Bob L
Established
I know someone has a web page on how to adjust the Depth of Focus on a lens but I can't seem to find it.
Does anyone know what web page has it.
Thanks
Does anyone know what web page has it.
Thanks
Depth of Focus
- Thread starter Bob L
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bmattock
Veteran
Bob L said:
Bob, let's make sure we're talking about the same thing here. Depth-of-field is that area in front and back of a properly-focused subject that remains in acceptable focus. Smaller apertures make deeper DOF.
Depth-of-focus is a different animal, and if you mean that, I think you want to adjust your lens to your camera - that is, to adjust your focal point on your camera's film plane.
Another way of saying that would be adjusting your rangefinder if you are talking about a rangefinder camera.
Best Regards,
Bill Mattocks
Bob L
Established
That's correct i wish to adjust lens to the camera, i believe it's done using a piece of ground glass where the film would be and adjusting it at infinity and the closest your lens would focus using shims in the lens.
P
pshinkaw
Guest
It depends on the camera. If the back opens or slides off you can use a groundglass or focusing screen taped to the film gate. If it is a bottom loader like a Zorki-1, you will have to either partially dismantle the camera or use the depth measurement method.
On back loaders, I have successfully used a piece of transparent plastic used to package lens caps on the peg racks at stores. Just use a piece of sandpaper to rough up the plastic on one side and place the rough side toward the lens.
For depth measurement, I made a facing jig out of a right-angle aluminum bar and cut a hole on one side. I then use the depth stick on a dial caliper to measure the depth fropm the face of the lens mount to the pressure plate. (First protect the pressure plate from scratches with a piece of film. Measure in several places. Don't forget to subtract the thickness of the aluminum angle.
The proper depth for an LTM camera is 28.8 mm +/- 0.02 mm. If it is off, the lens flange can be shimmed up or the existing shims can be removed.
-Paul
On back loaders, I have successfully used a piece of transparent plastic used to package lens caps on the peg racks at stores. Just use a piece of sandpaper to rough up the plastic on one side and place the rough side toward the lens.
For depth measurement, I made a facing jig out of a right-angle aluminum bar and cut a hole on one side. I then use the depth stick on a dial caliper to measure the depth fropm the face of the lens mount to the pressure plate. (First protect the pressure plate from scratches with a piece of film. Measure in several places. Don't forget to subtract the thickness of the aluminum angle.
The proper depth for an LTM camera is 28.8 mm +/- 0.02 mm. If it is off, the lens flange can be shimmed up or the existing shims can be removed.
-Paul
Kim Coxon
Moderator
Hi Bob,
Try this http://members.tripod.com/rick_oleson/index-123.html
Try this http://members.tripod.com/rick_oleson/index-123.html
Kim Coxon
Moderator
Hi Bob,
I thought you were talking about the camera body. If you are sure this is OK then which lens is it and is it out throughout the focus range or only close up?
Kim
I thought you were talking about the camera body. If you are sure this is OK then which lens is it and is it out throughout the focus range or only close up?
Kim
Bob L said:
bmattock
Veteran
I've got an old Zeiss Ikon ground-glass for 35mm - but seldom use it. It doesn't fit in every 35mm well, but when it does, it would be ideal for what you want to do, because it puts the ground-glass right at the correct film plane. However, I have heard of people using scotch-tape - I tried that and it did produce an image, but I noticed that it was not at the frame rail height, so I was not sure how much that mattered.
I presume you're going to adjust the rangefinder tab on the lens, or are you talking about adjusting the RF on the camera itself?
Best Regards,
Bill Mattocks
I presume you're going to adjust the rangefinder tab on the lens, or are you talking about adjusting the RF on the camera itself?
Best Regards,
Bill Mattocks
Bob L
Established
The lens is a old J12 that is out of focus at all range finder setting, the rangefinder for the camera is fine and the lens agress with the range finder marking on the lens, it may need a different size shim to adjust the Depth of Focus, I have the ground glass from a old Speed Graphic focusing screen and will be checking it in the morning.
Thanks all for your help , I think I have it now.
Thanks all for your help , I think I have it now.
Bob L
Established
Tried to adjust the Depth of Focus on a J12 lens that I have been having trouble with today, Could not get it to focus, Use a ground glass at the film plane and no matther what I did ( added shim, removed shims ) she still would not focus at infinty or even a close up's. Every thing is out of focus.
Anyone have a idea as to what to do next, beside dumping it, my other J12 and J8's works just fine with all my Kiev's so I know it's the lens and not the camera.
Anyone have a idea as to what to do next, beside dumping it, my other J12 and J8's works just fine with all my Kiev's so I know it's the lens and not the camera.
bmattock
Veteran
Bob L said:
Sounds odd. Could be one of two things that I can think of - either missing an element (has been mentioned, I believe) or an element (or two or more) installed backwards. I've done that one myself. Other than that, I can't think of anything.
Good luck with it, sorry to hear of the trouble.
Best Regards,
Bill Mattocks
