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Test Results: 24-85 CZ versus Canon 24-70/2.8L

 
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em_dee_aitch



Joined: 17 May 2007
Posts: 16
Location: Austin, TX

PostPosted: Thu Jun 07, 2007 12:33 am    Post subject: Test Results: 24-85 CZ versus Canon 24-70/2.8L Reply with quote

So, I grabbed the 24-85 that came up on eBay last week, and I have begun testing it against the 24-70/2.8L. The results so far are unexpected, a little weird, exciting, and pretty neck-and-neck...

I will have screen captures soon, but here's an initial text-only report...

I have shot three series thus far:

Series 1 - a dusk landscape shot at 70mm and 24mm at f11 only. The Canon wins every single shot.

Series 2 - a firestation shot at 24mm, 35mm, 50mm, and 70mm at 5.6 only in late afternoon daylight. The CZ wins every shot clearly other than the 50mm.

Series 3 - same firestation, different angle, same parameters, the CZ wins every single shot, all pretty clearly.

.... so, initially I'm going to conclude that the 50mm loss to Canon in Series 2 is probably due to focus error.

Regarding flare: The Canon handles it better in Series 1, which is maybe why it won the series. They both produce a very attractive star pattern on streetlamps and headlights. The canon pattern is an 8-point star, and the CZ pattern is a 14 piont star (wow, how'd they do that?). It will be interesting to see who wins at f11 in daylight.

Shadow detail: The CZ shows a little better shadow detail in the daylight series, but not really at dusk.

Depth of Field: The CZ achieves greater depth of field at 5.6 than the Canon does. This is particularly startling at 70mm where you don't expect a lot of depth. This is reminescent of shots from the famous Distagon 21mm in which the DOF is more than expected.

To me, the real stunner is that the CZ peaked so near wide open with the Canon having advantage of being 2 stops down, where Canon pro zooms are usually near their best. Will the CZ be able to pull it out at f11 during daylight where flare is not an issue? Time will tell...

Screen shots to come soon....
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em_dee_aitch



Joined: 17 May 2007
Posts: 16
Location: Austin, TX

PostPosted: Thu Jun 07, 2007 7:42 am    Post subject: Reply with quote

FOR ALL IMAGE COMPARISONS, CANON IS ON THE LEFT, AND CZ IS ON THE RIGHT. IMAGES VIEWED AS RAW IN PHOTO MECHANIC AT 100 PERCENT AND SCREEN CAPTURED, AND THEN PHOTOSHOP "SAVE FOR WEB" AT 100 PERCENT QUALITY. All shots taken on 5D.


Here are the "Series 1" dusk images, which consist of one 70mm shot and one 24mm shot, both at f11. The 70mm image is first.

This is center frame. Note at 70mm that CZ gets more magnification than Canon, so it's not really fair. In light of that, I think Canon ties or wins center frame here.



Left edge, above center, Canon clearly wins:



Bottom left corner, Canon wins:



Canon easily wins right edge:




Moving on to the 24mm frame...

At frame center, Canon wins. Note CZ's 14-point star flare pattern:



Top edge, right of center, Canon looks a little better to me:



Left side of 'zone B', corresponding to the approximate left edge of an APS-C camera such as a 30D - Canon wins:



Extreme left edge, Canon wins:

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em_dee_aitch



Joined: 17 May 2007
Posts: 16
Location: Austin, TX

PostPosted: Thu Jun 07, 2007 7:45 am    Post subject: Reply with quote

Series 2 images...

This at 70mm f5.6. Note again that CZ has more magnification at 70mm, but I think it's enough ahead to be called winner:



Lower right of 'zone B', approx the bottom right corner area of an APS-C such as 30D:



Upper right corner, Canon wins:



This represents a bit of a trend... Canon tends to win the extreme (full frame) corners, while CZ trounces it in the center...
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em_dee_aitch



Joined: 17 May 2007
Posts: 16
Location: Austin, TX

PostPosted: Thu Jun 07, 2007 7:49 am    Post subject: Reply with quote

This is 'Series 3.' This detail is left center frame at 50mm:



Right center frame:



After CZ wins the center, Canon wins left edge here, barely:



Canon wins top left corner:



Top right corner, Canon wins pretty clearly:



Last edited by em_dee_aitch on Thu Jun 07, 2007 7:58 am; edited 1 time in total
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em_dee_aitch



Joined: 17 May 2007
Posts: 16
Location: Austin, TX

PostPosted: Thu Jun 07, 2007 7:53 am    Post subject: Reply with quote

Series 4, an old plane hangar being restored... This shot at 50MM. CZ appears better at center frame:



This is bottom right corner, and it's one of the oddest details, because, even though the Canon looks superior overall, there are a couple spots within the detail where CZ looks better:



Left edge of same frame, Canon wins:

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em_dee_aitch



Joined: 17 May 2007
Posts: 16
Location: Austin, TX

PostPosted: Thu Jun 07, 2007 8:02 am    Post subject: Reply with quote

Thus far I'm thinking that there is not a clear winner between these two lenses, without going to a different criterion, such as speed or price. The CZ seems to rule the center most of the time, while the Canon seems to offer more even performance across the frame. CZ comes closest to matching Canon's edges at 35mm, at least as far as I can tell.
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jrn813



Joined: 26 Feb 2007
Posts: 90
Location: Cotulla, Texas

PostPosted: Thu Jun 07, 2007 2:07 pm    Post subject: Reply with quote

You Bought A Converted N 24-85mm On eBay?
Or Is It A MF 24-85mm With An Adapter?

John R

I Answered My Own Question....
I Found Your Purchase On eBay.

To Me It Looks Like You Might Need To "Fine" Tune The Focus On Your Contax.
You Should Check The Seial Number & What Version Of Firmware It Has, And See If
You Can Adjust The Lens....

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em_dee_aitch



Joined: 17 May 2007
Posts: 16
Location: Austin, TX

PostPosted: Thu Jun 07, 2007 5:53 pm    Post subject: Reply with quote

jrn813 wrote:
To Me It Looks Like You Might Need To "Fine" Tune The Focus On Your Contax.


Which images do you think show need for tuning? I think the Center frame shots of the fire trucks are showing the CZ near perfect at that focal length. I think it's even focusing correctly at the 70mm length night shot where it lost (but won during the day).

The guy I bought it from already spent a lot of time tuning it to his 5D, so it should be pretty close. It's already focusing better and more consistently than the 24-70, so I'm kinda scared to touch it!

One characteristic of the 24-70 on the 5D is that it does not focus very consistently on wide shots. You particularly see this when shooting group photos at events.

... and I've ordered a Brightscreen for the 5D, so once that gets here, I may repeat the fire station shot with manual focus. I don't think that will help the CZ, but it might help hte Canon.

The lens I bought is in the Conurus database as converted on April 7, so the last owner did not keep it very long... He explained to me that it couldn't quite beat his Leica zooms (which of course cost WAY more).
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jrn813



Joined: 26 Feb 2007
Posts: 90
Location: Cotulla, Texas

PostPosted: Thu Jun 07, 2007 11:35 pm    Post subject: Reply with quote

The Adjustment Can Be Done On Many Different Focal Lenths,
Each Effecting Only A + / - Parameter...

With Tolerances, Each Camera And Lens Are Unique ...
Most Of Your Posts, Do Not Have The "Zip" I Seem To Get From My 24-85mm
Even Though I Am Using The Older 1Ds....

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em_dee_aitch



Joined: 17 May 2007
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Location: Austin, TX

PostPosted: Fri Jun 08, 2007 7:40 am    Post subject: Reply with quote

Can you post some 100 percent crops of your zippy shots? Especially mid-frame, edge, and corner details?

ALSO - When it comes to "zip," it's very important to remember that I'm showing totally non-sharpened RAW pixels here... In most applications, viewing the "raw" will actually show you either a mildly sharpened preview (such is the default in Photoshop) or an embedded JPEG preview... I'm toggling to usharpened RAW in Photo Mechanic, which displays no sharpening at all, and I'm doing side-by-side screen caps from there without any sharpening in the 'save for web' command. For anyone else to compare to my results directly, they would need to use a similar technique to avoid any and all sharpening.

That being said... At the moment, I think I got all the zip at the center. I don't think any lens on a 5D could resolve the speaker grill on that fire truck much better than the shots above. And when taking a test shot of objects 40 or more feet away, I don't think critical focus matters anway, because if you're just a little off, it's just going to land a couple feet away in the frame, and that's where you can compare. My other concern, before killing a day in re-tuning the lens, is that tweaking the focus shouldn't really do anything to improve edge or corner performance. It would really only help at center where the focusing occurs... Probably the reason a lot of mine aren't zippy is that I'm posting lots of edge and corner... A couple of the subjects I chose are deliberately difficult, too. I think it's obvious the night shot is hard on a lens, but that plane hangar is, too - the wood is fine high frequency detail at the distance I was shooting it. And its bright white paint was pretty glary in the direct sunlight... At the same time I took a bunch of shots with a Nikkor PC 28mm, and (quite unexpectedly) it failed to resolve as much as the Canon zoom... Anyway, before we conclude that I don't have zip, remember that my copy of the CZ got more center detail on that wooden hangar than the Canon did.... I think we need more edge and corner samples from other people... And let's remember that the edge/corner performance I'm getting out of my CZ is not "Bad." It just happens to be less than the Canon. I know the Canon 24-70 takes a lot of crap in a lot of circles, but I think it's really a fine lens that doesn't deserve the bad rap (it probalby is a finicky one, but when Canon sets it up correctly, it's mildly excellent).
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jjlphoto



Joined: 17 Jan 2007
Posts: 102

PostPosted: Fri Jun 08, 2007 12:11 pm    Post subject: Reply with quote

The Canon 24~70/2.8L is a fine lens, certainly one of the leaders in the Canon EF line-up. I had one previously, but it is large, way too long at the 24 end, too heavy, etc. I like my Contax 24~85 because of its compactness and hand hold-ability. (And not to mention the quality.)
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em_dee_aitch



Joined: 17 May 2007
Posts: 16
Location: Austin, TX

PostPosted: Fri Jun 08, 2007 10:13 pm    Post subject: Reply with quote

[quote="em_dee_aitch"]
jrn813 wrote:
One characteristic of the 24-70 on the 5D is that it does not focus very consistently on wide shots. You particularly see this when shooting group photos at events.

... and I've ordered a Brightscreen for the 5D, so once that gets here, I may repeat the fire station shot with manual focus. I don't think that will help the CZ, but it might help hte Canon.


Replying to myself: It has occurred to me that re-running this in manual focus might prove the Canon's superior corner performance be just backfocus and not superior corner performance at all. Of course if that does turn out to be the case, it will mean a closer race in the center of the frame.... Can't wait until that screen gets here.
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