Dirt on SLT mirror

[antiphony]

Hi all,

bought an a65 and very impressed so far until on the 6th time of use I changed lens mid way through a shoot (camera switched off) and got many dirt marks on my images.

Now the translucient mirror always stays closed so the dirt must be on the mirror as it "protects" the sensor.

After blowing the mirror to free it from dust there was an improvement in the image quality but still some marks remained.

I then followed the sensor cleaning instructions from the manual, no improvement in image quality. I also raised the mirror and gave the sensor a blow. Still no reduction in marks appearing on the image.

I have read many other posts on this forum and others, and found that these two procedures clean the sensor in 99.99% of circumstances.

Therefore I must conclude that either I am particularly unfortunate and have a very sticky sensor, or the dirt marks are still on the translucient mirror.

What is the best way to remove the dirt from the mirror if blowing does not work?

Also......quite importantly,

Have any other users of the SLT system come across dirt on the mirror effecting image quality?

If so is this a design issue feature of the SLT system?

Thanks in anticipation.

[blaireau_photo]

Hello antiphony - Welcome to the Sony Forums

When you say that you have been 'blowing' into the camera, do you mean that you have blown into it yourself or have you been using a blowing tool. If you have just been doing it yourself, there is a chance that you have just been blowing the debris around and not removing the problem dirt. If you use a specialised blowing tool, you can direct a precise burst of air that will be more effective at removing these particles of dirt/dust.

Let me know if this works. If you are still having problems there are other possibilities involving a cleaning solution and other tools but it would be best to try this first as using a cleaning solution can get a little tricky due to the location or the sensor/mirror.

Thanks,

Simon

[mattuttl]

Hello, I've got an A77 I've had it about 2 weeks and I took it out on Sunday for a bit of a run, and noticed specs and circles on the resulting images, I have not changed the lens since popping it on the body when I unpacked it. I had 4 really noticible areas on an image of a white price of paper taken at the suggested F22 and with EV nocked up a couple of levels.

I had to 'puffer' the mirror which removed 1 and then release the mirror/translucent sheet to remove one of the another two, the final one wont come off with a puffer so I'm guessing some sort of wet clean is in order.

As you can imagine I'm not overly pleased with having to do this sort of thing this early into owership, I like you thought the stationary mirror would protect the sensor. I've added an image taken at f13 ISO100 and I've highlighted the two very visible issues the top one was on the mirror teh second less visible one was on the sensor. Sorry for the subject matter, still playing.

[antiphony]

Thanks for the replies.

Mattuttl: This is exactly what I see on my images too, top mark.

Coincidently in similar positions!

Blaireau_photo: I bought a rocket blower to do the necessary blowing, I heard stories of breath and spittle marks.

I took the camera back to the retailer I purchased from and they kindly offered

to fix the issue for £45 per hour and a turn around of 28 days. Not good.

I tried an independant camera shop, the repair guy is on holiday, of course.

But I did get conformation that the mirror was dirty, which it still was even after

the substitute repair guy gave it another blow.

He was not confident enough to get stuck into the more contact based cleaning as he had never worked on this type of system before.

He also told me that there was some dust on the sensor.

I have no qualms over getting stuck in and cleaning, as if this is going to be a feature of ownership I  am not willing to pay £35 - £45 each time this occurs.

Message was edited by: antiphony

[silawre]

I've owned a number of DSLR's and SLT's and not one has not got dirt on the mirror or sensor and through the built in cleaning system and the blower I have resolved all the issues.  On occasion it has taken four or five attempts but I have yet failed to resolve the problem.

I cannot believe the turn around time of your retailer that is very poor, mine will do it within 4 hours in store!

I have found that facing the camera body down when taking and putting the lenses on reduces the times when dirt appears.  Sadly regardless of the make or model it is a risk we all taken when changing lenses, especially when out in the field.  You can further reduce the risk by getting a changing bag which I have heard is fiddly but works well.

Whether it is an SLT or DLSR any interchangeable lens camera is prone to this risk!

Si

[Mick2011]

Very good advice, Si

I'd also add a point that's not always blindingly obvious: people should be very careful not to touch either the sensor chip itself OR the pellicle mirror in front of it, unless you're using the correct cleaning tools and solutions. BOTH are extremely delicate surfaces and if they get permanently marked a replacement can be very expensive!

Ok, as you were

Mick

[GoNz0-]

i find the design very poor,

1, the mirror does not seal the sensor making it a bit of a design flaw as zooming a lens is enough to blow crap round the mirror onto the sensor.

2, the sensor is always open, no shutter to keep crap out meaning it will get 99.99999% more dirty than any other SLR with a shutter that remains closed until the sensors exposed while a pictures being taken.

and thats why i wont buy another SLT from sony until they sort this, it cost me £30 to get the sensor cleaned the other week as i couldn't blow the crap off any more.

[Mick2011]

It's interesting to note that the Sigma SD14, which has an IR filter mounted right behind the lens, apparently sealing the entire inner chamber, is reportedly no less prone to sensor dust than any other DSLR/T. This may be because dust is generated by the camera itself, as the shutter curtains gradually wear over time. However IMHO it's simply because people buy SD14s specifically to remove the filter and shoot IR photography

In effect, if you never change a lens, you'll never see significant sensor/mirror dust. For me, it's the single most compelling argument in favour of 'superzoom' 18-200 lenses. The corollary is, the more lenses you have and more often you change them, the more dust you'll get. This is dust entry problem #1, by a long chalk, and it's true of all camera systems.

In terms of SLT design, the priority has been to create an ultra-fast, multiple FPS body complete with live view. This led to an always-open, translucent-mirrored capture device which is, unfortunately, going to be unsealed by design. If you've ever tried to replace the IR filter on a SD14, you'll have been left wishing the darned thing would just flip up out of the way like a SLT

It may be refined over time, and you make a good point that better-sealing the sensor would make the SLT system one of the least-dust-prone there is. Meanwhile the only answer is to take care to avoid dust while the lens is off...

     • Dust off the camera and lens and power down the camera, before changing

     • Dust off the replacement lens before fitting

     • Avoid dry and draughty/windy places wherever possible, while changing

     • Practice super-fast lens changes

In short, if there's no crap in there, it won't get blown around. Which I have to say, is actually more likely when you have a big flappy mirror paddling around inside like a Japanese fan, every time you take a shot...

Cheers

Mick

[GoNz0-]

the thing is mick, there is nothing stopping the curtain closing while the camera is of, thats the point of fail for me design wise.

[Mick2011]

You make a good point and I do agree, that the almost permanently-exposed sensor would logically be more prone to debris settling on it. I'm not sure it's a design flaw – which would imply an oversight – it seems to me to be more of a trade-off for the performance boost an exposed sensor permits. However I'd prefer to see the mirror make a better seal around its housing; I think this would make a much bigger difference than a closed shutter.

I suppose the point I was making was that, without proper care, dust is eventually going to find its way to the sensor on any system. I hear varying reports, but the majority seem to think the stationary mirror of the SLT setup ought to actually make the camera less prone to sensor dust than SLRs... this would definitely be the case with a better-sealed mirror, making the open shutter a moot point.

Interesting point, as I say. Sony people do read these threads and it's always good to get these issues aired.

Cheers

Mick