Sorry guys, but it's probably not a glass prism

Started Sep 5, 2007 | Discussions
David Kilpatrick Veteran Member • Posts: 5,436
Sorry guys, but it's probably not a glass prism

Because the leaked specifications clearly state it has a new INTERNAL COATING. That mean's its mirror prism, with improved reflective surfaces. You can not coat glass internally.

Now of course they could have got the wording wrong, but the other specs which used the 'roof mirror pentaprism' term (Sony's language for a porroprism) made it unlikely it would be a solid glass prism, and this one just backs that up.

So don't get annoyed and disappointed if they turn out to have made a brighter, better mirror prism and not fitted a glass prism.

David

Abahachi Regular Member • Posts: 101
Re: Sorry guys, but it's probably not a glass prism

I think you're wrong:
http://a700.ic.cz/
There a pentaprism viewfinder is stated.
--
Cheers

chych Senior Member • Posts: 1,320
Re: Sorry guys, but it's probably not a glass prism

Hah, the lens turned the wrong way when it was mounted...

Bengeo
Bengeo Regular Member • Posts: 463
Re: Sorry guys, but it's probably not a glass prism

David,

This site http://a700.ic.cz/ has screen dumps of the comparisons screens that I saw earlier when they were live and they say Mirror for the 100 and Pentaprism for the 700.

Andy
--
My Gallery:
http://www.ukexpert.co.uk/photopost/showgallery.php?cat=500&ppuser=4

 Bengeo's gear list:Bengeo's gear list
Olympus 150-400mm F4.5 TC 1.25x Olympus E-M1 Olympus OM-D E-M1X Olympus E-M1 III Olympus M.Zuiko Digital ED 9-18mm F4.0-5.6 +19 more
dnjake Senior Member • Posts: 2,702
Re: Sorry guys, but it's probably not a glass prism

Well as long as it is as bright as the 40D and the D80, it probably will not be a problem. But if Sony should fail to match up functionally in this area, it will be another major negative.
--
David Jacobson
http://www.pbase.com/dnjake

fjbyrne
fjbyrne Veteran Member • Posts: 8,425
There was one in the animations. nt
-- hide signature --

fjbyrne

 fjbyrne's gear list:fjbyrne's gear list
Sony a7 III Zeiss Batis 85mm F1.8 Sony FE 24-70mm F2.8 GM Sony Alpha DSLR-A700 Sony a6000 +14 more
Sonnarman
Sonnarman Contributing Member • Posts: 518
Re: Sorry guys, but it's probably not a glass prism

If the prism is as you suggest a porro-type David I do hope Sony have sealed it adequately. While I have nothing against mirrors per se, I have experienced major problems with another maker's 35mm SLR cameras when working in harsh atmospherics.

For example working for several months around volcanicly active landscapes, geyser or mud pool country, where not one, but three cameras' hollow mirror prism assemblies became heavily discoloured as sulphurated gases in the atmosphere gained access. No knowing how, or why, but obviously sealing of the mirror box housing was deficient.

The manufacturer quickly replaced one, then a second unit. Didn't have the heart to send the third back. Just bought no more of that unit.

XE 5 kept going throughout those years and environs without missing a beat. (Still does)
--
Sonnarman

 Sonnarman's gear list:Sonnarman's gear list
Konica Minolta Maxxum 7D Sony SLT-A77 Fujifilm X-E2S Sony DT 16-80mm F3.5-4.5 ZA Carl Zeiss Vario-Sonnar T*
Two Truths Veteran Member • Posts: 5,269
LoL

That's the funniest joke you've come up with so far!

I believe that what you are referring to was the "Spherical Acute Matte" coating, which is also featured on the KM 7D.

Did you miss the mini-site?

It stated Pentaprism, nothing less. It even had a blurb about it, and a comparison with the Alpha 100...

Alpha 100
Mirror
95%
0.83x
20mm
-2.5 to 1.0m-1

Alpha 700
Pentaprism
95%
0.9%
25mm
-3.0 to +1.0m-1

(This matches the KM 7D in every respect.)
--
Stuart / the Two Truths
http://www.flickr.com/photos/two_truths/
http://two-truths.deviantart.com/gallery/

dkloi Senior Member • Posts: 1,955
Re: Sorry guys, but it's probably not a glass prism

Because the leaked specifications clearly state it has a new INTERNAL
COATING. That mean's its mirror prism, with improved reflective
surfaces. You can not coat glass internally.

From I can remember of the microsite before it was taken down, I gather that they use improved AR coatings on some of the surfaces. I presume it is for the AE sensors and perhaps the one adjacent to the viewscreen.

Cheers,
Daniel.

 dkloi's gear list:dkloi's gear list
Sony RX100 II Konica Minolta Maxxum 7D Sony a5100 Sony a7 III Sony E 16mm F2.8 Pancake +22 more
Danel Senior Member • Posts: 2,905
Re: Sorry guys, but it's probably not a glass prism

Abahachi wrote:

I think you're wrong:
http://a700.ic.cz/
There a pentaprism viewfinder is stated.
--
Cheers

Agreed. And it is contrasted in the side by side spec sheet to the "mirror" in the A100.

 Danel's gear list:Danel's gear list
Canon PowerShot SD800 IS Canon PowerShot G15 Nikon D7000 Nikon AF-S DX Nikkor 35mm F1.8G Nikon AF-S DX Nikkor 18-200mm f/3.5-5.6G ED VR II +5 more
mezman Contributing Member • Posts: 963
Re: Sorry guys, but it's probably not a glass prism

I'm pretty sure it's a pentaprism. However I was a little disappointed to see it's still only a .9x magnification and 94% coverage. On an APS-C camera, that still adds up to a relatively small viewfinder. Especially in light of the D300's 100% view at .94x magnification.
--
Good luck and good light.
http://www.kennedyphotography.net

stevemark2 Forum Member • Posts: 92
Re: Sorry David, but it IS definately a glass prism!!

Have seen it clearly on the sony site when is was there ... comparing the alpha100 (mirror) with the alpha700 (pentaprism).

Sorry, but this time you were wrong

Stephan

Bill Force
Bill Force Veteran Member • Posts: 6,607
Re: Sorry guys, but it's probably not a glass prism

Yes. you're right. In the comparison it clearly states "pentaprism". One thing I didn't like in the comparison was the statement that the PC sync terminal was a Sony/Minolta proprietary terminal. Now I'll have to buy an adapter to use as a "standard" terminal. Oh well.
--

' You don't have to have the best of everything to get the best out of what you do have'.

Two Truths Veteran Member • Posts: 5,269
Re: Sorry guys, but it's probably not a glass prism

mezman wrote:

I'm pretty sure it's a pentaprism. However I was a little
disappointed to see it's still only a .9x magnification and 94%
coverage. On an APS-C camera, that still adds up to a relatively
small viewfinder. Especially in light of the D300's 100% view at
.94x magnification.

It is 0.9x with 95% magnification.

The D300 costs over two-fifths more than the Alpha-700!

The nearest competitor to the Alpha-700 is the Canon 40D...
That is 0.95x with 95% magnification.

However; the 40D is 1.6x crop rather than 1.5x crop. That gives you approximately the equivalent of 0.89x, which is smaller than the Alpha-700.

Jim Ogilvie Contributing Member • Posts: 799
Re: Sorry guys, but it's probably not a glass prism

That doesn't make much sense.

The PC sync terminal on the KM7D is industry standard, there is nothing proprietary about it. The flash shoe, on the other hand, is.

Bill Force wrote:

Yes. you're right. In the comparison it clearly states "pentaprism".
One thing I didn't like in the comparison was the statement that the
PC sync terminal was a Sony/Minolta proprietary terminal. Now I'll
have to buy an adapter to use as a "standard" terminal. Oh well.
--
' You don't have to have the best of everything to get the best out
of what you do have'.

-- hide signature --

http://avicdar.com (my portfolio - please visit!)

-----
KM7D
Sony-Zeiss 135 1.8
Sony-Zeiss 85 1.4
Minolta 50 1.7
Sony 35 1.4G
Tamron 28-75 2.8
Minolta 70-210 F4
Sigma 15-30

 Jim Ogilvie's gear list:Jim Ogilvie's gear list
Sony a7R III Sony a1
Bill Force
Bill Force Veteran Member • Posts: 6,607
Re: Sorry guys, but it's probably not a glass prism

I makes great sense if you have a terminal like I have on 2 Olympus cameras that only fit their proprietary cords. Get out in the world more?
--

' You don't have to have the best of everything to get the best out of what you do have'.

mezman Contributing Member • Posts: 963
Re: Sorry guys, but it's probably not a glass prism

Two Truths wrote:

mezman wrote:

I'm pretty sure it's a pentaprism. However I was a little
disappointed to see it's still only a .9x magnification and 94%
coverage. On an APS-C camera, that still adds up to a relatively
small viewfinder. Especially in light of the D300's 100% view at
.94x magnification.

The D300 costs over two-fifths more than the Alpha-700!

The nearest competitor to the Alpha-700 is the Canon 40D...
That is 0.95x with 95% magnification.

However; the 40D is 1.6x crop rather than 1.5x crop. That gives you
approximately the equivalent of 0.89x, which is smaller than the
Alpha-700.

True, no doubt about it the D300 costs more then the A700. But I was hoping for a little better viewfinder. That's been one of my biggest complaints with my move to digital is how tiny the viewfinders are, making manual focusing nearly impossible.

-- hide signature --

Good luck and good light.
http://www.kennedyphotography.net

Henry Richardson Forum Pro • Posts: 19,830
Sony screenshots & animation

Here are Sony screenshots and the animation. According to this it has a pentaprism:

http://a700.ic.cz/

-- hide signature --

Henry Richardson
http://www.bakubo.com

Jim Ogilvie Contributing Member • Posts: 799
Re: Sorry guys, but it's probably not a glass prism

Yeah, I get out in the world just fine, thanks.

The previous post stated that the PC sync was a proprietary KM/Sony PC sync. My point was that the KM7D had a standard sync, therefore to state that the PC sync on the A700 is 'proprietary KM/Sony' makes no sense, since KM never had a proprietary PC Sync.

Get it?

Bill Force wrote:

I makes great sense if you have a terminal like I have on 2 Olympus
cameras that only fit their proprietary cords. Get out in the world
more?
--
' You don't have to have the best of everything to get the best out
of what you do have'.

-- hide signature --

http://avicdar.com (my portfolio - please visit!)

-----
KM7D
Sony-Zeiss 135 1.8
Sony-Zeiss 85 1.4
Minolta 50 1.7
Sony 35 1.4G
Tamron 28-75 2.8
Minolta 70-210 F4
Sigma 15-30

 Jim Ogilvie's gear list:Jim Ogilvie's gear list
Sony a7R III Sony a1
Henry Richardson Forum Pro • Posts: 19,830
thanks for vf explanation

Two Truths wrote:

It is 0.9x with 95% magnification.

The D300 costs over two-fifths more than the Alpha-700!

The nearest competitor to the Alpha-700 is the Canon 40D...
That is 0.95x with 95% magnification.

However; the 40D is 1.6x crop rather than 1.5x crop. That gives you
approximately the equivalent of 0.89x, which is smaller than the
Alpha-700.

Thanks for the explanation. I never knew how you were supposed to compare those vf figures from different cameras.

-- hide signature --

Henry Richardson
http://www.bakubo.com

Keyboard shortcuts:
FForum MMy threads