Question about pentaprisms and digital cameras

[michael_altimier]

I was wondering if there are any DSLRs out there that use the old style

pentaprism focus mechanism were in the center of the mirror, there is a circle

divided in half and you focus by lining up any straight lines in the composition

in the center. I've just leaped into digital and I am really not digging

autofocus on any lines so far because it seems like I cant get the crisp focus I

could acheive with that style mirror, especially in low light or what have you.

Kinda nit-picky, but I'd appreciate any insight.

[shambrick007]

It's not the penta-prism or the mirror. It's the <a href = "http://www.katzeyeoptics.com/">focusing screen</a>.

[michael_altimier]

do those screens mess up the autofocus function at all?

[franklin_polk]

You're thinking of the 'biprism' or 'split screen' focus screen type. If you're shooting with a Canon or a Nikon, you can probably get a replacement focus screen with this feature fairly easily.

[franklin_polk]

Beaten to it! The focus screen won't effect AF, they are different mechanisms.

[Damon DAmato]

I love that style, and used them for 30 years on an F2s.

We always called it a "split image" focus screen.

 

It took a couple of thousand shots before getting used to using autofocus with those little brackets and the various modes.

 

Damon

[todd peach seattle, washi]

<i>

It's not the penta-prism or the mirror. It's the focusing screen.

</i>

<p>

The screen is a primary factor, for sure. But I'm thinking the big honkin' prism on an F2 or F3 is part of it too. I have not yet had the pleasure to handle a D3. Maybe it's an improvement.

[markci]

The versions of the F2 with the "big honkin" prism were that way because the meter was in the prism. The non-metered F2 prisms are quite small.

 

The F3 HP prism was large for reasons of high eye relief.

 

The screen is what matters.

[felixg]

For all the "traditional name" SLRs you can get replacement screens.

 

In my case (Pentax) there are split image, microprism (I have one of each) and various other options.

 

Personally I have always preferred a plain screen where possible, though a microprism spot is useful with very short focus lenses ... but if you want a particular variant, it's probably out there.

[donnie_strickland]

A year and a half ago, I bought a split-image/microprism-collar screen for my Pentax *istDS. Now manual focus is a snap.

 

I bought this screen new from a Chinese eBay seller; it installs just like a Pentax screen. Pentax doesn't offer these screens themselves, because, they told me, the screens will spoil both autofocus and metering (neither of which has happened).

[matthew_newton]

I prefer microprism screens to split images. Especially if you are in a shooting situation where the light levels are low or you are using slow glass (especially slow telephoto lenses) that top portion of the split image going dark makes it very hard to focus. With a microprism if it goes dark it is much easier to focus (well, not as easy as if the light levels/aperature was sufficient).

 

I had been wondering the same question Michael, so I am glad someone asked it. I've been thinking of a Cannon 5d one of these days and that was an issue for me as I would be using a lot of manual focus glass with it.

[felixg]

The Chinese sourced screen Donnie mentions works well in my experience, though I've heard (anecdotally) of some individual samples not being so good.

 

It is cut down from a larger film SLR screen, but seems none the worse from that.

[kali goddess]

"You're thinking of the 'biprism' or 'split screen' focus screen type. If you're shooting with a Canon or a Nikon, you can probably get a replacement focus screen with this feature fairly easily."

 

Sorry if it's a stupid question, but how can you get one? Is it something you can get at a local camera store, or do you need to install it yourself, and if so - how?

 

Thanks!

[todd peach seattle, washi]

Kelly -

 

Not a typical camera store item. There are others, but this is the one that's probably best known:

 

http://www.katzeyeoptics.com/cat--Canon-DSLRs--cat_canon.html

 

I don't know about the install. If you're not comfortable doinkin' around in the mirror / screen area, it's something a local camera repair place could do for you.

[kali goddess]

Thanks Todd! :)