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01-16-2008, 12:02 PM   #31
and
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I dotn see why the screen should affect auto focus, the AF sensor is not behind the screen so why should it get affected, I see no difference with my split prism screen.

WMBP: Yes natually I am talking about the max aperture, as long as the lens has Automatic aperture then metering will happen wide open and the lens will only be stopped down once you press the shutter.

This does mean the effects are more or less consistent with each lens, meaning f2.8 and faster lenes have no problems, f5.6 lenses always have problems. However I am not sure if the effect will be as pronounced outdoors as it is indoors, outdoors one half of the prism will not black out (if its daylight) so that should lessen the effect. I only use fast lenses, apart from f4 lenses which do have this problem to a certain degree but I use manual mode so often and especially using manual flash that this becomes less of an issue to me. But again do note that I am not talking about the katz eye in particular.

01-16-2008, 06:39 PM   #32
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just placed my order

Just placed an order for 1 Katz Eye (basic -- no Opti-Brite, no orientation marks). $101 including shipping (US Priority mail). I decided to buy it for the *ist DS rather than the K10D. At the moment, I use manual focus with the DS more than the K10D, anyway, it just seemed like the thing to do. If I like it as much as I hope, I'll consider buying another for the K10D.

Looks like I won't have it for at least a week, maybe two. When it arrives and I've had a chance to test it a bit, I'll be sure to follow up here with some comparison photos and my impressions.

Thanks again to all of you who responded, both those who have the Katz Eye and like it and those who don't and shared your anxieties. I'm a bit anxious myself but decided I had to give it a try if only to satisfy my curiosity.

Will
01-16-2008, 06:48 PM   #33
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QuoteOriginally posted by WMBP Quote
Just placed an order for 1 Katz Eye (basic -- no Opti-Brite, no orientation marks). $101 including shipping (US Priority mail). I decided to buy it for the *ist DS rather than the K10D. At the moment, I use manual focus with the DS more than the K10D, anyway, it just seemed like the thing to do. If I like it as much as I hope, I'll consider buying another for the K10D.

Looks like I won't have it for at least a week, maybe two. When it arrives and I've had a chance to test it a bit, I'll be sure to follow up here with some comparison photos and my impressions.

Thanks again to all of you who responded, both those who have the Katz Eye and like it and those who don't and shared your anxieties. I'm a bit anxious myself but decided I had to give it a try if only to satisfy my curiosity.

Will
Will

Any chance on some before and after shots?

what I mean is, with manual apature lenses, take a series of photos at a uniform surface, (my favourites are a block wall or paved roadway) at each apature in manual mode with the camera setting shutter speed. do a similar series after changing the focusing screne,

With each set, plot grey scale of the central portion as a function of f-stop.

I am curious as hell to know how much metering is affected, having done the same set of curves for all my lenses with both my *istD and K10D.
01-16-2008, 06:55 PM   #34
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Do test it out and report back about it I might still get one myself at a later time

01-16-2008, 06:57 PM   #35
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QuoteOriginally posted by Lowell Goudge Quote
Will

Any chance on some before and after shots?

what I mean is, with manual apature lenses, take a series of photos at a uniform surface, (my favourites are a block wall or paved roadway) at each apature in manual mode with the camera setting shutter speed. do a similar series after changing the focusing screne,

With each set, plot grey scale of the central portion as a function of f-stop.

I am curious as hell to know how much metering is affected, having done the same set of curves for all my lenses with both my *istD and K10D.
Doesnt thave to be that advanced, simply using manual mode and the green button to manually perform measurements with the camera on a tripod and writing down the different shutter times to see how they deviate.
01-16-2008, 06:57 PM   #36
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QuoteOriginally posted by Lowell Goudge Quote
Any chance on some before and after shots?

what I mean is, with manual apature lenses, take a series of photos at a uniform surface, (my favourites are a block wall or paved roadway) at each apature in manual mode with the camera setting shutter speed. do a similar series after changing the focusing screne,

With each set, plot grey scale of the central portion as a function of f-stop.

I am curious as hell to know how much metering is affected, having done the same set of curves for all my lenses with both my *istD and K10D.

Lowell,

I promise! I'm doing this as much as an experiment as anything. I mean, I hope it turns out that your anxieties -- all of which I share -- are outweighed by the advantages of the new focusing screen. But I'm not sure. I placed my order for a couple of reasons. First, Rachel Katz was very nice to answer a number of questions I wrote to her about before Christmas. Good customer service sells product! Second, I really want this to work. I dislike manual focusing without some assistance and I know that the blinking red "in focus" indicators on my DS and my K10D aren't doing the job perfectly. And third, I don't recall ever reading a comment by someone who was dissatisfied with the Katz Eye. I'm sure there's somebody out there. Aside from Sara Lee pastries, there's nothing that nobody doesn't like. But I have not seen posts from customers saying what I would expect, for example, "Manual focusing is easier now that I have the Katz Eye but auto-focus and metering are much harder."

Anyway, when it arrives, before I install it, I will take some test shots, then I'll do the installation, and take the same shots again.

I will however share with you my current hypothesis, which is that the shots won't necessarily prove much. The Katz Eye won't in itself alter the camera's ability to focus perfectly. It will just make it easier. So if I manual focus without the Katz Eye, but take the time to do it carefully, I expect that the results will be identical to what I get using the Katz Eye. I won't be disappointed if this hypothesis proves true -- so long as the Katz Eye does in fact make manual focusing easier and quicker.

Anyway, yes, I'll post a couple photos when it arrives. Maybe be end of the month, though -- and by that time, every thread on this forum will be buzzing with the new from PMA. ;-)

Will
01-16-2008, 07:52 PM   #37
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QuoteOriginally posted by WMBP Quote
Lowell,

I promise! I'm doing this as much as an experiment as anything. I mean, I hope it turns out that your anxieties -- all of which I share -- are outweighed by the advantages of the new focusing screen. But I'm not sure. I placed my order for a couple of reasons. First, Rachel Katz was very nice to answer a number of questions I wrote to her about before Christmas. Good customer service sells product! Second, I really want this to work. I dislike manual focusing without some assistance and I know that the blinking red "in focus" indicators on my DS and my K10D aren't doing the job perfectly. And third, I don't recall ever reading a comment by someone who was dissatisfied with the Katz Eye. I'm sure there's somebody out there. Aside from Sara Lee pastries, there's nothing that nobody doesn't like. But I have not seen posts from customers saying what I would expect, for example, "Manual focusing is easier now that I have the Katz Eye but auto-focus and metering are much harder."

Anyway, when it arrives, before I install it, I will take some test shots, then I'll do the installation, and take the same shots again.

I will however share with you my current hypothesis, which is that the shots won't necessarily prove much. The Katz Eye won't in itself alter the camera's ability to focus perfectly. It will just make it easier. So if I manual focus without the Katz Eye, but take the time to do it carefully, I expect that the results will be identical to what I get using the Katz Eye. I won't be disappointed if this hypothesis proves true -- so long as the Katz Eye does in fact make manual focusing easier and quicker.

Anyway, yes, I'll post a couple photos when it arrives. Maybe be end of the month, though -- and by that time, every thread on this forum will be buzzing with the new from PMA. ;-)

Will
Will

I dont expect the shots to show anything on focus, but maybe a lot on exposure accuracy. biggest trend I have seen, when comparing K mount lenses and exposure (using green button or DOF metering) is that for fast lenses, f1.4 and F2, there is a tendancy to under expose wide open on the K10 (1/2 to 1 stop) by apatures of F4 all lenses tend to over expose, worst is about 2 stops at about F11 where it tends to come back a little .

I don't know how the DS behaves with K mount lenses, hence doubly curious.

MF K mount lenses I have tested so far are SMC 50mm f1.4, SMC-M 100mm F4, SMC 135mm F2.5, SMC 300mmF4 (with and without 1.7x AF-TC) Vivitar MC 400mmf5.6 and Vivitar S1 70-210 f3.5.

AF lenses checked so far include Sigma 20-200 EX F2.8, and the two pentax power zooms 28-80 and 28-105mm. Using thumbwheel for controlling apature setting, green button exposure works very well, have not yet tried these lenses off the AE setting

Still have 3 AF zooms to go.
01-20-2008, 06:58 AM   #38
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QuoteOriginally posted by andrei46 Quote
Hi Will! Hi Lowell Goudge!
I have the same doubt as you; I sugest you to read in Fernando E. Aznar :: c r o q u i d e l u z :: - Manual Focus Ain't So Easy, por Jay Turberville
Regards!
This is a very informative article! It explains why, when I use the 'check DOF' at various apertures below f/5.6 there is no visible darkening of the image through the viewfinder... Has anyone repeated the test with a Katz Eye screen? And does the Katz Eye screen appear noticeable dimmer than the original Pentax screen (with slower lenses)?

Curt

01-20-2008, 10:38 AM   #39
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i have been using a katz eye on my K100D for close to 2 months now, i am extreamly satisfied,

i currently am in manual focus mode 100% of the itme even with DA lenses.

infact, the new focusing screen confirmed my long hunch that the AF on my camera isnt as smart as id like it to be, and mis-focusing to what i actualy want it to be about half the time (center focusing)

i think this should be installed in every camera!
01-20-2008, 12:11 PM   #40
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micro-lens focusing screen further issue?

The more I think about Fernando Aznar's article about the impact of the 'microlens bright screen' and J Clark's measured data, I wonder if this explains some of my exposure metering problems with fast lenses... particularly with P-TTL flash. Say, for discussion's sake, that the K10D focusing screen 'flattens out' in brightness at about f/4. The light metering is done (I think) from the screen. The light meter circuits/software measures an EV at open aperture, and sends a number to the aperture/shutter speed/ISO software which tels the appropriate mechanical bit to do their thing. As I understand the basic Pentax K-mount aperture control, the lens is not commanded to a particular aperture - rather, it is commanded to STOP DOWN from fully open a specific number of stops. If true, and the screen brightness doesn't change for a fast (f/1.4) lens versus a slower (say f/4) lens, the camera could call for an inadequate amount of stopping down... for example, if the meter read the screen and said 'ah ha... I need to stop the lens down two stops'; with the f/1.4 lens this would result in an f/2.8 aperture setting, while for the f/4 lens it would go to f/8. Assuming the camera system is truly set up 'biased' towards slower speed lenses, and the f/8 really is the correct exposure, the fast f/1.4 lens would badly overexpose the shot.

OK, in reality the camera knows something about the lens maximum aperture, at least if it is a modern Pentax lens, and the effect of the screen microlenses at faster lens apertures probably isn't really flat, so the camera software can apply a correction to the brightness read from the screen. However, what about older lenses, such as the legacy M42 lenses? Or non-Pentax K/A lenses? A puzzler, for sure!

All in all, I think I'd like to have the option of a non-microlens focusing screen (an old fashioned 'ground glass'??) just to see how it would work... though I suppose I'd need a software mod to program the light metering for a linear response at fast apertures!

I suppose one of the bright sides (no pun intended) is that I don't need to expend money on fast lenses - the system seems to be designed for f/4 or slower lenses! Hummmm... given the new 'fast' zooms are f/2.8 designs, the 'flat spot' must be closer to f/2.8 than f/4...

I think I may try repeating J Clark's screen brightness measurements on my K10D, if I can jerry-rig a suitable setup. I have a Pentax 1/21 spot meter, and a Takumar 50mm f/1.4, for starters... attaching the spotmeter to the viewfinder will be the challenge!

Again, I lay no claim to being an expert on any of this stuff - just a curious hobbyist... so anyone with similar or dissenting thoughts or experience, feel free to point out my errors in observation or logic!

Curt
01-20-2008, 12:17 PM   #41
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QuoteOriginally posted by WMBP Quote
Just placed an order for 1 Katz Eye (basic -- no Opti-Brite, no orientation marks). $101 including shipping (US Priority mail). I decided to buy it for the *ist DS rather than the K10D. At the moment, I use manual focus with the DS more than the K10D, anyway, it just seemed like the thing to do. If I like it as much as I hope, I'll consider buying another for the K10D.



Will
You can now stick the DS screen in the k10. Reported to cure the "manual lens metering problems" and some find it easier to manually focus with as well.
01-25-2008, 02:09 PM   #42
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got it!

My Katz Eye focusing screen arrived today and I have now installed it. I said I'd follow up here, so here are some quick notes.

I got the plain vanilla basic model, for my *ist DS. No opti-brite treatment, no special etching on the screen.

Installation really is easy, as long as you can follow instructions and assuming that you're not scared of doing this sort of thing. Tools needed: a small screwdriver, tweezers, a bulb blower, and a lens cleaning cloth. The screwdriver is used simply to unsnap the OEM focusing screen's containing tray from its little hinge. The tweezers are used to grab the old and new screens by the little tabs that are used to hold them and also to help you orient the screens properly. I've never done this before, so I read the instructions carefully and went very slow, but even so, I think it took me no more than 10 minutes.

First impression of using camera with the Katz Eye screen installed: Very nice. Manual focusing is much easier. The screen has a horizontal split in the middle and you can see the subject "coming together" as you focus. If the spot you're focusing on is itself horizontally oriented, it may help to tilt the camera just slightly for a second while focusing, then right the camera and shoot. Auto-focusing works well, too, and I can see more clearly when I don't agree with the auto-focus result.

I was worried about using the screen with the lens stopped down to, say, f/11. I don't see any problem with it at all. I must be missing something.

I promised some comparison photos earlier and I will post again in a day or two when I have had a chance to take those photos. It's easy enough to take the screen out that I don't mind doing it a couple more times for the purpose of some photos.

NOTE: These are quick, first impressions. I've shot only a dozen or two quick shots with the Katz Eye screen installed.

Will
01-25-2008, 02:48 PM   #43
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QuoteOriginally posted by WMBP Quote
My Katz Eye focusing screen arrived today and I have now installed it. I said I'd follow up here, so here are some quick notes.

First impression of using camera with the Katz Eye screen installed: Very nice. Manual focusing is much easier. The screen has a horizontal split in the middle and you can see the subject "coming together" as you focus. If the spot you're focusing on is itself horizontally oriented, it may help to tilt the camera just slightly for a second while focusing, then right the camera and shoot. Auto-focusing works well, too, and I can see more clearly when I don't agree with the auto-focus result.
Will
Will you know what I'd really love is a diagonal split image. Have one on my Ricoh XR2s, and it is great because most things are either horizontal or vertical not diagonal
01-25-2008, 02:55 PM   #44
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QuoteOriginally posted by Lowell Goudge Quote
Will you know what I'd really love is a diagonal split image. Have one on my Ricoh XR2s, and it is great because most things are either horizontal or vertical not diagonal
Lowell,

Yes, I agree that a diagonal split would make the most sense. I had a lovely Ricoh SLR in the 1980s--it was eventually stolen. I had forgotten that it had a diagonal split screen but I know that I've used such a screen in the past and perhaps it was in that camera. I have found the proprietress of Katz Eye, Rachel Katz, to be really terrific and responsive, so I may pass that on to her as a suggestion.

By the way, in connection with Ms Katz's responsiveness: I wrote to her a few minutes ago to confirm "from the horse's mouth" (so to speak) what jeffkrol said earlier in this thread, that the screen for the *ist DS can also be used in the K10D. In a few minutes I heard back from her confirming that this is the case. NOTE: She was careful to note and so I want to be careful to say that this is not the case with all the Pentax models. Apparently some use a different focusing screen. But now I plan to pull the new screen out of the *ist DS and give it a try in the K10D.

As I said, I'll be back here in a day or two with follow photos. I understand that folks are interested in know how the screen affects exposure so I'll try to set up some simple tests that might give us all some info about that issue.

Will
01-31-2008, 06:11 AM   #45
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Any pics yet? Me too has become interested in maybe buying a screen from them.
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