Pentax-A 50mm f1.2 - Is this a lens a real gem?

derekkite · 01-11-2015, 10:11 PM

Is the focus screen accurate? You use the same body for your other two 1.2 lenses?

**Pepe Guitarra** · 01-11-2015, 10:13 PM

Originally posted by derekkite

Is the focus screen accurate? You use the same body for your other two 1.2 lenses?

Yes, it is.

Sandy Hancock · 01-11-2015, 10:19 PM

I'm pretty sure you can't do in-body fine focus adjustment for A series lenses. You certainly have a pretty large discrepancy between Live view and PD focus confirmation.

For what it's worth, when I focus the A50/1.2 through the viewfinder (which is most of the time) I never use the focus confirmation beep - I *look* at the image in the viewfinder until the paper thin bit I want to be optimally focussed is in focus. Just like we did in the olden days

**Pepe Guitarra** · 01-11-2015, 10:27 PM

Originally posted by Sandy Hancock

I'm pretty sure you can't do in-body fine focus adjustment for A series lenses. You certainly have a pretty large discrepancy between Live view and PD focus confirmation.

For what it's worth, when I focus the A50/1.2 through the viewfinder (which is most of the time) I never use the focus confirmation beep - I *look* at the image in the viewfinder until the paper thin bit I want to be optimally focussed is in focus. Just like we did in the olden days

That is what I have been trying to do, and it is starting to pay off. I have taken about 200 shots this afternoon just trying to get the hang of it. Never mind my +2 +2 for reading lens prescription from my optometrist.

Ton answer the question about the camera, I try only to use the lenses wide open. Here is my Chinon Tamioka 55/1.4:

alexcam · 01-11-2015, 10:29 PM

I don't think the focus confirmation is sensitive enough for a 1.2 lens. The first manual lens I used on my K10 was a 1.7 and I used the focus confirmation to adjust focus. I didn't get many shots in focus.
Later on I installed an E-SS screen and have shot my K50mm f/1.2 with about a 75% of the pictures in focus.
Your best bet is live view/focus peaking, or hold the shutter down while slowly focusing. one of those shots should be in focus.

j2photos · 01-11-2015, 10:49 PM

Came across this today, it may be of some help.

RiceHigh's Pentax Blog: AF Fine Adjustment: "Apply All" and "Apply One" Fully Explained

**forest_bear59** · 01-11-2015, 10:50 PM

Focusing high Speed lenses with standard focusing screen is a very delicate matter. And even slight errors in adjustment - barely noticeable for Your eye - will render Your picture out of Focus. So LV will be Your rescue here.
With my K20D I have a properly adjusted KatzEye focusing Screen with split field and it's the only optical viewfinder of my cams I can get pictures taken with my Revue 1.2 lens with satisfying sharpness at the desired point.

Regards
Stephan

UlrichSchiegg · 01-11-2015, 11:41 PM

One of the reasons why EVFs (focus peaking in the view finder) vs OVFs are popular.

sTi · 01-12-2015, 01:31 AM

Could the problem be related to focus shift?
diglloyd - Focus - Focus Shift and Spherical Aberration

Remember: You never actually see the lens @ f/1.2 even through the viewfinder, it will always appear as if it was stopped down somewhat (the same is true for phase AF, which produces the focus confirmation). You can check this with optical depth of field preview, just compare f1.2, f2, f2.8, f4...

hoanpham · 01-12-2015, 04:42 AM

The A 50/1.2 is sharp enough at f1.2.

f1.2 on K5. Click to enlarge.

It looks like your images are out of focus.

**Pepe Guitarra** · 01-12-2015, 05:43 AM

Originally posted by hoanpham

...It looks like your images are out of focus.

Duh? Did you read the thread?

pinholecam · 01-12-2015, 06:58 AM

Pentax 50 f1.2??

Yes, its a sharp lens.

On any Pentax DSLR, the issue will be that AF confirm will have a tolerance.
I always found that turning the focus ring from far to near focus hit the 'right' spot more than going from near to far. (on my camera+lens combi)
Its just how it hits the in focus part within the AF confirm 'window'.

The EES precision focusing screen will help too (I used it on a 5D with the K50/1,2 )
There is a version from focusingscreen.com iirc.

SyncGuy · 01-12-2015, 07:27 AM

Nice images pinholecam!

But anyway, to TS, yes.. you'll need or definitely want, to use the Canon EE-S Screen as it is designed to be used with fast lenses.
The DOF which you see, is accurate up to f/1.2, whereas the stock screen is accurate to about f/2.8 only.

I've been using it ever since i got my Kr and i got it from focusingscreen.com

**Pepe Guitarra** · 01-12-2015, 07:45 AM

Ouch, those are not only sharp but painful. I took a class at the Leica store, and that is how they tell you to focus, from infinity to close up.

Originally posted by pinholecam

Pentax 50 f1.2??

Yes, its a sharp lens.

On any Pentax DSLR, the issue will be that AF confirm will have a tolerance.
I always found that turning the focus ring from far to near focus hit the 'right' spot more than going from near to far. (on my camera+lens combi)
Its just how it hits the in focus part within the AF confirm 'window'.

The EES precision focusing screen will help too (I used it on a 5D http://l.facebook.com/l.php?u=http%3A%2F%2Fwww.westernjournalism.com%2Fschoo...tu9N3x&s=1with the K50/1,2 )
There is a version from focusingscreen.com iirc.

**Pepe Guitarra** · 01-12-2015, 10:47 PM

Well, it is for sure. I have to go by the focus light and sign, then push a bit further the focus ring, and I get it MOST of the time. Here are samples wide open:

Stopped down at f4, no problem:

01-12-2015, 10:47 PM	#30
Pepe Guitarra Site Supporter Join Date: Nov 2010 Location: California Photos: Gallery \| Albums Posts: 2,223 Original Poster	I think I've got it down! Well, it is for sure. I have to go by the focus light and sign, then push a bit further the focus ring, and I get it MOST of the time. Here are samples wide open: Stopped down at f4, no problem:

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01-11-2015, 10:11 PM	#16
derekkite Pentaxian Join Date: Sep 2011 Location: Nelson B.C. Posts: 3,782	Is the focus screen accurate? You use the same body for your other two 1.2 lenses?

01-11-2015, 10:13 PM	#17
Pepe Guitarra Site Supporter Join Date: Nov 2010 Location: California Photos: Gallery \| Albums Posts: 2,223 Original Poster	Originally posted by derekkite Is the focus screen accurate? You use the same body for your other two 1.2 lenses? Yes, it is.

01-11-2015, 10:19 PM	#18
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,267	I'm pretty sure you can't do in-body fine focus adjustment for A series lenses. You certainly have a pretty large discrepancy between Live view and PD focus confirmation. For what it's worth, when I focus the A50/1.2 through the viewfinder (which is most of the time) I never use the focus confirmation beep - I look at the image in the viewfinder until the paper thin bit I want to be optimally focussed is in focus. Just like we did in the olden days

01-11-2015, 10:27 PM	#19
Pepe Guitarra Site Supporter Join Date: Nov 2010 Location: California Photos: Gallery \| Albums Posts: 2,223 Original Poster	Originally posted by Sandy Hancock I'm pretty sure you can't do in-body fine focus adjustment for A series lenses. You certainly have a pretty large discrepancy between Live view and PD focus confirmation. For what it's worth, when I focus the A50/1.2 through the viewfinder (which is most of the time) I never use the focus confirmation beep - I look at the image in the viewfinder until the paper thin bit I want to be optimally focussed is in focus. Just like we did in the olden days That is what I have been trying to do, and it is starting to pay off. I have taken about 200 shots this afternoon just trying to get the hang of it. Never mind my +2 +2 for reading lens prescription from my optometrist. Ton answer the question about the camera, I try only to use the lenses wide open. Here is my Chinon Tamioka 55/1.4:

01-11-2015, 10:29 PM	#20
alexcam Forum Member Join Date: Jun 2009 Location: Long Island, New York Posts: 50	I don't think the focus confirmation is sensitive enough for a 1.2 lens. The first manual lens I used on my K10 was a 1.7 and I used the focus confirmation to adjust focus. I didn't get many shots in focus. Later on I installed an E-SS screen and have shot my K50mm f/1.2 with about a 75% of the pictures in focus. Your best bet is live view/focus peaking, or hold the shutter down while slowly focusing. one of those shots should be in focus.

01-11-2015, 10:49 PM	#21
j2photos Veteran Member Join Date: Jun 2010 Location: Manteca, CA Photos: Gallery \| Albums Posts: 1,653	Came across this today, it may be of some help. RiceHigh's Pentax Blog: AF Fine Adjustment: "Apply All" and "Apply One" Fully Explained

01-11-2015, 10:50 PM	#22
forest_bear59 Site Supporter Join Date: Oct 2013 Location: Idstein (near Frankfurt - Germany) Photos: Gallery Posts: 147	Focusing high Speed lenses with standard focusing screen is a very delicate matter. And even slight errors in adjustment - barely noticeable for Your eye - will render Your picture out of Focus. So LV will be Your rescue here. With my K20D I have a properly adjusted KatzEye focusing Screen with split field and it's the only optical viewfinder of my cams I can get pictures taken with my Revue 1.2 lens with satisfying sharpness at the desired point. Regards Stephan

01-11-2015, 11:41 PM	#23
UlrichSchiegg Senior Member Join Date: Apr 2013 Photos: Gallery Posts: 298	One of the reasons why EVFs (focus peaking in the view finder) vs OVFs are popular.

01-12-2015, 01:31 AM	#24
sTi Forum Member Join Date: Feb 2011 Posts: 98	Could the problem be related to focus shift? diglloyd - Focus - Focus Shift and Spherical Aberration Remember: You never actually see the lens @ f/1.2 even through the viewfinder, it will always appear as if it was stopped down somewhat (the same is true for phase AF, which produces the focus confirmation). You can check this with optical depth of field preview, just compare f1.2, f2, f2.8, f4...

01-12-2015, 04:42 AM	#25
hoanpham Veteran Member Join Date: Nov 2009 Location: Strand Photos: Gallery \| Albums Posts: 1,366	The A 50/1.2 is sharp enough at f1.2. f1.2 on K5. Click to enlarge. It looks like your images are out of focus.

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01-12-2015, 05:43 AM	#26
Pepe Guitarra Site Supporter Join Date: Nov 2010 Location: California Photos: Gallery \| Albums Posts: 2,223 Original Poster	Originally posted by hoanpham ...It looks like your images are out of focus. Duh? Did you read the thread?

01-12-2015, 06:58 AM	#27
pinholecam Pentaxian Join Date: Oct 2009 Location: North Photos: Gallery Posts: 4,706	Pentax 50 f1.2?? Yes, its a sharp lens. On any Pentax DSLR, the issue will be that AF confirm will have a tolerance. I always found that turning the focus ring from far to near focus hit the 'right' spot more than going from near to far. (on my camera+lens combi) Its just how it hits the in focus part within the AF confirm 'window'. The EES precision focusing screen will help too (I used it on a 5D with the K50/1,2 ) There is a version from focusingscreen.com iirc.

01-12-2015, 07:27 AM	#28
SyncGuy Veteran Member Join Date: Oct 2011 Posts: 821	Nice images pinholecam! But anyway, to TS, yes.. you'll need or definitely want, to use the Canon EE-S Screen as it is designed to be used with fast lenses. The DOF which you see, is accurate up to f/1.2, whereas the stock screen is accurate to about f/2.8 only. I've been using it ever since i got my Kr and i got it from focusingscreen.com

01-12-2015, 07:45 AM	#29
Pepe Guitarra Site Supporter Join Date: Nov 2010 Location: California Photos: Gallery \| Albums Posts: 2,223 Original Poster	Ouch, those are not only sharp but painful. I took a class at the Leica store, and that is how they tell you to focus, from infinity to close up. Originally posted by pinholecam Pentax 50 f1.2?? Yes, its a sharp lens. On any Pentax DSLR, the issue will be that AF confirm will have a tolerance. I always found that turning the focus ring from far to near focus hit the 'right' spot more than going from near to far. (on my camera+lens combi) Its just how it hits the in focus part within the AF confirm 'window'. The EES precision focusing screen will help too (I used it on a 5D http://l.facebook.com/l.php?u=http%3A%2F%2Fwww.westernjournalism.com%2Fschoo...tu9N3x&s=1with the K50/1,2 ) There is a version from focusingscreen.com iirc.