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11-19-2016, 07:35 AM - 1 Like   #1
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Focussing screens for the K1 DIY split image

Hello everybody,

In recent years with APS-C bodies (K7 - K3) I used an split image screen from focusscreen.com actually a Nikon K3 screen sized back to APS-C
But for the K1 nothing is available yet.

The screens of the K1 are replaceable similar to the APS-C series.

The Pentax's screen is really large 26mm x 38.25mm so my "raw" material needs to be as large as possible the best candidate are the screens for the Canon 1D series.
I ordered a original Canon Ec-B screen (quiet affordable) and did a small modification, see the pictures below for a small tutorial.

UPDATE:

After some days of use I discovered that the focussing was not correct, (front focus) 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.

Disclaimer: modifications are at your own risk.

Happy snapping Gert Jan

My pictures GJ B&W | Flickr

Attached Images
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PENTAX K-3  Photo 
View Picture EXIF
PENTAX K-3  Photo 
View Picture EXIF
PENTAX K-3  Photo 
View Picture EXIF
PENTAX K-3  Photo 
View Picture EXIF
DMC-GM5  Photo 

Last edited by 6x7II; 12-28-2016 at 01:32 AM. Reason: extension of tutorial
11-19-2016, 07:43 AM   #2
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is that focusing screen from focusingscreen.com?
11-19-2016, 07:53 AM   #3
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I thought the k1 screen wasn't replaceable. Interesting.
11-19-2016, 08:06 AM - 1 Like   #4
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If I can put a Canon Ee-S focusing screen into the K1, my last reservation about it is gone.

11-19-2016, 08:56 AM   #5
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It would be interesting to compare the K1's focusing screens with other Pentax focusing screens. Yes, the famous Pentax LX and it's less-famous sibling Pentax MX had interchangeable focusing screens, see here for a comprehensive list:
Pentax Focusing Screens

Maybe these are 1:1 replacements without the need to remove tabs?
11-19-2016, 09:13 AM   #6
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QuoteOriginally posted by funktionsfrei Quote
It would be interesting to compare the K1's focusing screens with other Pentax focusing screens. Yes, the famous Pentax LX and it's less-famous sibling Pentax MX had interchangeable focusing screens, see here for a comprehensive list:
Pentax Focusing Screens

Maybe these are 1:1 replacements without the need to remove tabs?
Of cause that was the first thing I tried, because I do have a LX, but those screens are smaller 35.2mm x 25mm and just drops out of the frame, so this is not recommended :-)
Funny I always, thought the LX had a 100% coverage, but that can't be true, with a width less than 36mm.
11-19-2016, 10:09 AM   #7
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Is the thickness equal? If not different thickness shims must be used in order to keep viewfinder focussing OK. Is automatic exposure still OK?

11-19-2016, 10:26 AM   #8
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So, remove the tap and that's it? No need for adjustment?
11-19-2016, 10:32 AM   #9
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QuoteOriginally posted by 6x7II Quote
Of cause that was the first thing I tried
Thanks for the information.
The first time I changed a screen was with my Pentax *ist DS; here someone made a fitting replacement screen by modifying an old LX screen.

The result wasn't stellar, but so was the *ist DS itself.
11-19-2016, 10:56 AM   #10
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Very cool! As with the commenters above, I wonder about thickness and need for shims. Were you able to use a micrometer to compare thickness? Does the split image focus agree with magnified live view?


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11-19-2016, 10:58 AM   #11
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QuoteOriginally posted by tonezime Quote
If I can put a Canon Ee-S focusing screen into the K1, my last reservation about it is gone.
Would the Ec-S do? It is the same size as the screen used by the OP.


Steve
11-19-2016, 11:26 AM   #12
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QuoteOriginally posted by stevebrot Quote
Would the Ec-S do? It is the same size as the screen used by the OP.

Yeah, I guess I really meant "S-type" not specifically the Ee-S.
11-19-2016, 01:09 PM   #13
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QuoteOriginally posted by 6x7II Quote
Hello every body,

In recent years with APS-C bodies (K7 - K3) I used an split image screen from focusscreen.com actually a Nikon K3 screen sized back to APS-C
But for the K1 nothing is available yet.

The screens of the K1 are replaceable similar to the APS-C series.

The Pentax's screen is really large 26mm x 38.25mm so my "raw" material needs to be as large as possible the best candidate are the screens for the Canon D1 series.
I ordered a original Canon Ec-B screen (quiet affordable) and did a small modification, see the pictures below for a small tutorial.

Disclaimer: modifications are at your own risk.

Happy snapping Gert Jan

My pictures GJ B&W | Flickr
How about the accuracy of focusing using the new screen?

When I had the K-3, I purchased a focusing screen from Nikon - F6A. That screen also had a split-image circle. Focusing with it could be great if not a little problem. I couldn't find the shim that could deliver 100% focusing accuracy. The K-1 has more megapixels. I wonder, is it really possible to get 100% accuracy using DIY shims?

By the way, the K-1 has a very good focusing assist. When one is rotating a focusing ring, a corresponding red square lights up in a viewfinder, showing that an object is in focus. Taking into account that the K-1's autofocus is very accurate, manual focusing with the focusing assist should also be more accurate than with the DIY focusing screen.
11-19-2016, 01:28 PM - 1 Like   #14
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QuoteOriginally posted by skyer Quote
Taking into account that the K-1's autofocus is very accurate, manual focusing with the focusing assist should also be more accurate than with the DIY focusing screen.
At issue is precision.* The focus confirm feature has a focus sensitivity (ability to detect an OOF condition) of f/2.8 with the center AF point. This is acceptable for general shooting with f/2.8 and slower lenses, but does not offer acceptable precision for fine focus or at apertures wider than f/2.8. The better split image focus aides offer a focus sensitivity of f1.2 or better. The Canon S screens mentioned above provide focus sensitivity of f/1.8 but at the price of significant dimming at f/2.8 and narrower (affects metering).


Steve

* Precision is the ability to attain accurate focus over multiple attempts. Even a well-calibrated (accurate) system is fairly useless if precision is poor.

Last edited by stevebrot; 11-19-2016 at 02:14 PM.
11-19-2016, 02:31 PM   #15
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QuoteOriginally posted by stevebrot Quote
The focus confirm feature has a focus sensitivity of f/2.8 with the center AF point. This is acceptable for general shooting with f/2.8 and slower lenses, but does not offer acceptable precision for fine focus or at apertures wider than f/2.8. The better split image focus aides offer a focus sensitivity of f1.2 or better. The Canon S screens mentioned above provide focus sensitivity of f/1.8 but at the price of significant dimming at f/2.8 and narrower (affects metering).
I know about "f2.8 sensitivity". However, in practice this rule is not correct. I regulary shoot with 31 Lim, DA*55, 77 Lim and FA*85 at maximum opened apertures. When focusing on subjects that are situated not far than 3-5 meteres away and using a center AF point, the AF is very accurate even at f1.4-1.8.
I'm very scrupulous when it comes to AF accuracy. Sure, the Pentax autofocus is not 100% accurate all the time but if it were true that an autofocus is accurate only at f2.8 and above, I guess, I wouldn't use Pentax gear at all.
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