jcr
Member
My Hasselblad 503CW uses a rangefinder type of focusing screen ... wouldn't that qualify it as well as an RF MF camera ? 🙂
Solinar said:Put a lens cap on a viewfinder or rangefinder camera and you can practice focusing all you want.
Finder said:A rangefinder is a device that uses triangulation to determine object distance. A focusing screen is a device to determine focus from a projected real image. If the focused image is created by a small aperture like f/16, object distance will be impossible to determine. Rangefinders are not affected by the image-forming optics.
BTW, a rangefinder does not need to be mechanical. Electronic rangefinders exist. Nor do they have to be in a camera. Rangefinders are the distance calculating mechanism. Ordinance and golf have uses for rangefinders. The Leica is a rangefinder AND a viewfinder camera - one is simply built into the other.
EmilGil said:There is no rangefinder in a Hasselblad body, the mirror projects the image on a ground glass on the same distance from the mirror as the film plane. You then focus the lens to project a sharp image on the ground glass. A split screen is just a specially ground glass. This is something very different from a rangefinder, as pointed out above by Finder.
Finder is also right when it comes to stop-down focusing. The reason that you couldn't see any difference between your Leica and Hassy is that the Hassy focuses at maximum aperture. If you stop down the lens, your image will darken and you will see the depth of field. Once stopped down to f/16, an object 10m away will look equally sharp when the lens is focused at 8m as at 12m.
I guess I am the only one here with a Hassy with rangefinder screen and Leica M, and confirm ?
Kris said:No you're not the only one. I do have Accute Matte D with split screen
- and microprism.
You just haven't fully understood the difference between Leica RF and this 'rangefinder split image' on focusing screen.
When you change aperture on your lens, without depressing DOF preview, the lens stays wide open.
The split image does not work with lenses having maximum aperture slower than 5.6 - give or take.
You can try visualising a lens with max aperture of F8 by setting F8 on your 80/2.8 and lock that DOF lever. You'll now see that half of the split screen goes dark or black and it does not aid you to focus.
Finally, I think focusing a Blad is a b**** compared to an M3/M4/XPan. Can't focus accurately without the loupe. With the loupe up, I can't really see the whole image! The distance scale marked on the lens may be great for landscape stuff with plenty of DOF but when using Blad 150/2.8 or Summicron 90/2 wide open, there's no way I will not use focusing screen with loupe up (Blad) or focusing patch (RF camera).
EmilGil said:I don't know how to explain this for you to understand better JCR, but I'll emphasize once more: there is no rangefinder mechanism in a V-series Hasselblad body. You are using a projected image to focus your 'blad, not a split beam image as in a Leica. Even though you have a split image screen, this is not the same thing as a split beam finder.
The following explanation of a microprism split screen, such as the Acute Matte D, is taken from Richard Oleson at Photo.net:
This is hard to do without drawing a picture: the center circle consists of 2 prisms, each in the shape of a semicircle. One has the thick end toward your left, and the other has its thick end toward your right. The center of each prism is at the level of the ground glass, so the thin end is recessed into the glass and the thick end sticks out a little. When an image is in focus it hits at the intersection where both prisms are at the plane of the screen. If it's out, the prisms bend the image, one to the left and the other to the right, making it appear to split at the line between the 2 prisms.
Kris said:My apology JCR. I didn't realise you were trolling instead of looking for some clarification.
Maybe i should have kept myself away from RFF permanently. Can you please delete my account Joe/Ralph/Jorge?
EmilGil said:The lens must be cocked for you to be able to focus, if not your focus screen will be pitch black. The use of a winder does not alter this fact but it will relieve you from cocking the shutter and winding the film. Every time you wind the film, you will also cock the shutter of the mounted lens.
Let me try to explain it this way: Focusing your Leica, you use your finder and the patch. The patch is lit by a small hole in the camera body top cover to the left of the lens. The distance between this hole and the finder is the rangefinder base. Multiply this distance by your finder magnification (typically 0.72) and you have the EBL, effective base length. A long EBL simplifies focusing long and/or fast lenses accurately. The Hassy on the other hand is a single lens reflex type camera, SLR, which you focus by looking through the lens! Without a second hole/lens to form the rangefinder base, you can't focus this camera as a rangefinder.
This is the difference; a SLR is focused by looking through one lens, the RF by "looking through two lenses" (the finder and the beamsplitter image from under the shutter speed selector).
Jon Claremont said:Do you still have the box for the Hasselblad and the receipt?
If so, take it back to the shop and ask for your money back for this rangefinder.