Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
10-04-2012, 11:18 PM   #31
Loyal Site Supporter




Join Date: Apr 2010
Location: Tennessee
Posts: 5,801
QuoteOriginally posted by stevebrot Quote
Huh? Perhaps a different calculator? The image circle (diameter to provide minimum coverage) would be sqrt(24^2 + 36^2) = 43.3mm. Good design would indicate a little larger to accommodate variance in manufacturing tolerance.


Steve
What he is calculating is the radius of the image circle which is 21.633. 21.633 x 2 yields an image circle of 43.266mm. The Sony FF sensor measures 23.9 x 35.8mm which requires an image circle of 43.044mm. You have a tolerance of 0.222mm. Plenty....

10-04-2012, 11:21 PM   #32
Loyal Site Supporter




Join Date: Apr 2010
Location: Tennessee
Posts: 5,801
QuoteOriginally posted by JPT Quote
A very interesting find. Thanks!

Is the distance behind the rear element consistent with K-mount? It seems to me that previous patents showed a greater distance but I find it difficult to judge the scale. Why would it need image stabilisation when all K-mount bodies have SR?
Because there is reason to believe that Pentax wont use In-body SR on its full frame unit.
10-04-2012, 11:23 PM   #33
Veteran Member




Join Date: Dec 2010
Location: Manila
Photos: Gallery | Albums
Posts: 2,190
Nice find. I do hope they make one.

The lens project with the model they displayed at CP+ last year ...if the Photokina interview in the Russian site was true, was abandoned (remember this?


If they have any plans to build a 70-200 f2.8, by all means should they make it a go. Even if it isn't on the roadmap!

QuoteOriginally posted by Winder Quote
Because there is reason to believe that Pentax wont use In-body SR on its full frame unit.
I also believe in the possibility of this, if they want to keep the body size down, close to the K-7/K-5.
But that would mean a whole new line of lenses, if not DFA's. And of course, what will happen to DA* lenses if they will?
10-04-2012, 11:25 PM   #34
Loyal Site Supporter




Join Date: Apr 2010
Location: Tennessee
Posts: 5,801
QuoteOriginally posted by ogl Quote
Funny....Pentax had a lot of patents for lenses, but 99% of this lenses are never produced.
If this were Nikon/Canon/Sony I would agree, but this lens was designed by Pentax under Hoya. Why would a company with basically no R&D budget spend a dime developing a lens for a body it has no intention of ever building? Why would Hoya even consider it? It may never get built, but is an indication that Hoya/Pentax were investing resources into the development of a full frame system. No reason to even think about this lens if you're not moving in that direction.

10-05-2012, 01:05 AM   #35
Pentaxian
mecrox's Avatar

Join Date: Apr 2009
Location: Oxford, UK
Photos: Gallery
Posts: 2,117
I'd have thought that trying to patent everything you have in your research lab is a way of crystallizing the company's value when you come to sell it. At the time, this is exactly what Hoya were trying to do. Patents are what Ricoh emphasized they were after when they acquired Pentax, and given how cynical Hoya were it's surprising they didn't try to patent the tea lady. I wouldn't read too much into this. Until facts are produced, It's just another crazy FF rumour.
10-05-2012, 01:29 AM   #36
Pentaxian
Clavius's Avatar

Join Date: Feb 2011
Location: De Klundert
Photos: Gallery
Posts: 4,122
QuoteOriginally posted by mecrox Quote
It's just another crazy FF rumour.
It's not even that. The DFA 100 and DFA 50 didn't result in an FF camera either, so why would a DFA 70-200 do?
10-05-2012, 01:43 AM   #37
Pentaxian




Join Date: Apr 2007
Location: Romania
Posts: 9,343
QuoteOriginally posted by mecrox Quote
Patents are what Ricoh emphasized they were after when they acquired Pentax
I thought Pentax was what Ricoh were after when they acquired Pentax

This patent confirms what Pentax said in their interview: they are working on "full frame" technologies, in background; and it seems they did it even under Hoya.
10-05-2012, 02:42 AM   #38
Veteran Member
froeschle's Avatar

Join Date: Sep 2007
Location: Germany
Photos: Gallery
Posts: 552
Sigma 70-200/2,8 EX DG OS HSM
22 lenses in 17 groups
l = 197.6mm

Tamron 70-200/2.8 Di LD
18 elements in 13 groups
l = 194.3mm

Pentax 80-200/2.8 ED [IF]
16 elements in 13 groups
l = 195mm

70-200/2.8
17 elements in 14 groups
L = 296.16 (?!)

QuoteOriginally posted by http://photorumors.com/2012/10/04/pentax-patent-for-a-70-200mm-f2-8-lens/:
Canon patents for 600mm f/4 and 400mm f/2.8 lenses | Photo Rumors
For both those lenses, the “image height” is… 21.64mm – and don’t tell me they are almost full-frame…
QuoteOriginally posted by A 2012-189817:
[Effect of the Invention]
According to the present invention, focusing movement magnitude is made small, quick focusing is possible, structure is easy, and is low cost, and the electronic imaging device provided with a zoom lens system and this with the more outstanding optical performance is obtained.

[0002]
As a zoom lens system which aimed at a miniaturization and highly efficient-ization, 4 group zoom lens system which comprised the 1st lens group with positive refracting power, the 2nd lens group with negative refracting power, the 3rd lens group with positive refracting power, and the 4th lens group with positive refracting power is known sequentially from the object side (Patent document 1-3).

[0003]
These 4 group zoom lens systems mainly performed variable power by the 2nd lens group, and compensated the image surface fluctuation accompanying this variable power with the 3rd lens group, and the inner focus system which divides the 1st lens group into a pre-group and a rear group, and makes this rear group a focus lens group is used for them. Thereby, optical length cannot change in the case of zooming and focusing, but an optical system with little change of the f number can be acquired.

[0004]
[Patent document 1] JP,2002-6215,A
[Patent document 2] JP,2008-70450,A
[Patent document 3] JP,2002-162564,A

[0005]
However, since the zoom lens system of a Patent document 1 has too little lens number of sheets of each lens group (especially the 4th lens group), its chromatic-aberration-of-magnification change at the time of focusing is large. Since the Patent document 2 and the zoom lens system of 3 are made into the image blur correcting lens group (vibration proof lens group) which moves a part of 4th lens group in a direction orthogonal to an optic axis, there is much lens number of sheets, and their structure is complicated, and they are a high cost.
[Patent document 1] Sigma Corp.
[Patent document 2] Canon Inc
[Patent document 3] Canon Inc

10-05-2012, 02:55 AM   #39
Pentaxian
Mistral75's Avatar

Join Date: Feb 2009
Location: Paris
Posts: 3,003
QuoteOriginally posted by froeschle Quote
Sigma 70-200/2,8 EX DG OS HSM
22 lenses in 17 groups
l = 197.6mm

Tamron 70-200/2.8 Di LD
18 elements in 13 groups
l = 194.3mm

Pentax 80-200/2.8 ED [IF]
16 elements in 13 groups
l = 195mm

70-200/2.8
17 elements in 14 groups
L = 296.16 (?!)
L = 296.16mm is the optical length (the patent is not linked to any particular mount). You have to subtract the flange-to-sensor distance to get the lens's length, i.e. 296.16 - 45.46 = 250.7mm. Still lengthier than competition.
10-05-2012, 03:44 AM   #40
Veteran Member
eurostar's Avatar

Join Date: Dec 2006
Location: Albareto, Italy
Photos: Gallery
Posts: 817
I don't see why it should be a proof a FF is coming.

A 70-200/2,8 is just a 100-300/2,8 scaled down for APS-C.
10-05-2012, 03:57 AM   #41
Pentaxian
thibs's Avatar

Join Date: Jun 2007
Location: Belgium
Photos: Albums
Posts: 5,266
QuoteOriginally posted by eurostar Quote
I don't see why it should be a proof a FF is coming.

A 70-200/2,8 is just a 100-300/2,8 scaled down for APS-C.
LOL

Still, AFAIK Pentax never designed FF lenses but when obvious (a 55 prime for APS wouldn't bring much would it?, so the 55 was an FF).
Zoom are a different story. It doesn't anything but that Pentax has (and probably still is) looking into the matter.
That is encouraging. But the excitement should be contained, folks.
10-05-2012, 04:22 AM   #42
Pentaxian
RonHendriks1966's Avatar

Join Date: Jan 2009
Photos: Gallery
Posts: 8,714
QuoteOriginally posted by eurostar Quote
I don't see why it should be a proof a FF is coming.

A 70-200/2,8 is just a 100-300/2,8 scaled down for APS-C.
Well this can also be made for aps-c indeed.

I would buy it and sell my sigma!

I still prefer DA*135-270mm/f2.8 since that lens does make sence in creating a new lens that no competition has in it's portfolio and delevering on performance for a wide range of users. For sports it is good and with a TC it will deliver for nature photographers.
10-05-2012, 05:26 AM   #43
Veteran Member
maxfield_photo's Avatar

Join Date: Mar 2011
Location: Cincinnati, OH
Posts: 1,215
QuoteOriginally posted by eurostar Quote
I don't see why it should be a proof a FF is coming. A 70-200/2,8 is just a 100-300/2,8 scaled down for APS-C.
I have to agree. As others are quick to point out, one major obstacle to Pentax releasing a full frame camera is that they've let their line of 35mm glass lapse, particularly in the area of zooms. Basically any time they design a lens they have one of two options, to fill a 36x24 frame, or to only fill a 24x16 frame. Obviously the first option adds unnecessary bulk to the lens if it will only ever be mounted on an APS-C body (of course it does let APS-C shooters take advantage of the sharpest part of the image circle), but this design philosophy has left Pentax in a position of being unable to offer lenses to go with a full frame DSLR should they choose to release one.

And hey, what about some love for us film shooters? Canon and Nikon never abandoned their film users. I may be wrong, but I believe both companies still make a film body, and of course all their Fx/EF lenses can be used on film.

I view this 70-200 f/2.8, if indeed it ever sees the light of production, as a way of getting back to a path from which Pentax never should have strayed rather than the herald of an imminent full frame. And in keeping with that theme, I hope they include an aperture ring.

Last edited by maxfield_photo; 10-05-2012 at 05:44 AM.
10-05-2012, 08:42 AM   #44
Veteran Member
RuiC's Avatar

Join Date: Jan 2009
Location: Lisboa - The Grocery
Posts: 616
QuoteOriginally posted by Eagle_Friends Quote
[/COLOR][/LEFT]

look a 70-200mm f2.8!!!!!

FF on the horizon right? right?

QuoteOriginally posted by DSims Quote
I can't read Japanese, but are you sure the filing date isn't March 10, 2011? That would still be interesting, since it's pre-Ricoh. And it wouldn't have contradicted any of Hoya's claims that it wasn't working on FF, since it's a bit cropped.
QuoteOriginally posted by goubejp Quote
Image circle needed for 24*36 = sqrt (12*12 + 18 * 18) = 21,633 mm precisely
The patent is for a lens with an image circle of 21,64 mm so it fits;
I can't read Japanese but I don't see a patent for a lens giving image dimensions by its width and its height. It is the image circle that is specified here

You can read it in english here, filed by Pentax-Ricoh :

United States Patent Application: 0120229689
10-05-2012, 08:46 AM   #45
Veteran Member
Dr_who's Avatar

Join Date: Jun 2009
Location: Edmonton, Alberta, Canada
Photos: Gallery | Albums
Posts: 690
Pentax 100mm WR is Film/FF compatable, and that came out a long time ago and still no FF so I don't see why this would indicate ones in the horizon.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
70-200mm, elements, f/2.8, ff, full-frame, length, lens, patent, pentax
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Confirmed(?) that the new DA 560mm is a Petzal design DeadJohn Pentax SLR Lens Discussion 15 09-19-2012 02:22 AM
I sorta got published! VaughnA Photographic Technique 13 08-15-2011 09:36 PM
Lenses on a Safari.... well sorta Aknot Troubleshooting and Beginner Help 7 06-22-2011 04:31 AM
New sorta 123_casey_123 Welcomes and Introductions 2 06-05-2011 04:36 AM
So I got a K20D... sorta. Lurch Pentax DSLR Discussion 9 04-16-2011 04:48 AM



All times are GMT -7. The time now is 08:30 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top