Pentax K-5?
Posted 03/03/2010 - 22:44
Link
Shaky wrote:
On the other hand, with apologies to K7 owners it is an open secret that its sensor is inferior to that in the Kx.
Not at low ISO, even my K10D preforms better there then the K-X
On the other hand, with apologies to K7 owners it is an open secret that its sensor is inferior to that in the Kx.
Stefan
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
Posted 03/03/2010 - 23:41
Link
George Lazarette wrote:
The mount does not allow such an aperture on a 35mm camera, but it might well be OK on an APS-C camera.
G
Okay are you ready.Anvh wrote:
Also I believe a D-FA 50mm f/1.0 can not be made for the K-mount because it's to small.
Why?Also I believe a D-FA 50mm f/1.0 can not be made for the K-mount because it's to small.
The mount does not allow such an aperture on a 35mm camera, but it might well be OK on an APS-C camera.
G
f=F/D that will not change no matter.
Rigister of the K-mount is 45.5mm and it has a diameter of 45mm, there for theoretical the optimum lens would be a 45.5mm lens with an opening of 45mm and you will get f/1.01 now you need some flesh for the lens since it isn't made out of air so the 50mm f/1.2 is on the limit of the mount.
When you go past the register of the mount (lets say 30mm) your lens will need to go into the mount or you need to use an angenieux retrofocus design.
But you're right that it's easier to make faster lenses on APS-C then on 135 film but f/1.01 it the theoretical limit of the K-mount and what the practical limit is?
Satisfied with the answer or do I need to make a study out of it?
Maybe someone with more knowledge can help since this my limit
Stefan
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
Posted 03/03/2010 - 23:47
Link
That can't be right - there are f1.2 lenses in 42mm screw mount. The K mount is quite a wide throat, much wider than Nikon for example and significantly wider than 42mm.
I don't see why an f1 lens couldn't be made, especially as so many lenses break all the theoretical rules anyway these days.
I don't see why an f1 lens couldn't be made, especially as so many lenses break all the theoretical rules anyway these days.
Best regards, John
Posted 04/03/2010 - 00:37
Link
And then there are 400mm f/2.8 lenses, obviously they'd need a 143mm mount...
Dan
Dan
K-3, a macro lens and a DA*300mm...
Posted 04/03/2010 - 00:46
Link
45.5/42=1.08 more then enough room to make an f/1.2 lens.
I ain't 100% sure 45mm is right, got it from the pentaxforums.com.
The Nikon F-mount is 44mm for comparison and I know they are almost the same in size as the K-mount.
I ain't 100% sure 45mm is right, got it from the pentaxforums.com.
The Nikon F-mount is 44mm for comparison and I know they are almost the same in size as the K-mount.
Stefan
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
Posted 04/03/2010 - 00:52
Link
Daniel Bridge wrote:
And then there are 400mm f/2.8 lenses, obviously they'd need a 143mm mount...
It doesn't work like that and the design is different from the lens but well yes there are tricks to get a lower f-number then f/1 but it's going to be a macro lens.And then there are 400mm f/2.8 lenses, obviously they'd need a 143mm mount...
ps. actually you need to measure the front element with telephoto lenses but yes the rear also limits it don't ask me how and what at 2am
The 400mm f/2.8 has a filter diameter of 145mm, there fits your 143mm perfectly
Stefan
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
Posted 04/03/2010 - 07:14
Link
Anvh wrote:
Where does this info come from? Have you checked it?
Shaky wrote:
On the other hand, with apologies to K7 owners it is an open secret that its sensor is inferior to that in the Kx.
Not at low ISO, even my K10D preforms better there then the K-X On the other hand, with apologies to K7 owners it is an open secret that its sensor is inferior to that in the Kx.
Posted 04/03/2010 - 09:11
Link
Anvh wrote:
If Pentax wait long enough they don't need one...
I wonder how much of the market extra they should take then and how they must get a camera under the K-X?
2008, I know old numbers but you can see the models above the lowest entry level are more popular.
I would have thought the K200D's market penetration would've been higher, and I am surprised the K20D doesn't appear. It's not as if Pentax are invisible....
If Pentax wait long enough they don't need one...
I wonder how much of the market extra they should take then and how they must get a camera under the K-X?
2008, I know old numbers but you can see the models above the lowest entry level are more popular.
Z-1p, K-1, P50
F50 1.7. SMC-FAs 24, 35, 50 1.4, 85, 135. HD-FA15-30, DFA24-70, D-FA*70-200. The SMC-FA Limited Trinity.
Metz 45 CL-4, AF500FTZ. AF540FGZ.
Some Mamiya and some Nikon, and a Canon T70.
F50 1.7. SMC-FAs 24, 35, 50 1.4, 85, 135. HD-FA15-30, DFA24-70, D-FA*70-200. The SMC-FA Limited Trinity.
Metz 45 CL-4, AF500FTZ. AF540FGZ.
Some Mamiya and some Nikon, and a Canon T70.
Posted 04/03/2010 - 14:08
Link
KZ wrote:
Yes my uncle has the K-X and I the K10D so I can compare and there are comparisons of the K-7 and the K-X sensor and the conclusion was that the K-7 showed less artefact at lower ISO then the K-X.Anvh wrote:
Where does this info come from? Have you checked it?Shaky wrote:
On the other hand, with apologies to K7 owners it is an open secret that its sensor is inferior to that in the Kx.
Not at low ISO, even my K10D preforms better there then the K-X On the other hand, with apologies to K7 owners it is an open secret that its sensor is inferior to that in the Kx.
They placed the base ISO of the K-X at around ISO 400 making more effective at higher ISO but if you go lower then you also need to give in on quality.
And it was already a know that the K10D was better at low ISO then the K20D making it automaticly better at low ISO then the K-7 and the K-X
link
Quote:
Therefore, the K-x sensor outperforms the K-7 in low light situations whereas the K-7 outperforms the K-x in good light. This is further confirmed by the better resolution and more artifact-free images from the K-7.
Therefore, the K-x sensor outperforms the K-7 in low light situations whereas the K-7 outperforms the K-x in good light. This is further confirmed by the better resolution and more artifact-free images from the K-7.
Stefan
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
Posted 04/03/2010 - 14:10
Link
Pwynnej wrote:
Oh no but they only held 1.6% of the Japanese market that time Anvh wrote:
If Pentax wait long enough they don't need one...
I wonder how much of the market extra they should take then and how they must get a camera under the K-X?
2008, I know old numbers but you can see the models above the lowest entry level are more popular.
I would have thought the K200D's market penetration would've been higher, and I am surprised the K20D doesn't appear. It's not as if Pentax are invisible....If Pentax wait long enough they don't need one...
I wonder how much of the market extra they should take then and how they must get a camera under the K-X?
2008, I know old numbers but you can see the models above the lowest entry level are more popular.
It went up with the K-M and ever further up with the K-X, I really don't know what market share they have now.
Stefan
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
Posted 04/03/2010 - 14:29
Link
johnriley wrote:
That can't be right - there are f1.2 lenses in 42mm screw mount. The K mount is quite a wide throat, much wider than Nikon for example and significantly wider than 42mm.
I'm also not convinced it's correct, if I recall correctly there were several special order f/1 lenses for Nikon in the 50-85mm range.
That can't be right - there are f1.2 lenses in 42mm screw mount. The K mount is quite a wide throat, much wider than Nikon for example and significantly wider than 42mm.
Tim
AF - Pentax K5, Sigma 10-20/4-5.6, Tamron 17-50/2.8, Sigma 30/1.4, Sigma 70-200/2.8, Tamron 70-300/4-5.6
MF - Vivitar CF 28/2.8, Tamron AD2 90/2.5, MTO 1000/11
Stuff - Metz 58 AF1, Cactus v4, Nikon SB24, Raynox 150, Sigma 1.4x TC, Sigma 2x TC, Kenko 2x macro TC, Redsnapper 283 tripod, iMac 27”, Macbook Pro 17”, iPad, iPhone 3G
Flickr • Fluidr • PPG • Street • Portfolio site
Feel free to edit any of my posted photos! If I post a photo for critique, I want brutal honesty. If you don't like it, please say so and tell me why!
AF - Pentax K5, Sigma 10-20/4-5.6, Tamron 17-50/2.8, Sigma 30/1.4, Sigma 70-200/2.8, Tamron 70-300/4-5.6
MF - Vivitar CF 28/2.8, Tamron AD2 90/2.5, MTO 1000/11
Stuff - Metz 58 AF1, Cactus v4, Nikon SB24, Raynox 150, Sigma 1.4x TC, Sigma 2x TC, Kenko 2x macro TC, Redsnapper 283 tripod, iMac 27”, Macbook Pro 17”, iPad, iPhone 3G
Flickr • Fluidr • PPG • Street • Portfolio site
Feel free to edit any of my posted photos! If I post a photo for critique, I want brutal honesty. If you don't like it, please say so and tell me why!
Posted 04/03/2010 - 14:39
Link
The more I think about this the more I wonder if the size of the mount has anything to do with it.
Surely it is all dependent on the size of the front element and the amount of light getting into the lens? And the mount has no effect?
Surely it is all dependent on the size of the front element and the amount of light getting into the lens? And the mount has no effect?
Tim
AF - Pentax K5, Sigma 10-20/4-5.6, Tamron 17-50/2.8, Sigma 30/1.4, Sigma 70-200/2.8, Tamron 70-300/4-5.6
MF - Vivitar CF 28/2.8, Tamron AD2 90/2.5, MTO 1000/11
Stuff - Metz 58 AF1, Cactus v4, Nikon SB24, Raynox 150, Sigma 1.4x TC, Sigma 2x TC, Kenko 2x macro TC, Redsnapper 283 tripod, iMac 27”, Macbook Pro 17”, iPad, iPhone 3G
Flickr • Fluidr • PPG • Street • Portfolio site
Feel free to edit any of my posted photos! If I post a photo for critique, I want brutal honesty. If you don't like it, please say so and tell me why!
AF - Pentax K5, Sigma 10-20/4-5.6, Tamron 17-50/2.8, Sigma 30/1.4, Sigma 70-200/2.8, Tamron 70-300/4-5.6
MF - Vivitar CF 28/2.8, Tamron AD2 90/2.5, MTO 1000/11
Stuff - Metz 58 AF1, Cactus v4, Nikon SB24, Raynox 150, Sigma 1.4x TC, Sigma 2x TC, Kenko 2x macro TC, Redsnapper 283 tripod, iMac 27”, Macbook Pro 17”, iPad, iPhone 3G
Flickr • Fluidr • PPG • Street • Portfolio site
Feel free to edit any of my posted photos! If I post a photo for critique, I want brutal honesty. If you don't like it, please say so and tell me why!
Posted 04/03/2010 - 15:17
Link
thoughton wrote:
The more I think about this the more I wonder if the size of the mount has anything to do with it.
Surely it is all dependent on the size of the front element and the amount of light getting into the lens? And the mount has no effect?
Well just measured it and it's 45mm if you don't believe me measure it yourself The more I think about this the more I wonder if the size of the mount has anything to do with it.
Surely it is all dependent on the size of the front element and the amount of light getting into the lens? And the mount has no effect?
It depends on the size mount and the register distance (not so really on the front element besides with lenses of other design but you still have the limitation how big the rear element can be).
When you focal length is smaller then you register distance the lens must travel inside the mirror housing, that isn't a big problem but you can only go so far before hitting the mirror. actually most fast primes travel slightly into the housing and have a smaller rear element then you would think.
So if you want to have wide angle lenses you need to use different lens designs, they actually used a reversed telephoto design for it.
link
Quote:
A telephoto lens works by having the outermost (i.e. light gathering) element of a much shorter focal length than the equivalent long-focus lens and then incorporating a second set of elements close to the film or sensor plane that extend the cone of light so that it appears to have come from a lens of much greater focal length.
That's why the front element is important with these designs but the rear elements are still subjected to the physical limitations of the lens mount, does that make sense?A telephoto lens works by having the outermost (i.e. light gathering) element of a much shorter focal length than the equivalent long-focus lens and then incorporating a second set of elements close to the film or sensor plane that extend the cone of light so that it appears to have come from a lens of much greater focal length.
About the diameter, I believe the size mount for the Canon is 52mm so it's no wonder they could make an f/1 lens but they even hardly sold any of them because of the price.
Making a f/1 lens for the K-mount would be a lot more challenging and therefore going to cost more then the Canon 50mm f/1
I just searched for the Nikon lens but the fastest they had was an f/1.2 so would be interesting to see where you found the Nikon f/1 lens.
Stefan
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
Posted 04/03/2010 - 17:04
Link
So in 2008 Pentax sold absolutely nothing in Japan that wasn't a K200D?
Something seems fishey to me.....
Something seems fishey to me.....
you don't have to be mad to post here
but it does help
but it does help
Add Comment
To leave a comment - Log in to Pentax User or create a new account.
10412 posts
18 years
Dordrecht,
the Netherlands
Also I believe a D-FA 50mm f/1.0 can not be made for the K-mount because it's to small.
Will get back on that later if you don't mind
K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ