lmTrying Loc: WV Northern Panhandle

Ok, Maybe my thinking is flawed here.
I have done a little horseback riding. Not much, but I know that even when the horse is standing still, it is still moving, breathing, shifting, seating flies.
I also know that landscape photography requires max Depth Of Field (opposite of f1.8).
But would the fast f1.8, stopped down for DoF not bring in more light so that she can set the shutter faster to freeze shake (when the horse moves).
If I'm wrong here, will someone please explain it to me. I will apologize ahead of time if I messed up an if I confused anyone.

tdekany Loc: Oregon

F8 is F8 no matter how fast the lens is as far as light

Jaackil Loc: Massachusetts

Not exactly. As had been pointed out F8 is F8 no matter what the lens or its speed. A 1.8 lens lets in the same amount of light at F 8 as a 5.6 lens at F8. The reason people are recommending the 1.8 35 or 50 mm. Is they are relatively small and light. They are considered "normal" which means their feild of view is close to what the human eye sees. They both auto focus reasonably fast They are both pretty inexpensive. Most important they are extremely sharp glass. Personally I think this is a case where the P&S is a better choice or the 18-55 kit lens which is light inexpensive and gives a wider feild of view which is preferred for landscapes.

blackest Loc: Ireland

Totally true, but there is an assumption being made here, that f1.8 gives a shallow depth of field. No doubt that it can when focusing on near objects but there is something known as the hyperfocal distance this is a function of focal length and aperture. It's the distance where from that point to infinity is in focus and 1/2 that distance is also in focus (yes i know you know that but others might not).

I have attached 2 hyperfocal distance charts for 50mm and 35mm lenses. Lets take a look at f1.8 for the 2 lenses 228 feet and 112 feet with near focus points of 114 feet and 55.9 feet. For scale an American football field is 360 feet by 160 feet (an articulated lorry is about 54 feet)

90mm at f2.8 is 475 feet and for 135mm at f2.8 1068 feet. F2.8 seems a reasonably fast lens for these longer focal lengths.

Lets assume a sunny day 15 EV base iso of 100 and look at the shutter speed for f1.8 it's actually faster than 1/8000th to get 1/8000th at iso100 requires stopping down to f2. Also F8 at iso 100 would still give a shutter speed of 1/500th which should be fast enough to get an infocus shot on the back of a horse with a 50mm It might still be practical at 1/250th, i guess that depends on the horse.

So really this tells us a telephoto lens is going to be pretty useless in this situation a 50mm is pretty useful but the 35mm would be better. The kit 18 to 55 while being slower than the 35 or 50mm lenses should still be fast enough in good light. I think the best lens would be the 35mm but the slight zoom of the 50mm wouldn't be too bad either.

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DavidPine Loc: Fredericksburg, TX

I attempted shooting from horseback and found it difficult under any circumstances. Maybe a pocket camera like the RX100.

Lowrider Loc: Kennesaw, GA

Last year I spent 3 full days horse back riding in Utah. The dessert, the plains then the mountains. I took a 18-55mm and it worked perfectly. It got most shots right, which are landscapes and a good job up close. It was easy to manage on the horse but I took a belly bag and put the camera in it when I wasn't taking pictures like during showers in the mountains. You can also include a few accessories like lip ice or Aleve for the old posterior after the second full day.

blackest Loc: Ireland

So to be fair it depends on the cooperation of the horse :) Be nice to the horse ...

CindyHouk Loc: Nw MT

What a fun trip that would be. This old posterior is used to the saddle sores...lol We did a 10 day 80 mile round trip thru the Bob Marshall wilderness -- now that made my back side a little sore!

Mil

AGREE!