[Lvlug] Electronic Cameras: Durability of Image Sensors, etc.?

[Scott Piccotti]

On Dec 28, 2006, at 2:37 PM, Randy Kramer wrote:
> Thanks for the prompt and helpful response!

You're welcome, I'm happy to help. My question to answer ratio on  
this list isn't great, so it's nice to get a question I actually know  
something about.

> On my old Canon FTb-QL, I can lock the mirror up and presumably get  
> to the
> image sensor to clean it [...]  And I'd feel fairly comfortable  
> cleaning it, using one of those old soft brush thingies with a  
> rubber bulb to blow air.

You're a braver man than I.  ;-)
Those sensors are really fragile. Dust may be bad, but scratches are  
a lot worse.

DO NOT use one of those soft brush thingies. That kind of damage  
isn't covered by warranty. A bulb blower is best, but can also stir  
up even more dust. For stubborn bits, they make a special tool to  
pick particles of dust off the sensor. Ask about it when you stop by.

> (I have a preference for Canon.)

I like the Canon stuff a lot, especially for the S/N ratio in low  
light. (but that opinion may be outdated by now...)

> I guess that (locking the mirror up) wouldn't work with a  
> pentaprism, and at
> least some of the Canon's had something they called a penta-mirror-- 
> don't
> know about that either.

The pentamirror or pentaprism isn't in front of the sensor, so mirror  
lock-up works the same on just about any SLR. A pentamirror does the  
same thing as a pentaprism, it just uses mirrors instead of a solid  
chunk of glass. And technically, an SLR camera typically uses a "roof  
pentamirror". (what kind of nerd would I be without a little pedantry?)

See the illustration here:
http://en.wikipedia.org/wiki/Single-lens_reflex_camera

Mirror lock-up is usually used for long exposures. Without the motion  
of the mirror, the body vibrates less and you get a sharper picture.

> I guess I'll plan a trip to Dan's.  (I imagine they sell used  
> cameras as
> well.)

They do, but not as much anymore. Since everything went digital it  
seems there's less and less market for the used stuff.

> I'd be curious to know what you choose.

Me too! :) I'll keep you posted.

  ~scott