Hassy split screens darkening

[EASmithV]

Hello,

I have a Hassy split screen on loan, basically, and I'm noticing that in lower light conditions with a 150mm f/4 lens it seems to get a bit dark in the split image circle.
So far I really like it, and will probably end up getting it to keep it as an option, as it really helps when using the NC2 prism. However, the darkening issue is a bit of a concern. This is a non-acumatte version, would the acu-matte version eliminate this? I've read similar online, but I was wondering on hearing some first hand experiences. It does not seem to do this with the 60mm, only the 150, but seeing as how I need the 150 AND the NC2 at the same time for portraits and such, a split image screen that dosen't darken would be really valuable... So... Before I even think about the expense of another acu-matte screen with a split focus, I want to be sure it will actually suit my needs.

Thank you!

 

[rolleiman]

Split image screens are meant for use in good lighting conditions and favour lenses of 2.8 or faster. They are not ideal in low lighting conditions, where an acute matte screen would be better. Also split image screens were designed to be more useful with wide-angle lenses than with telephotos.

 

[brucemuir]

they all go half dark @ 5.6 and sometimes wider on longer glass.

try centering you eye exactly over the split and it sometimes helps.

 

[Sirius Glass]

They go dark at the larger f/stops and one half will go dark even sooner unless your pupil is lined up with the axis of the split image.

 

[cowanw]

Therfore you have to move your eye around to see each half separately and estimate where the images line up. Quite doable but perhaps as easy just to look at he ground glass portion. Don't forget that if you ever use a exposure prism, the split screen is not recomended.

 

[Sirius Glass]

I have had no problem with split screen and PME prism if I move my eye to the right position when the darkening occur.