Viewfinder view on om-2n

When I attach a OM 50mm be it my 1.4, 1.8 or 3.5 the view through my viewfinder is clean and sharp as is my OM 28mm 2.8 & 3.5

But when I attach a Tokina 17mm 3.5 the view through my viewfinder appears vague and speckled with spots/specks for want of better words, also it is not the easiest to focus.

My focusing screen is a 1-3.

Is this normal, what does it indicate, is the 17mm lens dirty?, is focusing screen dirty?, I have cleaned all lens thoroughly.

The same goes for other non OM lens, they are in the longer range eg Vivitar 80-200mm etc also less than stellar clarity.

My thanks in advance for any advice offered.

This sounds normal to me. The design of the microprisms and how they are angled on the screens, mean that they are only optimized for specific focal lengths and apertures, and lenses at the outer limits of this grouping have problems with the general screens.

With such a wide lens, I am guessing that maybe a clear field screen would be best. 1-5 seems to be a good fit. And Zoom lenses are always darker, you just have to put up with it or use a prime.

check out the Mir site:

http://www.mir.com.my/rb/photograph...mpusom1n2/shared/accessory/screens/index1.htm

Also you can double check that the automatic aperture mechanism is working by selecting a smaller aperture and using the DOF preview button the side of the lens barrel. The image should get darker when depressed. If nothing happens that could also be your problem.

You're not going to see spots or specks that are inside the lens. Same with the mirror unless it's really f**cked.
If you are seeing them and they're sharp they can be on the bottom of the prism or maybe at the eyepiece.
There may be a very slight possibility with the prism desilvering

Newt_on_Swings said:

This sounds normal to me. The design of the microprisms and how they are angled on the screens, mean that they are only optimized for specific focal lengths and apertures, and lenses at the outer limits of this grouping have problems with the general screens.

Click to expand...

As far as I know, focusing screen 1-3 does not have microprisms, it's a split prism surrounded by matte.

Maybe you can try 1-13, it's basically 1-3 with a ring of microprisms surrounding the split prism. Since 1-13 was introduced later than 1-3, I guess (a big guess) it may have better design.

I was wondering if the 1-3 focusing screen reference was a typo. The 1-13 was the standard focusing screen. I have quite a collection of OM screens and don't recall having run across a 1-3.

If it is a 1-3, your non-OM lenses may be somehow causing the matte surface to appear more contrasty. This can sometimes have a speckled look to it. But since this does not happen with the OM lenses, perhaps you are just seeing the quality defects in the off brands.