I have a hell of a time getting a decent shot from live view so no
thoughts on your problem here.
Dave
On Fri, Mar 18, 2016 at 8:36 AM, Rick Womer <rickpic...@gmail.com> wrote:
> The strangest things about these AF experiments are:
>
> 1. Front-focusing on LiveView, which (I thought) sought to maximize the
> contrast of the image on the sensor, and thus should be IN FOCUS regardless
> of the lens in use; and
>
> 2. The 16-45 front-focusing with LiveView, and back-focusing with viewfinder
> AF.
>
> Thoughts?
>
> Rick
>
> On Mar 17, 2016, at 10:57 PM, Igor PDML-StR wrote:
>
>>
>> Larry,
>>
>> I do not know what is _typical_ for different Pentax cameras and lenses, but
>> from the general point of view, I fully agree with what David wrote.
>>
>> Think about it this way: you have a set of deviation parameters
>> for the camera C1= {c1, c2, c3,c4, c5... }, and then a set of "coupled"
>> (sort of "reciprocal") deviations for the lens L1= {l1, l2, l3, l4, l5, ...}.
>> The number you get for each lens is an average number that sort of minimizes
>> the combined deviations {(c1,l1),(c2,l2), (c3,l3),...}.
>> Since each of those individual parameters are essentially random,
>> for a different set C2, the way you will need to minimize the combined
>> deviations C2*L1 could be very different from that for C1*L1.
>>
>> So, in general, yes, for the best result, you want to calibrate each lens on
>> each camera.
>> However, I suspect that there will be some correlation. So,
>> your first scenario of calibration will give (with some good probability)
>> the result that on average [over all your lenses] is better than
>> in case you haven't adjusted the calibration at all.
>>
>> Igor
>>
>>
>> David Parsons wrote on Thu Mar 17 22:19:46 EDT 2016:
>>
>> The adjustments would only be similar if the two cameras were
>> absolutely the same. Tolerances will be different from body to body
>> and lens to lens, so you'd want to calibrate each lens to each body.
>>
>> On Thu, Mar 17, 2016 at 7:03 PM, Larry Colen wrote:
>>
>>> I have been thinking of posting a related question. When you determine the
>>> per lens focus adjustment for a lens on one camera, does that number tend to
>>> work on another camera, perhaps with a slight offset.
>>>
>>> For example if on camera 1 you have
>>> lens A +5
>>> lens B +2
>>> lens C -1
>>>
>>> would you use the same numbers? Or if lens A works out to be +4, could you
>>> assume that the corrections would be
>>> lens A +4
>>> lens B +1
>>> lens C -2
>>>
>>> Or do they end up just being totally random?
>>
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> http://photo.net/photos/RickW
>
>
>
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