What's Up? Webcast: Understanding F Ratio

Рет қаралды 1,915

Күн бұрын

What's Up? Webcast: Understanding F Ratio
(Episode 149)
We take a look at F/ratios and understanding their function when it comes to telescopes. We take a look at how F/ Ratios affect visual as well as photography.
What's Up? webcast take place right here on the Sky-Watcher USA KZfaq channel every Friday from 10am to 11am Pacific.
For more information on Sky-Watcher products please visit www.skywatcherusa.com

Пікірлер: 10

@ronaldzincone841 10 ай бұрын

Another Skywatcher informative video with Kevin LeGore.

@michaeljarvis4612 4 ай бұрын

Extremely helpful video. Many Thanks.

@claudebaril9309 Жыл бұрын

Excellent. Thanks

@astralfields1696 Жыл бұрын

Finally someone explains the f ratio. Super important but often underestimated. You get your shiny new 4.7 10” DOB and then they are like ‘oh the comets? You need to spend an extra xxx$ to get rid of them’

@briankotak403 Жыл бұрын

Great explanation! Thanks for this. Dr B from Manitoba, Canada 🇨🇦

@halbohannon5908 Жыл бұрын

Outstanding !

@claudebaril9309 Жыл бұрын

I would have think that the image scale decreased by increasing the focal lenght and increase by decreasing the focal lenght ?

@claudebaril9309 Жыл бұрын

Unless we use Resolution for image scale ?

@DrJ_MKE Жыл бұрын

Does the use of a crop sensor DLSR need to be taken into account when calculating f-ratio? My f=420mm and 70mm aperture refractor is at f/6, so if the DSLR has a crop factor of 1.6, that changes the f=672, so would my actual f-ratio now be f/9.6?

@AntPDC Жыл бұрын

No. All the crop factor does is change field of view - NOT focal length, nor focal ratio. The same amount of photons per pixel are hitting the sensor regardless of sensor size. Thus, if you have an f/2 lens for example, it remains at f/2 regardless of whether you are using a "full-frame" or "crop sensor" camera. Same principle applies to telescopes. Focal ratio doesn't care what kind of sensor lies behind the optics which define it.