Why......... - DPChallenge Forums

Nikon AF-S DX NIKKOR 18-200mm f/3.5-5.6G ED VR II

09/11/2007 06:30:23 PM · #1

would Canon put live preview on the 40D and then make it so you could only manual focus while using it? What's so tough about autofocus with live preview? P&S cams do it. Nikon I hear has live preview with autofocus.

EBJones

Nikon D200

09/11/2007 06:42:28 PM · #2

Sounds like Nikon envy. . . . try this!

:)

slickchik

OM System OM-1

Olympus 12-40mm f/2.8 Pro

09/11/2007 06:52:28 PM · #3

Yeah, why is that!?

Canon EF-S 18-55mm f/3.5-5.6 II

09/11/2007 07:05:18 PM · #4

Originally posted by EBJones:

Sounds like Nikon envy. . . . try this!

:)

That's a funny ad Amazon has there. You can buy a Nikon D300 and a Canon 40D together for $3199.85. Must be an ad for the wishy-washy type that can't make up their minds.

Message edited by author 2007-09-11 19:06:58.

surfdabbler

Canon EOS-5D

09/11/2007 07:09:10 PM · #5

The reason is related to the way autofocus works on an SLR. The autofocus system is built into the SLR part of the camera. The mirror reflects the light away from the sensor/film to the viewfinder, and part of the viewfinder beam is split off to the exposure metering and focussing circuits. So, to activate autofocus, it has to drop the mirror to send some light off to the autofocus bits.

P&S cameras work totally differently, using the image signal that comes out of the sensor, algorithms are used to run the autofocus based on contrast detection. I don't know if it's better or worse either way.

Some live preview systems work on the main sensor with the mirror out of the way. Other live preview systems have a seperate video sensor in the viewfinder, which circumvents the problem by allowing all the systems to work as normal while the video is also taken from the viewfinder.

Nikon have taken the route of using 2 seperate autofocus systems, the normal one for the mirror down, and a seperate contrast system for live preview mode. I believe the seperate contrast system is actually slower than dropping the mirror, but it does maintain the live preview.

I guess Canon figured that dropping the mirror was quicker anyway, so they just skipped the contrast detection method. I don't know what the blackout time is, whether it is significant.

Canon EF 100-400mm f/4.5-5.6L IS

09/11/2007 10:16:08 PM · #6

Sounds logical to me. Thanks

chip_k

Canon EOS-20D

09/11/2007 11:06:22 PM · #7

Does the live preview cut off when you press the shutter button to get the AF or does it stay off unless you set your lens to Manual?

I'm hoping that it only temporarily cuts off so that I can use the rear AF button to get in the ballpark and then (fairly quickly) use the focus ring on the lens along with the live preview to get it nailed.

Is this plan going to work?

slickchik

OM System OM-1

Olympus 12-40mm f/2.8 Pro

09/11/2007 11:13:32 PM · #8

Originally posted by chip_k:

I push the "set button" in the middle of the wheel to activate live view and I do not have to change the lens to manual focus for live view to work. AF does nothing when the shutter button is pressed with live view.

jmsetzler

Sony Alpha a6400

Sony 16-50mm f/3.5-5.6 (E-mount)

09/11/2007 11:46:21 PM · #9

I would just wonder why they would put live preview on the 40d to start with...

fotomann_forever

09/12/2007 12:07:14 AM · #10

Originally posted by jmsetzler:

I would just wonder why they would put live preview on the 40d to start with...

My guess is because focus group studies indicated it was a wanted feature.

jmsetzler

Sony Alpha a6400

Sony 16-50mm f/3.5-5.6 (E-mount)

09/12/2007 12:11:38 AM · #11

Originally posted by fotomann_forever:

Originally posted by jmsetzler:
I would just wonder why they would put live preview on the 40d to start with...

My guess is because focus group studies indicated it was a wanted feature.

I'm sure that's the case, but I just can't understand why. A true TTL viewfinder is one of the extreme advantages of having an SLR. I'm sure the preview you get on the LCD is TTL, but why would someone want to look at that LCD when they can view directly through the lens?

I guess it's just a crutch that makes upgrading to that camera easier for someone who is used to not having an eye-level viewfinder.

chip_k

Canon EOS-20D

Canon EF 100-400mm f/4.5-5.6L IS

09/12/2007 12:19:57 AM · #12

Originally posted by jmsetzler:

I would just wonder why they would put live preview on the 40d to start with...

It makes it a LOT easier to set up shots on a tripod for one. I certainly won't want it all the time, but I definitely can see it coming in handy.

Also, I'm not sure if this is a feature that made it to poorduction, but I heard that they were going to offer magnification on the live preview. So, you can check your focus at 4x, allowing you to really dial in your focus for extra-crispness.

chip_k

Canon EOS-20D

Canon EF 100-400mm f/4.5-5.6L IS

09/12/2007 12:21:00 AM · #13

Originally posted by fotomann_forever:

My guess is because focus group studies indicated it was a wanted feature.

You need a 2-day time out from the forums for that incredibly BAD pun!

ben4345

Nikon D700

Nikon AF-S NIKKOR 24-70mm f/2.8G ED

09/12/2007 12:26:29 AM · #14

Originally posted by NstiG8tr:

Originally posted by EBJones:
Sounds like Nikon envy. . . . try this!

:)

That's a funny ad Amazon has there. You can buy a Nikon D300 and a Canon 40D together for $3199.85. Must be an ad for the wishy-washy type that can't make up their minds.

ROFLMAO!!!!!!!

Bear_Music

Samsung Galaxy S24, S24+, S24 Ultra

Sony 24-70mm f/4 Vario-Tessar T* FE OSS

09/12/2007 01:28:57 AM · #15

Originally posted by chip_k:

Originally posted by jmsetzler:
I would just wonder why they would put live preview on the 40d to start with...

It makes it a LOT easier to set up shots on a tripod for one. I certainly won't want it all the time, but I definitely can see it coming in handy.

Also, I'm not sure if this is a feature that made it to poorduction, but I heard that they were going to offer magnification on the live preview. So, you can check your focus at 4x, allowing you to really dial in your focus for extra-crispness.

I thought I heard it will magnify 5x and 10x. 10x mag coupled with MF makes this a must for macro work on a tripod. For studio work in general, actually. I'm sure the live preview was designed with this in mind.

R.

fotomann_forever

09/12/2007 01:35:43 AM · #16

Originally posted by Bear_Music:

This might let me, with my poor vision actually do good macro work. Couple it with a laptop screen and I'm golden.

garrywhite2

Canon EOS-7D

Canon EF 24-70mm f/2.8L USM

09/12/2007 02:03:43 AM · #17

Originally posted by NstiG8tr:

If you enable C.FnIII - 6, when you press the AF-ON it will interrupt the Live View display and auto focus. Not sure if you have already tried this.

fotomann_forever

09/12/2007 02:09:37 AM · #18

Originally posted by chip_k:

Originally posted by fotomann_forever:
My guess is because focus group studies indicated it was a wanted feature.

You need a 2-day time out from the forums for that incredibly BAD pun!

Thank you :-)

crayon

Samsung Galaxy S24, S24+, S24 Ultra

09/12/2007 03:22:25 AM · #19

Originally posted by fotomann_forever:

Originally posted by jmsetzler:
I would just wonder why they would put live preview on the 40d to start with...

My guess is because focus group studies indicated it was a wanted feature.

or... maybe for the same reason why we have a BACKSPACE key when we already have the DELETE key.

roba

Canon EOS-5D Mark II

Canon EF 70-200mm f/2.8L IS USM

09/12/2007 04:25:58 AM · #20

Originally posted by fotomann_forever:

This might let me, with my poor vision actually do good macro work. Couple it with a laptop screen and I'm golden.

Actually - with the large LCD, you won't need the laptop. I tried this feature yesterday on a buddy's new 40D at work, and it absolutely rocked (like internal tethering).

So much, infact, that I bought one today. :O)