Focussing screens for the K1 DIY split image

**UncleVanya** · 11-20-2016, 01:58 PM

Originally posted by 6x7II

Ok here I am back,

I did a check with a FA 77mm 1.8 limited.

There is 1% front focus hence I need a thinner brass sim than the one that came with my copy of the K1. Removing the sim (0.45mm) result in a back focus of 2.15% so the sim needs to be (2.15/1+2.15)*0.45 = 0.307mm the sims normally comes in steps of 0.05 so the nearest sim would be 0.3mm. The question is if Pentax will provide those, or do i have to look for some other material and cut it my self from plastic.

Could you 3D print one?

stevebrot · 11-20-2016, 04:11 PM

Originally posted by UncleVanya

Could you 3D print one?

What would be cool is if someone could craft a die to make shims out of sheet stock.

Steve

**clackers** · 11-20-2016, 04:55 PM

Originally posted by skyer

I was using Nikon D750. It's autofocus (with some lenses) is extraordinary, especially in regards to how accurate its autofocus is!

Technique and correct settings are most of people's problems. Here's a D750 user who simply couldn't get it to work:

Problem with AF-C AF mode - Nikon D750 - FM Forums

Originally posted by skyer

Please, compare manual focusing through the viewfinder to the manual focusing in LiveView.

And there's another ... the D750 doesn't have focus peaking, every Pentax does.

skyer · 11-21-2016, 04:24 AM

Originally posted by stevebrot

Film flatness is the challenge for accuracy with film photography.

Yes, film flatness is also an issue. Also, thank you, Steve, for your instruction on screen calibration!

Originally posted by clackers

Technique and correct settings are most of people's problems. Here's a D750 user who simply couldn't get it to work:
Problem with AF-C AF mode - Nikon D750 - FM Forums

It's obvious to me that the user's problem lies not in the AF but in a movement of his camera/baby. 1/125s is not fast enough for shooting movement. Also, D750 has a problem with the shutter shake. At 50mm, images were much sharper at 1/160 and ISO640 then at 1/50 and ISO200. This was a real problem. With K-1 and 50mm lens I can get pin-sharp images at about 1/15s quite easily.
However, when one photographs playing babies, usually it is needed to shoot at 1/200 and faster. So Nikon is still great in this regard.

Originally posted by clackers

And there's another ... the D750 doesn't have focus peaking, every Pentax does.

Well, it doesn't relate to our discussion at all. Personally, I think this feature is only usable for shooting video. Unfortunately, Pentax doesn't offer focus peaking in the video mode.

Gimbal · 11-21-2016, 08:07 AM

Originally posted by stevebrot

What would be cool is if someone could craft a die to make shims out of sheet stock.

Steve

Perhaps one could etch the shims out of thin metal sheets.

Nuij · 11-21-2016, 08:50 AM

Originally posted by Gimbal

Perhaps one could etch the shims out of thin metal sheets.

I used wire spark erosion for my K30 shimms

**clackers** · 11-21-2016, 03:16 PM

Originally posted by skyer

. Personally, I think this feature is only usable for shooting video.

I personally prefer magnified Live View, Skyer, because I think it's less misleading, but a lot of people across different camera brands really like focus peaking for manual focus lens.

You won't get that with the 750D.

stevebrot · 11-21-2016, 10:53 PM

Originally posted by clackers

I personally prefer magnified Live View, Skyer, because I think it's less misleading

You hit the nail on the head. All one has to do is watch the progression of the "peak" line as focus is racked far to near. Depending on contrast, the range of acceptable focus can be pretty broad. I never use it.

Steve

skyer · 11-22-2016, 04:52 AM - **1 Like**

Yes. I also never use focus peaking. I use siple 10% and higher magnification for manual focusing. In the video mode, in contrary, this feature would be very handful.

6x7II · 12-27-2016, 03:13 PM

I updated the opening post with the latest insights :-) see below

UPDATE:

After some days of use I discovered that the focussing was not correct, this was caused by a too small distance between lens and screen, hence I had to bring the screen a little up. In the body is a brass shim (metal frame) which can be removed too, one can replace this with a thinner one, or as I did, grind it back to the desired thickness.
However it is important that the thickness is uniform across the frame, in order to do so I glued it on a flat piece of wood and then gently grind it back. see the last picture.
The brass shim is just visible, totally on top of the picture with the K1 Body, Releasing the shim is done with the most right side release.

The focus conformation of the AF now matches the screen.

Second update I changed the splitscreen for a microprisma screen that serve my needs better. (Canon Ec-A)
This set up is now used for a couple of shoots and I am 100% happy with it.

stevebrot · 12-27-2016, 09:23 PM

Originally posted by 6x7II

The focus conformation of the AF now matches the screen.

Cool

You might want to reference against magnified live view using a resolution target. The gold standard for screen calibration is magnified live view. The focus confirmation using PDAF has significantly poorer precision than your split-image focus aid (>1.5 stops less precise).

Steve

6x7II · 12-28-2016, 01:29 AM

Originally posted by stevebrot

Cool

You might want to reference against magnified live view using a resolution target. The gold standard for screen calibration is magnified live view. The focus confirmation using PDAF has significantly poorer precision than your split-image focus aid (>1.5 stops less precise).

Steve

Hi Steve,
The pixel density on a K1 is less than on a K3 (25MP) vs 15MP on aps-c, hence the focussing is "less critical" as on a K3, I compared all options and would say that PDAF is the most accurate as long as you and the camera agree on where to focus

, imagine a tree with branches and small twigs, the AF-sensor selected is bigger that the twig and it is unclear which twig it will focus on to, now the micro prisms come in handy, because they show where the AF focused, and give you the opportunity to refocus.
So for me the focussing-aids on the screen are mainly an optical feedback of what the AF did

If one works from tripod the 10x magnification in live view does the same trick of optical feedback, but for portraits and documentary this is way to slow.

corsan · 12-28-2016, 02:50 AM

I wonder: Does the LCD-overlay work with a DIY focusing screen?

6x7II · 12-28-2016, 03:22 AM

Originally posted by corsan

I wonder: Does the LCD-overlay work with a DIY focusing screen?

Yes it works that is not touched :-)

**Schraubstock** · 12-28-2016, 04:24 AM

You may be able to procure a number different gauge pieces of brass foil and have shims cut by a precision laser cutter. Perhaps even paper. I have seen very intricately cut posts cards this way. The laser cutter would then use the original as a template. Ones in place, reordering would be a cinch.

Possible ? Just theorizing.

11-20-2016, 04:11 PM	#32
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by UncleVanya Could you 3D print one? What would be cool is if someone could craft a die to make shims out of sheet stock. Steve Last edited by stevebrot; 11-20-2016 at 07:44 PM.

12-28-2016, 02:50 AM	#43
corsan New Member Join Date: Jun 2016 Location: Nehren, Baden-Württemberg Posts: 19	LCD-Overlay and new focusing screen? I wonder: Does the LCD-overlay work with a DIY focusing screen?

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11-20-2016, 01:58 PM	#31
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,401	Originally posted by 6x7II Ok here I am back, I did a check with a FA 77mm 1.8 limited. There is 1% front focus hence I need a thinner brass sim than the one that came with my copy of the K1. Removing the sim (0.45mm) result in a back focus of 2.15% so the sim needs to be (2.15/1+2.15)*0.45 = 0.307mm the sims normally comes in steps of 0.05 so the nearest sim would be 0.3mm. The question is if Pentax will provide those, or do i have to look for some other material and cut it my self from plastic. Could you 3D print one?

11-20-2016, 04:55 PM	#33
clackers Otis Memorial Pentaxian Join Date: Jul 2013 Location: Melbourne Photos: Albums Posts: 16,397	Originally posted by skyer I was using Nikon D750. It's autofocus (with some lenses) is extraordinary, especially in regards to how accurate its autofocus is! Technique and correct settings are most of people's problems. Here's a D750 user who simply couldn't get it to work: Problem with AF-C AF mode - Nikon D750 - FM Forums Originally posted by skyer Please, compare manual focusing through the viewfinder to the manual focusing in LiveView. And there's another ... the D750 doesn't have focus peaking, every Pentax does.

11-21-2016, 04:24 AM	#34
skyer Senior Member Join Date: Apr 2012 Location: Orel, Russia Posts: 251	Originally posted by stevebrot Film flatness is the challenge for accuracy with film photography. Yes, film flatness is also an issue. Also, thank you, Steve, for your instruction on screen calibration! Originally posted by clackers Technique and correct settings are most of people's problems. Here's a D750 user who simply couldn't get it to work: Problem with AF-C AF mode - Nikon D750 - FM Forums It's obvious to me that the user's problem lies not in the AF but in a movement of his camera/baby. 1/125s is not fast enough for shooting movement. Also, D750 has a problem with the shutter shake. At 50mm, images were much sharper at 1/160 and ISO640 then at 1/50 and ISO200. This was a real problem. With K-1 and 50mm lens I can get pin-sharp images at about 1/15s quite easily. However, when one photographs playing babies, usually it is needed to shoot at 1/200 and faster. So Nikon is still great in this regard. Originally posted by clackers And there's another ... the D750 doesn't have focus peaking, every Pentax does. Well, it doesn't relate to our discussion at all. Personally, I think this feature is only usable for shooting video. Unfortunately, Pentax doesn't offer focus peaking in the video mode.

11-21-2016, 08:07 AM	#35
Gimbal Pentaxian Join Date: Apr 2007 Location: Sweden Posts: 2,106	Originally posted by stevebrot What would be cool is if someone could craft a die to make shims out of sheet stock. Steve Perhaps one could etch the shims out of thin metal sheets.

11-21-2016, 08:50 AM	#36
Nuij Forum Member Join Date: Feb 2014 Location: Ospeldijk Posts: 60	Originally posted by Gimbal Perhaps one could etch the shims out of thin metal sheets. I used wire spark erosion for my K30 shimms

11-21-2016, 03:16 PM	#37
clackers Otis Memorial Pentaxian Join Date: Jul 2013 Location: Melbourne Photos: Albums Posts: 16,397	Originally posted by skyer . Personally, I think this feature is only usable for shooting video. I personally prefer magnified Live View, Skyer, because I think it's less misleading, but a lot of people across different camera brands really like focus peaking for manual focus lens. You won't get that with the 750D.

11-21-2016, 10:53 PM	#38
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by clackers I personally prefer magnified Live View, Skyer, because I think it's less misleading You hit the nail on the head. All one has to do is watch the progression of the "peak" line as focus is racked far to near. Depending on contrast, the range of acceptable focus can be pretty broad. I never use it. Steve

11-22-2016, 04:52 AM - 1 Like	#39
skyer Senior Member Join Date: Apr 2012 Location: Orel, Russia Posts: 251	Yes. I also never use focus peaking. I use siple 10% and higher magnification for manual focusing. In the video mode, in contrary, this feature would be very handful.

12-27-2016, 03:13 PM	#40
6x7II New Member Join Date: Aug 2013 Posts: 21 Original Poster	I updated the opening post with the latest insights :-) see below UPDATE: After some days of use I discovered that the focussing was not correct, this was caused by a too small distance between lens and screen, hence I had to bring the screen a little up. In the body is a brass shim (metal frame) which can be removed too, one can replace this with a thinner one, or as I did, grind it back to the desired thickness. However it is important that the thickness is uniform across the frame, in order to do so I glued it on a flat piece of wood and then gently grind it back. see the last picture. The brass shim is just visible, totally on top of the picture with the K1 Body, Releasing the shim is done with the most right side release. The focus conformation of the AF now matches the screen. Second update I changed the splitscreen for a microprisma screen that serve my needs better. (Canon Ec-A) This set up is now used for a couple of shoots and I am 100% happy with it.

12-27-2016, 09:23 PM	#41
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by 6x7II The focus conformation of the AF now matches the screen. Cool You might want to reference against magnified live view using a resolution target. The gold standard for screen calibration is magnified live view. The focus confirmation using PDAF has significantly poorer precision than your split-image focus aid (>1.5 stops less precise). Steve

12-28-2016, 01:29 AM	#42
6x7II New Member Join Date: Aug 2013 Posts: 21 Original Poster	Originally posted by stevebrot Cool You might want to reference against magnified live view using a resolution target. The gold standard for screen calibration is magnified live view. The focus confirmation using PDAF has significantly poorer precision than your split-image focus aid (>1.5 stops less precise). Steve Hi Steve, The pixel density on a K1 is less than on a K3 (25MP) vs 15MP on aps-c, hence the focussing is "less critical" as on a K3, I compared all options and would say that PDAF is the most accurate as long as you and the camera agree on where to focus , imagine a tree with branches and small twigs, the AF-sensor selected is bigger that the twig and it is unclear which twig it will focus on to, now the micro prisms come in handy, because they show where the AF focused, and give you the opportunity to refocus. So for me the focussing-aids on the screen are mainly an optical feedback of what the AF did If one works from tripod the 10x magnification in live view does the same trick of optical feedback, but for portraits and documentary this is way to slow.

12-28-2016, 03:22 AM	#44
6x7II New Member Join Date: Aug 2013 Posts: 21 Original Poster	Originally posted by corsan I wonder: Does the LCD-overlay work with a DIY focusing screen? Yes it works that is not touched :-)

12-28-2016, 04:24 AM	#45
Schraubstock Site Supporter Join Date: Oct 2010 Location: Melbourne Photos: Gallery Posts: 3,386	You may be able to procure a number different gauge pieces of brass foil and have shims cut by a precision laser cutter. Perhaps even paper. I have seen very intricately cut posts cards this way. The laser cutter would then use the original as a template. Ones in place, reordering would be a cinch. Possible ? Just theorizing.