Katz Eye focusing screens

[Josh66]

Sorry if I put this in the wrong forum, I wasn't really sure where it belonged.
(I did do a search, but I didn't find an answer to my question.)

In the next week or two I want to get one of the Katz Eye focusing screens for my 350D. (I just can't seem to manually focus accurately with the stock focusing screen.)
My question is: Is the OptiBrite treatment worth it?

It says that it makes the view finder brighter at smaller apertures - but the lens will always be at max aperture (unless I press the DoF preview button) until the shutter opens, right?

Like on my 50 f/1.4 even if I stop it down to f/22, it's still wide open until I actually take the picture.

I could be wrong, but it seems like the OptiBrite treatment is only beneficial if you're using a lens that actually stops down to whatever aperture you want to use before you take the picture (which none of my lenses do). Does that make sense?

If I had lenses like that I could see why I might want to get the treatment, but will it offer any advantage at all if I'm always looking through the lens at max aperture?

Sorry if I didn't explain it very good, hopefully I got my point across though.

 

[Don Simon]

My question is: Is the OptiBrite treatment worth it?

It says that it makes the view finder brighter at smaller apertures - but the lens will always be at max aperture (unless I press the DoF preview button) until the shutter opens, right?

Like on my 50 f/1.4 even if I stop it down to f/22, it's still wide open until I actually take the picture.

I could be wrong, but it seems like the OptiBrite treatment is only beneficial if you're using a lens that actually stops down to whatever aperture you want to use before you take the picture (which none of my lenses do). Does that make sense?

My guess is that by "smaller apertures", it does not mean when using smaller apertures with the same lens, but rather when using lenses with smaller maximum apertures.

For example, when you look through your viewfinder with your 50mm f/1.4 mounted, you will always be looking through it wide-open unless you use DOF preview (as you say)... however, if you were to mount something like an f/4-5.6 zoom, the image through the viewfinder would be darker. Presumably the OptiBrite treatment is designed to increase brightness significantly even when using "slower" lenses.

Having said that, I have no idea how well it works so can't tell you if it's worth it or not.

 

[Big Mike]

There is/was a photographer around here who loved his Katz-eye screens. That was a few years ago, and I don't know if they even had OptiBright back then. I don't know anyone else who uses those screens...sorry.

 

[sabbath999]

Watching this thread... I am about to get one put into my D80 (will do it when the D300 gets here) so I can use it better with macro. I am definitely getting optibrite option.

 

[Josh66]

For example, when you look through your viewfinder with your 50mm f/1.4 mounted, you will always be looking through it wide-open unless you use DOF preview (as you say)... however, if you were to mount something like an f/4-5.6 zoom, the image through the viewfinder would be darker. Presumably the OptiBrite treatment is designed to increase brightness significantly even when using "slower" lenses.

Ahh... That makes a lot of sense. I hadn't thought of that. Thanks. :thumbup:

 

[Garbz]

Yes but on the same token how is this compensated for in the camera's metre. Since the camera metres the light it sees after the focusing screen, and they claim it benefits different quantities of light in different ways it leads me to believe that this product is
a) snake oil
b) a pain in the a...

- Guess only. I have no idea if this optibrite treatment actually works.

 

[Josh66]

Yes but on the same token how is this compensated for in the camera's metre. Since the camera metres the light it sees after the focusing screen, and they claim it benefits different quantities of light in different ways it leads me to believe that this product is
a) snake oil
b) a pain in the a...

- Guess only. I have no idea if this optibrite treatment actually works.

From the FAQ section on the Katz Eye website:

Generally, most of the light meter effects (if there are any) are caused by the presence of the prism itself, and not by the brightness of the screen or the OptiBrite treatment. In most cameras, OptiBrite treatment will cause a maximum of 1/3 f-stops shift of the light meter.

That should be easily adjusted for with exposure compensation, right?

Hmm... I should have read that first. I didn't really notice that section until now.

In general, if you shoot primarily with lenses having a maximum aperture of f2.8 or faster, the improvement from the OptiBrite treatment is mild and the treatment is really optional at that point. However, if you frequently use lenses with smaller maximum apertures, shoot in low light conditions, or do stop down shooting with full manual lenses, then the improvement from the OptiBrite treatment is quite significant and can be well worth the cost.

Just to make sure I understand this... With the OptiBrite treatment, and without compensating for it in-camera, it would have a tendency to under-expose - correct? (The meter would think that there was more light than there really was.)

 

[Garbz]

Yep. But what I question is how they specify this effect as being variable. I would think if you get a 1/3rd stop increase than you should have this affect regardless of aperture and brightness.

You can compensate for this using the EV compensate button. Some cameras like the D200 have an override setting in the menus themsevles which allow you to bias the exposure mode without using the EV compensation button.