Difference Between f2.8 and "Consumer" Lens

[jamesev]

Would there be any discernable difference between a shot with say a 300mm prime lens that goes to f2.8 that cost about £4000 but actually set at say f7 and a 70-300 thats set at 300mm and f7 that costs about £800.

And if so can someone please explain what it is?

[RichardTaylor]

Yes (And I don't own a 300 F2.8), especially when viewing very large prints..

See here for Canon 70-300 F4.5-F5.6 IS USM (I own one)

Basicially a bit soft above 200mm, especially compared with the 300 F2.8,

Canon EF 70-300mm f/4-5.6 IS USM Lens Review


See here.
Canon 300 F2.8 IS L

Canon EF 300mm f/2.8 L IS USM Lens Review

One other thing to keep in mind, and this is from personal observation.
Lens hoods for primes are a lot more effective than those for zooms.
Especially important when flare may be a problem.

Also keep in mind high quality lenses focus a lot faster, and more accurately than than "consumer" lenses.

I am not a Nikon shooter, however having a look at Fred Miranda user feedback tells a similar story for Nikon.

[gturner]

Originally Posted by jamesev

Would there be any discernable difference between a shot with say a 300mm prime lens that goes to f2.8 that cost about £4000 but actually set at say f7 and a 70-300 thats set at 300mm and f7 that costs about £800.

And if so can someone please explain what it is?

I have used both and the difference is significant.
- AF Tracking speed (remember AF works at the max aperture, not the set aperture)
- Colour reproduction & contrast
- sharpness massively different. (on the 2.8, a small bird at 50 paces at 100% crop you can see single feather detail. It is that good.)

here is my post about it
Testing $4500 a beast lense

[RichardTaylor]

I feel the same about my Canon 135 F2 L, even though I own another three L zoom lenses.

[ravncat]

There are several differences, I shoot nikon, but have very few 2.8 lenses...

I should take time and make some photographs for you, but I don't know when I will have time, so i'll just enumerate what I know of in general, these will generally hold true for your lenses - even at f8 or f11 - but as to how strong such things are in these two lenses, I cannot say.

In general, many lenses follow the following traits -

Sharpness increases as stopped down (especially corners) (Until reaching diffraction)
Abberations (Chromatic abberation and coma for example) decrease as stopped down
ghosting can disappear as you stop down
Vignetting goes away as you stop down.

Some things don't change much or change very little when stopping down.
- Distortion.
- lens contrast (And maximum lens resolution)
- flaring
- Color reproduction
- AF tracking speed (Depends on max aperture and lens/camera motor and AF system)
- Actual Focal length. (Depends on design, most lenses have breathing with focus distance)

- Also, Most lenses have a sweet spot, where everything is optimal a few stops down from wide open.

So at f7 or f8 - the 70-300 and say a 300 2.8 (I have neither, I have a 28-300, and a 300 f4 (I had the older 70-300g which is much inferior to the 70-300 vr) - Vingetting is probably gone. Nikon uses similar coatings and glass.

Your main differences are going to be in

resolution (the 300 2.8 has a higher resolving power (via mtf) than the 70-300. (though if you don't have enough pixels, or really good technique, you might not notice these differences, the 70-300 is also softer towards 300 than it is at 200)

Distortion (the 300 is designed to have very little distortion, the 70-300 will have more distortion as a compromise to allow zooming)

AF speed (300mm has faster maximum aperture)

Contrast (again part of the lens design itself, it's just a bit more contrasty - how much, I can't say)

Focal Length (your 300mm is going to stay closer to 300mm at different focus distances, your 70-300 will be a bit shorter at closer focus distances - only really getting to 300 at infinity focus),

Now - depending on your eyesight - that's going to be a huge difference, or just a little - and it's gonna depend alot on how subjective you think things are - I'd say it's definitely a visible difference - It's worth noting that the distortion can be corrected in post- You can crop in just a bit if you are focusing closely, the image can be sharpened and contrast can be added. - and while you can add to both - you can get to a point that is oversharp, or too much contrast. The issue is the time you spend in post. ( Of course, sharpening won't add fine detail that isn't there. )

I love my 300 f4 for it's qualities at f4 and 5.6 that just blow away any of my other options. Not having to do stuff in post, and getting more done through optics than afterward.

Hopefully that's helpful to you

[Jim Bryant]

This true ravncat. The main differences are quality and of course the $$$$$$. If money isn't an object and you are really serious about your photography get the Canon white lenses.
At one time I owned the Canon f4 300mm white lens. It was a lot cheaper than the f2.8 and also sharp as a tack.