Erik van Straten
Veteran
Dez
Bodger Extraordinaire
The easiest way I know to check a lens for focus accuracy at close range is shown below. The measuring tape is set at 30 degrees to the film plane, so a focus error of one inch will appear as a two inch difference on the scale. The camera is on a tripod, and is focused on the clothespin.
Since the falloff is rather gradual, it is difficult to be really accurate, but I look at this picture and estimate a front focus of 1.5", since the in-focus field will be deeper beyond the focal point than in front of it. This shot is with my M5 at 1m distance. I'll repeat with my M3 to see if I get the same result. Both cameras' rangefinders are exactly correct at infinity.
I see a number of people who are sending their lenses away to be adjusted for correct focus at f1.1. The obvious question is why didn't they come from the manufacturer set correctly? I'm sure Cosina has more extensive measuring equipment than Don or Sherry. Yes, the lens is a bargain compared to the Leitz equivalents, but it still costs a thousand dollars, which is not peanuts. Am I wrong in expecting that they should come from the factory properly set up?
Cheers,
Dez
Since the falloff is rather gradual, it is difficult to be really accurate, but I look at this picture and estimate a front focus of 1.5", since the in-focus field will be deeper beyond the focal point than in front of it. This shot is with my M5 at 1m distance. I'll repeat with my M3 to see if I get the same result. Both cameras' rangefinders are exactly correct at infinity.
I see a number of people who are sending their lenses away to be adjusted for correct focus at f1.1. The obvious question is why didn't they come from the manufacturer set correctly? I'm sure Cosina has more extensive measuring equipment than Don or Sherry. Yes, the lens is a bargain compared to the Leitz equivalents, but it still costs a thousand dollars, which is not peanuts. Am I wrong in expecting that they should come from the factory properly set up?
Cheers,
Dez
Ljós
Well-known
Ahem, it is entirely possible that the rangefinder of your M5 is a tiny bit decalibrated. Absolutely do check with your M3, too. If you get the same misfocus, then yes, most likely your lens is out of spec. COULD be in spec though and both your rangefinders out by the same amount
I lived with a lovely collapsible Summicron that frontfocused by 1,5 - 2 centimeters... you quickly learn to focus and "lean in". That said, nothing beats a rig that focusses exactly where it should.
Dez
Bodger Extraordinaire
Ahem, it is entirely possible that the rangefinder of your M5 is a tiny bit decalibrated. Absolutely do check with your M3, too. If you get the same misfocus, then yes, most likely your lens is out of spec. COULD be in spec though and both your rangefinders out by the same amount
I lived with a lovely collapsible Summicron that frontfocused by 1,5 - 2 centimeters... you quickly learn to focus and "lean in". That said, nothing beats a rig that focusses exactly where it should.
Yes the camera could certainly be at fault as well- even both cameras- although getting the same result would be suspicious, and the degree of front focus here is serious for such a fast lens. To check that, I'll also do a focus test with a few lenses which I know are correct at close range. This is a bit of a pain with film though. I's almost enough to make me go looking for an A7, or maybe some kind soul in the Toronto area would be willing to lend me an M9?
Cheers,
Dez
Ljós
Well-known
I agree, these tests with film are a pain.
An A7 would not do you any good though, because the rangefinder-calibration does not come into play that way. Of course, if you had access to an M9, M8 etc. with established rangefinder accuracy, it would be a matter of minutes.
Hope you can sort this out soon. In the meantime, consider "leaning in" for important shots, it could tide you over for a while.
Cheers, Ljós
An A7 would not do you any good though, because the rangefinder-calibration does not come into play that way. Of course, if you had access to an M9, M8 etc. with established rangefinder accuracy, it would be a matter of minutes.
Hope you can sort this out soon. In the meantime, consider "leaning in" for important shots, it could tide you over for a while.
Cheers, Ljós
raindog61
Established
I picked up my lens about 4 or 5 months ago. Right away, I realized it's not a lens you simply slap on your camera body and start firing away. It does take a lot of practice to get some nice results from this lens when photographing at the minimum distance.
I do find using a viewfinder magnifiier has helped quite a bit.
Here's an interesting article on the 50mm f1.1. It goes into depth about focus shift and how to get the sharpest focus, wide open and at close distances.
http://www.ultrasomething.com/photography/2010/08/ruminations-on-a-50mm-f1-1-nokton/
I do find using a viewfinder magnifiier has helped quite a bit.
Here's an interesting article on the 50mm f1.1. It goes into depth about focus shift and how to get the sharpest focus, wide open and at close distances.
http://www.ultrasomething.com/photography/2010/08/ruminations-on-a-50mm-f1-1-nokton/
Erik van Straten
Veteran
Dez
Bodger Extraordinaire
Ah but an A7 would do me a lot of good! If I were using one of them I wouldn't care about the front focusing.
Cheers,
Dez
Dez
Bodger Extraordinaire
Understood, but it's a lot more difficult to determine the close focus accuracy. The moon is a wonderful infinity target. It is certainly possible for the cameras to be off at the close end. It's a remarkable coincidence if they are both off by the same amount. I guess there are no conclusions to be drawn until I develop the results of my multi-lens test with the M3.
Cheers,
Dez
Erik van Straten
Veteran
This is what you need to adjust the rangefinder of an M3. Really a specialists job I would say.
What I mean is that I think that many rangefinders of the old Leicas need adjusting. Maybe this is the reason that the results with the Nokton f/1.1 are often unsatisfying.
Erik.
What I mean is that I think that many rangefinders of the old Leicas need adjusting. Maybe this is the reason that the results with the Nokton f/1.1 are often unsatisfying.
Erik.
Pioneer
Veteran
I bought mine used so decided it was easier for me to send it to Don. He has done similar work for me in the past and I definitely do not have those capabilities myself. My own experience may be similar to others.
It took awhile to notice the back focus. I rarely test lenses in this manner and I had enough keepers on film with my M6 I didn't really notice it as a lens problem. It was also my first lens faster than 1.4 so felt it was my own technique that needed improving.
It wasn't until I bought my M9 that I really noticed that I had a problem. I then tested the lens using the LensAlign but even then wasn't really sure that it was the lens or the camera. That is why I sent both the camera and the lens to Don. I am glad I did because I now have a very accurate lens, and I know the camera rangefinder is accurate as well.
In the end, I do agree with Helen. This is certainly a lens worth owning. I have no idea how it compares with a Noctilux since I have never owned one. I do know this one is a fine performer so I think I'll keep it.
BTW, I have not noticed any focus shift at infinity. Of course, like the back focusing, it may take awhile for me to pick up on it.