85mm 1.8 - A few questions

keith204

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Alllright, race season is coming up, and I am looking for a way to take better pictures. Primarily, faster pictures would be nice! At the track, flash is hard to use, becasue it lights up the dirt floating through the air. So, max aperture is critical. I currently ONLY shoot with my 70-200 2.8, at 2.8. Currently, I also shoot at the wider end of that focall ength, between 70-100mm primarily. So, 85mm would be a fine focal length. Another fact...I use AI servo a LOT, so I need a good, accurate, fast-focusing lens.

Questions:
  • Does the 85mm 1.8 have a fast, accurate focus?
  • Has anyone used the 85mm 1.8 for action photos?
  • What type of shutter speed increase would I be looking at? For instance... if the ambient light provided 1/60 at f/2.8, ISO 1600... whatabouts would the shutter speed be at f/1.8 and ISO 1600?
  • Is the 85mm sharp at 1.8?
If you have experience, let me know! Thanks!
 

newrmdmike

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my nikon 85 1.8 doesn't have that fast of focus i feel like, at a distance its reliable, up close its less accurate, but its easy to focus manual, and to tell when its not perfectly focused.

if at 2.8 ur getting 1/60 then at 1.8 you would get 1/250th (is that right? or is it not a full stop from 2 to 1.8?)

i would shoot f/2 its not as shart at 1.8

i love my 85 1.8
 
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keith204

keith204

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my nikon 85 1.8 doesn't have that fast of focus i feel like, at a distance its reliable, up close its less accurate, but its easy to focus manual, and to tell when its not perfectly focused.

if at 2.8 ur getting 1/60 then at 1.8 you would get 1/250th (is that right? or is it not a full stop from 2 to 1.8?)

i would shoot f/2 its not as shart at 1.8

i love my 85 1.8

1/250th? That's amazing! For reals? I'm not totally sure how stops work.
 

kundalini

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I have the Nikkor 85mm f/1.8 and am very pleased with the color and contrast it gives. 9 blades and gives nice bokeh. I haven't tried to use in action situations, but the focus speed works well enough for me. I tend to use it at f/2 to f/2.8 more often because I find it sharper than at f/1.8. One more advantage is the smaller size and lighter weight than lunking a zoom around.
 

ThomThomsk

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f/1.8 and f/2.8 are one and a third stops apart. f/2 and f/2.8 are a whole stop. So 1/60th at f/2.8 gives you a theoretical 1/170th at f/1.8.
 

Big Mike

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It is a USM lens, so the focus should be pretty good. I couldn't tell if it's 'Ring USM' (the good type of USM) though.

Focus speed also has a lot to do with the camera, since it's the camera that tells the lens what to do.
 

newrmdmike

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thoms right, i knew it wasn't quite 2, but didn't know exactly how much.
 

dipstick

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I don't know what kind of races you shoot, but what about DOF? 1.8 will give you a pretty shallow depth of field, not always suited for action shots.

A prime can also be limiting in terms of getting the compositions you want when you are unable to change your distance from your subjects.
 

Deadeye008

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Are we talking about Nikon or Canon here. The canon 85mm 1.8 has the "ring USM" so it should be very fast. Just as fast as your 70-200 2.8 USM(if it's canon) I would imagine.
 

schumionbike

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If you get the 85 mm 1.4 then you'll get the 1/250 shutterspeed. 1.4 and 2.8 are two full stop apart.
 

JerryPH

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1/250th? That's amazing! For reals? I'm not totally sure how stops work.

The concept is simple... every time you open a full stop, it doubles the light so you can half the speed.

If at F/2.8 you were shooting at 1/60th, then at F/1.8 you would be at 1.5 stops faster... so, from 2.8 at 1/60th you go to 2.0 and 1/120th... and to 1.8 you go to 180th, since thats a 1/2 stop. The full stop is an F/1.4 and thats where you would get 1/250th.

Full stops are:
1.4, 2.0, 2.8, 4, 5.6, 8, 11, 16, 22, etc...
 
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keith204

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I don't know what kind of races you shoot, but what about DOF? 1.8 will give you a pretty shallow depth of field, not always suited for action shots.

A prime can also be limiting in terms of getting the compositions you want when you are unable to change your distance from your subjects.

DOF will be a problem with this. Looking back through the pictures, a common problem is the front of the car being in focus, but the back being out of focus. Great point.

Are we talking about Nikon or Canon here. The canon 85mm 1.8 has the "ring USM" so it should be very fast. Just as fast as your 70-200 2.8 USM(if it's canon) I would imagine.

A quick search of the threads he has started,and you'll see he is talking Canon.

http://www.the-digital-picture.com/Reviews/Canon-EF-85mm-f-1.8-USM-Lens-Review.aspx

That should tell you everything you need to know. (It's ring USM by the way, so it'll focus as quick as you 70-200 if you bought a Canon model)

I have a Sigma 70-200 f/2.8, which has HSM and focuses pretty fast.

The concept is simple... every time you open a full stop, it doubles the light so you can half the speed.

If at F/2.8 you were shooting at 1/60th, then at F/1.8 you would be at 1.5 stops faster... so, from 2.8 at 1/60th you go to 2.0 and 1/120th... and to 1.8 you go to 180th, since thats a 1/2 stop. The full stop is an F/1.4 and thats where you would get 1/250th.

Full stops are:
1.4, 2.0, 2.8, 4, 5.6, 8, 11, 16, 22, etc...

Thanks! This makes a whole bunch more sense. I assume the same still applies with ISO...ISO 100, 200, 400, 800, 1600, etc...is this so?

Thanks for the specific advice everyone.
 

frXnz kafka

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The concept is simple... every time you open a full stop, it doubles the light so you can half the speed.

If at F/2.8 you were shooting at 1/60th, then at F/1.8 you would be at 1.5 stops faster... so, from 2.8 at 1/60th you go to 2.0 and 1/120th... and to 1.8 you go to 180th, since thats a 1/2 stop. The full stop is an F/1.4 and thats where you would get 1/250th.

Full stops are:
1.4, 2.0, 2.8, 4, 5.6, 8, 11, 16, 22, etc...

Isn't 1.8 a third stop? I believe 1.7 is the half stop. So he'd be shooting at 1/160th
 

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