BebuLamar

You move to the same distance as if you were using the longer lens and then crop to get the head shoulders portrait.

selmslie Loc: Fernandina Beach, FL, USA

That's why we consider an 85mm lens to be a portrait lens, to reminds us that we need to back up for a head and shoulders shot.

JBRIII

In astrophotography they talk a lot about pixel # versus size. As number goes up, pixels become smaller and can't hold as many electrons. This can cause a pixel to fill up and spill over into other pixels called blooming. You can of course shorten your exposure time, but then you may lose dim objects. Although astro images can have a very wide range of bright and dim objects, I would think eventually the same sort of effects would happen with any image if pixels become too small as numbers increase but sensor size remains the same.

selmslie Loc: Fernandina Beach, FL, USA

I can understand where you are going with this but the "spilling over" metaphor is more appropriate for raw file limits.

What's more likely the case is that the light from the star is getting diffused as it passes through the atmosphere and it ends up getting recorded in several adjacent RGB pixels whereas it might have all landed on a single pixel if the image were recorded with less interference from the atmosphere.

Larger pixels will reduce the odds that this spread out light ends up appearing to bloom over several adjacent pixels.

The other issue is that, even if it is headed for a single pixel, when demosaicing the data under the color filter array, it will contribute to several adjacent pixels. The way to overcome this is to remove the color filter array and skip the demosaicing step. Of course, that leaves only a grayscale image.

User ID

Burghbyrd said EFFECTIVE focal length, which is factually flawless. But you jumped on him as if he had refered to ACTUAL focal length.

You simply did not read what was written and instead saw his statement through the filter of one of your favorite nits to pick. Acoarst, such an off the mark knee jerk response is in very faithful compliance with UHH Sacred Tradition.

Longshadow Loc: Audubon, PA, United States

Nailed that one.......

JBRIII

I'm just reporting what they say. There are makers, not minor players, who have cameras with anti-blooming tech.

selmslie Loc: Fernandina Beach, FL, USA

It's not clear who "they" are.

JBRIII

The camera manufacturers.

I know that discussions on how Astros cameras should be made is a very heated topic among even the biggest makers. These cameras are often cooled to well below ambient temps, are often B&W and cost us much as top of the line consumer cameras. For the longest time they were CCDs, but that has changed. Also, video is a popular way, with images then selected and stacked.

These cameras could be attached to a camera lens and used to construct a camera for everyday use, but they require a computer (PC, MAC, ?) to use and a filter wheel for any non black and white imaging. The result would be large, awkward, etc. and not useful for things that move.

selmslie Loc: Fernandina Beach, FL, USA

Which manufacturers? Maybe some links would help so it doesn’t just look like hearsay.

But the general idea is sensible. Larger pixels are less prone to noise.