Numerical aperture meaningin physics

…microscope are determined by the numerical aperture (N.A.) of the objective. The N.A. is defined as the sine of half the angle of the cone of light from each point of the object that can be accepted by the objective multiplied by the refractive index (R.I.) of the medium in…

Numerical aperture meaningin optical

In this first run, at least, I’ve made the assumption that the vast majority of users in a brand forum are actually users of gear of that brand. On DPReview, users can elect to publish their brand ownership. Therefore, we can ask questions such as, how likely are owners of different brands to reveal what gear they own? Well, …

Super strong connection between Olympus and Panasonic – obviously! But beyond that, both Olympus and Panasonic owners are rather egalitarian, and seem to own all other brands to a nearly equal extent – even, or perhaps disproportionately, Pentax!

I should point out one thing, and that’s the fact that the strong relationship between Sony, Nikon and Canon is presumably at least partly fuelled by the fact that I selected the most “pro” forums for this first set. For those three brands, that means full frame only. It’s reasonable that a person having a preference for full frame cameras of one brand would also select a full frame camera as their back-up, and it might be of a different brand. When other (esp. APS-C) forums are included, things will probably get a bit more diverse than this.

Numerical apertureformula

Canon users, by contrast, have very little experience of other systems – quite a bit less than even Nikon! Sony, again, provide a contrast with Canon, having perhaps absorbed some switchers still holding on to older gear. I find this fascinating as Canon users were previously demonstrated to have poor memory skills. So let’s look at their brand allegiances first.

It seems that Fujifilm users, at least the ones on DPReview forums, are most knowledgeable about other brands. Given that Fujifilm X is still a relatively new system, I would guess that some of them are switchers that still own a previously bought camera.

Numerical apertureof optical fiber

Nikon users also love Sony more than anything else, although Canon, Fujifilm and Panasonic all make strong showings. Olympus is lagging behind.

Numerical apertureunit

What I did find interesting is that lots of forums show a strong connection with Canon gear, but the reverse is not really true, suggesting that those who are now active in those forums were Canon users in the past. Food for thought, I think.

And what do you know – if Canon users own a second camera, it’s often a Sony, a Fujifilm or a Nikon. How does it look from the Sony side?

Next we can ask, how much do owners of certain brands actually know about other brands at all? Do they, or have they, actually owned cameras of other brands, suggesting they know what they are talking about when criticising those other brands?

Numerical apertureof microscope

He designated the term numerical aperture (N.A.) as the measure of the objective’s ability to collect diffracted light and thus also of its power to resolve detail. On this basis it is obvious that the greater the magnification of the objective, the greater the required N.A. of the objective.…

Numerical apertureof lens

This is consistent with Sony users having slightly more gear to show off than others, or being keener to list it on the website. Also note that Sigma includes fixed lens cameras, which would be listed as a single item, while ILC+lens would be two items. So we don’t need to read too much into the Sigma item, other than to note that it might be the number of lenses (interchangeable or fixed) that drive the number of gear items. People do not seem to be aiming to own a particular number of items.

Not much to note yet, except the biggest different is between Sony (59%, proud to show, apparently) and Canon (51%, a little more secretive). These two groups often argue over video features, colour science, and which autofocus is faster and more accurate – perhaps there is a further cultural difference hinted at by the above data that further drives that conflict.

I’m embarking on another data science project to try and find out if there are any particular patterns in what cameras people own, if they own more than one brand. To do this, I’ve once again used the DPReview user data as a basis, in this first pilot run obtaining data from just shy of 200 users from each of six brand-oriented forums – so the data was pre-segmented for me by users being active in one or several brand-themed forums.

…a microscope is called the numerical aperture (NA) and is equal to the sine of half the angle subtended by the aperture at an object point times the index of refraction of the medium between the object and the objective lens. For binoculars, telescopes, and photographic lenses in which the…

The picture is almost identical to Sony, except that the connection with Pentax is stronger. So let’s see if the Pentax crowd feels the same way about Fujifilm.

That specifically means looking at the effect of including Ricoh in the Pentax counts, including data from the non-pro/FF Nikon and Canon forums, and implementing distinctions between Sigma cameras and lenses, and “Panasonic Leica” vs. Leica products (M mount etc.). Maybe I’ll even get around to doing compacts, who knows? There is also the issue of distinguishing between those forum participants who actually have gear of that brand, and those who contribute their thoughts although their actual gear is of a different brand.