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05-13-2014, 04:42 PM   #646
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QuoteOriginally posted by HenrikDK Quote
Just received two s-type screens - one for my K-3 and one for my K-5. .......

........

Do one of you have the s-screen without marking, so you can check the exposure live/no live, and see if you get different results?

This is disappointing... Half a stop maybe, but 1.5 seems a bit much....

Just tested the K-5 with unmarked S screen and FA77tld.
Indicating 1/3 stop underexposed if LV is 'correct'
Can't say I ever noticed an issue with it,
though I do tend to preserve highlights quite agressively
My screen is the original Canon FF version that I massaged to shape in the workshop

05-13-2014, 07:31 PM   #647
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QuoteOriginally posted by HenrikDK Quote
Using my 18-135mm on my k-3 with the s-screen I now get under exposure by about 1.5 stop. The same lens on my k-5 exposes correctly, and (maybe more convincingly) switching the k-3 to live view immediately jumps the exposure by about 1.5 stop. Using my 31mm I see no difference in these scenarios. Switching to spot metering (from auto) reduces the difference to 2/3s of a stop, and now there is a 1/3 stop under exposure on the 31mm as well. Btw, I did cover up the view finder. I then tried my 21mm Ltd., and got same results as the 18-135mm

It is possible the AF markings messes things up. These markings are pretty bright with the slower lenses. The different results using spot metering seems to suggest this is partial true, but not the complete explanation.

Do one of you have the s-screen without marking, so you can check the exposure live/no live, and see if you get different results?

This is disappointing... Half a stop maybe, but 1.5 seems a bit much....
Did some more testing. Pictures last night was taken in my basement (so dark). I did some quick testing outside today, and the exposure difference was much smaller - about 1/3 of stop. Just tried in my basement again, and depending on the subject I am back to 1 to 1.5 stop underexposure on the slow lenses.

I did not document this well enought to post the results, but will later this week. I still suspect the AF lines which are VERY apparent when light is low, is messing up the exposure.

As long as it is isolated to to low light situations I suspect I will be fine - I would usually be using faster lenses anyway.
05-13-2014, 08:01 PM   #648
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That doesn't surprise me. A slow lens or low light causes the screen to darken considerably.
05-13-2014, 08:40 PM   #649
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QuoteOriginally posted by derekkite Quote
That doesn't surprise me. A slow lens or low light causes the screen to darken considerably.
Yes - screen goes much darker. What I don't understand is why that would cause significant UNDER exposure? Unless - as theorized - the bright AF lines messes up the auto exposure.

Again it would be great if someone without etched markings tested the exposure in low light as well...

05-13-2014, 09:48 PM   #650
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My Ee-s screen is sitting at the postoffice awaiting for me to pick up. (no markings on mine) I'll let you know how it goes on my K10 :P
05-14-2014, 04:04 AM   #651
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I have noticed significant under-exposure at times with k3, (ee-s screen with the simple bracket markings) and the DA*60-250 in combination with the AF1.4x. Of course, this results in a minimum aperture of f5.6. And I didn't notice the issue with any other lenses - though I mainly use f1.2 - f4 max aperture glass.

So my experience supports that once you get to f5.6 lenses, under exposure can occur in combination with the screen, but the larger apertures are generally ok.

This doesn't really prove it's the screen - I didn't try to switch the screen back over to prove it (it's not that difficult to correct with and I'm too concerned about the potential to ham-fistedly introduce dust/scratches).

I've also seen that in some cases under exposure can happen quite suddenly as the light drops. I was taking some evening shots last night and past a certain darkness the same scene very suddenly started to underexpose. From memory, this was while using LV when (I'm assuming) the screen is 'not in play' for metering purposes. This was under pretty extreme shooting conditions (long fl, exposure, and very low light) so I'd not expect very accurate metering in any case.

Would also be interested to hear if the AF bracket markings make any difference!

As with all of these minor quirks, understanding them better makes them easy to correct (see also pentax flash behaviour at times! )
05-14-2014, 05:35 AM   #652
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QuoteOriginally posted by johnc Quote
So my experience supports that once you get to f5.6 lenses, under exposure can occur in combination with the screen, but the larger apertures are generally ok.
So at least two people with AF brackets that experiences this. I'm not completely crazy

QuoteOriginally posted by johnc Quote
This doesn't really prove it's the screen - I didn't try to switch the screen back over to prove it (it's not that difficult to correct with and I'm too concerned about the potential to ham-fistedly introduce dust/scratches).
I was comparing my K-3 with the S screen and my K-5 with original screen, and then thought of using Live View (that should be completely unaffected by the focusing screen). The latter is obviously much easier. Neither method of comparing would be exactly right, but I would not expect the error to be more than 1/3 a stop or so (Just remember to cover the viewfinder!). In short I'm pretty confident it is the S screen causing this.

As long as this is isolated to low light/slow lens combinations I can live with it.

Looking forward to see if those of you without markings get better results.
05-14-2014, 09:44 AM   #653
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QuoteOriginally posted by HenrikDK Quote
So at least two people with AF brackets that experiences this. I'm not completely crazy



I was comparing my K-3 with the S screen and my K-5 with original screen, and then thought of using Live View (that should be completely unaffected by the focusing screen). The latter is obviously much easier. Neither method of comparing would be exactly right, but I would not expect the error to be more than 1/3 a stop or so (Just remember to cover the viewfinder!). In short I'm pretty confident it is the S screen causing this.

As long as this is isolated to low light/slow lens combinations I can live with it.

Looking forward to see if those of you without markings get better results.
It doesn't really prove it is the brackets - I have had the issue intermittently with the TC+DA*60-250 (not using Live View) - but so far did not nail down the cause. It was not really related to low light either - noticed it on a relatively bright (if overcast) day. I was wondering if it was a contacts issue of some sort but not really been able to replicate it 'on demand'. Just tried the combination again indoors and out here - and it is all working very well, no underexposure!

My experiences with sudden underexposure in very low light in LV last night surely was not anything to do with the screen at all. But as I say, this was a rather unusual usage profile in any case.

Will keep trying to work it out!

05-14-2014, 10:14 AM   #654
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QuoteOriginally posted by johnc Quote
It doesn't really prove it is the brackets
Agree 100% on the AF brackets - they may not be the culprit. I am 99% sure it is related to the screen, though.

I did notice last night that the issue was worse when pointing at a lighter object. Live view and k-5 compensated very well - the s screen equipped k-3 underexposed.
05-15-2014, 09:03 AM   #655
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QuoteOriginally posted by HenrikDK Quote
So at least two people with AF brackets that experiences this. I'm not completely crazy



I was comparing my K-3 with the S screen and my K-5 with original screen, and then thought of using Live View (that should be completely unaffected by the focusing screen). The latter is obviously much easier. Neither method of comparing would be exactly right, but I would not expect the error to be more than 1/3 a stop or so (Just remember to cover the viewfinder!). In short I'm pretty confident it is the S screen causing this.

As long as this is isolated to low light/slow lens combinations I can live with it.

Looking forward to see if those of you without markings get better results.
I also would like to know if the screen without markings works better. I am a little reluctant to pay another $80 to find out ;-(
05-15-2014, 08:11 PM   #656
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indeed! I'll let you know when i put mine together on Monday! :P
05-16-2014, 04:41 PM   #657
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QuoteOriginally posted by HenrikDK Quote
Using my 18-135mm on my k-3 with the s-screen I now get under exposure by about 1.5 stop. The same lens on my k-5 exposes correctly, and (maybe more convincingly) switching the k-3 to live view immediately jumps the exposure by about 1.5 stop. Using my 31mm I see no difference in these scenarios. Switching to spot metering (from auto) reduces the difference to 2/3s of a stop, and now there is a 1/3 stop under exposure on the 31mm as well. Btw, I did cover up the view finder. I then tried my 21mm Ltd., and got same results as the 18-135mm

It is possible the AF markings messes things up. These markings are pretty bright with the slower lenses. The different results using spot metering seems to suggest this is partial true, but not the complete explanation.
I have expended some effort on this issue and got very similar results to yours and came to much the same conclusion. I will be attempting to contact focusingscreen.com to see if they are aware of this issue and to provide them with example photos taken with different lenses using both the K-3 primary metering system and the live view metering with the same lens.


Steve

---------- Post added 05-16-14 at 04:54 PM ----------

Here are a few example photos of a subject with even luminance (north-facing cellular blinds at 3:00 in the afternoon), Av mode with matrix metering at ISO 100. Note that the exposure settings (aperture and shutter speed) are more important than the apparent brightness of the images. I think that Lightroom did something funky on import of the DNGs. Yes, I should have probably shot them as JPEG...my bad.

FA 35/2 Using K-3 Main Meter


f/8 @ 1/15s



FA 35/2 Using K-3 Live View


f/8 @ 1/13s



DA 18-55/3.5-5.6 @ 35mm Using K-3 Main Meter


f/8 @ 1/50s (almost two stops below the live view metering). Based on the dimness of the viewfinder, I would have expected 1-2 stops over the live-view version.



DA 18-55/3.5-5.6 @ 35mm Using K-3 Live View


f/8 @ 1/15s



Crummy photo showing the viewfinder with DA 18-55 @35mm



The heavy vignette in this photo is artifact while the relative brightness of the frame lines is not. They really jump out.

The Setup





I will allow the reader to draw their own conclusions.


Steve

Last edited by stevebrot; 05-16-2014 at 09:41 PM.
05-16-2014, 05:38 PM   #658
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Did you have clouds outside?
05-16-2014, 06:06 PM   #659
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QuoteOriginally posted by tromboads Quote
Did you have clouds outside?
Nope cloudless sky, though the window is north-facing (sun on other side of house at this latitude at this time of year). The exposures for each pair were made a few seconds apart to minimize any difference in light between meter readings.


Steve

Last edited by stevebrot; 05-16-2014 at 09:34 PM.
05-18-2014, 08:06 PM   #660
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Well. Dam!! My K10 now has an AV mode

As it turns out, the complaints from the kats eye focusing incorrectly, where simply that there were no shims installed... .. With the 2 provided with the ee-s, its still a tiny tiny tincy bit back, but im pixel peeing like a dork to make that claim. The ee-s is in for the moment, I'll see if I miss the split prism more, or enjoy accurate AV mode. ..

The overall "darkness" mentioned is no different to the katseye,

And with a blank screen It certinaly feels like a cinema now. I also agree with ones eyes doing more work without the split screen. I'll see how that progresses over time.

Now the exposure accuracy is always what I expected it to be, but never was with the katseye. I quickly tried a Tak 55 f1,8, Tak 50 f1.4, an A 50 f1.7, and a Tak 200 f4 and they all expose correctly when stopped down, all the way to f22. FREAKING AMAZING ! Heck I should have taken the punt years ago :P I just palmed it off as if one was going to use a non-stock different screen you'd forgo the right to correct computed exposures. How silly!.

I concur with the linear type function that others have claimed. My camera feels brand new (hugs his K10)

Also for those still scared, installation was a piece of p**s.

Simply put, the best piece of photographic equipment I have paid for. I was manually adjusting exposures all the time, Oh what a fool I was.
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