Comparing sharpness of 16-80 to other lenses

Started 9 months ago | Discussions thread
Iuvenis Senior Member • Posts: 1,275
Re: Comparing sharpness of 16-80 to other lenses

HatWearingFool wrote:

Iuvenis wrote:

HatWearingFool wrote:

Iuvenis wrote:

biza43 wrote:

Ok, so we should expect actual performance from a lens to be not as good as the simulated data.

No, it's not as simple as that. For example, Lens Rentals' real world test of the Nikon 70-200 f2.8 gave better results than Nikon's simulated mtf charts. See these links:

However, Fuji lenses should be broadly comparable with other Fuji lenses using the same Fuji charts, so I think this exercise was still worthwhile.

Lens rentals themselves caution against comparing mtf charts from various manufactures and against their own. Everyone is measuring different ways. So you can compare Nikon to Nikon, but not Nikon to cannon or Nikon to lensrentals.

Lens rentals aren’t saying the Nikon lens is better than Nikon’s chart claims, they are just measuring differently.

But yes you should be able to compare Fuji generated graphs against each other.

From the site:

”It’s also important to not compare apples to oranges. In the old days lensmakers proudly displayed the MTF charts of their creations as measured in the lab. Not many manufacturers do that today (Zeiss and Leica are the only ones I believe). The other manufacturers present their data differently and use different methods to obtain it, so it can be misleading to compare MTFdata from two different manufacturers. The MTF chart may be computer generated from a theoretical model, or may only show part of the data we discussed above.”

I think you miss my point. I was responding to someone who was wondering if real world MTF results would be lower than theoretical MTF results.

You can't compare Lens Rentals test of the Nikon 70-200 against (say) Canon's MTF graph for their 70-200 f2.8.

You can compare Lens Rentals' mtf chart of the Nikon 70-200 and Nikon's theoretical mtf chart for the 70-200 and say that the Lens Rentals chart is better.

Given they are for the same lens, you can then say that theoretically modelled mtf, which is what most manufacturers use, is not necessarily higher than real-world mtf. It could be lower (and in the case I gave, it is)

You can’t compare Nikon’s modelled results to lens rental’s actual results for the same reason you can’t compare theirs to Cannon’s.

You don’t know how the conditions they are modelling compares to the conditions lens rentals are measuring. Not what they have included in their model.

No, you still don't get my point. The question was whether measured testing of a lens will inevitably result in an mtf chart that is worse than its manufacturer's theoretical mtf chart. The answer is no, because there is at least one lens for which this is not the case.

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