Risk of SLT mirror degradation over medium term?

[artington]

I suppose this is really a question for you David but of course all thoughts are welcome.

I have not so far gone down the SLT route but am increasingly tempted by the a99. However, while I am unconcerned about the small attenuation in light transmission caused by the fixed mirror, I do wonder about the potential for the mirror to haze up over a longer period. Glass gets dirty on exposure to the air and, while the a99 is weather sealed, the mirror will be exposed to air when lenses are changed. I wonder whether this could lead to a build of of haze/dirt over a period of a few years. Clearly this will never be a problem with a conventional DSLR because the mirror swings out of the light path at the moment of exposure.

[Dr. Harout]

Getting haze/dirt on that mirror will take much much longer than the same to get on a lens itself.

[bfitzgerald]

Impossible to tell bar over an extended period of time. I would have hoped Sony would have done enough testing on the mirror material to ensure this does not happen. But you never can tell until we ask the same question years from now.

[Atgets_Apprentice]

The a33/55 have been around almost 2 years now, why not ask an owner?

[bfitzgerald]

I think the OP might be thinking of a bit longer term than 2 years. There are ways to tests things for age effects temperature, accelerated use..exposure to light etc etc.

[artington]

My concern is more to do with atmospheric exposure. The brochure for the a99 highlights the "newly developed coating on the surface of the optical low-pass filter [on the sensor]" and the "anti-dust mechanism that vibrates the filter at high speed ..." but makes no comment at all about the potential for, or measures to remove, dust (or anything else) from the fixed mirror, which is between the lens and sensor. And unlike a lens I'm not sure I should be at all comfortable in cleaning it.

[Old Hydro]

My concern is more to do with atmospheric exposure. The brochure for the a99 highlights the "newly developed coating on the surface of the optical low-pass filter [on the sensor]" and the "anti-dust mechanism that vibrates the filter at high speed ..." but makes no comment at all about the potential for, or measures to remove, dust (or anything else) from the fixed mirror, which is between the lens and sensor. And unlike a lens I'm not sure I should be at all comfortable in cleaning it.

I once asked a professional if he had any sensor cleaning swabs and could I use one on the A850. He said he sends his gear out, but that he also know of professional who cleaned the sensor and mirror in his camera(s) by holding them out the window when someone was driving at 50 mph. Said it worked better then a blower.

[Greg Beetham]

I have never really envisioned anyone attempting to clean the trans-mirror in an SLT, I doubt that it is possible by conventional means, maybe with some hi-tech cleaning agent perhaps, but I would think in the main you would simply replace it anytime you became unhappy with it for any reason.
It probably wouldn’t even hurt to have a spare one on hand, if it could be stored safely.
Greg

[artington]

I have never really envisioned anyone attempting to clean the trans-mirror in an SLT, I doubt that it is possible by conventional means, maybe with some hi-tech cleaning agent perhaps, but I would think in the main you would simply replace it anytime you became unhappy with it for any reason.
It probably wouldn’t even hurt to have a spare one on hand, if it could be stored safely.
Greg

Yes, this would be a possible solution. Not sure about keeping a spare though - I should imagine alignment is critical so it would probably need to be a factory replacement.

[Greg Beetham]

I’ve seen threads where people have removed the mirror and taken shots without it being there, apparently it just clips in at the bottom (I don’t have an SLT so I can’t confirm) and once it is its in place so to speak, so I got the impression false or otherwise that it was no major deal to take the mirror out and put it back. But yes it would have to go back in the proper position for everything to be calibrated back to normal one would think.
Greg

[Headcell]

Have a look at this article: http://thesybersite.com/sony/a55/index.htm. The final quarter of the feature takes a closer look at the mirror.

Perhaps of more interest would be this video: http://www.youtube.com/watch?v=cU5TqeoqRnQ.

[Chris Malcolm]

Spare SLT mirrors can be bought, and while Sony do not recommend that users replace it themselves, there are several users who have described doing so without difficulty. There isn't an alignment problem -- such alignment as is required is supplied by it snapping into place.

I have also seen several reports of users removing specks of dust from it by using a small soft brush.

[classiccameras]

I think the SLT mirror days are numbered and we could see a NEX system in future DSLR bodies.

Ever since the SLT was introduced by Sony on the A33/55, there has been mixed views as to how good it was. Its been a controvercial talking point with some review sites who have lacked enthusiasm in their reports. On the other hand, some review sites have heaped praise on the system with the little cheap A37 getting high marks from at least 5 review sites and have praised the image quality. The SLT is not a problem for me as I bought an A37 recently and I am very pleased with it. Its actually nicer to use than my Nikon D5100 and IQ is on a par to my eyes.

I think some of the review sites who did not give the system high marks used lame excuses saying the SLT system and high ISO noise and smeared images from over aggressive noise reduction was the area holding the camera back from being up there with the top contenders. They also trot out the 1/2 stop loss in light transmission to the sensor so resolution is lower than similar 16mp cameras.
Its almost as if Sony don't trust Sony owners to adjust their own noise levels, Just look at Pentax, probably the most comprehensive in camera noise filter adjustment out there and Olympus almost the same.
It would be interesting to know what Sony think privately about its future.

Pete

[bfitzgerald]

I think the SLT mirror will go but they have to nail the AF issues esp for moving subjects to do that (note the OM-D weak point here)
As for lame excuses I do think Sony's jpegs need quite a bit of work..you might pass them off as usable in some situations, you'd not likely be impressed the more you move into low light situations with it.
I do honestly think Canikon have better jpegs. Pentax are not bad as well, though recent models have gone backwards here in jpeg processing. And raw NR is a def no no too.

[classiccameras]

Yeah, I noticed that about Pentax, I thought the K20D and Kr Jpegs were pretty good, but later models no so good.

Most owners and commentators have for years praised Olympus for their Jpeg processing saying the best there is, I have to agree. I will add one more camera to that position and thats Fuji. My old Canon 450D, although dreadful at blowing high lights and over exposing, gave some pretty good Jpegs. Had to run the camera almost all the time on -05.

This is what we found when I worked in the trade.
The vast majority of the mass market camera users, will probably only ever use Jpegs which is why Canikon and Olympus had developed their Jpeg processing for the mass market. Bright over saturated colours sell cameras. In the overall scheme of things, mid range and pro DSLR cameras account for a tiny section of the market in comparison to entry level models. For every Canon and Nikon mid and pro models we sold, we would sell 50: Canikon entry level DSLR's with Sony not far behind. Compacts sold the best of all. M4T stuff such as the Panasonic and Olympus also sold fairly well but not as well as the budget DSLR.