Well, with only 24 hours of CFV experience under my belt, I am probably not the best person to give advice on this matter... but that never stopped me in the past ...
Included with the CFV comes a new focus screen with very dark lines showing the edge of the sensor. It is very obvious what will be in the image and what will be outside of it.
So, you can frame the image very easily but you also have about a centimetre of the focus screen outside the image area which might be useful in some circumstances (e.g. incoming movement).
As a wearer of spectacles, I actually find this new "CFV-etched" focus screen to be quite helpful. As the glasses keep my eye back from the viewfinder window, I used to have to move around a bit to see all the edges. Now, with my glasses firmly up against the rubbber eye-cup, the dark line showing the edge of the image is clearly visible from the central eye position.
Very easy to see the area being captured with the included screen. The remaining area does indeed aid in seeing action just about to enter the frame ... very much like using a Leica M Rangefinder with it's superimposed viewfinder framing lines for many lenses.
For those who have used a Hasselblad for decades, it'll take a little time to switch your "intuitive" framing over to keeping the action with-in the clearly marked frame lines. It's not an issue when shooting at a leisurely pace or on a tripod, but when doing things like faster paced candid wedding work you have to pay attention for the first couple of times. The wierd thing is that when you pop off the CFV back and replace it with a film back you have to remember to use the whole screen : -)
The DPS hood is a HASSELBLAD product . The number is 3072534 ,
Unfortunately this hood is not produced any more . It has a magnification of 5.5 and you can add a diopter according your eyesight (far distance) .
I got mine from RobertWhite in England . They might still have one , because the DPS hood is still in their product list .
True enough , when disconnecting the CFV and then using a film back , you must not forget , then to use the whole screen . If you have used a DPS hood with your CFV back , then you also have to replace the hood and that makes it easier to remember .
For me , the DPS hood is a great help .
Hence the put-tape-over-it advice.
It's not a new thing: users of 16 backs have the same problem. Despite the boundary lines being clearly visible, you have to get used to the fact that you do not get all you see. Some find it easy, others less so.
But I am afraid that I am so addicted to my 45-degree prism viewfinder that I would struggle with the reversed framing and downward-viewing angle of the DPS. But I bet you get sharp focusing with one of those devices.
I use flip magnifiers on all my V cameras with 45 degree finders. Indispensable IMO.
Q.G. it really isn't all that difficult to get used to the framing lines any more than it is in a rangefinder camera. Just something to initially pay attention to ... then it becomes second nature even in hectic shooting situation like a wedding. I don't even think about it any more, and I swap back and forth between the CFV and film backs all the time.
What I have done is, drew on the Adobe Indesign the outline of the frame in CFV and blacken the outside the frame (a bit) and drew also 8x10 cropline and grided cropline for 5x7 in vertical and horizontal position.
I print out the artwork and took overhead clear plastic sheet and copy it. After that I cut the plastic to fit the focusing screen housing before I put the PM prism. work like charm.
ANy PM will show u full frame (the whole focusing screen) 2.5 or 3X. after a while u get used to the center and ingnore arounding the outside of the CFV crop. it is nice to see where my 8x10 and 5x7 crop goes inside the CFV square crop. Generally no problem with any PM prisms.
sorry, my english is not good, so forgive me.