damaged rear element of a carl zeiss 150 mm CF f4 T*

[charles_stephens1]

<p>Stupidly i was resetting the priming button with a screw driver that slipped and chipped the rear element about a 1/16"in diameter give or take, it is very obvious when looking at the lense but i do not see any indications looking through the viewer should i toss it and buy a new one ? </p>

[m_allegretta]

<p>So sorry to hear about the damage. Please take test images of the blue sky at f/4 and f/16. Examine the negative for any dark/light spot. If the density is uniform, most images will not be affected. I say "most" because if shooting towards the sun light, the scratch can be a source of flare that will show up on the negative.</p>

[Robin Smith]

<p>You probably won't notice it, so just keep using it. You may be surprised what damage you can do to a lens and experience no noticeable change in the resulting image. The main annoyance will be that the resale value will fall.</p>

[Aoresteen]

<p>Sorry for your damage.</p>

<p>The proper tool is not a screwdriver but a slip-free device like this one:</p>

<p><img src="http://i36.photobucket.com/albums/e5/aoresteen/Hasselblad/Hasselblad%20jam%20tool_zpss77tvs49.jpg" alt="" width="400" height="300" /></p>

<p>$20 from B&H</p>

<p>http://www.bhphotovideo.com/c/product/995353-REG/fotodiox_hassy_tool_camerakey_tool_for_hasselblad.html</p>

<p> </p>

[sheldonnalos]

<p>It will be fine. I've shot a beat up Hasselbad 150 lens that was far worse than what you describe with no ill effects. You can actually have much worse and it will still work fine. I've done tests where you put a piece of 1/4" by 1/4" paper on the rear element of the lens, blocking the light path. You can't even tell it's there until you stop down.</p>

<p>Keep shooting with it.</p>

[ondebanks]

<p>Keep using the lens; it will be absolutely fine. To prevent any flare, the standard remedy is to cover the chip with black ink/paint. Light cannot then scatter off it onto the film. For an extreme case of when this treatment was used, see <a href="http://astroanecdotes.com/2015/03/26/the-mcdonald-gun-shooting-incident/">here</a>!</p>

<p>Blacking out an inner portion of an optic is equivalent to setting up a "central obstruction"; far larger ones are standard in reflecting telescopes, like the Hubble Space Telescope. In your case, it will result in a negligible loss of light and of contrast in relatively flat or featureless areas. It will have no impact on resolution of detail.</p>