Are there any Auto focus f1.2 lens for Pentax K mount?

leekil · 10-04-2016, 09:37 PM - **1 Like**

As I commented earlier today on a 1.2 thread elsewhere -- I thought that the DSLR sensors can't actually take full advantage of faster lenses, so there is no great advantage to super-fast lenses. This could be different, however, depending on your camera/camera type.

Described here:

F-stop blues - DxOMark

https://forum.dxomark.com/index.php?topic=371.0

http://luminous-landscape.com/an-open-letter-to-the-major-camera-manufacturers/

**Digitalis** · 10-04-2016, 09:47 PM

Originally posted by leekil

I thought that the DSLR sensors can't actually take full advantage of faster lenses, so there is no great advantage to super-fast lenses.

In my testing Pentax DSLRs are able to take advantage of the extra light gathering capacity of faster lenses. Unfortunately I'm on my work laptop...i'll post some data on this. DxO are full of it.

Leumas · 10-04-2016, 10:31 PM

Originally posted by leekil

As I commented earlier today on a 1.2 thread elsewhere -- I thought that the DSLR sensors can't actually take full advantage of faster lenses, so there is no great advantage to super-fast lenses. This could be different, however, depending on your camera/camera type.

Described here:

F-stop blues - DxOMark

https://forum.dxomark.com/index.php?topic=371.0

http://luminous-landscape.com/an-open-letter-to-the-major-camera-manufacturers/

Seems kinda bogus... I just set my k70 to manual and snapped three shots, going down 1 stop on the aperture with each one, starting at f1.4. There was an obvious decrease in light with each one that almost correlated exactly in exposure as a second set of shots where I decreased each shot 1 stop via ISO. So there's obviously a benefit to fast lenses.

**RGlasel** · 10-04-2016, 10:41 PM

Originally posted by Digitalis

DxO are full of it.

You mean like this psycho-babble?

“We have been very surprised,” explained Frédéric Guichard, chief scientist at DxO Labs, “to find out that some of the gain from wider lens openings seems to be offset by the present state of sensor technology. Our measurements all point in the same direction: as you go further than f/ 4 – to f /2 and wider, the accrued quantity of light falls marginally onto the sensor. A stronger and stronger part of this additional light is blocked or lost. I am therefore inclined to question the real benefit of faster lenses.”

Ultimately, someone has to actually look at photographs in order for photography to have any meaning to real people. There are photographs that have the power to evoke an emotional response from people, what happened to produce those photographs seems somewhat disconnected from "the accrued quantity of light falls marginally onto the sensor. A stronger and stronger part of this additional light is blocked or lost."

redcat · 10-04-2016, 11:30 PM

Pentax has 50mm 1.2 MF before, it was a success, they might revive that lens with AF someday, we never know

AFAIK, the 85mm f1.2 from Canon is a huge success, size and price tag are downsize of these kind of lens though ^^

**Kerrowdown** · 10-05-2016, 12:19 AM - **1 Like**

Originally posted by enyceckk

Are there any Auto focus f1.2 lens for Pentax K mount?

Thanks,

What and take away the frustration of missing focus manually.

noelpolar · 10-05-2016, 12:20 AM - **1 Like**

Originally posted by RGlasel

You mean like this psycho-babble?

“We have been very surprised,” explained Frédéric Guichard, chief scientist at DxO Labs, “to find out that some of the gain from wider lens openings seems to be offset by the present state of sensor technology. Our measurements all point in the same direction: as you go further than f/ 4 – to f /2 and wider, the accrued quantity of light falls marginally onto the sensor. A stronger and stronger part of this additional light is blocked or lost. I am therefore inclined to question the real benefit of faster lenses.”
."

Must be reffering to Canon sensors....

gorme · 10-05-2016, 03:00 AM

Well the statement of Frédéric Guichard is valid for the case of high chief ray angle lenses. This is verified mainly for the following cases :
> Wide angle lenses
> Small size sensors with non-telecentric lenses (typical of smartphone industry).
Basically the thing is that the maximum admissible chief ray angle for a pixel is around 30°... A limitation inherent to the pixel technology, and not only to the brand ^^

As for the 50mm f/1.2 I find it usable on FF if you have some time to focus it (liveview can help) but would probably not be using it under f/1.8 iif I need to get the shot.

Dan Rentea · 10-05-2016, 05:16 AM - **1 Like**

Originally posted by paulh

I can't even see how AF at f/1.2 would be practical hand-held - even the slightest movement would throw it off. Of course on a tripod it would be a different story - but then on a tripod manual focus might be preferable anyway.

At 105mm and f1.4 the DOF should be similar to the 85mm f1.2 lenses. We have a very good photographer in Romania who's reviewing for Nikon Romania the new lens arrived to the table - Nikon 105mm f1.4

He's a photojurnalistic type of photographer and for these images (see in the link below some images at f1.4 and 105mm) he didn't use a tripod. You have to be an experienced photographer to handle the tiny DOF at 85mm or 105mm and I also want to mention that not everybody likes the look of the f1.2 or f1.4 lenses.

Nikon 105/1,4 - obiectivul acesta va... - Mircea Bezergheanu | Facebook

And below it's a portrait of an authentic romanian peasant (same photographer as above), taken at 105mm f1.4. I admit that I don't always like portraits taken at f1.2 or f1.4, but this image speaks for itself.

https://www.facebook.com/photo.php?fbid=10207529091804665&set=pb.1210472777....type=3&theater

**Just1MoreDave** · 10-05-2016, 10:02 AM

Originally posted by Kerrowdown

What and take away the frustration of missing focus manually.

Exactly!

The DA* 55/1.4 is only f1.4 so it completely fails on bragging rights. But plug its numbers into a depth of field calculator and notice it has just slightly less DOF wide open than a 50/1.2. My copy comes with the thrill of manual focusing until it finally wakes up - it's like a frat boy on a weekend. Pictures are great, weather sealing is great, you just won't win any gear-measuring contests.

**Kerrowdown** · 10-05-2016, 12:48 PM

Originally posted by Just1MoreDave

Exactly!

We all know it's all about bragging rights as you so rightly point out.

noelpolar · 10-05-2016, 02:41 PM

Originally posted by Dan Rentea

And below it's a portrait of an authentic romanian peasant (same photographer as above), taken at 105mm f1.4. I admit that I don't always like portraits taken at f1.2 or f1.4, but this image speaks for itself.

I'm not sure that if this shot was mine that I'd wouldn't have wished I'd opened up the lens a bit... maybe a stop?

**clackers** · 10-05-2016, 03:01 PM

Originally posted by noelpolar

I'm not sure that if this shot was mine that I'd wouldn't have wished I'd opened up the lens a bit... maybe a stop?

Good for the novelty value, though, Noel.

I toyed with the idea of hunting down a K50 f1.2 (the bokeh in shots I've seen is like an oil painting), but decided to be practical and go for the DA*55. For it, I reckon f2 is a good sweet spot balancing bokeh, 3D separation, sharpness, etc.

**clackers** · 10-05-2016, 03:02 PM - **1 Like**

Originally posted by Dan Rentea

At 105mm and f1.4 the DOF should be similar to the 85mm f1.2 lenses. We have a very good photographer in Romania who's reviewing for Nikon Romania the new lens arrived to the table - Nikon 105mm f1.4

Thanks for posting these, Dan ... it's always interesting to see someone bothering to push the limits of these things.

Here's a Melbourne example:

Using Sony A7 II + Mitakon 50mm F0.95 for Wedding Photography | Melbourne Wedding Photographer Will Chao

noelpolar · 10-05-2016, 03:47 PM

Originally posted by clackers

Good for the novelty value, though, Noel.

I toyed with the idea of hunting down a K50 f1.2 (the bokeh in shots I've seen is like an oil painting), but decided to be practical and go for the DA*55. For it, I reckon f2 is a good sweet spot balancing bokeh, 3D separation, sharpness, etc.

F2 is where I start to use the K50/1.2 mostly.... I am quite fond of it...

10-05-2016, 05:16 AM - 1 Like	#24
Dan Rentea Veteran Member Join Date: Sep 2014 Location: Bucharest Posts: 1,716	Originally posted by paulh I can't even see how AF at f/1.2 would be practical hand-held - even the slightest movement would throw it off. Of course on a tripod it would be a different story - but then on a tripod manual focus might be preferable anyway. At 105mm and f1.4 the DOF should be similar to the 85mm f1.2 lenses. We have a very good photographer in Romania who's reviewing for Nikon Romania the new lens arrived to the table - Nikon 105mm f1.4 He's a photojurnalistic type of photographer and for these images (see in the link below some images at f1.4 and 105mm) he didn't use a tripod. You have to be an experienced photographer to handle the tiny DOF at 85mm or 105mm and I also want to mention that not everybody likes the look of the f1.2 or f1.4 lenses. Nikon 105/1,4 - obiectivul acesta va... - Mircea Bezergheanu \| Facebook And below it's a portrait of an authentic romanian peasant (same photographer as above), taken at 105mm f1.4. I admit that I don't always like portraits taken at f1.2 or f1.4, but this image speaks for itself. https://www.facebook.com/photo.php?fbid=10207529091804665&set=pb.1210472777....type=3&theater Last edited by Dan Rentea; 10-05-2016 at 06:05 AM.

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10-04-2016, 09:37 PM - 1 Like	#16
leekil Pentaxian Join Date: May 2016 Photos: Albums Posts: 2,003	As I commented earlier today on a 1.2 thread elsewhere -- I thought that the DSLR sensors can't actually take full advantage of faster lenses, so there is no great advantage to super-fast lenses. This could be different, however, depending on your camera/camera type. Described here: F-stop blues - DxOMark https://forum.dxomark.com/index.php?topic=371.0 http://luminous-landscape.com/an-open-letter-to-the-major-camera-manufacturers/

10-04-2016, 09:47 PM	#17
Digitalis Site Supporter Join Date: Mar 2009 Location: Melbourne, Victoria Photos: Gallery Posts: 11,695	Originally posted by leekil I thought that the DSLR sensors can't actually take full advantage of faster lenses, so there is no great advantage to super-fast lenses. In my testing Pentax DSLRs are able to take advantage of the extra light gathering capacity of faster lenses. Unfortunately I'm on my work laptop...i'll post some data on this. DxO are full of it.

10-04-2016, 10:31 PM	#18
Leumas Veteran Member Join Date: Aug 2016 Posts: 454	Originally posted by leekil As I commented earlier today on a 1.2 thread elsewhere -- I thought that the DSLR sensors can't actually take full advantage of faster lenses, so there is no great advantage to super-fast lenses. This could be different, however, depending on your camera/camera type. Described here: F-stop blues - DxOMark https://forum.dxomark.com/index.php?topic=371.0 http://luminous-landscape.com/an-open-letter-to-the-major-camera-manufacturers/ Seems kinda bogus... I just set my k70 to manual and snapped three shots, going down 1 stop on the aperture with each one, starting at f1.4. There was an obvious decrease in light with each one that almost correlated exactly in exposure as a second set of shots where I decreased each shot 1 stop via ISO. So there's obviously a benefit to fast lenses.

10-04-2016, 10:41 PM	#19
RGlasel Site Supporter Join Date: Sep 2013 Location: Saskatoon Photos: Gallery \| Albums Posts: 3,229	Originally posted by Digitalis DxO are full of it. You mean like this psycho-babble? “We have been very surprised,” explained Frédéric Guichard, chief scientist at DxO Labs, “to find out that some of the gain from wider lens openings seems to be offset by the present state of sensor technology. Our measurements all point in the same direction: as you go further than f/ 4 – to f /2 and wider, the accrued quantity of light falls marginally onto the sensor. A stronger and stronger part of this additional light is blocked or lost. I am therefore inclined to question the real benefit of faster lenses.” Ultimately, someone has to actually look at photographs in order for photography to have any meaning to real people. There are photographs that have the power to evoke an emotional response from people, what happened to produce those photographs seems somewhat disconnected from "the accrued quantity of light falls marginally onto the sensor. A stronger and stronger part of this additional light is blocked or lost."

10-04-2016, 11:30 PM	#20
redcat Veteran Member Join Date: Jul 2014 Location: Paris Photos: Gallery Posts: 1,939	Pentax has 50mm 1.2 MF before, it was a success, they might revive that lens with AF someday, we never know AFAIK, the 85mm f1.2 from Canon is a huge success, size and price tag are downsize of these kind of lens though ^^

10-05-2016, 12:19 AM - 1 Like	#21
Kerrowdown PEG Moderator Join Date: Aug 2008 Location: Highlands of Scotland... "Hold Infinity in the palm of your hand" - William Blake Photos: Gallery Posts: 57,867	Originally posted by enyceckk Are there any Auto focus f1.2 lens for Pentax K mount? Thanks, What and take away the frustration of missing focus manually.

10-05-2016, 12:20 AM - 1 Like	#22
noelpolar Veteran Member Join Date: Oct 2013 Location: Goolwa, SA Photos: Gallery Posts: 4,310	Originally posted by RGlasel You mean like this psycho-babble? “We have been very surprised,” explained Frédéric Guichard, chief scientist at DxO Labs, “to find out that some of the gain from wider lens openings seems to be offset by the present state of sensor technology. Our measurements all point in the same direction: as you go further than f/ 4 – to f /2 and wider, the accrued quantity of light falls marginally onto the sensor. A stronger and stronger part of this additional light is blocked or lost. I am therefore inclined to question the real benefit of faster lenses.” ." Must be reffering to Canon sensors....

10-05-2016, 03:00 AM	#23
gorme Senior Member Join Date: May 2014 Location: Galway - Ireland Posts: 213	Well the statement of Frédéric Guichard is valid for the case of high chief ray angle lenses. This is verified mainly for the following cases : > Wide angle lenses > Small size sensors with non-telecentric lenses (typical of smartphone industry). Basically the thing is that the maximum admissible chief ray angle for a pixel is around 30°... A limitation inherent to the pixel technology, and not only to the brand ^^ As for the 50mm f/1.2 I find it usable on FF if you have some time to focus it (liveview can help) but would probably not be using it under f/1.8 iif I need to get the shot.

10-05-2016, 10:02 AM	#25
Just1MoreDave Site Supporter Join Date: Feb 2007 Location: Aurora, CO Photos: Gallery \| Albums Posts: 6,340	Originally posted by Kerrowdown What and take away the frustration of missing focus manually. Exactly! The DA* 55/1.4 is only f1.4 so it completely fails on bragging rights. But plug its numbers into a depth of field calculator and notice it has just slightly less DOF wide open than a 50/1.2. My copy comes with the thrill of manual focusing until it finally wakes up - it's like a frat boy on a weekend. Pictures are great, weather sealing is great, you just won't win any gear-measuring contests.

10-05-2016, 12:48 PM	#26
Kerrowdown PEG Moderator Join Date: Aug 2008 Location: Highlands of Scotland... "Hold Infinity in the palm of your hand" - William Blake Photos: Gallery Posts: 57,867	Originally posted by Just1MoreDave Exactly! We all know it's all about bragging rights as you so rightly point out.

10-05-2016, 02:41 PM	#27
noelpolar Veteran Member Join Date: Oct 2013 Location: Goolwa, SA Photos: Gallery Posts: 4,310	Originally posted by Dan Rentea And below it's a portrait of an authentic romanian peasant (same photographer as above), taken at 105mm f1.4. I admit that I don't always like portraits taken at f1.2 or f1.4, but this image speaks for itself. I'm not sure that if this shot was mine that I'd wouldn't have wished I'd opened up the lens a bit... maybe a stop?

10-05-2016, 03:01 PM	#28
clackers Otis Memorial Pentaxian Join Date: Jul 2013 Location: Melbourne Photos: Albums Posts: 16,397	Originally posted by noelpolar I'm not sure that if this shot was mine that I'd wouldn't have wished I'd opened up the lens a bit... maybe a stop? Good for the novelty value, though, Noel. I toyed with the idea of hunting down a K50 f1.2 (the bokeh in shots I've seen is like an oil painting), but decided to be practical and go for the DA*55. For it, I reckon f2 is a good sweet spot balancing bokeh, 3D separation, sharpness, etc.

10-05-2016, 03:02 PM - 1 Like	#29
clackers Otis Memorial Pentaxian Join Date: Jul 2013 Location: Melbourne Photos: Albums Posts: 16,397	Originally posted by Dan Rentea At 105mm and f1.4 the DOF should be similar to the 85mm f1.2 lenses. We have a very good photographer in Romania who's reviewing for Nikon Romania the new lens arrived to the table - Nikon 105mm f1.4 Thanks for posting these, Dan ... it's always interesting to see someone bothering to push the limits of these things. Here's a Melbourne example: Using Sony A7 II + Mitakon 50mm F0.95 for Wedding Photography \| Melbourne Wedding Photographer Will Chao

10-05-2016, 03:47 PM	#30
noelpolar Veteran Member Join Date: Oct 2013 Location: Goolwa, SA Photos: Gallery Posts: 4,310	Originally posted by clackers Good for the novelty value, though, Noel. I toyed with the idea of hunting down a K50 f1.2 (the bokeh in shots I've seen is like an oil painting), but decided to be practical and go for the DA*55. For it, I reckon f2 is a good sweet spot balancing bokeh, 3D separation, sharpness, etc. F2 is where I start to use the K50/1.2 mostly.... I am quite fond of it...