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Old Dec 19, 2005, 11:59 AM   #11
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D20nut wrote:
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perhaps you could clarify thata bit ..getting lost in your larger and smaller and defocusing terms and exactly how the whole lense could be used for focusing. I presume you mean this latter point in terms of light gathering capability.:?
See this diagram: http://konicaminolta.com/products/co...x7/ope01b.html

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Old Dec 19, 2005, 12:59 PM   #12
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that link don't work no more NHL
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Old Dec 19, 2005, 2:34 PM   #13
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It works for me...


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Old Dec 19, 2005, 3:19 PM   #14
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ya soooooooooo good info on how Af systems worknot all germain to the issueas to whyan F4 lense like 24-105is slightly softer in poor in low light verses a kit lense of a similar speed.

anyhooooooooooo...onward




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Old Dec 20, 2005, 5:02 AM   #15
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D20nut

IMO you're slightly confused by different issues:
1. The EF 24-105L is a very good lens as compared to the 'kit' lens - all you have to do is to check its superior MTF's curves from the Canon site
2. My point was to illustrate that all part of a lens is used (even on a cropped camera) - The 20D just cropped the best part of the image and not the lens
3. And finally a wider aperture in no way indicates a softer lens - again just check the MTF's of the EF 300 f/2.8L against its EF 300 f/4L. The 300 f/2.8L MTFs simply blow away any other lenses out of the water...
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Old Dec 20, 2005, 9:41 AM   #16
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Didn't mean to sound strident NHL..Thanks for walking through this with me ..

My quary has to do with the very understandings that you articulate re the two lenses . The kit lens is SUPPOSEDLY the poorer lens re the manufacturer's stats. Reality bit that ..or so it seems

I took various shots of a huge page of fine print at different focal lengths and apertures. I took shots focused on one small price tag about 1 inch across as well.I took 30 degree shots ofa magazine.. In these tests I was within 10 feet of the testsubject as this will be the range I need for critical focus.

IN EVERY comparison the two lenses were either hard to tell apart or the 24-105 was clearly inferior. The kit lens was underexposed at the same apertures but was slightly sharper. (I also took out door shots. In some shots the 24-105 seemed to have an advantage..but it ws not clear who the overall winner waseven after looking closely at roof lines, tree branches and small detail )

Anyways I tried the price tag test in the shop with the two lenses and repeated what I found for the guys there..36 -50 mm at 8 feet or so, tripod IS off. All four copies we tried lost to the kit lense wide open ..in those tests.

MY wild guesses as to what was going on ...

A.the 24-105's I tested somehow has issues with D20 bodies ( but we tried two ) focusing front or back by a millimeter ??

B. The 24-105 copies I tried were all "bad copies"

C. The kit lense was being tested in a manner where it shone for one brief moment - exactly where the 24-105 stumbles a tick.

D. My tests were all bogus and I need to re test in some other manner.

What bugs me is I took a shot of a cup in the sunlight with both lenses. In that shot the 24-105 was gorgeous !!!! The kit lense detuned the shot and had less sharpness hence my conclusion ..

In good light the 24-105 rocks. Drop the light and poof we are in the basement optically with the likes of the sloppy, plasteeeek kit wonder I hate ??

If you have any suggestions I am all ears ..I need a great 24-105+ range zoom ..If you know of any others to try ..let me know. ( Tamron 24-135 gets good reviews)















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Old Dec 20, 2005, 8:08 PM   #17
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I wonder ..the 24-105 is wieghty and hangs out there on a tripod. Could it be that vibrations from the shutter operation at slow speed set up a slight vibration ..big enough to shake the lense and blur the image where such would not happen with the lighter kit lense.? It would only take the smallest of nudges to mess things up.

He graspeth at straws..


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Old Dec 21, 2005, 1:21 AM   #18
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Yes you should be testing with mirror lockup.

But secondly it just goes to show once again what we have been saying in these forums for ages and ages.

"The 18-55 kit and the 17-85 kit may have many problems, but sharpness is generally not one of them."

Look at the MTF charts. Sure the 24-105 is better, but that's not the surprise; the surprise is how good the kit lenses are. Good enough that lens variation and calibration may play a significant role in comparisons. Good enough that anything less than perfect technique in testing may play a role. Good enough that most of the time there's not much in it. Good enough that the first thousand copies off the production line of the new lens may be noticably worse.

Frankly good enough that the kit lens has a completely undeserved reputation as a poor performer. And (brutally) good enough that if you can't get some pretty good photographs with it then the problem is far more likely to be behind the camera body than in front of it.

A lot of us will be getting the 24-105 anyway because of the 20 properties a lens can be evaluated on, sharpness is only one of them.

P.S. And isn't learning to get the best out of your equipment, exploiting its strengths and working around the weaknesses part of the craft of photography? I know that my camera and lenses just keep getting better and better the more I practice with them. Weird eh?

Edit: Some old pros, and I'm fairly sure NHL does this at times, sometimes look at a scene - the light, the composition and the mood and think... "You know I have just the right lens in my bag somewhere... ah yes here it is a 1954 vintage Zeiss 28mm which is just going to render this scene beautifully."

My point really is that by putting the 24-105 L on your camera and testing against a lens which is actually quite sharp in the centre you might be missing the versatility and beauty that the new lens might be capable of under the right conditions. Is it sharp enough for the kind of photographs you take? How much work did you do in PS to sharpen up the 24-105? Is the problem that you are seeing related to accutance or resolution? (And if you don't know then should you really be pronouncing on relative sharpness?) Most important of all - what do the prints look like?

I do think equipment is important, and it's not just about the photographer, but I do find it difficult to understand why you might not be happy one day to look at a scene and think to yourself ... "You know, I remember having to take photographs of price tags under mixed shop lighting once before so I'm gonna get out that crappy old plastic 18-55 because it's going to give me nice colour and contrast and centre sharpness, and I just can't think of a better lens for the job!"



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Old Dec 21, 2005, 3:41 AM   #19
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Peripatetic a very useful and accurate addition to this thread! As you said, often there are many more things to a photo than having the "best lens" or "best camera body".... e.g. the one using them counts for more than 90%! (and as you said, working within the limitations and knowing how to use the equipment at hand!)

I've got some "cracking" (meaning: superb!) photos from a 3megapixel P&S Fuji digital camera I've had till now (Finepix F601). Just got a 350D which I'm v happy with! Even the 18-55 kit lens can make great photos (even though I wouldn't consider myself a fantastic photographer, I get some good photos in..

So, D20Nut, realise what peripatetic writes is very important! For your info.. I also have the "non L version but still better than kit lens" 28-135mm Canon lens, which I use for 90% of the time (the 18-55mm kit lens for wider landscape images or when I need a lighter travel kit.... or for more discrete usage!!) As peripatetic said (and in summary) - learning and using the equipment is much more important than minor "lines per millimetre differences" between lenses! Though of course a good lens will often allow extra flexibility in certain situations.

Thanks peripatetic for being a useful contributor to many threads on this site, I've found a lot of what you've said (written) v useful! (& very true!)

Happy Christmas

PJ
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Old Dec 21, 2005, 8:54 AM   #20
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For what its worth the difference superficially seems to be one of resolutionrather than acuteness between the two.( * my use of resolution here implies the ability of the lens to render an image relative to contrast and factors beyond bare optical sharpness. The 18-55 seems more capable in lower light , the 24-105 trounces it in great light.)

It is rather stark in the price tag shots. The 24-105 shots are quite noticeably blurry relative to the 18-55 under close scrutiny. I tried stopping down the 24-105 to get it to render the tags as the 18-55, but no luck . The 24-105 I had just seemed slightly less contrasty than the 18-55 no matter what I did . I am sure I could play around in PS and fix the 24-105 images to some extent , butthat should not be needed with such an expensive lens.

Now as you can gather I am new to photography. I am an artistand feed my self off the product of what I render from a source rather removed from the mechanical. ( I do not to imply a slur against photography here ) I am simply looking for a good lens to take sharp sharp sharp well resolved pictures of my paintings and also function as an all round field lens. I thought the 24-105 would do the trick.

Now to be honest I am thinking I did not give the lens enough of a chance so I am going back to the store. I am going to plant the cam on a steady tripod, usethe timer, and try again. I may also take it home for more trials ..I will see.There were just enough shots from the 24-105 that wowed me to make it worth another try. It may yet prove its $1000+difference to the kit lens.The problem indeed may be ..behind the camera!!

It could beI am trying to push a zoom to places only a prime can go , but again this 18-55 plasteeeeeeeek wonder seems to do so with aplomb. It may just win and I will then buy a 70-200 2.8 to augment its range. I am getting hooked on straight photography. Its rather faster than painting, but just as challenging.

I greatly appreciate all your interactions with me on this whole deal. Its been very helpful.

**I am thinking that a lot of people would never think to even try the kit lenses against an L series. I just happened to do so cuzz ..well I am ignorant in this whole field andnot a photographer. :sad:
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