Medium Format Forum

Register a free account now!

If you are registered, you get access to the members only section, can participate in the buy & sell second hand forum and last but not least you can reserve your preferred username before someone else takes it.

Do sensors wear out with frequent use Aptus 17 with 160000 actuations


Could the sensor of an Aptus 17 digital back with 160,000 actuations be as good as new? Do sensors ever require overhauling after a specified number of actuations?

As far as I know, an Aptus has no moving parts relating to the image-capturing process. In theory, the number of actuations is irrelevant to the quality of a back's images. Is this correct?
Hi Roger,

Sensors do not wear out based on # of actuations. Semiconductor chips *can* degrade over time, like we all know computers sometimes die. You Aptus is if you look at it closely basically a small computer that happens to have one chip that is light sensitive.

But wearing out, no.

Circuits tend to age with electrical use. Also, environmental conditions (humidity, temperature, ...) affect the ageing of the circuits on a chip. Handling and activities such as cleaning (using approved materials and chemicals) _may_ also affect the surface of the chip.

Ask the seller of that back, since it is the local one you told me about, if you can try it for a weekend. The Aptus 17 back is a good back - but you need to verify quality in person to be assured that you are getting what you want.

Personally, 160,000 actuations seems to be a lot....

Dave Klemp
Interesting, how do electrical circuits age with use? Just curious.

I don't think the actual surface of the sensor chip is exposed for cleaning, there is a protective cover. Of course that cover filter could be damaged, but it is easy to inspect a MF digital back. ( Some of those are AA filters on some sensors like those found in 35mm DSLRs).

If you don't mind revealing the details, but how much are you paying? I know these backs very well and can give some indication of value for money.

Things to look for:

Find out how old the back is. It can't be to old, but it could be an older Leaf Valeo to Aptus upgrade which would still use the same sensor with new hardware.

160,000 actuations is not terribly excessive IMO ... if the back was used on a regular basis. If it is about 3 years old, that would be about 1000 shots a week. But it could indicate studio production use or a refurbished rental unit. See if you can discover its history.

Inspect for any signs of impact no matter how small.

Make sure the CF card door latches securely and isn't loose. The card should insert firmly but not need to much pressure to install. It should be a firm pressure to eject the card also ... not hang-up or be stubborn.

On the Aptus, make sure the digital back release works without hang ups. When you install the back on the camera it should snap on firmly and not move afterward (no play).

Be sure to install the latest version of Leaf Capture 11 available on the Leaf or Kodak site.
Then hook up the back mounted on a camera to the computer via a firewire that should come with the back. This will allow you to test the tethered operation and assure that the firewire functions are working properly. If the back's firmware needs to be updated, tethering with Leaf Capture 11 will trigger that process, and automatically update the firmware.

If you get the back, you may want to also download the Leaf RAW converter which allows you to convert to DNGs file format.
To give an impression of how a sensor fits together I took this shot from a small digicam sensor (Kodak DC3400 for the curious). The quality of the picture is not all that brilliant (no macro stuff available right now, or a CFV to dissect


- the actual chip is housed in a ceramic housing
- the chip is connected to gold plated pins using minute gold bonding wires (you can't really see those here)
- there is a coated glass window to let the light in
- the ceramic housing is hermetically sealed against moisture, gases etc
- there is quite some space (relatively speaking) between the glass window and the sensor chip

Although MF sensors are a different kettle of fish of course, they will also be housed in a similar protective housing. See for ex&le

So unless someone was heavy handed enough to scratch the glass window or something entirely stupid like that the sensor should be well protected in its cozy housing.

I'm sure Austin chime in to either correct me, or add additional information.

Interesting, how do electrical circuits age with use? Just curious.


Presume you are talking about AC circuits which are subjected to sinusoidal wave effects. The ON/OFF of the current heats and eventually age hardens the wiring.

Ever wondered how the wires in an electrical plug become loose when they have only ever been in the wall socket. It's the same sinusoidal effect that eventually causes the screws to loose their grip.

None of this happens in a DC circuit.

Hope that helps and is not stating the obvious. :)

Hi Gary,

Well.. I would not exactly compare AC power circuits with a digiback. And a digiback is not DC either, it contains digital circuitry clocked at high frequencies.

But you are right, there are aging effects to consider like flexible circuit boards degrading, contamination in the air attacking components (I have had my hands on disk drives where the soldering material had been attacked by SO2 in the air, from a heavily polluted industrial area), moisture taking its toll, heat (for ex&ly drying out the electrolytical capacitors; ever seen your PC's powersupply go 'poofff'? Often that is that problem), temperature cycling causing thermal stress cracks in components, soldering joints etc. But even not using things can kill them, the same electrolytic capacitors hate to be left unused. That is why you have to use your electronic strobes ever so often: to keep the caps in good shape. You could have components that are substandard out of manufacturing. I have seen memory chips like that, misaligned masks in the chip factory making them as unreliable as can be.

Or in other words: there are lots of ways for electronics to die. But using the sensor for what it is designed to would be the least of my worries.

Go and make pictures. If worried about dying electronics, order a fresh box of Portra

Hi Wilko,

> I'm sure Austin chime in to either correct me, or add
> additional information.

The sensor cells do typically deteriorate over time. I don't have any data on this though, since I haven't been involved in any studies dealing with this. The manufacturers will typically provide this data if asked.

But, that said, my understanding is these imaging sensors will last far longer, as they are input only devides, than a display will, since those are active output devices. Depending on the technology used, they are going to be subject to heat/temperature type failures long before passive deterioration I'd guess.

The best gauge for this would be to see how older equipment still performs, from either finding someone who still uses it, or checking eBay.

Your LCD display will probably be the first thing to go on any of these new fandangled cameras...and we've seen a LOT of evidence of that from databacks and camera bodies.


Hi Austin,

Of course everything deteriorates over time.

But the $100 question (wel, 25k$ maybe in this case) is if the sensor deterioration is accelerated by use. OK, light is a form of energy you expose the sensor to, but is the amount of energy enough to damage it? Short of putting it under high-intensity shortwave UV I doubt it is to be honest.

What would you expect to happen? More dead sensor sites accumulating over time? I've seen interesting failures in CMOS where the transistor's gate oxide had been contaminated with metal ions. But that was all due to process errors in the wafer fab, not outside sources.

So like you say, your LCD will most likely die much earlier. Or the stupid battery. Or your nice proprietary RAW->something converter is no longer supported by Redmond's latest or..

"Choose your worries wisely"

Hi Wilko,

> But the $100 question (wel, 25k$ maybe in this case) is if
> the sensor deterioration is accelerated by use.

Simple answer -yes-. Qualified answer requires another question, is it significant....I belive no.

I have been designing with digital imagers since the mid to late 70's, and have run hundreds of thousands of captures...and I've never seen a significant failure that I can contribute to use. Due to me blowing the device up, sure.

I believe I have possibly seen some degredation, but again, I have done no controled study on this, so I can't say for sure, and it's pure speculation on my part. What I may advise it having the PRNU recalibrated every so many years. I wonder if Hasselcon will do that for you?


Hi Austin,

Right, this sounds like very convincing to me. It might (and I speculate of course) be that higher density sensors are more sensitive to damage due to their smaller design rule. A bit like higher density memories being more sensitive to incoming cosmic radiation.

As for the PRNU, do you know what the reject criteria are for a high MP sensor? For things like TFTs the reject criteria are based on what the failure is (pixel dead, or constant on), them being clustered together and where they are in the screen (centrally located failures deemed more disturbing). But I have no idea how this works for sensors.