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SLT


strawman 11 22.0k 16 United Kingdom
22 Aug 2012 4:40PM

Quote:Basically these are all non-problems.
In your opinion.

Quote:mirror shake exactly as you take a photo
Where it is likely to be an issue I find myself using a tripod and can lock up the mirror otherwise with a modern balanced mirror its a non-problem.

Quote:compromised AF accuracy
Its not that different from the SLT. As long as there is a mirror and a different light path to the sensor and as long as you are using predictive phase detection autofocus the SLT and SLR share common potential issues to cause AF errors. If you are that hung up on it you ought to ditch the SLT and go for a mirror less system as frankly all others compromise spot AF accuracy. Go find out how phase detect AF works and you will see items that need calibration, It is a lot more complicated than just the issue of having a moving mirror or not. You A700 must have had terrible AF to be as bad as you say.

Quote:I bought the A77 (rather than the A65) because it has AF fine tune
Sony know enough about the error issues inherent in the phase detection AF system that are common to SLRs and the SLT to put the feature in. I have a £300 DSLR I can show you has accurate and repeatable AF. Its not hard to find.

And remember some of the AF problems occur because of calibration issues in the lens. It is why people with problem equipment are often ask to send in lenses and the camera.

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mikehit e2
5 7.1k 11 United Kingdom
22 Aug 2012 5:38PM

Quote:Longer battery life - who cares, buy a spare battery
Better dynamic range - In the view finder maybe, but I'd rather see what the picture is going to look like
Lower noise - 1/2 a stop. Who cares.



But you are the one who says SLT is superior 'in every way'. What you mean is 'every way that you care about'.

Battery life - I would not want to go on a 4-week trek in the Himalayas with something that has the battery life of SLT. DSLRs is bad enough.
Noise - half a stop is important to some people
Dynamic range - ditto
Steppenwolf 3 1.0k
23 Aug 2012 2:57PM

Quote:But you are the one who says SLT is superior 'in every way'.


Er, where did I say that? I was referring to Sony's opinion (or one of their PR people).


Quote:Where it is likely to be an issue I find myself using a tripod and can lock up the mirror otherwise with a modern balanced mirror its a non-problem.


It's always an issue Strawman. And with the very high resolution that some modern cameras deliver it's becoming more of an issue. It's less of an issue than the focus problems though. I notice that you never commented on DK's article about DSLR focus that I posted on another thread.
strawman 11 22.0k 16 United Kingdom
23 Aug 2012 4:03PM
I did a google search for
Quote:David Kilpatrick slt focusing
Are you certain you want me to comment as I sort of agree with him, and he does not say what you do.

No1 hit is this comment by DK He looks in this to have a similar understanding of AF as I do. For reference that indicates accurate focusing to f5.6 while the competing cameras offer accurate focusing to f2.8. (A77 to 7D for example). So in that case the SLT cameras have average to worse measurement of AF position.

So it cannot have been that article so I found this one further down

It is a fair article and it is true that there are fewer variable in the path, so advantage SLT and we both agree on the best spot accuracy system
Quote:The simplicity of the SLT design for collimation and adjustment can only be bettered by direct focus detection from the sensor itself
Hence my comment that SLT is not the best.

And he goes on to say.
Quote:Accuracy of lens mount alignment is no more, nor less, an issue than with other designs and the same goes for sensor adjustment.
So he recognises that there are more parameters than just the mirror in getting good focus.

So I have to say based on what I have read I agree with David Kilpatrick but I think you have not understood what he has written. In short the DSLR has a more complex light path to calibrate, agree, but the SLT and DSLR designs need to be calibrated. Agree. The competing DSLR designs have more accurate AF modules than the ones Sony use, agree also.

So a correctly calibrated DSLR say a 7D, will have a more accurate AF performance than the A77 where spot accuracy is required. All proven in information from David. It is easier to calibrate an SLR than a DSLR also true. But we are talking about the best are we not. My search also turned up threads on AF accuracy problems on SLT's but lets not go there as after all you have told me they do not have focusing problems. If sony invested in better precision AF sensors then there is still the issue of which is best calibrated.

Again for most users, with f5.6 or slower lenses its not a big issues but if you want repeatable or the best, you want more precise AF modules and precise calibration. And you want the lens position and info data to be precise as well. Phase detect AF has many variable. Especially if you want to do it fast. Perhaps Sony do not run as fast an AF strategy as Canon do, so perhaps the noted sports and wildlife performance difference is traceable to that also.
Steppenwolf 3 1.0k
23 Aug 2012 6:10PM

Quote:So I have to say based on what I have read I agree with David Kilpatrick but I think you have not understood what he has written.


I think it's you who doesn't understand, Strawman. BTW you needn't have googled to find the information because I provided a link for you a couple of days ago - which you didn't read.

His article is based around his experiences with the SLTs :

"My own experience with the Alpha 55 has been that when focus is correctly confirmed, it is very accurate indeed, more so than with previous models from the Alpha 100 to 700."

He then attempts to explain this in terms of the way the two systems work. He does admit that he hasn't got all the answers. However, the empirical evidence is that the SLTs deliver better focus. I've had 3 DSLRs and they've all been unreliable on focus yet the SLT is spot on - doesn't prove anything but it seems I'm not the only one who has noticed this. My guess is that you haven't actually tested your DSLR in the most difficult conditions. Like I have said, I use long lenses at wide aperture (sometimes f2.8) and it's very obvious when the focus is wrong. I notice from your portfolio that you don't do this. The nearest you get is the kite and the three owls and - although it's difficult to tell with such downsized pictures (200Kb) - the focus doesn't look great to me. Maybe I'm just more picky about focus than you are.

Another comment DK made about the SLTs is interesting:

"The SLT mirror of the 77 diverts 30% of light to the AF module, but this is actually more than the old semisilvered patch and double mirror system used to let through in SLRs. The AF sensor itself may not be any more sensitive, itís simply getting a much better image feed."

But in the end it's not down to theory - like I have said you need to actually try out an SLT.
strawman 11 22.0k 16 United Kingdom
23 Aug 2012 10:55PM
I googled for the information to see what else he had written on the subject. I have no problem with that article as it does not disagree with what I have written it just fails to back your assertions. He looks to be realistic in his understanding of what the camera can and cannot do while you do not have such a balanced view. Read again the link I put in where he describes the focusing accuracy of the SLT cameras. Do I believe him or you. Tell me why would I believe you over him.

He says the SLT cameras can accurately focus f5.6 smaller aperture lens settings, but not wider f2.8 lens settings like many of the competition. He has asserted that and given evidence of his experiment to prove it. So please add that into your message. Its the same guy so must be true.

Please read it again and this time look at what he does actually say, it backs what I have told you. That the SLT is more accurate in AF performance than the A100 to A700 cameras is plausible. That it is easier to calibrate is plausible. That does not remove the need to have an adjustment/calibration of the camera autofocus system. Heck even Sony worked that out and gave the camera micro adjust. So you have David and Sony telling you what you have not understood.

Next images, by all means compare sharpness of A3 images I down-sized to 1000 x1000 pixels that some time later became downsized to 600 pixel wide shots automatically on this site. I can show you the A3 images that were judged to be perfectly sharp prints, pop round and enter the real world. Any time. Of course your images show us what ah yes you have not any on display. I remember some why not put them back up so we can see..... After all its good to talk in theory about the performance of a system, lets see some results.

Its a good debate, how much do we sharpen images for posting here. I am open to suggestions. Same goes for prints, how sharp do you want them.

In all this argument I have not claimed perfection, rather that your assertions on superior performance are not exactly correct your claims of the SLT being better do not always stack up. There is a difference.

I know about the light level given to the AF sensors it is very high is it not, especially when the competition manage to resolve focusing accuracy to a better level of detail. So is the level of transmission set by a technology limitation of SLT. The SLT is easier to calibrate, but not necessarily more accurate than the DSLR.

Remember in a camera you judge the performance of the system. So add more pixels, people will look in greater detail, you need greater focusing precision and greater stability etc if you wish to use the resolution. But Sony have fitted lower precision AF sensors than the benchmark products. Give the camera a faster frame rate and more pixels well you need to have a far bigger buffer or you just fill the buffer and it captures images too slow. I have a high respect for Sony products and own a few, the ex Minolta division are just letting Sony down by producing cameras that fall short in the blindingly obvious regions. A77 buffer 13 raw images, 7D 25 RAW images. A77 fast frame rate fill the buffer in just over 1 second 7D over 3 seconds. Now if you want AF and a stopped down lens the A77 drops to a lower frame rate than the 7D while the 7D does it all at its maximum frame rate. Its just an example. And remember the Canon is the older product. Its like Sony went for the marketing buzz words but did not bother to go for the in-depth system design.

P.S I do use an f2.8 lens and an f1.8 lens. Seldom at those settings, but they exist. The shots at F4 require a level of precision of focus do they not?

I have used an SLT system, have you used a good SLR system.

In the end in all of this I want you to understand that you are claiming the SLT system has superior performance, but I think it has achieved some areas of slight improvement, some areas of loss, and a lot of neutral areas.

Sorry sport you are over blowing the SLT trumpet and you are not understanding. Sorry.
kodachrome 3 530
24 Aug 2012 7:16AM
Do you think SLT days are numbered and they may opt for NEX technology in future DSLR/SLT cameras.

Koda
strawman 11 22.0k 16 United Kingdom
24 Aug 2012 8:42AM
I think you are correct, in that you may find this happening at the entry level cameras. A lot will depend upon the outcome of the business review being held by the new Sony CEO on the company business. It losses have been bad (market share and money for the big Sony company not just cameras) and he has declared he is prepared to leave markets if that is the correct decision. Again this has to be seen at the big company level, not just A and NEX cameras. Imaging is important to Sony so hopefully they will not pull the plug on the new full frame cameras. I hope he makes the correct calls.

But it is probably also true that as the EVF and other technologies improve many of the mirror type cameras will migrate towards mirror less designs.
Carabosse e2
11 39.7k 269 England
24 Aug 2012 11:15AM

Quote:Do you think SLT days are numbered and they may opt for NEX technology in future DSLR/SLT cameras.




Yes. Mirrorless certainly seems to have gained an astonishing market share in the Far East - including the Japanese home market - in a very short time, i.e. zero to over 50% in about 3 years. At that rate, sales of mirrored cameras may be down to negligible within the next 3 years or so.
mikehit e2
5 7.1k 11 United Kingdom
24 Aug 2012 11:34AM
I agree. SLT is a subsection of the DSLR market which is shrinking because an increasing proportion of the new generation of photographers are turning to MFT (though I am not as pessimistic as CB on that one because the mantra 'DSLR for quality photographs' is still very strong when advice is given out).
I read somewhere that even their NEX range are suffering because of the size comparison with MFTs and if this goes any further Sony may pull out of that and concentrate on sensor manufacture.

We have the Sony NEX and Canon EOS-M - APS-C with theoretically better image quality than MFT but the OM-D has blown that wide open. But they could build a situation of being the 'link' to what is seen as serious DSLR photography
Then there is the MFT ranges from Panasonic and Olympus - but without Nikon and Canon in the consortium how viable is this if those two big guys decide to really pull their weight (and the chance of Canon/Nikon pulling together is nil so maybe they will stay fractured)
Then there is Nikon - ploughing its own furrow but I suspect will be little more than a niche for brand loyalists

The problem is that all of these manufacturers are trying to second guess why people bought a DSLR in the past - up until recently it was either a phone, a compact or a full-blown DSLR and reasons formoving up to a DLSR are many and varied.
Carabosse e2
11 39.7k 269 England
24 Aug 2012 11:49AM
APS-C plus mirrorless is starting to look like an uncomfortable mix............., i.e. little camera bodies with (relatively) big lenses.

It could be that cameras with sensors the size of M4/3 and even Nikon's, which I gather has been more successful than predicted, may be the way forward.

The top of the range DSLR will survive for quite a while, if only because pros need big cameras to make themselves look convincing - just as as few decades ago you needed something like a TLR rather than 35mm.
mdpontin 10 6.0k Scotland
24 Aug 2012 12:20PM

Quote:Again this has to be seen at the big company level, not just A and NEX cameras. Imaging is important to Sony so hopefully they will not pull the plug on the new full frame cameras. I hope he makes the correct calls.


I'd be very surprised if Sony pulled out of imaging. They were huge in the digital compact market not so long ago, and buying Minolta (which was itself merged with Konica) gave them a toe-hold in the dSLR market which they have certainly worked hard on developing. Then there's their presence in the pro video market. That said, the company as a whole has a recent history of missed opportunities and strange decisions, so who can say?
Carabosse e2
11 39.7k 269 England
24 Aug 2012 12:31PM
Sony's place in the pro video market is longstanding. Their entry into stills photography is relatively recent.

Maybe they will turn to making camera phones. Grin
Steppenwolf 3 1.0k
27 Aug 2012 4:09PM

Quote:I googled for the information to see what else he had written on the subject. I have no problem with that article as it does not disagree with what I have written it just fails to back your assertions. He looks to be realistic in his understanding of what the camera can and cannot do while you do not have such a balanced view. Read again the link I put in where he describes the focusing accuracy of the SLT cameras. Do I believe him or you. Tell me why would I believe you over him.


Your usual filibuster Strawman. Sorry I didn't manage to read much of it.

I think I accurately reflected DK's views on the SLT AF in an earlier post, where I quoted him:

"My own experience with the Alpha 55 has been that when focus is correctly confirmed, it is very accurate indeed, more so than with previous models from the Alpha 100 to 700."

And I linked that article where he attempted to give a few pointers as to why - which you didn't understand. I'll simplify it for you - the SLT doesn't have any moving parts which is always an advantage when fractions of a millimetre are significant.

The other link you posted (to the photoclubalpha forum) is dubious - DK does get facts wrong sometimes. He says that the new Sonys use f5.6 crosshairs (rather than f2.8) - like Nikon now does. I'm not sure that this is true. The A700 had a central f2.8 crosshair - which BTW did NOT focus an f2.8 lens correctly all the time - but I can find no information that says that Sony has now gone to f5.6. He's certainly wrong in saying that this will lead to BF on f2.8 lenses. The differential focus that wide aperture lenses can display can be either BF or FF depending on the quality of the lens. What he said was a reply to a forum poster and I think he took less care with it than he would with an article.

I read what DK said about the more accurate focus and decided that I'd give the A77 a try - no, not in a shop but by buying one. I'm glad I did because the AF is spot on.

Like I said Strawman, you should write the back page of the AP. I don't think that old geezer has had a go at SLTs yet. You could show him thing or two - "These pellicle mirrors are the work of the devil" etc etc "May God have mercy on your soul". And such like. I guess you were around when they invented the SLR. I'll bet you didn't like it.Grin
kodachrome 3 530
30 Aug 2012 7:42AM
I read on the Mirrorless Rumours Site that Sony will eventually be concentrating on NEX technology only in their future plans, full frame cameras will stop being made, but no dates given. Might I remind every one that this is only a rumour from a rumour site.

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