PDA

View Full Version : Why do Digital Cameras use SLR (DSLR)?



Anour
10-08-2006, 07:09 AM
Fellows
My understanding of SLR, before digital took over, was that it showed exactly what the film would have seen without the error of a view finder.

Now that we have a "chip" instead of film that sees the image before saving it and an EXACT duplicate of that is available electronically on the LCD (on back of the camera or viewfinder) , what is the point of having an SLR mirror anymore?

Thanks
Anour

timmciglobal
10-08-2006, 08:03 AM
dSLR's do NOT (in general) have life previews (IE: LCD's which show you image as your composing a shot)

dSLR's have mirrors because at top is a prism or pentamirror that shows you the reflected image. No LCD in the little viewfinder, just glass and a mirror.

They have them because the size plates they use require a lot of energy and heat up quickly if left exposed constantly (IE: like P&S do during live preview) and thus would be impracticle) Panasonic and Olympus do have live preview MOS sensors which do both have LCD and mirror but they acheive that at cost of bright viewfinder using a partially transparent mirror.

Tim

coldrain
10-08-2006, 08:18 AM
The Panasonic L1 and the Olympus E-330 do not have a partially transparent mirror. The L1 only has live preview when the mirror is up and out of the way.
The E-330 either has the mirror out of the way and preview via its big sensor, or preview via a small sensor located near the view finder.

If you want to show what you see through the lens in a view finder, you just need to have a mirror in front of the sensor. This is one big reason for "SLR". Another, like Tim said, is that the sensors get too hot for live preview. They are bigger than the onces in compact digital cameras. And a 3rd reason is that electronic view finders just never can approach optical view finders in judgeing things in the image.

Riley
10-08-2006, 10:38 AM
as to, what is the point of an slr anymore

the place we are at with dSLRs we have arrived at via evolution
for the moment, the slr is the tool that offers the most flexibility
interchangeable lenses, wide / normal / tele /macro
system options such as TTL flash / ring flash
together with these features, the slr has enhanced sophistications
like faster more accurate autofocus
like more accurate and more extensive metering options
higher and more useable iso

now remember slr film cameras only had an optical finder via the prism
no LCD on the back at all, there is still a core of photographers that will prefer the finder to the LCD. but as EVF's become better and more useful, we wont need the slr at all, well not for the reflex prism anyway
but we are not at that place quite yet

the moving mirror actually makes some things more difficult
the more sophisticated cameras need to be able to meter and focus when the is mirror down, and when the mirror is up. adding complications and sometimes duplication of systems
the mirror also adds an amount of shake or vibration
and it makes a noise, making candid shots harder to achieve
it adds an amount of shutter lag, and adds cost and weight to the camera

Riley

timmciglobal
10-08-2006, 11:50 AM
Your right coldrain, my mistake. It uses a poro mirror and a second CCD. The mirror doesn't go up during one of the live modes for that.

Tim

Anour
10-08-2006, 12:54 PM
Thanks Timmciglobal , Riley and Coldrain for your informative comments.

I understood three reasons for DSLR (from your comments):
1) DSLR Sensor gets hot if left on (like P&S)
2) It was an evolution of SLR (maybe to encourage professionals to switch)
3) Optical image is better than LCD for judgement (maybe because it is really 3D)

I am not a professional photographer, just love photography. However, as a technocrat who earns his salary by predicting the impact of technology in an engineering field (not related to photography), I still do not see a FUNDAMENTAL reason for having that moving part (mirror) with all its complications.

Reason #3 above is fundamental and would probably help extend the mirror life in the market but sensors getting hot is just a matter of technology. It is just a matter of time before better sensors with fraction of their present power consumption (cause of heat) would be available. I do not know what percentage of professional photographers have switched to digital but, if not the majority, that will be a matter of time too.

My prediction (as an outsider) is that the "moving part" is on its way out and professional cameras become smaller (in body) with full lens interchangeability and gadgets.

How off am I in my prediction ?

Riley
10-08-2006, 01:02 PM
Anour I think you are spot on
its just a matter of time and availability ot the technology
that said, some photographers have a tendency to resist change
which presents some obscure solutions

Riley

Norm in Fujino
10-08-2006, 10:08 PM
How off am I in my prediction ?

No one knows but the shadow (i.e., only time will tell). There is talk in some circles that electronic viewfinders will eventually replace the mirror, but that time hasn't come. Current evf technology simply isn't up to the visual quality of an optical vf.

cwphoto
10-08-2006, 10:17 PM
Personally I'd prefer to use a Pellicle Mirror than go to an EVF.

Today's EVFs just don't cut it for pros or discerning users, but we already have the technology to do away with the moving mirror. It never really went mainstream manly due to the loss of 2/3rd f-stops to the media, but with today's clean-free high ISO sensors I reckon it's time for the Pellicle Mirror to make a comeback.

I would buy two pro-level cameras immediately for this feature if it was on the market.

forno
10-08-2006, 10:44 PM
i think it will be a long time before there is a EVF that can pan as well as a OVF and even longer for it to be accepted

cwphoto
10-08-2006, 11:02 PM
i think it will be a long time before there is a EVF that can pan as well as a OVF and even longer for it to be accepted

I tend to agree, sometimes it's hard to build a better mousetrap.

forno
01-08-2007, 05:32 PM
We all chipped in and got the old cheese a Canon S3 IS for his birthday, awesome little camera that takes fantastic pics. Using it back to back with a P&S with a 2" LCD and EVF it performs well in this department but when I took my DSLR out and started taking some pics you realise how far ahead the OVF is on all levels

cwphoto
01-08-2007, 06:56 PM
We all chipped in and got the old cheese a Canon S3 IS for his birthday, awesome little camera that takes fantastic pics. Using it back to back with a P&S with a 2" LCD and EVF it performs well in this department but when I took my DSLR out and started taking some pics you realise how far ahead the OVF is on all levels

OT: Gontran, how's your Dad enjoying the S3 now that he's had it for a month?

forno
01-08-2007, 07:05 PM
OT: Gontran, how's your Dad enjoying the S3 now that he's had it for a month?

Well he has been pretty busy with other stuff so apart from initially being speechless and overwhelmed he has taken a few early shots, still getting a feel for it in auto

The old bastad has a great eye for composition though:cool:

cwphoto
01-08-2007, 07:06 PM
Well he has been pretty busy with other stuff so apart from initially being speechless and overwhelmed he has taken a few early shots, still getting a feel for it in auto

The old bastad has a great eye for composition though:cool:

Old Bastards usually do. :D

You should get him to join DCRP!

forno
01-08-2007, 07:08 PM
Old Bastards usually do. :D

You should get him to join DCRP!

So he can show me up:D

LOL, I have given him the link for the S3 pics thread.

Being an architect he should have an eye for comp:)

Nickcanada
01-09-2007, 04:51 AM
Hey CW, I see you got a new camera at christmas, do you ever use it? I sometims wish I had a small P&S, until I try using an EVF. I can't do it :D maybe with a bit more practice. but seriously I miss my A95, in a weird way.

Forno: How is the OVF on the S3? The way they make them on the smaller P&S, it's a wonder that they still put them on at all!

Rhys
01-09-2007, 05:00 AM
One idea that goes through my mind is whether some system could be worked out whereby an electronic viewfinder could be included on a dSLR. imagine this: two sensors - one a tiny VGA sensor that reads off the mirror and then feeds to a display in the viewfinder. The other is the real sensor. This would mean no lag while waiting for the CCD to discharge and recharge. It would be nice if also that the small sensor/LCD could be lifted out of the way to allow direct vision by simply pressing a button. Looks to me like the best of all worlds. Of course if it were to be done then the cost would be very high initially. It'd be a bit like having the good old EOS RT in action!

cwphoto
01-09-2007, 05:03 AM
Hey CW, I see you got a new camera at christmas, do you ever use it? I sometims wish I had a small P&S, until I try using an EVF. I can't do it :D maybe with a bit more practice. but seriously I miss my A95, in a weird way.

Yeah sometimes - the girls took it away when they went to Perth for a week. I need to use it more. :(

Nickcanada
01-09-2007, 10:51 AM
So are the kids intrested in playing with the big guns yet? I could just imagine... "Dad, I've got the old 1D and 16-35, I'll be back at 10" :eek:

hehe.

Riley
01-09-2007, 11:00 AM
big guns

once upon a time
35mm was considered amateur format
if you felt you had even half a chance of being published with 35mm
it had to be kodachrome 25asa
maybe...just maybe 64asa
but it would need to be one hell of a good frame
i still hate the stuff

somewhere in there, canon decided to name their 35mm 'professional'

Rhys
01-09-2007, 11:02 AM
big guns

once upon a time
35mm was considered amateur format
if you felt you had even half a chance of being published with 35mm
it had to be kodachrome 25asa
maybe...just maybe 64asa
but it would need to be one hell of a good frame
i still hate the stuff

somewhere in there, canon decided to name their 35mm 'professional'

35mm was the professional format for newspapers once plate cameras had gone and for cheap wedding photographers.

Nickcanada
01-09-2007, 11:24 AM
big guns

once upon a time
35mm was considered amateur format
if you felt you had even half a chance of being published with 35mm
it had to be kodachrome 25asa
maybe...just maybe 64asa
but it would need to be one hell of a good frame
i still hate the stuff

somewhere in there, canon decided to name their 35mm 'professional'


I was refering to his EOS 1D Mark 2 N. That's a big gun to me :o

forno
01-09-2007, 01:20 PM
Forno: How is the OVF on the S3? The way they make them on the smaller P&S, it's a wonder that they still put them on at all!

Nah its a Electronic view finder, with 3 modes, just the image, image with exif and histo, image with exif histo and grid lines in 3rds.

You can have these modes either on the LCD or in the view finder

Me no like:o

Takes a great pic though

cwphoto
01-09-2007, 03:27 PM
So are the kids intrested in playing with the big guns yet? I could just imagine... "Dad, I've got the old 1D and 16-35, I'll be back at 10" :eek:

hehe.

The girls are too busy doing their hair/makeup and discussing the latest tunes to worry about the fancy gear, but Tom and Nick haver taken a shine to the 1D.

Have you ever seen a 5yo (let alone a 4yo) try to take a photo with a 1D and 24-70/2.8? It's hilarious - they can barely pick it up! :D

forno
01-09-2007, 04:02 PM
How about I give you my 350 w/ 50 1.8 for the boys to play with in return for your used 70-200 2.8 IS:p

cwphoto
01-09-2007, 04:13 PM
How about I give you my 350 w/ 50 1.8 for the boys to play with in return for your used 70-200 2.8 IS:p

You need therapy - this 70-200/2.8 IS thing has really got to you.

Do you wake up with the cold sweats too? :p :D

forno
01-09-2007, 04:33 PM
You need therapy - this 70-200/2.8 IS thing has really got to you.

Do you wake up with the cold sweats too? :p :D



I dream of hearing the IS angels huminng their tune infront of the throne of the lenegdary and regal !D:D


PS, I WILL WON A 70-200 IN THE NEXT 24MNTHS

mjsneddon
01-24-2007, 08:10 PM
It may change in the future but for now, the optical view finder of an SLR is clearly superior to any other type.