Jump to content


Photo

Lens - 'moderately dusty' inside - should I buy?


  • Please log in to reply
4 replies to this topic

#1 Patrick Cooper

Patrick Cooper
  • Basic Members
  • PipPipPipPip
  • 868 posts
  • Other

Posted 22 March 2007 - 01:36 PM

I'm trying to decide whether I should bid on a 75mm lens currently on ebay. This lens seems to be in overall good shape but according to one of the seller's replies to my questions, there is some fine dust between the elements inside the lens. And that he could only see it when shining a torch / flashlight into the lens. With light from a window, the dust is not visible. I then sent another question - asking how much dust was in there - a lot of dust, or a few specs? His reply was that 'it's moderately dusty.'

The majority of my lenses are pretty clear from dust (particularly the inside of them.) So I'm not sure what to expect from a lens that is 'moderately dusty' inside. As the incoming light intercepts the various particles of dust, would there be much of a degrading effect? Any loss of sharpness or detail? Or would it only mean that there would be an increased chance of flare? In short, would the item be worth bidding on if all the other aspects of the equipment sound in good order? By the way, according to the seller, there is no fungus, haze or scratches with that lens.

There are only a few hours left in the auction.
  • 0

#2 Nick Mulder

Nick Mulder
  • Basic Members
  • PipPipPipPip
  • 1023 posts
  • Other
  • Auckland, New Zealand

Posted 22 March 2007 - 02:12 PM

personally I'm ok with dust.

light should hit it and stop right there - so its just a slight T-stop reduction, nothing really ... maybe a little diffraction around the edges actually

Any haze, oil, fungus or otherwise translucent material will unfortunately scatter the light and make it incoherent when it reaches the film. Barely noticeable in most cases until that critical shot ...

With eBay you never know - I personally respect the sellers potential honesty, which is a plus, but then maybe he/she has cottoned onto that factor - "Admit one flaw, and the rest will go unnoticed" - eBay really brings out the shittiness in some people and somewhat less often the greatness in them ...

Always a gamble.
  • 0

#3 Robert Glenn

Robert Glenn
  • Basic Members
  • PipPipPip
  • 247 posts
  • Other

Posted 23 March 2007 - 11:37 AM

dust is just a fact o life. I heard from an agenieux tech that he has never seen an image affected by particulate matter in a lens, so you can take his word for what it's worth. Lenses are more affected by problems in the rear I believe.
  • 0

#4 chuck colburn

chuck colburn
  • Basic Members
  • PipPipPipPip
  • 389 posts
  • Other
  • orygun

Posted 23 March 2007 - 12:29 PM

RobertNC/Patrick Cooper,

I agree with your Angenieux tech. But since most zoom lens rear groups are a self contained, (seperate housing) set of optics, there is little chanch of dust getting inside. Just keep the last element clean the way you would the front one. Speaking of front elements, I would not worry to much about that either unless it is a very short focal length which can be subceptible to flare from scratches. More so the smaller the stop that is used.
Some or my presonal 35mm still lenses were on the border of being filthy inside (like some car mechanics the last thing I wanted to do after servicing lenses all day was to work on my own) and I never was bothered by it in my prints. So Patrick, since the lens you are talking about is not a wide angle I would not be to concerned about the dust. Also since lenses of this focal length tend to be of simple (fewer elements) design, I don't think it would be to exspensive to have a CLA done to it. 75mm is not such a common focal length I would be interested in hearing about what brand it is.

Chuck

Edited by chuck colburn, 23 March 2007 - 12:30 PM.

  • 0

#5 Patrick Cooper

Patrick Cooper
  • Basic Members
  • PipPipPipPip
  • 868 posts
  • Other

Posted 26 March 2007 - 08:41 AM

This 75mm lens was a Minolta lens and belonged to a twin lens reflex. Although it was at a cheap price a few hours before the auction end, the bidding took a sudden sharp turn.
  • 0


Wooden Camera

Paralinx LLC

Glidecam

Metropolis Post

Gamma Ray Digital Inc

Rig Wheels Passport

Ritter Battery

Media Blackout - Custom Cables and AKS

Opal

Tai Audio

Visual Products

rebotnix Technologies

The Slider

FJS International, LLC

Willys Widgets

Abel Cine

CineLab

Technodolly

Aerial Filmworks

Broadcast Solutions Inc

CineTape

CineTape

Willys Widgets

Paralinx LLC

Visual Products

Opal

Glidecam

Abel Cine

Tai Audio

Technodolly

Metropolis Post

rebotnix Technologies

Media Blackout - Custom Cables and AKS

Ritter Battery

FJS International, LLC

The Slider

Broadcast Solutions Inc

Aerial Filmworks

CineLab

Gamma Ray Digital Inc

Wooden Camera

Rig Wheels Passport