U screen v. U screen...

If you are living on the periphery of Super Telephoto Society

with a 400/5.6 or if you are in the underclass with a 300/4.0 or

4.5 you will likely find the "U" screen a pleasant

experience. The "U" screen is basically a "B"

screen but with the Fresnel lens cut for a 100mm or longer lens

for the F3 and a 200mm lens or longer for the F5. Lenses like the

200/4.0 IF AI & AIS Micro-Nikkor, the 180/2.8 ED(s) with

tubes and even the 105/4.0 Micro-Nikkor with PN-11 gain image

brightness with the "U" screen, the latter having an

effective focal length of 210mm at 1:1.<br>

<br>

The Fresnel lens collects the light from the focusing screen

proper and guides it to the condenser. The Fresnel and condenser

lenses concentrate the light from the viewing screen and deliver

it to the prism and the eye. When the Fresnel is mismatched to

the focal length of the lens the edges of the viewing image get

progressively dim. The "B" screen is designed for

normal and wide angle lenses and the edges and over all viewing

experience with long lens suffers. This is especially noticeable

with slow super telephotos. The effect works both ways so the

"U" screen is very unsuited to super wide angle lenses

and even unsuited to normal lenses. Any vignetting or moire

phenomenon affects the focus screen image only and not the film.<br>

<br>

There are some interesting differences between the "U"

screen for the F3 and the F5. With a slow lens like the 400/5.6

the F3 screens get a little gritty looking. Since the light is

collected correctly from the edges of the focus screen with a

"U" screen, the grittiness at those edges is reduced.

The "U" screen for the F5 causes some out of focus

areas to break up into pseudo bad bokeh of the multi-line type.

Occasionally multi colors can be seen. The effect is a touch like

a transmission diffraction grating. This effect might be annoying

at first but the focus and viewing ease is great and in minutes I

find I just ignore these oddities. Anyway the "B"

screens are only worse. I find the dim edges of the B screen

particularly annoying with the F5 and 400/5.6.<br>

<br>

With some lenses exposure compensation is required for the F5 as

the image in the finder is brighter and the meter cells are above

the focusing screen. Without compensation under exposure will

result. With the F3 the meter cell is below the focus screen in

the bottom of the mirror box so no exposure compensation is

needed.<br>

<br>

For those with faster super telephotos I cannot give glowing

reports because I do not own one of those but I can say the F5

"U" screen is recommended for all the AF-I and AF-S

lenses longer than 300mm. The 300/2.8 ED-IF AIS (new) and AF 200/4.0D

ED-IF Micro may show some vignette. The "U" screen for

the F3 appears to be recommended for everything from 105mm to

2000mm.<br>

<br>

If you shoot either the 400/5.6, 300/4.0 or 4.5 or shoot any

super telephoto lens at dawn or dusk my advice is buy a "U"

screen. Your eyes will thank you!<br>

<br>

All the best,<br>

<br>

Dave Hartman.

Hi Dave

I have a F3 400/5.6 combo and use the "R" screen with that combination. I can highly

recommend it because it still have the split image rangefinder which is really handy

with the IF version of the lens. Just removing your hand a bit roughly can throw it of,

but the split image is a confirmation that focus is spot on.

It is also gridded like the "E" screens for composition, aligning.

If you see one cheap at a camera store I urge you to try it out.......

Regards

Jon

Yup, I've used the U screen for years, for both the F3 and F4, using it with a 300 2.8 and 400 .28, with both the TC-14b and TC-301 on both lenses, and I really really like them. I used to switch to the H series in the F3 for nightime football and baseball, made darkness sport shooting Fun!

This sounds delicious. Why couldn't they make one for the FM3A?

Arnab,

 

I can�s see any reason why Nikon can�t make more types of focus screens for the FM3a and other bodies. I guess it�s a lack of demand or perceived lack of demand.

 

Regards,

Jon,

 

Years ago I had an "R" screen for my F2 but a friend nagged me till I give it to him. I just bought another and I�ll give it a shot.

 

Best,