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02-17-2015, 10:07 AM   #751
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QuoteOriginally posted by lm4187 Quote
If the EE-S is a micro-Fresnel lens design (I suspect it is), then the micro lenses are concentric around the center point of the screen (optical axis). If you cut the screen in half, you would be destroying the symmetry of the system and get very unintended results from your efforts.


If, on the other hand, the EE-S is merely a finely-grained (ie, random) matte screen (doubtful, but possible), then you would be good to go.

I don't think I would take the chance.

I know there have been online posts by people who have done their own conversions; you might search the web to find out their methods and experiences. Sorry I don't have any specific links.

Cheers,
Lou
Thanks for that Lou, clearly I'll need to investigate this further.
Update looking at the reflection off the screen when held at certain angles to the light it shows circular refractive patterns that I would be inclined to attribute to a fresnel as you suggeted Lou.


Last edited by marcusBMG; 02-19-2015 at 11:19 AM.
03-27-2015, 04:03 AM   #752
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QuoteOriginally posted by dlacouture Quote
Seems like the flow have ebbed down...

No more manual focus aficionados out there? Everyone already switched to the EE-S?
Ahhh, it's something I'm putting off because of the sheer choice of stuff out there. It's hard to know what to get. But, I have reached the point where I want more accurate control over focussing, and I always shoot manual anyway. So, time to dip my toe in the water! I use a k10d, and an embarrassingly large selection of lenses (ebay is a terrible temptation!). I remember using an old slr when I was a kid, and the screen had a focus ring. So, what to go for nowadays?!
03-27-2015, 05:32 AM   #753
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I have tried a few split-prism screens with micro-prism ring. I'm finding I like the micro-prism ring more than the split-prism.
03-28-2015, 01:08 AM   #754
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QuoteOriginally posted by AquaDome Quote
I have tried a few split-prism screens with micro-prism ring. I'm finding I like the micro-prism ring more than the split-prism.

Same here. I swapped the split prism screens on my two MX bodies back in the seventies for micro-prism ring type.


I would have changed the screen on my K5 to one instead of the ee-S but if it hadn't have worked properly it would have been too much cash to waste.


I've still got the two original MX split screens lying around somewhere. I've also still got the two bodies.

03-31-2015, 02:14 AM   #755
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Any suggestions where to find the micro prism screens? I'd like to try one I focus manually and the little red box is irritating me all the time now!!

I've just looked at katzeye's website and there's a notice saying they've sold the business! I know they were very expensive, which is a shame as they look like they had good stuff?

Last edited by Tarragon; 03-31-2015 at 02:25 AM.
04-02-2015, 02:39 PM   #756
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K 5 spot metering with replacement screens?

I just happened across this thread and, rather than read every entry, let me ask my question.

I installed a KatzEye in my K 10D and found that it made focusing fast lenses - f1.4, and f1.2 - much easier and more accurate. However, the spot metering function became problematic. As a use of center weighted metering on film Pentaxes this didn't bother me too much. The good folks at KatzEye did mention this for the K 10 and, while their site is misbehaving, they suggest a similar problem with the K 5.

I now have a K 5. Is it subject to the spot metering anomaly with the Canon screen you've been using?

Thanks!
04-06-2015, 04:06 AM   #757
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QuoteOriginally posted by grhazelton Quote
I now have a K 5. Is it subject to the spot metering anomaly with the Canon screen you've been using?
No, I don't have any problems with spot metering - it is the dark/light split screen that messes up the spot metering, and the EE-S doesn't have that.

I do, however, have problems with underexposure in other metering modes. I believe it's caused by the etchings in the screen. The "frame" markings made by focusingscreens.com are clear, unlike the stock screen's black markings, and this seems to confuse the metering (centre weighted or matrix) under certain conditions (typically bright light). I have noticed this the most with slower lenses, like the kit lens. Not so much, if at all, with fast lenses.

If my assumptions are correct you will not have this problem with a plain EE-S screen without any markings.
06-19-2015, 05:09 AM   #758
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I've just installed a focusingscreen K3 type in my Pentax K5 - I really wanted the split as I find eyeballing focus a little tricky (that's why I love my rangefinders, too).

Just how accurate should I expect focus to be? I've not put any shim in yet. Testing with a Zeiss M42 135/3.5 wide open, I'm getting that at the closest focus (1m), the actual plane of sharpest focus is perhaps 2mm behind the point that the screen indicates, and at 15m, it's maybe 5cm in front.

These are both significantly below 0.5% errors (and oddly in opposite directions) - is it worth playing about with the shims, or are the corrections that even the thinnest shim would introduce greater than the small inaccuracies I'm finding? Indeed, am I measuring random operator error rather than any problem with the screen here?

Cheers
Jamie

06-19-2015, 07:38 AM   #759
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QuoteOriginally posted by JamieWakeham Quote
I've just installed a focusingscreen K3 type in my Pentax K5 - I really wanted the split as I find eyeballing focus a little tricky (that's why I love my rangefinders, too).

Just how accurate should I expect focus to be? I've not put any shim in yet. Testing with a Zeiss M42 135/3.5 wide open, I'm getting that at the closest focus (1m), the actual plane of sharpest focus is perhaps 2mm behind the point that the screen indicates, and at 15m, it's maybe 5cm in front.

These are both significantly below 0.5% errors (and oddly in opposite directions) - is it worth playing about with the shims, or are the corrections that even the thinnest shim would introduce greater than the small inaccuracies I'm finding? Indeed, am I measuring random operator error rather than any problem with the screen here?
Use the shims -- you definitely need them with those screens. You should be able to absolutely nail it. But you'll probably want something faster than f/3.5 to calibrate it. I can focus a f/1.4 wide-open (or even an f/1.2 come to think of it) by eye with that screen. (I actually use a magnifier also though.)
06-19-2015, 08:26 AM   #760
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Thanks. I'll have a go with my Takumar 85/1.8 when it comes home, then - it's off being CLAd at the moment.

What I'm a little suprised about is that I'm front-focussing at distance and back-focus when close up - this is what made me wonder if it was actually random user error. Wouldn't a shim only shift the focus one way or the other?
06-19-2015, 08:39 AM   #761
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QuoteOriginally posted by JamieWakeham Quote
Thanks. I'll have a go with my Takumar 85/1.8 when it comes home, then - it's off being CLAd at the moment.

What I'm a little suprised about is that I'm front-focussing at distance and back-focus when close up - this is what made me wonder if it was actually random user error. Wouldn't a shim only shift the focus one way or the other?
It is easy to fool yourself. First thing is make sure you have the diopter on the eyepiece set where it needs to be for you and don't touch it. And then when you do your calibration, lock everything down on a tripod so that you'll be able to switch Live View on/off without changing distances at all. Focus on something at an angle so that some part of it will always be in focus (even if not the part you are aiming at, you'll be able to tell where it is focusing), and then compare where you think you're focusing in the viewfinder with where you are actually focusing (by looking at live view). And this part is important -- your eyes/brain are always trying to adjust, make things right, so if you are doing this process for more than a few minutes intensively, your eyes start to fool you (at least mine do). As soon as you start to feel like geez I can't even tell what I'm focusing on then stop, take a break, go look at something far off. You want it to work with "fresh eyes". And then when you feel like you've got it, just leave it be and come back and double-check in a while with fresh eyes and see if you are still hitting your spots...
06-19-2015, 08:59 AM   #762
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QuoteOriginally posted by JamieWakeham Quote
I'm getting that at the closest focus (1m), the actual plane of sharpest focus is perhaps 2mm behind the point that the screen indicates, and at 15m, it's maybe 5cm in front.
Welcome to the Pentax Forums!

The above is your focus plane (aka plane of focus). If you shim, you will be aligning your new screen to the focal plane in the camera. Whether you can improve on your current adjustment depends heavily on what you are using for shims. The gradations with the Pentax shim set are quite small (0.05 mm in the range of 0.15mm to 0.55mm). If you are using the plastic shims from focusingscreens.com, the options for adjustment are less fine.

Since you are seeing front focus, you will need a somewhat thinner shim than what is currently in place. If there is no shim, there is nothing you can do. Be aware that your existing shim, if any, fits behind a second frame between your screen and the bottom face of the pentaprism. Any replacement belongs there.

As for calibration, I would suggest a fast 50 (f/2 or wider) and a distance to target of about 20x the focal length. The important thing is to be in that range where there room for fine control (near minimum focus distance) and that the lens have a long focus throw. While the Lens Align is popular on this site, any flat high contrast target will work. What is important is that the target provide a clear vertical line to work against and that the plane of focus is parallel to the focal plane.

Actual focus evaluation goes like this:
  • Make your best effort at manual focus using the magnified live view, this is your standard
  • Without touching the focus ring, switch to the optical viewfinder
  • If needed, adjust the focus to align the focus split image
  • Record "0" for none, "-" for nearer, or "+" for farther on a sheet of paper
Repeat the above steps 10 times, defocusing before each time. A preponderance of results (4 or more out of 10) indicates either no change or an adjustment up or down.

If you add or subtract a shim, repeat the above to confirm.

Fun, eh?


Steve

Last edited by stevebrot; 06-19-2015 at 09:08 AM.
06-19-2015, 09:11 AM   #763
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QuoteOriginally posted by stevebrot Quote

Actual focus evaluation goes like this:
  • Make your best effort at manual focus using the magnified live view, this is your standard
  • Without touching the focus ring, switch to the optical viewfinder
  • If needed, adjust the focus to align the focus split image
  • Record ")" for none, "-1" for nearer, or "+1" for farther on a sheet of paper
I find that I have to do the reverse, because of the above mentioned compensations of my eye/brain. If I set the focus on the live view to a certain mark and then check THAT in the viewfinder, I find my brain *trying* make that mark in-focus rather than just seeing objectively what mark actually is. My eyes will start to freak out after a few minutes of this. It works much better for me if I choose a mark by eye in the viewfinder, rack back and forth with the focus ring so I can perfectly center it, and then check that on the live view, where I can even zoom in and I can much easier objectively evaluate if I hit what I'm trying to hit. And this mirrors the actual process of taking pictures in the field that you want to achieve -- being able to look through the viewfinder only, focus on what you are focusing on and actually hitting that target...
06-19-2015, 04:46 PM   #764
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QuoteOriginally posted by vonBaloney Quote
If I set the focus on the live view to a certain mark and then check THAT in the viewfinder, I find my brain *trying* make that mark in-focus rather than just seeing objectively what mark actually is. My eyes will start to freak out after a few minutes of this. It works much better for me if I choose a mark by eye in the viewfinder,
Those instructions are for split-image on a flat target. You can do it in reverse, but it is much easier to see the error with the split image than in live view.


Steve
06-19-2015, 04:54 PM   #765
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QuoteOriginally posted by stevebrot Quote
Those instructions are for split-image on a flat target. You can do it in reverse, but it is much easier to see the error with the split image than in live view.
Aha. Of course the screen in question in this thread is an S-type non-split. (I've never used a split screen yet on digital.)
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