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Old Mar 25, 2008, 2:46 PM   #11
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JimC wrote: Yep, some zooms like the Sigma 100-300mm f/4 are pretty sharp.

But, going back to my original point. You can't get zooms as bright as you can primes in some focal lengths.

Therefore, you can't beat them for sharpness at an aperture the zoom lens doesn't have available. ;-)

If you use a dimmer zoom, you're going to get softer photos in some lighting due to motion blur or blur from camera shake, versus a prime with a wider available aperture.

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Old Mar 25, 2008, 2:58 PM   #12
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JimC wrote:
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But, going back to my original point. You can't get zooms as bright as you can primes in some focal lengths.

Therefore, you can't beat them for sharpness at an aperture the zoom lens doesn't have available. ;-)

If you use a dimmer zoom, you're going to get softer photos in some lighting due to motion blur or blur from camera shake, versus a prime with a wider available aperture.
True for the Nikon...

But have you checked the Canon 50mm f/1.4 and f/1.8? They are not particularly sharp at theses apertures to start with! :-)
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Old Mar 25, 2008, 3:07 PM   #13
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You don't have f/1.4 (4 times as bright as f/2.8 ), or f/1.8 (approximately 2.6 times as bright as f/2.8 ) if you're using a zoom lens. So, you're going to get slower shutter speeds for any given ISO speed in low light, which can make for blurry photos and/or noisy photos due to needing higher ISO speeds.

Also, you can always set the prime to a smaller aperture (higher f/stop number) for sharper images if lighting permits. For example, set the prime to f/2 or f/2.5 (or even the same as the zoom at f/2.8 in better lighting indoors).

With the zoom, if lighting is too low, you don't have the option of going with wider apertures than f/2.8 to prevent blur from subject movement or camera shake (with the exception of the Olympus 35-100mm f/2.0, which I doubt is sharper than these primes at f/2). The other f/2 zoom Olympus has been talking about for about 3 years now isn't shipping yet AFAIK.


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Old Mar 25, 2008, 3:29 PM   #14
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NHL wrote:
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But have you checked the Canon 50mm f/1.4 and f/1.8? They are not particularly sharp at theses apertures to start with! :-)
But what zoom compares to the 50mm 1.2L or the 35mm L?

You have to do apples to apples. You want to use possibly sigma's best lens to argue one side of the argument but ignore Canon's best primes like the above or the 300mm 2.8, 400mm 2.8 or even 135 2.0
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Old Mar 25, 2008, 3:46 PM   #15
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Or, use my first example (Canon 200mm f/1.8L). You can't get any lens sharper than this one at the same apertures, zoom or prime.

It grades at a 4.8 on photodo's scale that only goes to 5 for it's MTF tests. No other lens even comes close.

Check out it's MTF chart at http://old.photodo.com/nav/prodindex.html

Of course, no zoom even has f/1.8 available. You'd have to use f/2.8 with zooms, requiring much slower shutter speeds for any given lighting and ISO speed.

JimC wrote:
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Or, take a lens like the Canon 200mm f/1.8L. You can't get zooms that bright, and you can't get any lens that's sharper at 200mm (most lenses are not even close).
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Old Mar 25, 2008, 3:56 PM   #16
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JimC wrote:
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Or, take a lens like the Canon 200mm f/1.8L. You can't get zooms that bright, and you can't get any lens that's sharper at 200mm (most lenses are not even close).
And, of course, it isn't just about sharpness and shutter speed. Bokeh is very much an important part for many photographers. And sometimes you can't back up to use a longer focal length at a narrower aperture - assuming of course the zoom has a comparable blade design to even create similar quality bokeh at a further distance from your subject.


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Old Mar 25, 2008, 4:06 PM   #17
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JimC wrote:
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Yes, zooms are improving in quality. But, compared to better primes, they're not quite there yet, from a sharpness, contrast, and bokeh perspective, using the same focal lengths and apertures.
Yep. Bokeh is very important. I mentioned it in my first post to this thread.

For example, try doing this at a 100mm focal length using a larger subject with this framing using a zoom lens.

The background contained ugly concrete, including a building. That background would have ruined the image (at least compared to this one) if it would have been taken with most zoom lenses, and the out of focus highlights would not have been this smooth.

Konica Minolta Maxxum 5D, Minolta 100mm f/2 Autofocus Lens, with the aperture wide open at f/2


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Old Mar 25, 2008, 11:09 PM   #18
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Wowzee... :shock:

Did I touch on a raw nerve or something?
-> All I was trying to show was two examples of why this argument can go either way i.e. a prime can be sharper than a zoom, and a zoom can also be sharper than a prime. It all depends on what two prime or zoom combination you're comparing each other against. I was very careful not to generalize, and I never said any one choice is any better than the other...

Now would I still go out and buy a 50mm for my new D300 even though it's faster and slighly sharper than the 16-50 f/2.8 that DarkDTSHD originally asked?
Categorically NO and here's why:
1. I already have an EF-50 f/1.4 with USM
2. Most if not all Nikkor short primes do not have AF-S
3. The last time I use this 50mm was some two years ago (and it showed some bad case of CA in high contrast area in bright light)





With respect to my EF-85mm f/1.2, it has seen even less use as this 85mm f/1.2L is actually still stored in its original box (or my Minolta 85mm f/1.4G). I'm perfectly aware of the better bokeh etc... May be I don't do as much studio work as before (and in the studio I shoot with the lens closed down for maximum sharpness as the bokeh is replaced by the backdrops), but outdoor I've found that even a 500mm zoom can have a great bokeh with f/6.3 but with much better perspective than a shorter focal lenght:





-> Even in low-light (with the help of a good fill):





Now would I use my 70-200 f/2.8 EX to do macro shots?
Of course not - I'll get another f/2.8 prime out for that: :lol::-):G
http://forums.steves-digicams.com/fo...mp;forum_id=11
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Old Mar 26, 2008, 6:10 AM   #19
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NHL wrote:
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I was very careful not to generalize, and I never said any one choice is any better than the other...
But that was the OP's question!

DarkDTSHD wrote:
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... Is there any reason why any of you would still buy a fixed focal lens like a 50 or 85 f/1.8 or f/1.4? Especially if you are planning to buy a zoom that offers those forcal lengths (e..g. 70-200 or 17-55).
Yes. There are reasons why I would still buy a fixed focal length lens. What about you?
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Old Mar 26, 2008, 6:18 AM   #20
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Long zooms are great. But, they're not always very practical for larger subjects at closer ranges.

I have trouble trying to use anything much over 100mm for the type of shooting I tend to do more often (anything more tends to be too long, if I want to stay at a reasonable distance to my subjects for anything other than head and shoulders types shots).

In low light, the zooms sometimes don't cut it either, even with f/2.8.

There are pros and cons to either lens type, and a zoom gives you more flexbility if conditions allow for one.

As for that Minolta 85mm f/1.4G not being used much, feel free to send it to me and I'll try to help you break it in some. :-)

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