Fine Tune a Lens???
Dec 19, 2017 11:42:23 #
frankraney wrote:
You obviously didn't read the thread and understand it. It's also obvious you do not understand Manufacturing. There are always allowed tolerances and everything that's manufactured because it can never be done perfect every time so acceptable tolerances are created for each and everything that's manufactured. I used to be held to a 5% tolerance and teased if we got that and couldn't get less. tolerances are there for a reason, and that reason is it's impossible to get it perfect every time.
Indeed. Good designers work closely with manufacturing and fabrication/machining to understand what tolerances are achievable/workable, and design parts and assemblies such that the item can be assembled and work correctly even if all the tolerances “go the wrong way”
Dec 19, 2017 11:47:33 #
RRS
Loc: Not sure
Jim Bob wrote:
When I pay for a lens, I expect it to work. When ... (show quote)
Just shoot at F/8.0 and all your lenses will work very well. In electronics all parts have a tolerance, the parts make up the whole. If you buy test equipment made up with components with a 10 to 20 % tolerance it will work but if you care about how close it will be in it's testing ability then you buy the same test gear that was built with either 1 or 2 % tolerances and it will give more accurate readings. Hey they both work. The example you mention can very easily be fixed with an item in the cameras menu, Fine Tune or Micro-Adjust. There's a big difference between something that can be adjusted and sloppy manufacturing. I sure wouldn't try to have a car dealer take back my new car if the idle speed was 400 RPM's too high, I'd adjust it.
Dec 19, 2017 12:01:32 #
Jim Bob wrote:
When I pay for a lens, I expect it to work. When ... (show quote)
I guess you also expect that car to never need a wheel alignment? For casual driving your car will be fine. For casual Photography, you do not need to fine tune your camera, shoot at f/8 and up. If you buy an expensive sports car and want to push the vehicle to its limits, expect to have it occasionally tuned up.
Dec 19, 2017 14:59:41 #
dsmeltz wrote:
I guess you also expect that car to never need a wheel alignment? For casual driving your car will be fine. For casual Photography, you do not need to fine tune your camera, shoot at f/8 and up. If you buy an expensive sports car and want to push the vehicle to its limits, expect to have it occasionally tuned up.
Certainly not right off the lot. If you do, I feel sorry for you.
Dec 19, 2017 16:05:13 #
Jim Bob wrote:
When I pay for a lens, I expect it to work. When ... (show quote)
Then please dont buy into the truth. If you were an engineer, or draftsman, or a machinist, you would have no issue with this. However since you are obviously not familiar with anything mechanical, please go ahead and believe that the world is flat and that the moon is made of cheese. But also, you can now stop arguing with the truth and reality... nothing you say, think, or do is going to change what is real and true. and yes I am getting snarky... it has gone on for way to long and is no longer relevant to the list.
Dec 19, 2017 19:57:56 #
nikonkelly wrote:
Then please dont buy into the truth. If you were ... (show quote)
Nice try at misdirection-usually the province of those who don’t know what they are talking about. One does not need to be an engineer to expect products to perform as they are designed. Have you ever considered what warranties are about? Of course not.
Dec 19, 2017 20:08:50 #
Are you so unrealistic as to believe that we are talking about trying to fix a broken lens?
Dec 19, 2017 22:15:58 #
There’s a fundamental difference between the car and an interchangeable lens camera. The car has interchangeable parts, but that’s not a part of it’s typical use. If you repair the car, for instance change a tie rod end, then you must typically check/adjust the toe-in (ie: calibrate it). Or if you change the mass air flow sensor, then the on-board computer will recalibrate itself to the new sensor to produce the correct fuel air mixture.
On the other hand, suppose we’re talking about a system like a DSLR where parts are interchanged as part of it’s day-to-day use. Yes, the lens will mount and you can take pictures as long as the mechanical parts are within tolerance, but they may need calibration to get the absolute best performance. Let me give you another example. Suppose you purchase an oscilloscope and as is often the case, you buy probes separately. You’ll note that there is a calibration loop on the front of the scope and there’s a cal adjustment on the probe. So you attach the probe and clip it onto the calibration loop. You’ll certainly see a signal, but it may not be a square wave where the top is flat - it may be tilted. Since you want to have an accurate instrument, you then calibrate/adjust the probe to get a perfect square wave and now you have an accurate measurement system. Will it give you a trace without calibration? Sure. Is it the best accuracy that can be achieved? No.
On the other hand, suppose we’re talking about a system like a DSLR where parts are interchanged as part of it’s day-to-day use. Yes, the lens will mount and you can take pictures as long as the mechanical parts are within tolerance, but they may need calibration to get the absolute best performance. Let me give you another example. Suppose you purchase an oscilloscope and as is often the case, you buy probes separately. You’ll note that there is a calibration loop on the front of the scope and there’s a cal adjustment on the probe. So you attach the probe and clip it onto the calibration loop. You’ll certainly see a signal, but it may not be a square wave where the top is flat - it may be tilted. Since you want to have an accurate instrument, you then calibrate/adjust the probe to get a perfect square wave and now you have an accurate measurement system. Will it give you a trace without calibration? Sure. Is it the best accuracy that can be achieved? No.
Dec 20, 2017 08:08:31 #
Jim Bob wrote:
Nice try at misdirection-usually the province of those who don’t know what they are talking about. One does not need to be an engineer to expect products to perform as they are designed. Have you ever considered what warranties are about? Of course not.
Warranties cover problems beyond normal use tolerances.
Dec 20, 2017 10:08:56 #
Dec 20, 2017 10:35:44 #
dsmeltz wrote:
Warranties cover problems beyond normal use tolerances.
Correct. The important word is "normal". It is not normal for a new lens to visibly misfocus.
Dec 20, 2017 10:55:22 #
TriX wrote:
There’s a fundamental difference between the car a... (show quote)
Come on, what a dumb response. The concept applies to both machines/items.
Dec 20, 2017 10:59:20 #
you know Jim bob, you are right. we are just a bunch of idiots who suck up all of the bs that canon and nikon push to us. every lens and camera should be made to exact specs, at least to 1/10000 of an inch... that should work for nearly everyone... well except for those who can not afford to pay the extra $5000 that would be added to the cost of each camera. But none the less, you are right. Now can we get back to reality.
Dec 20, 2017 11:00:41 #
nikonkelly wrote:
you know Jim bob, you are right. we are just a bunch of idiots who suck up all of the bs that canon and nikon push to us. every lens and camera should be made to exact specs, at least to 1/10000 of an inch... that should work for nearly everyone... well except for those who can not afford to pay the extra $5000 that would be added to the cost of each camera. But none the less, you are right. Now can we get back to reality.
Well you said it. Who am I to disagree? This relativism crap needs to stop. To let some of you tell it, nothing should function as it is designed and manufactured to function. Everything needs to be fixed immediately after it leaves the sales floor or lot. Rubbish.
Dec 20, 2017 11:08:43 #
This whole issue will disappear as we transition to mirrorless. Since a mirrorless camera focuses on the same sensor used to record the image the mismatch between the image sensor and the focus sensor will vanish.
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