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10-11-2010, 11:14 PM   #16
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I have the Katzeye split lens and finds that sometimes the split lens feature is easier to use and other situations, the crystaline mat is easier to use. The split lens does mess up the spot metering feature by about 2 stops, but i was rarely using that anyway. But we could debate this forever, even during film camera days, some cameras had the split lens, others not.

I do a lot of nightime shooting where i need to grab a focus. I find that the optibrite treatment certainly does help. I was over at a friends house (who uses a Canon 50D). His wife was looking thru both of our cameras and asked him why my camera has a brighter viewfinder than his? So yes it does make a difference. I haven't noticed any metering problems with the optibrite treatment.

10-12-2010, 09:29 AM   #17
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QuoteOriginally posted by stevebrot Quote
For what it is worth, the stock screen is brighter than the Katz Eye with Optibrite, but it does so by compromising the focus precision. I have no idea how it works, but the view with the stock screen always shows the DOF as it would appear at about f/4 unless the maximum aperture is less than that. As a result, manual focus with fast primes is sort of a hit or miss proposition. I can't say whether the LL-60 that Albert uses does this since I have never used that screen.

The LL-60 has clearly noticeable grain in the screen, just like the older Pentax screens I have used. The focus on any of the lenses I have used on it (including the 55/1.8 Tak) pops in and out for me. My main reason for using the screen is still the metering, but the older "grainy" screen was a nice benefit for manual focusing.

Caveat: All my camera bodies, film and digital are pentaprism, not pentamirror, so I cannot speak to how the screen would work for focusing in a pentamirror camera.
10-12-2010, 10:39 AM   #18
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for all those interested, although I am no absolute authoity on the subject, I cannot see any company, whether it is pentax or another maker, offering a third party focusing screen as either a standard or an option in a camera.

The fact is that all the cameras have interchangeable screens, although not all bodies have optional ones from pentax. The *istD had several (LF, LL and LI - 60), as did the K10D (LF, LL and LI - 80). The K7 actually has 4 optional ones,
(MF, ML, MI, ME-60) screens. the ME60 is a plain matt screen not available on the earlier cameras.

When I got involved with the great K10D/K20D metering issue with manual lenses, I did several tests. the results I have posted many many times and show a graph. the graph is the change in greyscale measured by my image editor (equate to exsposure) as a function of aperture.

This chart showed two specific things, fist of all, there was a big difference between theK7D, K10D and *istD in metering with manual lenses (my test lens was the SMC - Pentax 50mmF1.4 or more commonly the K50/1.4). Secondly, it showed that by placing the *istD screen into the K10D ( they are the same size) the K10D could be made to meter exactly the same as the *istD, suggesting that 100% of the metering problem was the behavior of the focusing screen.

The chart also showed that the metering of the K7 was somewhat better than the K10D but still had issues, when compared to the *istD and that the cheap diagonal split image I installed in the K10D also made life better, but again not as good as the *istD.

The bottom line is that any interchangeable screen would need to have the exact same finish and reflective characteristics of the stock screen, or there will be metering issues, and therefore the only options in focusing screens that pentax could offer and warrent, are the ones they presently offer.

As for user programmable exposure, it would be nice, but don't wait for it, unless it is based upon A lenses only, and is in the form of an EV vs Fstop correction.

With respect to unpredictable metering, I would have to disagree, the metering is quite predictable, and is a function of the actual aperture when metering.

Other tests I did, but have not posted, showed great consistency for each lens as a function of aperture, with a very general statement that lenses at F1.4-F2 would under expose by 1-1.5 stops, correcting this by F4-5.6 and leading to +1.5-2 stops by F18-11 before falling back towards +1 by F32.

What each person needs to do is to map out the behavior of their lenses on their bodies. You shold know how your system performs.

As to getting cameras calibrated with other screens, please also note the following. I asked pentax if they woulc calibrate my K10D with an *istD screen, they said "O- They do not do or support custom modifications", When I took my K10D in for service, they reported that the installed split image focusing screen would lead to exposure errors specificlly with spot metering.
10-12-2010, 03:56 PM   #19
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QuoteOriginally posted by Lowell Goudge Quote
With respect to unpredictable metering, I would have to disagree, the metering is quite predictable, and is a function of the actual aperture when metering.
Lowell, first, thanks for your informative and very detailed post, which I intend to unashamedly file for own reference on this oft contentious topic.

Re: the unpredictable metering claims; I was one who mentioned that in a previous response in this discourse on here.
So I feel obligated to explain where I got it from.

Erratic (and unpredictable), metering is one decided impression I sensed after reading loads of peer contribs on the topic, in various online places, mostly referring to the Katz product as these things often do.
So I will declare, again, that it wasn't from first-hand user/owner experience, like yours or others' assessments here.

eg. This lengthy one being a prime example, but like most public free-for-all convos in forums you do need to read the lot to extract that usual 5-10% of real gems of potentially worthwhile or seeming credible info:
My thoughts on Katz Eye, for what it's worth.: Pentax SLR Talk Forum: Digital Photography Review

I think too that it's probably understandable that a lot don't go to the tech depths or [semi] formal testing that you have - leading to many who conclude and express in more subjective ways, that for them, the experience with all or certain alternate screens proved simply not worth piss-farting around with.
And that's fair enough too, when sincere.

Btw: You do put a solid argument for the Katz/Optobrite product, in that it obviously can serve and benefit a small niche of users - provided they possess the aptitude and understanding to manage using it in their photography overall.
And I still believe they're no way suitable for the average DSLRphile or, an apposite default for mfgrs, like you suggest.


10-12-2010, 06:18 PM   #20
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Do a search on K10/20 metering and find my chart

As for testing, while an absolute amature may not go through and test the metering performance of his camera with each lens he owns , I would expect any serious photographer to have done so. I say this because when a serious photographer is taking a shot there is a certain expectation that the shot would turn out as expected. This will take place be ause he either has taken a few moments to test every variant he has or plans to use or he has shot with the combos so much he has made the compensation as the result of past errors and experience. IMO a simple test with 8 to 16 frames for each lens is a minimal investment to make in search of a first time correct shot
11-01-2010, 09:17 PM   #21
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I've had a Katzeye w/Optibright installed for about a week now on my K20D. A little back story: I used to shoot film, 35mm, and my Canon AE-1 had the split/prism and I NEVER had a shot out of focus, blurry from shake yes, but missed focused.. We never even discussed such a "silly" thing back then unless we were shooting moving subjects.. well, since I had my K20D end of 08 I've been frustrated by slightly missed focus (how much/often depends on the subject of course). I also host a rather large camera club here in Tucson (400 members) and over the past two years I've shot with just about everything brand/model camera you can buy.. and they all can get tripped up at times using AF. well, the link below take you to what you can do EVERYTIME with a Katzeye screen. Shot about a foot away with a M 50mm F1.4 at 1.4.

Pros & Cons:

+ Brighter than stock, not that stock is bad at all.. but it is brighter.
+++ More contrasty than stock and makes using the ground glass area usable
+++ Due to being more contrasty using DOF preview now really gives you an idea of DOF where the stock screen tends to give the feeling lots more is in focus than really is.
+ Metering seems the same, maybe spot is off a bit.. but nothing a photographer isn't used to calibrating for anyway as meters are all a bit different from each other
+ Thanks to Pentax super easy to install (run your bathroom shower hot for a bit and change screens in there to keep dust down).
++ Price, compared to how much I've spent in gear to take tack sharp images this $150.00 is nothing to ensure focus is dead on every time.
+++ Reaching their support (Rachael) is quick and easy and very friendly, helpful and responsive.

-- Preface: I've built high precision race engines for over 20 years and to "us" 1/2 thousand of an inch can make the difference between wining and losing a race due to vibration, drag on engine parts, etc. So I have a huge amount of respect for such extremely fine measurements. On to the "con". When I went to install it I noticed I had to put what consider a fair amount more pressure on the frame that holds screen for it to latch, and it didn't latch solid sounding. In fact, I had to use the rubber gloved finger tip to apply enough pressure (using the tweezers wasn't enough) and take the tweezers and push the retaining click into the frame. After about 20 shots, as I feared, the frame opened and the screen fell onto the mirror. Upon trying to remove the lens I felt the resistance and tilted the camera a bit and the lens came off. This could have been disastrous as whatever caught on the lens (probably the screen itself) could have shattered, bent the screen frame, etc.

I wrote Rachel and asked "what up with this". Below is her reply:

"Hi Roger,

It sounds like what's happened here is that the latch has become slightly
bent, so that it does not readily grab the little tab on the frame when the
frame is pressed closed. The KatzEye screen is in fact very slightly
thicker than the Pentax screen (a few thousandths of an inch), but it is
well within the thickness the frame is designed to accommodate and we have a
great many of these in the field without a problem. I have seen this happen
with the latch before though, and it can easily occur if slightly too much
force was used in opening the frame or if it was bent slightly off by the
factory. The solution is just to bend the latch ever so slightly, so that
it grabs the tab with a bit more force. I'd be happy to do that for you if
you want to send in the camera or you could attempt it yourself by simply
opening the frame and very gently pressing the empty latch toward the rear
of the camera. I am sorry you have encountered this difficulty and if there
is anything else I can do to help resolve the problem, please do not
hesitate to let me know."

Now, having owned two K20Ds and worked with at least four more via my local club, I'm 100% confident my latch isn't wasn't bent nor anything else "odd" with my camera. I believe, and short of testing it a few more times with different bodies and screens, it is directly due to that "few thousands" of inch she referred to. Now, I don't think anything is being harmed using this screen (although if/when I install the OEM screen I may find different), but could foresee whatever the hinge mechanism is being flexed a bit, maybe even pulling it enough that in the future an OEM screen might not close down quite as snug as prior. Personally, I'd like to see them use the same thickness screens within Pentax's thickness tolerances, whatever those might be.. and for all I know this "thicker" screen is within that. But, to date I've not had any screen snap in place differently than another.

Quite possibly the "sweet" fix if this is an issue is obtaining the MF shims and using a slightly thinner one so the install "click" is the same. But, I really doubt I'm ever taking this puppy out Now, on the other hand I've read many people that installed this on their K20D and never a mention of it being more difficult to install.. then again, Rachel did have the cure and said she's familiar with it.. so, I mustn't be the only one.

I did ask her about performing this upgrade to OEM screens, they have tried and didn't like the results so far, but haven't given up on perfecting it. Maybe some day?

Some observations and thoughts:

* MF focus must be right on and adjusted if not, these are shims above the screen.. Pentax will adjust it for you, or you can order their shims and do it yourself. Katzeye offers the service as well for a nominal fee.

* With this installed you will quickly learn the K20Ds auto focus is deadly accurate.. WHEN it knows exactly what to focus on.. you'll soon get a feel for if there is any stronger contrast closer or further than your focus point within about 15% of your screen area around the focus point it locks onto that.. in other words, if you only shot flat services with strong contrast your AF will probably be dead on every time. In my club I'm finding this true to variing extents with all brands of cameras.. Possibly Canon being "smarter" than most, but still has the same problem.

* Makes an excellent double check to your auto focus, you know instantly if it missed focus.

* Once you know MF is dead on, calibrating your lenses AF becomes a piece of cake.. just use the split and straight line to focus on.. once AF makes it "straight" it's right on.

* None of my DA* lenses are really in focus at infinity as were lenses of the old days.. so walking and flash shooting (using infinity as a trusted mark) isn't possible.. with this it is... just focus on something in the infinity range and you're good to go.

* From what I understand AF does NOT pass through the focus screen at all.. BUT, and I may be on drugs here, but I sure seem to think AF is working in lower light (I'm talking a modeling light in a softbox at about 40 watts in a pitch black studio).. and working quite well.. can the brighter screen help.. I don't know.. and again, I only shot once so far in such dim light.. but don't think I could have ever done that before.. odd.. your mileage may vary.

In summery:

If you've missed the sure focus of days gone by, get it NOW..

If you have never used a split/prism, but have been frustrated with missed focus.. this baby will make you smile

hope that helps..

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