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Full Version: Bokeh Monster now focuses to infinty on my D750.
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Hi guys,

         Finally my M42- Nikon F glassless adapter arrived, it took over three weeks from Japan, but at 0.99€ inc. postage (yes you read right) it shows that patience is a virtue. It fits perfectly with no play at all......I could now study what was needed to be done so the lens can focus to infinity without resorting to a reduction of IQ with an optical adapter.

  Calculations:   M42 registration distance 45.46mm.......Nikon registration distance 46.5mm...difference 1.04mm  also there is a flange on the adapter which has a thickness of 0.83mm.....

 1.04+ 0.83mm= 1.87mm  therefore...the lens mount/barrel assembly need to be shortened by 1.87mm.......here's how I went about it.

 Firstly the removable M42 mount does not seat completely when screwed into the adapter (first image), there is a gap of 2mm, the thread has a tail which is what is preventing the seating of the mount......first job, remove the 2mm tail after the thread using a friends lathe.....no thread was removed! ..the mount now seats fine.

 

 Next the rear body needed 1.87mm off the face A and B (last image), this give the appropriate distance for IF on a Nikon body, that done I cleaned off the swarf and metal dust thoroughly and reassembled the lens to test...... Knock me down with a feather if it wasn't spot on, I must admit to thinking I would have to over-shorten slightly and repack with a paper gasket, but I didn't have to.

  My call is it's fairly sharp wide open but with plenty of flare way better than on APSc (Pentax)  ( no sniggering Klaus and Marcus! Tongue  I know this lens will never win any awards) I'm pleased with look of the portrait it's got a relaxed "oldie worldie" look about it, we will have to see what gives with it's 15 blades  vis a vis "the old bokeh balls scenario" when out late evening and night shooting!

 

 

  It's all about the look!

 

The job took a couple of hours, mostly measuring and remeasuring!

 

 

BTW. That's my fiend who lent me the use of his lathe. Photo F2.8

You do know that the aperture blades only come into play when the aperture is closed down, right? Wink 

The outdoor shot shows the old coating tech (white objects radiate, just like with my Nikkor-H 85mm f1.8), stopping down lessens that. And the portrait of your friend shows it is a nice lens, period. 

Great You are enjoying it.

The lens seems great, however about the portrait you showed, I can see the eyes have different colors most likely because of the lighting something I would have avoided. Sorry but couldn't control myself
Quote:Great You are enjoying it.

The lens seems great, however about the portrait you showed, I can see the eyes have different colors most likely because of the lighting something I would have avoided. Sorry but couldn't control myself
That's David Bowie's brother! I jest!

 

Tonia,I think you are right! it was poor PP on my part rather than the lighting...

Quote:You do know that the aperture blades only come into play when the aperture is closed down, right? Wink

The outdoor shot shows the old coating tech (white objects radiate, just like with my Nikkor-H 85mm f1.8), stopping down lessens that. And the portrait of your friend shows it is a nice lens, period. 
 There are 15 ever ready aperture blades in this lens BC, even when using the lens wide open they are waiting in the wings playing cards!  Smile 
Quote:That's David Bowie's brother! I jest!

 

Tonia, I think you are right!  it was poor PP on my part rather than the lighting....
 

  Re-processed!

I found the version with one eye in the shadow better, more natural. This new one has an uneasy weirdness to it, now.

Anyway, again thumbs up for the conversion.  

 

PS: how much MFD have you now lost on the Pentax?


 

Quote:I found the version with one eye in the shadow better, more natural. This new one has an uneasy weirdness to it, now.

Anyway, again thumbs up for the conversion.  

 

PS: how much MFD have you now lost on the Pentax?
 Thanks BC as always!

 

Actually I had lightened the the eye in the first image and darkened it again in the second.......the second is more true to life.

 

   But that's life.....what's good for the goose isn't always good for the gander!

 

"PS: how much MFD have I now lost on the Pentax"?

 

 To be quite honest I've not checked.... the 1.87mm shortening of the sensor distance is enormous in terms of 5mts to infinity obviously......but at the short end (I've just looked at the focus scale) at a guess I'd say six inches (150mm) nothing of any worth.  Any way now, according to the scale, MFD is a whiff under 1.5mts

 

  Edit: Now the lens has identical MFDs on both the Pentax and the D750!

 

  The focus throw is 355° on this mother!