Why it is called a "Reflex" camera

Nikon AF-S DX Zoom Nikkor 18-55mm f/3.5-5.6G VR

02/14/2008 09:38:15 AM · #1

My daughter was asking about my new camera, since it seemed odd to her that a camera that can take multiple lenses is called a SINGLE lens reflex. I explained to her about rangefinders and twin lens reflexes and why this made an SLR something different because you frame, focus and shoot all through the same lens. She then asked a very logical question about why then is my Canon S5 IS not an SLR, since it does all those function through the same lens. I did not have the best answer for her, but that got me researching it and the question seems to revolve around exactly what the term "reflex" refers to. I'm sure this is old news to many fols here, but I'm sure I'm not the only one that didn't know this bit of trivia.

Reflex Camera:
Camera that uses a mirror and prisms to reflect light passing through the lens into the viewfinder, showing the photographer the exact scene that is being shot. When the shutter button is released the mirror springs out of the way, allowing light to reach the film. The most common type is the single-lens reflex (SLR) camera. The twin-lens reflex (TLR) camera has two lenses: one has a mirror for viewing, the other is used for exposing the film.

Message edited by author 2008-02-14 09:39:07.

RainMotorsports

Nikon D60

02/14/2008 09:48:16 AM · #2

Very good question and just out of curiousity I went to wikipedia the inaccurate source of all the worlds information.

The only thing i found is the Mirror was listed as a "Reflex Mirror" in a diagram.

Tamron SP AF 28-75mm f/2.8 XR Di for Canon

02/14/2008 09:54:06 AM · #3

Wikipedia was the first place I looked as well. It gave an excellent description of SLR's and TLR's, but did not say exactly what makes it a "reflex". A quick google search turned that up, though.

LeeD

Canon EOS-30D

02/14/2008 10:37:29 AM · #4

I'll do a little more research, but it may be linked to the "Red" Reflex which is what is used in ophthalmology for refraction and certain retinal diagnosis. Overly simplified... the red reflex is what you see when a light strikes the retina (shows up in pictures as "red eye")

Spork99

OM System OM-1

Canon EF 100mm f/2.8 USM Macro

02/14/2008 10:37:39 AM · #5

Duh...Because the mirror "reflex" light.

;-)

fotomann_forever

02/14/2008 10:38:54 AM · #6

From the American Heritage dictionary:

Reflex ADJECTIVE:

1. Bent, turned, or thrown back; reflected.

Edit to add:

NOUN:

1.
1. Something, such as light or heat, that is reflected.
2. An image produced by reflection.
3. A copy or reproduction.

Message edited by author 2008-02-14 10:44:36.

LeeD

Canon EOS-30D

Tamron SP AF 28-75mm f/2.8 XR Di for Canon

02/14/2008 10:46:06 AM · #7

Originally posted by Spazmo99:

Duh...Because the mirror "reflex" light.

;-)

Actually that seems to be correct.

Single Lens.... the viewer and the "film" both use the same (singular lens) to view/capture the image. The image is "reflected" AKA reflex (as pointed out by Leroy) to the eye of the viewer. When the shutter is engaged, the mirror flips out of the way exposing the exact same image to the "film"

Message edited by author 2008-02-14 11:04:38.

Sony FE 24-105mm f/4 G OSS

02/14/2008 10:52:14 AM · #8

See how educational this place is?

MelonMusketeer

Nikon D7000

Nikon MF 50mm f/1.4

02/14/2008 11:06:56 AM · #9

Originally posted by Spazmo99:

Duh...Because the mirror "reflex" light.

;-)

Oh, thanks. I thought it meant that if you bonk your leg just below the knee with the camera while sitting that you leg will jump.

fotomann_forever

02/14/2008 11:12:17 AM · #10

Originally posted by MelonMusketeer:

Originally posted by Spazmo99:
Duh...Because the mirror "reflex" light.

;-)

Oh, thanks. I thought it meant that if you bonk your leg just below the knee with the camera while sitting that you leg will jump.

That too! :-D

JustinM

Sony Alpha a7 IV

02/14/2008 01:13:05 PM · #11

Originally posted by yospiff:

See how educational this place is?

Oh shoot, that's the reason this place isn't as exciting as it first looks. JK :)

Canon EF 100mm f/2.8 USM Macro

02/14/2008 02:08:52 PM · #12

Well to better answer your direct question. First let me say the S5 is a great camera but it is not a slr for one particular reason. The view finder is a TFT color LCD electronic viewfinder. Your seeing what the sensor and chip is translating not actually looking through the glass lens. Where as the G9 is a SLR with a fixed lense. It purely is based on if your looking through the lens or getting a digital reproduction. Hope this helps

Spork99

OM System OM-1

02/14/2008 03:35:27 PM · #13

Originally posted by coronamv:

WWhere as the G9 is a SLR with a fixed lense. It purely is based on if your looking through the lens or getting a digital reproduction.

No.

A Canon G9 is most definitely NOT an SLR camera. A rangefinder perhaps. Calling a camera "reflex" is based on the usage of a mirror/prism or, reflex system to reflect the image coming through the lens to the photographer's eye. It has absolutely nothing to do with the camera being digital or not.

Message edited by author 2008-02-14 15:35:47.

sabphoto

Samsung Galaxy S8/S8+

02/14/2008 03:38:13 PM · #14

and to throw a wrench in the puzzle...is the new olympus DSLRs, that allow you to compose with the back LCD or the eyepiece, still Single lens reflex or double?

02/14/2008 03:44:02 PM · #15

I would not consider the G9 to be an SLR either. Actually, I would consider it further away form an SLR than the S5 is because it has a rangefinder style viewfinder that is not even using the image coming through the main lens.

I do think digital is starting to blur the lines some. If someone comes out with an SLR class camera and the only difference is an electronic viewfinder of high resolution, is it an SLR? Technically not, but still functionally like one.

Canon EF-S 18-135mm f/3.5-5.6 IS STM

02/14/2008 03:45:24 PM · #16

Originally posted by sabphoto:

and to throw a wrench in the puzzle...is the new olympus DSLRs, that allow you to compose with the back LCD or the eyepiece, still Single lens reflex or double?

Well, if you are composing on the viewfinder, that technically makes it a point and shoot, doesn't it?

SteveJ

Canon EOS-7D

02/14/2008 03:49:44 PM · #17

I am no expert? But I was lead to believe that the 'reflex' part of a SLR/DSLR was the fact that the mirror springs up when the shutter button is pressed. So, it is down for focusing and composing, and lifts - a reflex - when shot is taken.

Just what I was told years ago.

Canon EF-S 18-135mm f/3.5-5.6 IS STM

02/14/2008 03:53:48 PM · #18

Originally posted by SteveJ:

I was lead to believe that the 'reflex' part of a SLR/DSLR was the fact that the mirror springs up when the shutter button is pressed.

That was my initial thought as well, though after reading up on it and discussing it here, I am now thinking it has more to do with the use of the mirrors and prisms to direct the light.

SteveJ

Canon EOS-7D

02/14/2008 03:59:29 PM · #19

Originally posted by yospiff:

Originally posted by SteveJ:
I was lead to believe that the 'reflex' part of a SLR/DSLR was the fact that the mirror springs up when the shutter button is pressed.

That was my initial thought as well, though after reading up on it and discussing it here, I am now thinking it has more to do with the use of the mirrors and prisms to direct the light.

This is the same thing, cause when the mirror lifts, the light is directed to the sensor/screen, rather than being directed via pentaprism or pentamirror to the eyepiece. The whole process of capturing an image on film or via a sensor is the use of light:)

02/14/2008 06:59:51 PM · #20

You better go look at the G9 it uses a slr system of viewing it just has a fixed lens. It is a single lens prismatic based viewfinder that reflexes to allow the sensor to capture what the viewer was seeing in real time.

02/14/2008 07:22:17 PM · #21

Originally posted by coronamv:

I looked. From Steve's Digicams:
You can frame your pictures with the color LCD or to save precious battery power you can use the optical finder. This is a coupled viewfinder with approx. 80-85% coverage and dioptric adjustment.
and if you look at the images on this page you can see that the viewfinder goes above the lens and through the body like other compacts.

Message edited by author 2008-02-14 19:22:54.

02/14/2008 10:05:07 PM · #22

Sorry for the confusion not a digital file or image I am talking about the View finder being a TFT LCD like most PS only a handful have SLR optical viewing. I will try to find a photo of the difference, but trully you should buy an old slr and take it apart. Reflex refers to the motion of the mirror moving out of the way of the image capturing device. IE Film or sensor. The prizm is only used to invert the image you see through the viewfinder

Originally posted by sabphoto:

and to throw a wrench in the puzzle...is the new olympus DSLRs, that allow you to compose with the back LCD or the eyepiece, still Single lens reflex or double?

02/14/2008 10:11:43 PM · #23

Oh wait your right now I am glad I did not by the g9 over the Lumix I bought for my sweety on Valentines day. Wow The Specs are missleading to a point. But here is a good link to explain SLR technology.
SLR DIAGRAM