Lens Calibration (Page 5): Did you not read my earlier text that refutes that?

mwsilvers Loc: Central New Jersey

billnikon wrote:

Home kit calibrations correct focusing for one distance and one focal length. Not an ideal way to calibrate a lens.

Did you not read my earlier text that refutes that?

TriX Loc: Raleigh, NC

billnikon wrote:

Home kit calibrations correct focusing for one distance and one focal length. Not an ideal way to calibrate a lens.

The statement that the correction is only accurate for one distance and may make it impossible to focus on infinity has been made many times in the past, but it's only that - an untested statement. If you'll look at the link I posted on page 1 of an actual test, you'll see real data of correction vs distance, which demonstrates that in this test, neither assertion is correct. If you or anyone else has actually tested this often repeated assertion, and found the opposite, then please post the actual data.

BTW, Canon allows two corrections on a zoom lens. Would it be better to have a dozen corrections in FW for every zoom? You bet, and some after market lenses provide multiple points, but is 1 or 2 corrections better than nothing? It is, and if you doubt that, look at the second link I posted of a focus target for a Canon 135 f2L taken both with and without correction. Can you see the difference?

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

mwsilvers wrote:

Did you not read my earlier text that refutes that?

Look, you believe lens calibration is great, I do not believe in lens calibration. I will leave this thread at that. No further comment is needed by either of us.

mwsilvers Loc: Central New Jersey

TriX wrote:

The statement that the correction is only accurate... (show quote)

Let's not forget that newer Tamron and Sigma zoom lenses have 16 separate distance and focal length settings. My Sigma 18-35m f/1.8 mounted on my Canon 7D Mark II went from excellent to extraordinarily sharp after spending what seemed like a very long time calibrating it. But, the effort was worth it.

mwsilvers Loc: Central New Jersey

billnikon wrote:

Look, you believe lens calibration is great, I do not believe in lens calibration. I will leave this thread at that. No further comment is needed by either of us.

There is no right or wrong here. It's whatever works for you. But I would be remiss in not asking you if you have ever tried to calibrate your lenses? A lot of people do try, but give up too soon because of the effort and attention to detail required. By the way, your images are excellent. I see you don't store the originals or include EXIF data so its difficult to tell from the thumb nails whether there is a potential for your images to be sharper if the lenses were calibrated. But, since you sell your images I certainly understand not wanting to post high resolution copies. In addition, although I don't know what lenses or apertures you normally use for most of your images, calibration is most critical for faster lenses shot wide open. When stopped down to f/8 to f/16 the improvement in sharpness may not be obvious or significant in many situations

RRS Loc: Not sure

mwsilvers wrote:

Let's not forget that newer Tamron and Sigma zoom lenses have 16 separate distance and focal length settings. My Sigma 18-35m f/1.8 mounted on my Canon 7D Mark II went from excellent to extraordinarily sharp after spending what seemed like a very long time calibrating it. But, the effort was worth it.

Hey guys, it seems that billnikon has a good thing going for him and that's great. Isn't strange though that the lady that does his printing sees that those files could benefit from sharpening, maybe she has better eyes, and her expertise in printing could be the difference. I wish that all my cameras and lenses were as sharp out of the box as Bills but sadly they weren't and my photography has benefitted from all my time making corrections. Different kinds of cameras all being used by different people with different results, if it works for you then go for it. Some things will never change.

marionhughes

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TriX Loc: Raleigh, NC

billnikon wrote:

Look, you believe lens calibration is great, I do not believe in lens calibration. I will leave this thread at that. No further comment is needed by either of us.

I'm good with that - we can agree to disagree like gentlemen.

Cheers,
Chris

OnDSnap Loc: NE New Jersey

abc1234 wrote:

An open question. For those of you who said your ... (show quote)

I too use the Reiken FoCal Pro software, very easy to use once you get set up...Took me about a day to do all my bodies and lenses, worth every minute.

OnDSnap Loc: NE New Jersey

TriX wrote:

I'm good with that - we can agree to disagree like gentlemen.

Cheers,
Chris

And that's fine... Me,I always believed in a slogan I've used in business for 40 yrs., "Good isn't enough when better is possible"

RRS Loc: Not sure

OnDSnap wrote:

I too use the Reiken FoCal Pro software, very easy to use once you get set up...Took me about a day to do all my bodies and lenses, worth every minute.

Thanks, I almost bought that software until I read all of the reviews on B&H. The other problem is I believe that you need to be tethered to the computer to make it work. That would work I think for my short to normal lenses but cause a major problem for my long lenses. Any thought would be much appreciated.

TriX Loc: Raleigh, NC

RRS wrote:

Thanks, I almost bought that software until I read all of the reviews on B&H. The other problem is I believe that you need to be tethered to the computer to make it work. That would work I think for my short to normal lenses but cause a major problem for my long lenses. Any thought would be much appreciated.

During calibration, the camera needs to be tethered to the computer via a USB cable (15’ max for a passive cable) and the target distance varies depending on the FL. On the shortest FLs, the ideal distance for the target may only be 6’, while for 600mm, it may be 35’. Whether you can accommodate a 35’ unobstructed view from your camera to the target indoors depends on the interior dimensions and arrangement of your house, but if you have a laptop, simply take it and the camera outdoors and do your calibration for your longest lens there.

RRS Loc: Not sure

TriX wrote:

During calibration, the camera needs to be tethere... (show quote)

Thanks, is 35' actually doable for a 600mm lens. With what I am doing now it's more like 100'. I could actually shoot out of my office window at a target set up outside after shutting off the heat to this room to account for heat distortion. Has the program shut down half way through an alignment, that seem to be a common complaint?

OnDSnap Loc: NE New Jersey

RRS wrote:

Thanks, I almost bought that software until I read all of the reviews on B&H. The other problem is I believe that you need to be tethered to the computer to make it work. That would work I think for my short to normal lenses but cause a major problem for my long lenses. Any thought would be much appreciated.

The Laptop stays where the camera & tripod is located, I do have 15' & 25' tethers (which either one works) but you need only a 8'-10' patch cable. Like I said the tripod and camera are in the same local as the laptop so that's not an issue. Fortunately my son in law is a teacher and I get to use the gym or hallways in one of the schools he teaches for when I need to check the longer glass. Concrete floors, zero wind and I use Luma Cube/s to assure I have sufficient lighting to light the target. I'm sure your local school would allow you to utilize a hall way after school hours while the janitors are cleaning up...Or perhaps a mall on a Sunday morning that allows joggers in for an early run.

TriX Loc: Raleigh, NC

RRS wrote:

Thanks, is 35' actually doable for a 600mm lens. With what I am doing now it's more like 100'. I could actually shoot out of my office window at a target set up outside after shutting off the heat to this room to account for heat distortion. Has the program shut down half way through an alignment, that seem to be a common complaint?

One of the features that I really like other than calibration is that you can profile the acuity vs aperture. Not only does it show the “sweet spot” of the lens and where diffraction sets in, it gives you an accurate measurement of the lenses acuity, so you get a feel for which of your lens are the sharpest (and at what FL for zooms), and you can immediately tell if a lens is up to snuff (ie: you got a bad or mediocre copy). If takes all the subjective judgements out of both that and the calibration process, so you get solid, objective measures. I have also found it to be repeatable and accurate (comparing the suggest calibrations to real tests of a resolution target).