.8 (I prefer brighter primes for most low light use).

In addition to the camera manufacturer's zoom lenses, look at lenses like these for concerts where you're close enough to use them and light is bright enough to get by with an f/2.8 zoom (these are probably the most popular third party f/2.8 "standard" zooms): Sigma 18-50mm f/2.8, Sigma 24-70mm f/2.8, Tamron 28-75mm f/2.8 (and there are more).

If you're on a tight budget, check out the older Tamron SP 35-105mm f/2.8 on the used market. It's not as wide as some of the newer zooms, but it's good on it's long end (it's a sharper lens compared to the newer Tamron 28-105mm f/2.8 ), and it's often available at bargain basement prices used.

In a longer lens capable of maintaining f/2.8 throughout it's focal range, the best third party lens is the Sigma 70-200mm f/2.8 EX DG APO Macro (and the older non-DG, non-Macro versions can be good, too). EX lenses are Sigma's best.

http://www.sigmaphoto.com/lenses/len...mp;navigator=3

The camera manufacturers also have f/2.8 lenses in this focal range (they're all over $1,000 and this Sigma f/2.8 zooms in this focal range usually run around $800-900 at reputable online vendors like http://www.bhphotovideo.com ).

But, if light is very low, your best bet is a prime (non zoom). Even if light is good enough for f/2.8 (the best you can do in a zoom for most models), a prime with wider available apertures (f/1.4, f/1.8, f/2) are going to be sharper if stopped down to f/2.8 compared to an f/2.8 zoom shooting wide open.

You'd also have even larger apertures (smaller f/stop numbers) available if you really needed it using a brighter prime. In primes, I'd do this for a DSLR with an APS-C size sensor:

Sigma 30mm f/1.4 EX DC (only works on a DSLR with a sensor smaller than 35mm film) or Camera Manufacturer's 28mm or 35mm lens (f2 or brighter f/1.4)

and Camera Manufacturer's 50mm f/1.8, f/1.7 or brighter f/1.4

and Camera Manufacture's 85mm or 100mm f/2, 1/1.8, f/1.4

Even Longer Prime (135mm, 200mm, 300mm) if needed

[schatham]

Jim (and everyone) thank you for the replies.

I had looked at the 30D Canon (as well as the new XTI). They are offering a kit lens & a zoom lens at a pretty decent price.

I'm thinking the lens would be too "slow" to do low-light photography.

http://www.usa.canon.com/consumer/co...;modelid=11922

In case the link doesn't work, it's a 75-300mm zoom lens. The description is: "EF 70-300mm f/4-5.6 IS USM

Telephoto Zoom Lens


Item Code: 0345B002


The EF 70-300mm f/4-5.6 IS USM telephoto zoom lens has been developed to meet the high-performance standards that today's photographers demand. Improved Image Stabilizer Technology provides up to three stops of "shake" correction, and the "Mode 2" option stabilizes images while panning with a moving subject. Compared to the original Canon EF 75-300mm IS zoom lens, this telephoto lens has faster autofocus, and overall the lens is lighter and has a smaller diameter than the original. The zoom ring can be locked at the 70mm position, making this powerful lens easy to transport, too. "

Opinions?

What is the general concensus of Canon lenses? Some of the folks I know who use Canon cameras (not DSLR's) generally like them.

[JimC]

It's not suitable for low light photos of non-stationary subjects without a flash. You'll want a brighter lens.

In a zoom, you'll want f/2.8 available throughout the focal range.

But, a brighter (f/2, f/1.8, f/1.4) prime ( fixed focal length) lens is better when light gets low.

I'd get a 50mm f/1.8 AF lens for starters (around $100 new).

[MrPogo]

That's what should be arriving in the post tomorrow for me (albeit the Nikon version, for my D50).

JimC wrote:

I'd get a 50mm f/1.8 AF lens for starters (around $100 new).