Question about the Canon Rebel XTi

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Martin

Lifer
Jan 15, 2000
29,178
1
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Originally posted by: PokerGuy
Originally posted by: Martin
The sensors on DSLRs are physically much larger compared to crappy P&Ss. The Rebel has a 3.3cm^2 sensor, while your old P&S probably had something around 0.3cm^2. Being so large is one of the reasons dslr sensors can produce such fine pictures, however their power consumption is huge so if they are used for live preview, battery life would be abysmal. So you're left with a choice: crappy pictures and lcd, or great pictures and viewfinder.
Now that makes sense. Too bad, because the pics that my wife is showing me are amazingly sharp. She's taken some with difficult lighting (as the sun's going down etc), but the pics are terrific. This camera is growing on me now that I've toyed with it a little.

LCD preview is great on P&S, since their viewfinders don't correspond exactly to the picture that will be taken, but when your viewfinder goes through the lens (as in SLRs) the LCD becomes mostly useless. I know I don't miss that feature at all...
 

JulesMaximus

No Lifer
Jul 3, 2003
74,589
986
126
Originally posted by: Martin
The sensors on DSLRs are physically much larger compared to crappy P&Ss. The Rebel has a 3.3cm^2 sensor, while your old P&S probably had something around 0.3cm^2. Being so large is one of the reasons dslr sensors can produce such fine pictures, however their power consumption is huge so if they are used for live preview, battery life would be abysmal. So you're left with a choice: crappy pictures and lcd, or great pictures and viewfinder.

I'd be more inclined to believe the overheating myth than this one. You cannot view an image TTL with a DSLR because the mirror and the shutter are blocking the image from the sensor. What you are looking at through the viewfinder is what you will see after you depress the shutter.

I've owned a few SLR cameras and a couple DSLR cameras, I know how they work...and your points are just plain wrong. You cannot use the sensor for live preview on a DSLR camera...at least not a Canon or Nikon (two of the best in the business).

BTW-I can get days of shooting out of a battery in my DSLR. Battery life is far superior to any P&S camera.
 

FilmCamera

Senior member
Nov 12, 2006
959
1
0
*sigh*

I think that a camera that has your "basic feature" of LCD preview of what you are shooting, but has a crappy viewfinder (e.g. just about every P&S out there) is a showstopper, not vice versa.

And...if your wife loves it and is going nuts with it...why take it back?

:confused:
 

tfinch2

Lifer
Feb 3, 2004
22,114
1
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Get the Olympus E-330. It has an optical viewfinder, and a nice huge display on the 2.5" LCD.
 

FilmCamera

Senior member
Nov 12, 2006
959
1
0
Originally posted by: tfinch2
Get the Olympus E-330. It has an optical viewfinder, and a nice huge display on the 2.5" LCD.

That might be a good choice for his wife. Though I prefer Canons. However the Rebels and the Olympus are too small for me. I like a good sized grip for my hand.
 

NaOH

Diamond Member
Mar 2, 2006
5,015
0
0
WOW.....I declare ban on lack of any camera knowledge before throwing down nearly a grand..........just WOW
 

PokerGuy

Lifer
Jul 2, 2005
13,650
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Originally posted by: FilmCamera
*sigh*

I think that a camera that has your "basic feature" of LCD preview of what you are shooting, but has a crappy viewfinder (e.g. just about every P&S out there) is a showstopper, not vice versa.

And...if your wife loves it and is going nuts with it...why take it back?

:confused:
I'm not going to take it back anymore, under threat of bodily harm from the wife.
 

fuzzybabybunny

Moderator<br>Digital & Video Cameras
Moderator
Jan 2, 2006
10,455
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Originally posted by: Kalvin00
Originally posted by: JulesMaximus
Originally posted by: Kalvin00
lol, you can't do that

It has to do with the sensor of it overheating, I think. Same reason DSLRs don't do video.

Actually, that's not true. When you look through the viewfinder of a single lens reflex camera you are are actually viewing through the camera's lens. There is a mirror that flips up when the shutter is depressed and that (basically) exposes the image sensor to what you are looking at through the lens.

Ok. Somewhere I read that it overheated, guess whatever site it was, was wrong.

I think both of you are right, to a point.

DSLRs don't do live LCD preview because the mirror is blocking the sensor. Ok... but if you flip up and lock the mirror, it will no longer be blocking the sensor, so this reasoning is a bit off, although not entirely.

DSLRs don't do live LCD preview because the sensor will overheat itself from constantly being on. On Medium Format digital backs this is true. These cameras have to use peltiers to cool their sensors, like people do with CPUs when they're doing extreme overclocking. However, Non-Medium Format DSLRs will not do this. People take star trail pictures all the time with DSLRs, and these pictures require the sensor to be on and the mirror up for HOURS at a time.

Battery Life: Kinda. Leaving the mirror up and the sensor active, power draw is not linear. I'm not sure why, but the rate of power draw actually starts to increase the longer the mirror is up and the sensor is left active. This is a problem that astrophotographers have to contend with, but it's not too much of a problem with current high capacity batteries. Still, a battery that can operate a camera normally for two weeks on a single charge will be nearly empty after a single night of astrophotography.

There are many reasons why using the same sensor for both picture-taking and preview is difficult.

1. Metering. SLRs meter the picture when the mirror is down. There is a metering mechanism located in the viewfinder area. If you flip up and lock the mirror, there is no light entering this metering area because it's all hitting the sensor. There would then have to be an additional, seperate sensor-based metering system.

2. Autofocus. SLRs autofocus when the mirror is down. Like the metering, the focus determination mechanism is located in the viewfinder area. With the mirror locked up, all the light is hitting the sensor, so there would have to also be an addition, seperate sensor-based focus-detection system on top of the viewfinder-based system.

3. Engineers would have to find a way to get their pretty 8MP+ sensors to record constantly only low-quality images. This may require more processing power in the camera to downsize 30 images a second on the fly or require a redesign of the sensor to "lump" pixels together.

4. With all this additional processing, power and heat may now become a serious problem.
 

Martin

Lifer
Jan 15, 2000
29,178
1
81
Originally posted by: JulesMaximus
Originally posted by: Martin
The sensors on DSLRs are physically much larger compared to crappy P&Ss. The Rebel has a 3.3cm^2 sensor, while your old P&S probably had something around 0.3cm^2. Being so large is one of the reasons dslr sensors can produce such fine pictures, however their power consumption is huge so if they are used for live preview, battery life would be abysmal. So you're left with a choice: crappy pictures and lcd, or great pictures and viewfinder.

I'd be more inclined to believe the overheating myth than this one. You cannot view an image TTL with a DSLR because the mirror and the shutter are blocking the image from the sensor. What you are looking at through the viewfinder is what you will see after you depress the shutter.

I've owned a few SLR cameras and a couple DSLR cameras, I know how they work...and your points are just plain wrong. You cannot use the sensor for live preview on a DSLR camera...at least not a Canon or Nikon (two of the best in the business).

BTW-I can get days of shooting out of a battery in my DSLR. Battery life is far superior to any P&S camera.

Well, overheating and high power consumption are pretty much the same thing. If there was enough power and cooling, there is nothing to stop you from just lifting the mirror and feeding the video to the LCD. You would not be able to use both LCD and viewfinder, but there is hardly a reason for that...
 

Stan

Senior member
Jan 4, 2005
614
0
0
"Well, overheating and high power consumption are pretty much the same thing. " == lol.
 

kami333

Diamond Member
Dec 12, 2001
5,110
2
76
Originally posted by: Gooberlx2
Originally posted by: Kalvin00
lol, you can't do that

It has to do with the sensor of it overheating, I think. Same reason DSLRs don't do video.

No, it has to do with the fact that the mirror which reflects TTL viewing into the viewfinder is blocking the sensor. The reason olympus has accomplished feature (on their e-550 i think) this is because they have a second sensor in the view finder itself.

It's a moot point because the way a SLR should be held for good pictures (aka not point and shoot) would negate the advantage of having the feature.

edit: Beat ya to it Jules. :p :D

That depends on the situation and what you effect you are going for.

Situations where I wish I had a tiltable live preview LCD:
Shooting overhead in a crowd (I've resorted to shotgunning)
From a ground level perspective (my gf pretends not to know me whenever I start crawling on my hands and knees with my camera, you get some interesting viewpoints but I've gotten tripped over/stepped on a couple times)
Street photography (holding a DSLR to your face is definately not discreet)
Tripod work (including when doing panoramas)

I think people tend to forget that the mirror and viewfinder in a SLR/DSLR is a mechanism that was invented to get around a physical problem, there's no reason to stick to it just for "tradition" once we can make a new mechanism like EVF (almost there, maybe a couple more years for perfection)
 

mugs

Lifer
Apr 29, 2003
48,920
46
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Originally posted by: PokerGuy
Yipes... thanks for the info folks, I'll be returning this junker today. Even my old 5 year old 3 MP nikon had an LCD on it where you could see what you were shooting, but yet these $800 cameras can't accomplish the same thing? I'm sure there's logical reasons for it, but that's pretty crappy. Oh well, off to read a little bit and see what camera I should get instead.

Oh my... I think both you and the camera are better off that way. A DSLR is wasted on you. ;)
 

technophile82

Senior member
Jun 5, 2005
238
0
0
wow this thread was amusing. although, i went from a canon point-and-shoot to a rebel XT and was looking for a display on the lcd myself, i wasnt really as bothered by it as much as the OP was. 9000 pictures later, i have 3 lenses (other than the kit), and i sold my XT to upgrade to a 30D. once you go DSLR, youll never look back.
 

soydios

Platinum Member
Mar 12, 2006
2,708
0
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First, the XTi is NOT a junker.

The whole point of a Single-Lens Reflex camera is that you see exactly what image will be recorded through the viewfinder. There is no LCD preview option because the sensor doesn't receive any light until after you hit the shutter release and the mirror moves up and out of the way.

My advice: do a little more research on what getting a Digital SLR entails. It's a helluva camera, you just need to know some photography basics to get the most out of it. Once you do, you'll be stunned.

I have a Nikon D50, and I'm in love with the thing. Battery life is epic, image quality is amazing coming from a point-and-shoot, low-light without a flash is great. But, I got the DSLR so I could have creative control over my photographs.
 

PokerGuy

Lifer
Jul 2, 2005
13,650
201
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Originally posted by: mugs
Oh my... I think both you and the camera are better off that way. A DSLR is wasted on you. ;)
Originally posted by: Mike
Wow, good call on returning it. Don't think you have the capacity to use a DSLR right now.

No doubt a DSLR is wasted on me, and no doubt I really can't take advantage of it's great features..... but it's not meant to be used by me, it's meant to be used by my wife --- and she will use it properly and be able to take advantage of it's features.

This thread has been informative, I appreciate the comments and info.

I am surprised that there hasn't been more progress toward a mainstream EVF yet, I guess there have to be some serious technical / engineering issues to overcome.

The camera is definitely not a 'junker' in the sense of it's quality or capability, it's just missing (what is to me) a big feature.

 

fuzzybabybunny

Moderator<br>Digital & Video Cameras
Moderator
Jan 2, 2006
10,455
35
91
Originally posted by: PokerGuy
I'm not going to take it back anymore, under threat of bodily harm from the wife.

Hehe, I can just picture it.

PokerGuy: I'm taking it back!

Wife: NOOOOO *roundhouse kick*

/PokerGuy
 

randomlinh

Lifer
Oct 9, 1999
20,846
2
0
linh.wordpress.com
some people need to read the thread... the OP was getting drilled after he already admitted he didn't quite understand SLR's... heh.

kudos to your wife, and good idea to listen to her :)
 

91TTZ

Lifer
Jan 31, 2005
14,374
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Originally posted by: randomlinh
some people need to read the thread... the OP was getting drilled after he already admitted he didn't quite understand SLR's... heh.


But it's more fun to bash somebody for 15 pages, even if they corrected their mistake on the third post of the thread.
 

mugs

Lifer
Apr 29, 2003
48,920
46
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Originally posted by: PokerGuy
I am surprised that there hasn't been more progress toward a mainstream EVF yet, I guess there have to be some serious technical / engineering issues to overcome.

I think it's because photographers don't WANT it. My eye has a "resolution" far higher than 320x240 or whatever the resolution of those little LCDs are. I can see a picture much more clearly through the viewfinder (on a DSLR) than on the LCD on the back. I can't even tell if my picture is a little blurry on the little LCD, so how am I supposed to know if it is correctly focused? DSLR photography is a world apart from point and shoot photography... you and your wife need to do some reading on the basics. :)