p.1 #1 · DIY adjustment guide for CZ 50 and 28 for infinity
Here is a rough guide to adjusting the 50mm 1.7 MM and 28mm 2.8MM if they fail to reach infinity with your adapter.
50mm - remove the rubber focus grip and slightly loosen the 3 x head screws - this releases the clamping action of a semi circular ring inside the lens which locks onto the focusing helical. Slide the now loose focusing ring slightly away from infinity and then slightly squeeze it to grip the helical and focus back on infinity. It should only need a slight movement of a couple of MM at most. CAUTION! if you undo the screws to much they will disengage with the inner ring and you will have to remove the front assembly thus: Using the proper friction tool or ( as I did ) a small roll of electricians tape unscrew the lens ring ( the one with the serial number on). You will need to apply a bit of force to get the required friction. The roll of tape is good as the sides are sticky and the center is open so as not to touch the lens. Under this are 3 screws which when removed give access to the clamping ring. CAUTION! this also holds the front element in place so keep the lens upright!
28mm - simply unscrew the front of the lens beyond the focusing ring - it comes off in one piece together with the lens ring. You can also use the 'electricians tape' method as with the 50mm. Down the side of the inner lens barrel are 3 screws which hold a clamping ring - loosen these and adjust in the same way.
I use an angle finder-C to set the lens up and then check 100% blowups on screen at max aperture. Previous to my adjustment both lenses were focusing a little short of infinity ( Not realy noticable through the VF even with the angle finder) but obvious at 100% on screen - whan properly adjusted landscape images 'snap' into focus that even stopping down coud not compensate for previously.
p.1 #2 · DIY adjustment guide for CZ 50 and 28 for infinity
Never realised it was that easy!
Just followed your instructions on my 50 F/1.7 and it now focuses spot on infinity at 1.7. Slacked the screws 1 turn and moved in from infinity a couple of mm.Nothing happened on the first attempt because I forgot to squeeeze the barrel to get a grip on the helical. The second attempt infinity snapped into focus and I tightened up the screws and replace the rubber ring.
Pity it is not that easy with the 28 f/2.8. I must send for that removal tool. I see they are only 8 euro.
p.1 #3 · DIY adjustment guide for CZ 50 and 28 for infinity
It's easier with the 28 - just get a good grip on the front end and unscrew it! Try wearing a rubber glove to get some friction.
May 27, 2006 at 10:50 AM
Andi Dietrich Offline [X]
p.1 #4 · DIY adjustment guide for CZ 50 and 28 for infinity
Sounds indeed interesting, I tried once to make a lens go over infinity by playing with those screws, but this was not possible in my case. I suppose a lens which hits the mirror will still do so when it is adjusted in your way?
p.1 #5 · DIY adjustment guide for CZ 50 and 28 for infinity
bathman wrote:
Sounds indeed interesting, I tried once to make a lens go over infinity by playing with those screws, but this was not possible in my case. I suppose a lens which hits the mirror will still do so when it is adjusted in your way?
Yes unfortunatley as the lens group moves further back.
p.1 #6 · DIY adjustment guide for CZ 50 and 28 for infinity
shirozina wrote:
Here is a rough guide to adjusting the 50mm 1.7 MM and 28mm 2.8MM if they fail to reach infinity with your adapter.
Using the proper friction tool or ( as I did )
Shirozona -- Where can the friction tool be purchased? The 25/2.8 and 50/1.4 do not have screws on the barrel like the 50/1.7
With the fixed-element lenses, this looks like the best fix. Tired of this adaptor problem. Every cheap adaptor is too thick, I know, I've tried them all . . . .
