85mm shootout... (Pixel peeping!)

[scr7b]

Ok, I'm stuck in a hotel room with not much else to do, so I thought I'd have a go at some lens comparisons.

This one has surprised me, so I thought I'd share it. The comparison is between the 17-85 EF-S and the 85mm f/1.8, both at f/5.6 (Max aperture on the 17-85 at this focal length). I would have expected the 85mm prime to easily outperform the EF-S zoom, but this doesn't seem to be the case. I would say the 17-85 has the edge here. These are 100% crops from the centre of the frame. Notice the small difference in focal length too.

Both shots with tripod, remote release and mirror lockup. IS was turned off on the 17-85.

[guitarman]

I'd like to see that same comparison with the 17-40 F4 L instead of the 17-85. I had the 17-85 and got rid of it in favor of the 17-40.

[scr7b]

I'd like to see that same comparison with the 17-40 F4 L instead of the 17-85. I had the 17-85 and got rid of it in favor of the 17-40.

Well, I'm not doing much else here, I'll knock one up for you... watch this space!

[tommykjensen]

Is this the right way to compare a EF-S and EF lens?

I mean You compare 85 mm on a EF-S lens against 136 mm EF (85x1,6).

[scr7b]

Is this the right way to compare a EF-S and EF lens?

I mean You compare 85 mm on a EF-S lens against 136 mm EF (85x1,6).

The focal length multiplier is the same on EF and EF-S... 85mm = 85mm.

[tommykjensen]

The focal length multiplier is the same on EF and EF-S... 85mm = 85mm.


Ehh no.

EF-S 17-85 is equvilent to 17-85 on 35 mm film.
EF 85 is equvilent to 136 mm on 35 mm film.

Why else has Canon made an EF-S version of the 28-135 mm IS lens?

[blue_max]

For a fair comparison, the focus must be in the same place. On the 85mm lens shot, the knife is very soft. The 85mm is a very capable lens.

Graham

[scr7b]

I'd like to see that same comparison with the 17-40 F4 L instead of the 17-85. I had the 17-85 and got rid of it in favor of the 17-40.

Here it is...

http://photography-on-the.net/forum/showthread.php?p=621900

[massi.ra]

Ehh no.

EF-S 17-85 is equvilent to 17-85 on 35 mm film.
EF 85 is equvilent to 136 mm on 35 mm film.

Why else has Canon made an EF-S version of the 28-135 mm IS lens?

:confused: ??? :shock:

... does not make sense. Sure?

[scr7b]

Ehh no.

EF-S 17-85 is equvilent to 17-85 on 35 mm film.
EF 85 is equvilent to 136 mm on 35 mm film.

Why else has Canon made an EF-S version of the 28-135 mm IS lens?

No.

On the 20D:
17-85 is equivalent to 27-136mm on 35mm film.
EF 85 is equivalent to 136mm on 35mm film.

On the 20D, an 85mm EF lens is the same as an 85mm EF-S lens.

Regardless of cropping factor, the focal length of a lens is the same, hence 85mm = 85mm.

[tommykjensen]

Then how do You explain the difference in focal length?

If the 85 mm on both lenses is exactly the same the photos You have posted should have been exact matches.

If what You are saying is true I see absolutely no reason to buy any of the EF-S lenses.

[tommykjensen]

Even Canon says the focal length on EF-S should be multiplied with the crop factor.


http://www.canon.co.uk/For_Home/Product_Finder/Cameras/EF_Lenses/Zoom_Lenses/EF-S_10-22mm_f-3.5-4.5/
http://www.canon.co.uk/For_Home/Product_Finder/Cameras/EF_Lenses/Zoom_Lenses/EF-S_18-55mm_f-3.5-5.6/

Couldn't find a document for the EF-S 17-85 lens.

[scr7b]

Even Canon says the focal length on EF-S should be multiplied with the crop factor.


http://www.canon.co.uk/For_Home/Product_Finder/Cameras/EF_Lenses/Zoom_Lenses/EF-S_10-22mm_f-3.5-4.5/
http://www.canon.co.uk/For_Home/Product_Finder/Cameras/EF_Lenses/Zoom_Lenses/EF-S_18-55mm_f-3.5-5.6/

Couldn't find a document for the EF-S 17-85 lens.

That's right. Now read what I wrote above.

[Wazza]

Aye Tommy?

Any given lens, say a 85mm, becomes converted with the "crop factor", so it's 136mm.

Doesn't matter whether it's a 85mm EF, or a EF-S.
The only difference, is EF-S, is the different, deeper mount, which can only fit consumer range cameras (300D/20D etc).

Anyway, as to the image, the 85 prime, I think is focused too deep. Bring the focus forward a touch.

[scr7b]

Anyway, as to the image, the 85 prime, I think is focused too deep. Bring the focus forward a touch.

I'm now thinking you might be right about that... The 85mm should be better than this. I'll look into re-testing!

[tommykjensen]

Aye Tommy?

Any given lens, say a 85mm, becomes converted with the "crop factor", so it's 136mm.

Doesn't matter whether it's a 85mm EF, or a EF-S.
The only difference, is EF-S, is the different, deeper mount, which can only fit consumer range cameras (300D/20D etc).


Then I don't understand the difference between EF-S and EF and the need for the EF-S mount.

Someone please explain better why Canon made the EF-S mount and why Canon describe the EF-S 10-22 mm as the same as a 16-35 mm.

[tommykjensen]

That's right. Now read what I wrote above.

Do You have a link that explains what You are trying to tell me ;-) (I do know that 85=85 ;-) )

[martook]

Tommy:
On a 1D you use the 16-35, get a brilliant lens that is really wide!
The same lens, used on a 20D, gives you 26-56mm. Still a brilliant lens of course, but not very wide.
That's why they have made the 10-22 as well, but only for EF-S cameras... that's the 16-35 lens for us that can't afford a full frame camera.

[Wazza]

I think the reason is that EF-S are fitted only to 1.6x crop factor bodies, which use up a greater range of the lens diameter. If it was used on a full frame body, I'm sure there would be vignetting.

Of course, I haven't read all the EF-S vs EF threads, so don't really understand it myself, but that's my thought, that it's only directed at the specific body, and generally EF-S are cheaper (yeah right! - 60mm EF-S Macro for example).

The only reason ALL EF-S lens have given a 35mm film equivalent, is because they will only ever mount to that, and will only give that. Whereas my 17-40L, can be anything from 17-27mm at the widest, depending whether it's on a 1DS, 1D, or 20D series of camera. So it varies.


And good luck scr7b, in trying it again.
The only reason I said that, is the foreground is all soft, and not one point does it get sharp, until the fabric behind.

[scr7b]

And good luck scr7b, in trying it again.
The only reason I said that, is the foreground is all soft, and not one point does it get sharp, until the fabric behind.

Well... According to the DOF calculator, at that subject distance (about 4 metres), at 85mm, f/5.6, the depth of field should have been 0.47 metres... so everything in that crop should be sharp.

http://www.dofmaster.com/dofjs.html

[scr7b]

And good luck scr7b, in trying it again.
The only reason I said that, is the foreground is all soft, and not one point does it get sharp, until the fabric behind.

Well... According to the DOF calculator, at that subject distance (about 4 metres), at 85mm, f/5.6, the depth of field should have been 0.47 metres... so everything in that crop should be sharp.

http://www.dofmaster.com/dofjs.html

[tommykjensen]

Sorry for the confusion. It seems I didn't read my own link properly :oops:

[RichardtheSane]

Back to the test...

1/5 of a second with (maybe) flash is not an ideal situation to be testing, even tripod mounted.

Maybe try the same test with better light so the shutter speed can be increased.

[scr7b]

Sorry for the confusion. It seems I didn't read my own link properly :oops:

No worries mate! ;)

[scr7b]

Back to the test...

1/5 of a second with (maybe) flash is not an ideal situation to be testing, even tripod mounted.

Maybe try the same test with better light so the shutter speed can be increased.

There was no flash, but I hear what you're saying about the shutter speed... I'll repeat the test another time, the light is fading here now (I'm in China...)

[Huckaback Photo]

The EFS lenses were designed to cover the actual sensor size on 1.6 crop camera bodies,
in other words project the image to fit that smaller sensor.
and therefore will not cover a full frame or 35mm sensor, hence Canon developed a new mount to stop people fitting those lenses on full frame bodies.

However I have used one EFS lens on my 1D Mk 2 body by fitting a 12mm extension tube, this moves the projecting EFS lens mount away from inside the body mount .
this set up is fine just close up pictures, as you will lose infinity focus.
The main problem in buying EFS lenses is if you ever move on to full frame ,that lens is no good to you.

Martin (Huckaback Photo)

[blackviolet]

oh, bummer.... i thought we were going to get a CDS xfactor warning :(

[I Simonius]

Aye Tommy?

Any given lens, say a 85mm, becomes converted with the "crop factor", so it's 136mm.

Doesn't matter whether it's a 85mm EF, or a EF-S.
The only difference, is EF-S, is the different, deeper mount, which can only fit consumer range cameras (300D/20D etc).

Anyway, as to the image, the 85 prime, I think is focused too deep. Bring the focus forward a touch.

I just got the 85 and it definitely back focusses by about 3.5 mm, but would it make that much difference at 5.6 as in tthat pic?

[I Simonius]

Then I don't understand the difference between EF-S and EF and the need for the EF-S mount.

Someone please explain better why Canon made the EF-S mount and why Canon describe the EF-S 10-22 mm as the same as a 16-35 mm.

they mean
the 10-22 ON A 1.6 crop camera
is the same as
16-35 ON A full frame camera

[eosnob]

The 85mm shot looks out of focus. What focus method were you using?

[scr7b]

The 85mm shot looks out of focus. What focus method were you using?

It was autofocus, but as I said in an earlier post, at that aperture, depth of field is 0.47 metres (about 18 inches) so it isn't out of focus.

It has been mentioned that at 1/5th second exposure, there could have been some camera shake, but I used a cable release with mirror lockup... I can't be 100% though so I'll definately repeat the test.

What it does show though, is that the 17-85 lens is pretty good on its own...

[CyberDyneSystems]

oh, bummer.... i thought we were going to get a CDS xfactor warning :(

:lol:

Just for you...

http://members.bellatlantic.net/~vze2hdzu/pics/Redalert02.gif