"Penta-mirror" v.s. pentaprism view finder

arroyoshark

Rambling Lead-in:

I am new to this site... a n00b, but I am not new to photography. Recently rolled into this site from ADVrider.com.

I used SLR cameras (Pentax & Olympus) for many years and was a slave to a B&W darkroom. I took lots of pics with these cameras. I have had experience in exhibiting photo prints in juried exhibitions and have been represented many years ago in a gallery. All my SLR's had pentaprism view finders.

Due to some life circumstances, I set those cameras down in 1990. A short time later I started carrying an Olympus infinity jr. point and shoot camera as it was simply easier to pack and take along.

About 2 years ago I picked up a Canon A-80 digital point and shoot and have really enjoyed this new medium. I have taken 2 classes in digital photography so far and am enrolled in fall Photoshop and Electronic Color Theory and Practice classes at local Community College to help me fully transition into producing and printing better images with digital cameras. I am shopping for a Digital SLR before the fall semester starts.


I have been lurking here for some time following the threads on the Canon Rebel XT350 and the Canon 20D. Both seem impressive cameras to me. I have smallish hands and the Rebel XT seems like a good fit. It also seems more convenient to pack for trips. My budget is somewhat limited so leaning towards the Rebel XT and using savings over 20D to buy a better lens.

The Issue:

I have been very impressed with the extensive base of knowledge and experience of members of this site. I'd like to tap into some of that now. What is concerning me is the fact that the Canon Rebels use several mirrors to rectify and convey the image to the view finder. I have looked through the Rebel 300 and 350 XT in stores. The image view seems clear enough, if not just a bit dark, but I notice the "tunnel" effect mentioned in threads on the site. That is not particularly troubling to me at the moment. The viewfinder of the 20D, Nikon D70 and even the Pentax 1st seem a bit brighter and don't have the tunnel effect, but these cameras all have pentaprisms.

I am curious about the ruggedness of the "penta-mirror" view finders. In particular, will the several mirror surfaces have more potential to attract dust and dirt, clouding the viewed image?

Has there been any history of the mirrors coming loose inside the cameras and distorting the viewed image?

Seems like a pentaprism would have less surfaces to attract dust and, since they are a single piece would be structurally more rugged.


Thoughts, experiences?? :dunno

ziggy53

I have the XT and I was curious about its durability as well. I haven't read anyone having problems and I just did a Google against, +"penta-mirror" +durability, +"penta-mirror" +fragile, etc.

I still couldn't find anyone complaining about their camera and damage to the "penta-mirror" assembly, and there are quite a few cameras now using the technology.

It would appear that penta mirror technology has been used for telescopes for years with no obvious problems.

I am guessing that most camera failures will come from the shutter mechanism and electronic circuits of the cameras, unless they are dropped or abused.

I also come from a film background and Canon and Pentax 35mm SLRs with PentaPrisms, and even a couple of medium format cameras with PentaPrisms. I find the viewfinder of the XT perfectly usable and not a hinderance, as some would imply.

I haven't taken the camera apart, but it looks like the mirror box is pretty well sealed, so I don't think dust will be a major problem.

20 years from now may be a different story. I do suspect that digital camera bodies will not hold much appeal or value in 20 years, so I don't think there will be much of a used market or reason to need that sort of durability. I will put most of my money in lenses and flashes. (Not that a 20 year old flash will have much value either, but light is still critical to have.)

I do think that there is nothing, absolutely nothing, wrong with PentaPrism technology, so you really can't go wrong with the 20D in that regard, and it is definitely a step up from the XT in other regards as well. It's also slightly heavier, but still pretty light. Either camera is very capable and competent. Neither is weather-sealed.

Let us know what you do,

ziggy53

pathfinder

Welcome to dgrin Arroyshark!! Where exactly is fin del sendero? I try to visit NM every year on 2 wheels or 4.

As to pentaprism versus mirrors. Pentaprisms are genrally brighter and seen in the better cameras. The multi mirror pentaprism replacements are generally less bight and yield a smaller image when looking through the viewfinder. Once again, a minor compromise made in keeping the cost down. Serviceable, but not the very best. Kind of like buying cheaper binoculars - works fine if you don't plan to look through them very often or compare them to a really good pair.

One of the lesser discussed aspects of dSLRs is that on the more inexpensive ones, the viewfinders are not near as good as they used to be on film slrs. They are smaller, darker, and harder to focus manually. The trend for manufacturers is to favor autofocus - so who needs a bright viewfinder with a split image reticle?!

Those of us who grew up on good manual focus SLRs tend to be the ones who notice the difference. The same is true in lenses - a shift from faster optics to smaller aperatures. Again favoring AF over manual focus.
I love AF, but it just does not work all the time - especially in very dim light, and that includes Canon's very best cameras. Only on the 1 series Canons and the Nikon equivalents are view screens replaceable with a split image reticle.

arroyoshark

pathfinder wrote:

Welcome to dgrin Arroyshark!! Where exactly is fin de sendero? I try to visit NM every year on 2 wheels or 4.

As to pentaprism versus mirrors. Pentaprisms are genrally brighter and seen in the better cameras. The multi mirror pentaprism replacements are generally less bight and yield a smaller image when looking through the viewfinder. Once again, a minor compromise made in keeping the cost down. Serviceable, but not the very best. Kind of like buying cheaper binoculars - works fine if you don't plan to look through them very often or compare them to a really good pair.

One of the lesser discussed aspects of dSLRs is that on the more inexpensive ones, the viewfinders are not near as good as they used to be on film slrs. They are smaller, darker, and harder to focus manually. The trend for manufacturers is to favor autofocus - so who needs a bright viewfinder with a split image reticle?!

Those of us who grew up on good manual focus SLRs tend to be the ones who notice the difference. The same is true in lenses - a shift from faster optics to smaller aperatures. Again favoring AF over manual focus.
I love AF, but it just does not work all the time - especially in very dim light, and that includes Canon's very best cameras. Only on the 1 series Canons and the Nikon equivalents are view screens replaceable with a split image reticle.

Thanks for the welcome.

Both you and Ziggy provided interesting perspective. Using the optical viewfinders on D-SLR's is different for me than on my SLR's. Guess I didn't want the penta-mirror system to become a deal breaker for the Rebel XT, but I have been concerned about it.

I also used to use 2-1/4 cameras as well as 4x5 view camera, which suited my photographic style. Some of the bells and whistles current cameras have may be lost on me, such as lots of frames per second, etc. I am looking for a good D-SLR with as many mega-pixels as I can afford...for the same reason as I liked the 4x5 format.


I have found that even on the Canon A-80 that its idea of an auto focus point and depth of field is not the same as mine. At least I can use shutter-priority and Aperture priority modes to affect the outcome a bit.


Pathfinder, "fin del Sendero" translates to "end of the trail"...or in this case the end of the Santa Fe Trail. :jose

PM me when you come to NM again. Maybe we can do some riding and photographing.

GadgetGav

arroyoshark wrote:

I am curious about the ruggedness of the "penta-mirror" view finders. In particular, will the several mirror surfaces have more potential to attract dust and dirt, clouding the viewed image?

Has there been any history of the mirrors coming loose inside the cameras and distorting the viewed image?

Seems like a pentaprism would have less surfaces to attract dust and, since they are a single piece would be structurally more rugged.


Thoughts, experiences??

I dropped my DRebel onto a tiled floor and the penta mirror has not moved. I wouldn't suggest you do the same just to get more data points, but I think it's rugged enough..!
edit
Oh, there are also hacks out there to replace the focussing screen in the Rebel with something with a split viewfinder. I've been tempted to try that myself one day.

pathfinder

GadgetGav wrote:

I dropped my DRebel onto a tiled floor and the penta mirror has not moved. I wouldn't suggest you do the same just to get more data points, but I think it's rugged enough..!
edit
Oh, there are also hacks out there to replace the focussing screen in the Rebel with something with a split viewfinder. I've been tempted to try that myself one day.

Interesting. Apparently I'm not the only person who misses the split image reticle. Do you have a linky for this hack? I think this interferes with the center weighted light meter setting also.

arroyoshark

pathfinder wrote:

Interesting. Apparently I'm not the only person who misses the split image reticle. Do you have a linky for this hack? I think this interferes with the center weighted light meter setting also.

Do the light meters on digital slrs meter off the viewfinder screen?


Seems like I recall many years ago some 35mm slr metered off the front of the shutter curtain, but don't remember brand or model.

pathfinder

arroyoshark wrote:

Do the light meters on digital slrs meter off the viewfinder screen?


Seems like I recall many years ago some 35mm slr metered off the front of the shutter curtain, but don't remember brand or model.

Kind of apparently.

I've been searching, trying to find out where I found this fact - that using center range finder reticles interfere with metering, - but can't seem to find it. The Canon interchangeable focusing screens only are available on the 1 Series cameras - Here is a link to them - but no where does it say that the center weighted light meter is unavailable
http://www.bhphotovideo.com/bnh/controller/home?ci=1&sb=ps&pn=1&sq=desc&InitialSearch=yes&O=SearchBar&A=search&Q=*&bhs=t&shs=Canon+focusing+screen&image.x=0&image.y=0

OK!! - when alll else fails!! - Read the Manual!! On page 167 of the manual for the 1DsMkll it says "The Ec-A, Ec-B,Ec-I, and Ec-L have a prism at the center. A correct exposure reading cannot be obtained with evaluative metering or spot metering based on the center area where there is a prism. Use center weighted metering or off-center spot metering with such focusing screens." SO I was kind of right and kind of wrong, but now we know the truth. RTFM!! Not sure what this would mean for a hack that replaces the screen in a 10D or some such.

luckyrwe

I used to be the type of person who avoided Pentamirrors at all costs, knowing the pentaprisms were a better choice, albeit heaver and more expensive. My opinion changed when I found out my Canon 1D Mark II has a Pentamirror!

Seems they can make them a lot better than they used to!

pathfinder

luckyrwe wrote:

I used to be the type of person who avoided Pentamirrors at all costs, knowing the pentaprisms were a better choice, albeit heaver and more expensive. My opinion changed when I found out my Canon 1D Mark II has a Pentamirror!

Seems they can make them a lot better than they used to!

Now I am confused!! Canon USA's website lists the specifications for the viewfinder of the 1DMkll as having an eye-level pentaprism. AM I misunderstanding something here? Where did you find the statement that the 1DMkll has a penta-mirror? From Canon's website...

arroyoshark

pathfinder wrote:

Kind of apparently.

I've been searching, trying to find out where I found this fact - that using center range finder reticles interfere with metering, - but can't seem to find it. The Canon interchangeable focusing screens only are available on the 1 Series cameras - Here is a link to them - but no where does it say that the center weighted light meter is unavailable
http://www.bhphotovideo.com/bnh/controller/home?ci=1&sb=ps&pn=1&sq=desc&InitialSearch=yes&O=SearchBar&A=search&Q=*&bhs=t&shs=Canon+focusing+screen&image.x=0&image.y=0

OK!! - when alll else fails!! - Read the Manual!! On page 167 of the manual for the 1DsMkll it says "The Ec-A, Ec-B,Ec-I, and Ec-L have a prism at the center. A correct exposure reading cannot be obtained with evaluative metering or spot metering based on the center area where there is a prism. Use center weighted metering or off-center spot metering with such focusing screens." SO I was kind of right and kind of wrong, but now we know the truth. RTFM!! Not sure what this would mean for a hack that replaces the screen in a 10D or some such.

I have sooooo much to learn...again. :cry