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Tips on how to focus well with AcuteMatte and split image finder


New Member
I have a CM501 with waist level finder, Acute-Matte focusing screen with the split image finder in the middle of it. I am new to this system and have never used this kind of focusing screen before.

What are the secrets of getting it right? What is the best I can do if I want to focus on a subject's eyes and these are not right in the middle of the frame? What does it mean when the little split image thing turns partially dark?

In short, I am asking for useful tips and advice for focusing.

Thank you very much in advance.

One half of the split image rangefinder will darken when either your eye in not exactly over the thingy (using a prism finder, with its fixed eyepiece, helps. It's a bit more diffcult when using the waist level finder), or when using a 'slow' lens (f/4 or faster is fine, but problems begin at f/5.6)

You do need to find some bit in your subject that lends itself to this type of focussing, i.e. an edge, preferably straight, that can run across the split image.
And that thing needs to be in the bit of your subject you want to have in focus. Locating such a thing can be tricky.

If the bit you want in focus is not in the center of the image, just point the camera so that it is, focus, and recompose.
Focus will shift ever so slightly when moving the camera such that the bit you focussed on is in its original place again, but not enough to be a problem.
But you always have the option to use the focussing screen instead of the central split image, i.e. watch the out-of-center bit (in your ex&le your subject's eye) while focussing.
Judit, in addition to QG's excellent tips, I have 3 suggestions:

1. if your screen is fitted so that the "split" runs horizontally and you are taking an image of things that have horizontal "lines" that would be the best thing to adjust you focus against; then you can always remove the finder and tip the screen out and refit it so that the "split" runs vertically (taking care to re-fit the screen the correct side up).

The effect desired is to have the "split" not run in the same direction as the features you are using to focus against. For ex&le having the split run horizontally is good for trees which are vertical; whereas some architecture has horizontal lines making it easier to focus against if the "split" runs vertically.

Or, you can just do what QG suggested and use the outer area of the focus screen and watch it "sharpen" in the viewfinder.

2. Practice makes perfect. Just practice a lot in varying situations and you will get the hang of it - especially the "focus then recompose part". Remember that the pop-up magnifier in the WLF is a great aid to getting the focus split-image sharp. Then using the WLF without the magnifier up is for composing your shot.

3. Make use of the Depth Of Field feature on the lenses - when you think the focus is good, activate the DOF lever and check how it looks before you fire the shutter.
Id start off making the eyes in the middle of the frame and get good at doing that first. There is loads of chance to crop a bit later.

One other thought, its easy to loose sharpness through other factors too. For ex&le, using the 80mm standard lens, it does not have that much depth of filed and at wide appertures you have to be asolutely spot on. Get as much depth of field as you can so focusing is not so critical. This also goes together with minimising movement artefacts (smaller apperture and slower shutter). If you can you need a tripod, and if possible pre release the shutter using a cable release. This makes a really big difference. ASA400 film is absolutely fine for medium format portraits so this should also help you to push the apperture a bit smaller.


Best wishes


I bought a new screen from with a diagonal split screen and cuff. Together these are brilliant at assisting with the focusing.

I also made sure I was using fast enough film to allow fast enough shutter speeds and aperture that were acceptable give the 'blads very shallow depth of focus when opened up.

I then purchased a view finder magnifier which was also very helpful. Apart from that, I echo the comments above that it is a matter of practice. Depending on your style of shooting, I found that moving from auto-everything to a manual camera took a great deal of effort but was ultimately a delight to savor.