FM2n viewfinder through 'cheap' lens?

[photos by kiem]

I attached one of the inexpensive lens - well the Tamron 28-80 f/3.5

to the FM2n. At certain zoom, the half circle through the viewfinder

turns dark. I read somewhere from mir.com that says that only cheap

lenses do this. If this is a Nikkor lens with the f/3.5, wont it do

the same thing? I suspect its the aperture opening size, and not

because of a 'cheap' lens.

 

BTW, My other lens do fine, the Nikkor 50mm f/1.4 AI manual, and the

50mm f/1.8 AF.

[link]

You're right. As you zoom in the effective aperature closes and the finder gets darker.

 

The only solution is to focus using the ground glass, or use a faster lens.

[jose f.]

Slow lenses -- lenses with a maximum aperture around f/4 -- cause the focusing aid to go dark. Doesn't matter whether they are cheap or expensive. The 75-150E and an old 55/35 Micro don't darken the split image on my FM2n, though.

 

If you want to use the lens and the blacking-out is distracting, you can replace the K focusing screen with an E or a B.

[bobar57]

"I read somewhere from mir.com that says that only cheap lenses do this. If this is a Nikkor lens with the f/3.5, wont it do the same thing? I suspect its the aperture opening size, and not because of a 'cheap' lens."

You're more or less in the right track, isn't the apperture, but the ambient light, in dim places you will also will have the same effect with the Nikkor 50mm f/1.4 AI manual, and the 50mm f/1.8 AF. That is a problem with center split image viewfinder. I preffer the plain one.

[40mm]

It seems you have a variable aperture zoom. I find somewhere about f/4.5-f/5.6 is about the threshold for split finder darkening on an FM2n.

[david_h._hartman]

If your eye is well centered behind the FM2 eyepiece a lens with an aperture of f/4.0 should be no problem blackout wise. By f/4.5 it�s a bit more difficult but not that bad. At f/5.6 great care is need in centering the eye but it�s still possible, possible but not worth the trouble, try a B2 or E2 screen.

 

I�m sorry I don�t have any cheap lenses on hand. The f/4.0 was an 80~200/4.0 AIS, the f/4.5 a 300/4.5 ED-IF AI and the f/5.6 was a 400/5.6 ED AI. They are all Nikkors.

 

When the spit image rangefinder blacks out you are looking at the inside of the lens not through it. There is a screen for the F, F2 and F3, an "R" screen, with a slope on the split image rangefinder prisms designed for lens from f/3.5 to f/5.6. The "R" screen has a narrower base for it�s rangefinder so it can look through those lenses.

 

Sorry it�s not the ambient light level. In dim light such as tree twigs against a dim night sky the 300/4.5 ED-IF AI is still useable and eye centering is important but not that difficult. No the 50/1.4 AIS doesn�t back out at any light level. Try it. I just did.

 

Cheers,

[richard_oleson]

My guess is that your zoom lens is not maintaining the f/3.5 aperture through the zoom range, but dropping to about f/5.6 or so at the 80mm end. Is it marked to indicate a variable aperture?

 

The viewfinder cutoff should not occur with any lens, cheap or expensive, at f/3.5..... but it will appear around f/5.6 in either case.

 

rick :)=

[ebogaerts]

Kiem,

 

All good suggestions here for helping to solve your problem. After being in photography for a number of years, I finally got tired of having to deal with the split image viewfinder, even if it WASN'T darkened with a slow zoom.

 

As has been said, there are alternative focusing screens that do away with it. If you find the split image viewfinder invaluable, you may not want to get rid of it. However, Nikon makes alternative focusing screens for the FM2, and you can also look into purchasing a Beattie screen.

[david_h._hartman]

<em>"The viewfinder cutoff should not occur with any

lens, cheap or expensive, at f/3.5..... but it will appear around

f/5.6 in either case." --Richard Oleson<br>

</em><br>

If a lens exhibits poor evenness of illumination regardless of

cost range finder blackout will occur at somewhat larger stops.

If the find is a high eyepoint finder sloppy eye alignment will

be much easier.