[systemA]

Actually, this may not be true:

translated from the K-7 review posted at dc.watch.impress.co.jp on July 14th.

"...This reduction in light transmission was done in order to attain ease of manual focus and see boke. Generally when you increase the transmission of a camera's focusing screen diffusion decreases making it harder to grasp the exact point of focus. In other words, brightness of the finder and ease of focus are inversely proportional..."

Fumio Nakamura

Personally, I don't notice any difference, but I do feel that I can detect critical focus better with the K7 than with previous pentaprism models.

Scott

I'm not quite sure I understand...is Mr. Nakamura saying it is actually easier to see differences in bokeh with a darker focusing screen in a low-lit environment, by optical preview through the viewfinder? I find it difficult to imagine a scenario where having a darker image in the viewfinder would actually benefit manual focusing.

[JohnBee]

The nature of the mat screens brigthen subjects as they come into focus.
As commonly seen with split prisms, lowering the OOF screen intensity helps with accuracy.
It's a real controversial issue tbh.

The whole Katzeye/Optibright angle is based on the opposite.
And to be honest, I'm on the fence with that also. Sometimes when I shoot in low light, I'm grateful that I have another stop in the viewfinder.
Other times... I find it to work against me in brighter scenes as it is cooler than stock.

[GoremanX]

The whole Katzeye/Optibright angle is based on the opposite.
And to be honest, I'm on the fence with that also. Sometimes when I shoot in low light, I'm grateful that I have another stop in the viewfinder.
Other times... I find it to work against me in brighter scenes as it is cooler than stock.

That may be why Katz Eye doesn't recommend the Optibright treatment for those who typically shoot with wide apertures or in bright light.

[JohnBee]

That may be why Katz Eye doesn't recommend the Optibright treatment for those who typically shoot with wide apertures or in bright light.

I would say so.

Optibright can come at the cost of saturation/contrast, which can be detrimental when trying to adjust a split prisms in certain cases. It doesn't always get in the way but when it does, it can be a real drag. Luckilly, AF confirm still works with split screens and if you couple this is the prismatic collar, then it doesn't really become a show stopper.

I think it really comes down to what people feel is most important. I've gotten so used to nailing focus with AF confirm + split screen that it's become almost second nature for me. Whenever I play with the wife's Kx with stock screen, it just seems so lifeless.

[deejjjaaaa]

That's the nature of the product unfortunately. This is why the AF systems are so practical. No more screen calibrations

except that you have AF adjustments for PDAF... I used a supplied shim w/ jinfinance's screen, however I did not need them neither for 2 cowy07's screens nor for focusingscreen.com's K3 screen.

[deejjjaaaa]

I've tried many screens over the years and the Katzeye with Optibright is the best you can get in terms of brightness and blackout performance.

if you are talking about split prism performance - all screens cut out from Nikon K3 are the same...

Nikon | Imaging Products | Nikon FM3A

"...In addition, for the manual focusing camera, a special attention has been paid to the focusing screen. It is designed with improved diffusion of transmitted light and also the same technology as adopted in F3 for the central split. The diffusion is increased by the addition of grids onto the smooth split prism surface, thereby eliminating possible blackout even when a slightly darker lens is mounted. Complete blackout of finder image never occurs even when the aperture is stopped down to f/22 and the preview button is pressed..."

[JohnBee]

except that you have AF adjustments for PDAF... I used a supplied shim w/ jinfinance's screen, however I did not need them neither for 2 cowy07's screens nor for focusingscreen.com's K3 screen.

Our experiences have been the complete opposite.
Over the course of four bodies(1 Nikon), and aprox. 8 screens(in total), none of them were ever 100%. Though I've found that once a camera was shimmed, the screens remained pretty accurate even when we changed them.

Another issue I've found is that it's quite easy to overlook proper calibration. Taking our K3 from focusingscreen for example, to the naked eye it looked and felt accurate, however... when I calibrated it on a macro scale, it was OOF. Not in a big way, but enough to put doubt into the other units. Turned out they all needed a bit of fine tuning.

[slow2focus]

Our experiences have been the complete opposite.
Over the course of four bodies(1 Nikon), and aprox. 8 screens(in total), none of them were ever 100%. Though I've found that once a camera was shimmed, the screens remained pretty accurate even when we changed them.

Another issue I've found is that it's quite easy to overlook proper calibration. Taking our K3 from focusingscreen for example, to the naked eye it looked and felt accurate, however... when I calibrated it on a macro scale, it was OOF. Not in a big way, but enough to put doubt into the other units. Turned out they all needed a bit of fine tuning.

Is this pic showing it is OOF? I have the k3 screen from focusingscreen, after using both shims from them for the total of .29mm, I am about right to slightly back focus. With the copper shim from stock, it is .35mm, I am front focus. I don't know of any material that will give me ~.32 or so... I am asking because you mentioned fine tuning, just wondering what other material can be used to do the tune. Also, how do you do adjust via the macro scale?

Thanks

[JohnBee]

I don't know of any material that will give me ~.32 or so... I am asking because you mentioned fine tuning, just wondering what other material can be used to do the tune. Also, how do you do adjust via the macro scale?

Hi, the image I posted is the product we use to micro-adjust our screens. They are thin adhesive leaflets with nice edges that make micro-adjustments a snap.
And... though they can be hard to remove(in the event you decided to take it back a notch). You can easily remove it with a product like Goo-Gone and start over again.

So by cutting and applied thin layers to each side of the shim, it is very easy to adjust and achieve perfect focus.

PS. never apply the strips on your screen! only on the shim.

If however you're shim is to thick, then you will need to order some thinner models from Pentax(they are very cheap 3.5USD)
For reference, here are the K200 and K20D shim part no's.

K200D
76570.M02200A - 0.15mm
76570.M02200B - 0.20mm
76570.M02200C - 0.25mm
76570.M02200D - 0.30mm
76570.M02200E - 0.35mm
76570.M02200F - 0.40mm

K20D
76830.M02200A - 0.15mm
76830.M02200B - 0.20mm
76830.M02200C - 0.25mm
76830.M02200D - 0.30mm
76830.M02200E - 0.35mm
76830.M02200F - 0.40mm

As for the micro/macro scale, we use a machining ruler and calibrate our lenses by focusing at its nearest capacity(macro).
This way the DOF effectively shows the BF/FF and what changes need to be made to calibrate your screens to perfection.

Additionally, if I had any other advice to to give from my own experiences it would be the following:

1. Always wear latex gloves when you're working with your screen.
2. Try to work in a higher humidity area to help reduce airborn particles.
3. Always turn your camera upside down when installing and removing your screen.
4. Once you have your screen calibrated to perfection, you can clean it in a Styrofoam cup(soft and safe) filled with distilled water and a few drops of dish liquid.
You can then rinse it by passing it in two clean water(distilled) washes and blow the droplets off afterward. So three cups in total.

a) You can then blow-dry your screen to get a crystal clean finish, however, you must be extremely careful as the forced air will easily blow your screen out of your clasp.
However... if you turn it sideways, this will not happen, and it will force the droplets to fall away from the screen.

b) The final step in washing a perfect screen is to have a way to absorb the droplets from the bottom of the screen. Otherwise, the water will leave watermarks on the screen(none permanent) and you'll have to start over again. One way to avoid this problem is to get the remaining droplets off the screen before they dry. I like to use a roll of toilet paper and dap the screen corner on the face of the roll to end-up with a spotless, pristine focus screen every time.

It may take a little practice to get a working process down, but once you've have it worked out, you'll be basking in perfect focus all the time.

Hope this helps

[deejjjaaaa]

With the copper shim from stock, it is .35mm, I am front focus. I don't know of any material that will give me ~.32 or so...

hammer it... just a little bit

[systemA]

Just wanted to add that I've done a somewhat thorough, not quite scientific test regarding FS brightness.

I recently acquired a Ec-B Grid screen (the one at focusingscreens.com) and compared it to the OEM L80 and Jinfinance $30 focusing screen. Tests were with two manual focus lenses, a Jupiter-9 85/2 lens and a Toyo 300/5.6 mirror lens. I had two camera bodies side by side (k10d and k20d) and swapped each lens from camera to camera, after aiming at specific targets indoors in low light.

The L80, as expected was the brightess. I'd say it's roughly ~1/2 stop brighter than the Jinfinance screen. The Jinfinance screen was in turn, around ~1/3-1/4 stop brighter than the Ec-B. This was most evident when using the 300/5.6 and aiming at a almost unlit area in the living room. I could barely focus on a picture frame with the Jinfance screen, but with the Ec-B screen, I could only make out the outline. The difference is subtle, but it's conclusive enough to say that the JF screen is just a tad brighter than the Ec-B.

edit: Also did some quick tests with the Jupiter-9 again regarding "blackout" when stopping down. Good news is that the Ec-B does much better here, none/very little black out below f/5.6, blacking out maybe ~30% getting to f/8, and to ~70% at f/16. The Jinfinance screen is ok below f/4, but blacks out very quickly to maybe ~80% by f/5.6 and completely black above that. So there is the trade-off

Also one more note regarding the Ec-B that I forgot to mention, is that the screen has a slight magenta tint compared to the JF and L80 screens. Not sure why that is, but it is a bit annoying and evident when looking through the viewfinder.

[GoremanX]

If however you're shim is to thick, then you will need to order some thinner models from Pentax(they are very cheap 3.5USD)

So... what if, with NO shims, I'm still short of my target?

I just received my K3 focusing screen today, and while trying to calibrate it, I first tried with 2 shims, and it was way off. Then I removed one shim and it was better. Then I removed the last shim, and it was even better, but still not enough.

The K3 screen is much thicker than the regular K-7 screen, so its lower surface already ends up sitting lower in the camera body even before any shims are applied. Adding shims below the screen doesn't actually change its position, and adding shims above it only makes things worse.

[JohnBee]

Simply put... you return that screen as defective because it is not compatible with the K7.
PS. make sure it's not backward. The handly tab doesn't always work to show propper orientation.

[GoremanX]

Simply put... you return that screen as defective because it is not compatible with the K7.
PS. make sure it's not backward. The handly tab doesn't always work to show propper orientation.

I tried turning it over and it won't close at all.

But I ignored some of the advice in this very thread: remove the factory Pentax shim. Since everyone refers to it as a "copper" shim, I was looking for something copper-coloured. But the factory shim is a silver-coloured metal plate.



Once removed altogether, the camera's auto-focus and the split prism of the focusing screen match up perfectly. So in my case, I needed no shims at all (as opposed to the factory shim with the original focusing screen).

Now if only I hadn't dropped my brand new focusing screen on the floor while installing it it doesn't look very pretty. There are some bad scratches near the edges.

As far as brightness goes, my initial thought was that the K3 focusing screen was way darker than the original K-7 one. However, after switching back and forth, I've determined that this isn't really the case. The split prism and the microprism collar are so much brighter than the matte part of the screen, most of the screen ends up seeming darker than it really is. The regular Pentax screen is matte all over. so the darkness is uniform throughout and there's no contrast to fool the eye. I want to check some more tonight, but I'd put the K3 screen at about 1/3 to 1/2 of a stop darker than the factory K-7 screen. This isn't much of a difference, and it helps make the split prism easier to use.

In bright light or with a fast lens, the split prism is super-easy to use. So is the microprism collar, as long as there are sharp contrast lines to aim for. However the etched-in lines I opted for are nearly invisible and therefore useless as a framing aid. The whole viewfinder looks uniformly bright, I see no contrast at all caused by the matte.

In dimmer light or when using a slower lens, the contrast is more noticeable. The split prism becomes darker, but I can still use it for focusing. The etched-in lines are clearly visible. The microprism collar is bright, and it's easy to make out focus. The matte gets slightly brighter as I get closer to accurate focus, which is a good indicator of proper focus ring direction. Unfortunately, these aren't my usual shooting conditions.

In almost no light or with manual aperture set all the way down to F16, the contrast is massive. The split prism gets very dark, and making out my subject for proper focus becomes frustrating. The microprism ring looks even brighter because of the increased contrast, but making out focus with it is nearly impossible. I have to rely mostly on the matte, just as I did with the factory K-7 focusing screen. The etched-in lines are extremely bright. It's ironic that they become more useful as the focusing tools become more useless. I almost wish I hadn't selected those, since they just make the contrast seem more blatant in low light and they're invisible in outdoor daylight.

Overall, I'm fairly happy with this focusing screen. I'd be even happier if I hadn't dropped it on the floor and ruined it, but I'll have to live with that I guess. As a result, I've gotten very good at changing out the focusing screen. With this in mind, I'm interested in trying out the one that's available on eBay with the dual 45 degree split prism at $29.99.

Is there such a thing as Focusing Screen Buying Addiction?

[JohnBee]

I tried turning it over and it won't close at all.

But I ignored some of the advice in this very thread: remove the factory Pentax shim. Since everyone refers to it as a "copper" shim, I was looking for something copper-coloured. But the factory shim is a silver-coloured metal plate.

Aaaah the old shim issue.
I had no idea it was like that on the K-7(makes good sense).
It was the same for the K20D actually and I had forgotten all about that.
The K200D shim actually floats atop the screen mount so it's was always a no brainer. The K20D(like the K-7) is not always so obvious.

Glad to hear you got it sorted out.
And you are very lucky to have a calibrated result as well.

PS. if the scratches are on the edges they may not actually affect the view. Did you try washing it to see if they were actually damages to the material? Sometimes it could be surface dirt.

And the answer to your question regarding screens is yes. I've purchased about eight screens(some replacements), since my start with Pentax. Though it ended with a Katzeye