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Old Aug 20, 2011, 4:45 PM   #1
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Default Lenses and Bodies

Back in the 35mm days you bought a manual focus lens and never thought about whether or not it would focus. The only reason it wouldn't was if you glasses needed a correction. The good old days.

I have (3) bodies-Ist DS, K10d, and K20d plus an assortment of lenses. About 2 yrs ago I bought the K10d with the DA 16-45-really disappointed in the sharpness of the photo's. Basically put it in a drawer for a long time and used the DS. Still only has about 1300 shutter actuations. In a weak moment I bought a 17-70 to use on the K20d. It was OK but nothing great. Last week I mounted the 17-70 on the K10d and it was amazing. This body has no front or back focus adjustment so it is what it is. I put the 16-45 on the DS and that has worked great. Both probably won't be removed from the bodies for a while. Didn't know that lenses might be body specific (for lack of a better term).

For a test of the 17-70 & K10d I shot a UPC barcode from about 15-0. Not only could I see the barcode I could read the tiny numbers under the barcode. Don't think I could ask for anything better.

Anyone else have this experience with lenses?
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Old Aug 21, 2011, 8:53 AM   #2
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Yes I have had lenses that focused correctly on one body but not on another. One, an FA 35mm f2 seemed to have an actual problem with infinity focus until I adjusted it on the K20D but others, such as my FA 50mm f1.4 worked really well on the K10D and K20D (and my wife's K100D) but never really got along with my DL. I guess you have discovered the combinations that will work best for you.
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Old Aug 21, 2011, 11:27 AM   #3
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Glad it wasn't just me. Think with all this technology they could get it right. Never understood why the K20d and others have the focus adjustment. After spending $600 + on a lens I want it to work right the first time.
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Old Aug 21, 2011, 11:49 AM   #4
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A lot of this has to do with production tolerances. Let's say a .10 deviation is enough to visually identify a misfocus (I'm just pulling numbers out of my hat here to make a point.) The camera and lens manufacturer may have .05 production tolerances. Let's say one lens example uses that full .05 in one dirction while the camera body uses its full .05 in the other direction. Together, that's the .10 deviation that allows you to see a misfocus. And - key point - both camera and lens are operating within specification.

Because these production deviations vary by specific camera and lens examples, the results you get can vary. Now, one might say the manufacturers should have tighter tolerances. This would most definitely be a good thing. But it would also cost more money. And the cost of getting that last increment of quality goes up way out of proportion to the cost of getting to the acceptable level for a given price point.

Of course, buying used cameras and lenses makes the equation even more difficult because one has no idea how the product as been treated, meaning parts can be knocked out of alignment from being knocked around.

The digital age has made things even more of a challenge, at least in recent years, because the higher-resolution sensors make even minor misfocusing much more obvious. But the focus-adjustment features in the latest cameras do help, which is no doubt why the camera makers put them in.

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Old Aug 21, 2011, 2:18 PM   #5
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Based on your post their could be a chance that someone could buy a lens and have it not work on their camera because of tolerances. It appears that I am lucky to have (3) different body's and that the lenses I have will at least work on one of them.
If a Pentax customer only has one camera they could end up witha useless lens and have to go thru all kinds of aggravation trying to get what they pay for. Think it's time to tighten tolerances and make these lenses work-their big advertising scheme is all about all their lenses working on all their bodies-no matter how old or new. I have been a Pentax customer since 1980 so I have quite a bit of experience with their lenses. I wonder if C & N have these issues-never have gone to their forum.
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Old Aug 22, 2011, 11:46 AM   #6
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Quote:
Originally Posted by DMJJR View Post
Based on your post their could be a chance that someone could buy a lens and have it not work on their camera because of tolerances. It appears that I am lucky to have (3) different body's and that the lenses I have will at least work on one of them.
If a Pentax customer only has one camera they could end up witha useless lens and have to go thru all kinds of aggravation trying to get what they pay for. Think it's time to tighten tolerances and make these lenses work-their big advertising scheme is all about all their lenses working on all their bodies-no matter how old or new. I have been a Pentax customer since 1980 so I have quite a bit of experience with their lenses. I wonder if C & N have these issues-never have gone to their forum.
There are absolutely similar issues with CaNikon... and third-party Lenses like Sigma and Tamron. That isn't to say it's a massive, rampant problem... but it does happen. It used to happen in the film days as well. It's just that the lower resolution involved with film made it a lot less obvious.
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Old Aug 22, 2011, 4:50 PM   #7
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As far as I know all dslr's have the same problem.
Thats the reason they are placing the front/backfocussing adjustments in them.

I know that if you send Nikon your camera and all you Nikon lenses they will calibrate them (for a small ? fee)
I guess Pentax has the same service.

My k10 had problems with focussing, until I send it in for repairs, got it back with a new safox version.
(although it took me a year before I was shure about that focussing problem.)

The K20d needed a adjustment of -7 to get my lenses focussing correctly

Then my first K-5 didn't need any adjustments, only the stains made me send it in, the second one needed a +4.

I don't mind as long as I can calibrate the body.

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Old Aug 22, 2011, 5:27 PM   #8
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G'day fellas

Several things here ...
Some time ago I read an excellent article [can't find it in today's searching] from a lens & camera rental mob where he/they had noticed that certain lenses & certain cameras in their suite of rental items 'matched' for focus and others didn't match for focus

He/they did some examining and came up with similar thoughts to above ... microscopic differences in manufacturing - sometimes they cancel each other out, sometimes they exacerbate differences > maybe someone else here can do a better google for it and find the article
[EDIT - found the article ... "www.canonrumors.com/tech-articles/this-lens-is-soft-and-other-myths/"]

Another article on lens / camera performance is here
http://www.northlight-images.co.uk/a...djustment.html

It may be of assistance
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Old Aug 23, 2011, 12:14 AM   #9
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Ozzie - maybe this is the link you were referring to ? I've seen another article on this too - maybe from B&H.

http://www.lensrentals.com/blog/2010...nd-other-facts

Fact is JMJJR that if they tighten up the tolerances further then that means the contractors will increase their costs too, so with all the extra costs involved it becomes a case of diminishing returns, to the point you could be paying an extra 30-50% for each of your lenses.

If you can get the job done in-camera for minimal cost and with maybe only 1:100 lenses being totally incompatible with a specific camera then that is the most cost effective, and acceptable to the paying public, way to go.
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Old Aug 23, 2011, 1:33 AM   #10
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Can you adjust the focus...in camera....by yourself with a K10D or a KM body ?

I have around 7 Pentax lenses...so far the focus and clarity seems excellent....but just in case in the future.
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