As a follow up to my previous question about the Sony Alpha 77: Is it bad to use old lenses on a new camera?

I mostly do Urbex and Landscape photography. Are there any other disadvantages to SLT-cameras other than losing some light and having an EVF and are the two mentioned before really that bad? How much light do you lose using an SLT?


2 Answers 2


I own a Sony A77 SLT camera.
I am an 'avid' photographer. As well as well composed and static shots I enjoy pushing the camera to its limits in various ways including situations where correct timing of shutter release is critical. Overall I am happy with the tradeoffs that come from the EVF system.

  • One factor that biases me is that I have been waiting for such a system since 2003 when I bought a Minolta 7Hi "bridge" camera. That was a then high end no DSLR with a respectable 5 Mp sensor which was usefully larger than that of most point and shoots, and an EVF. By modern standards the EVF was utterly terrible. But the "photo making" abilities that it added made me realise that someday there would be "SLRs" that worked that way - and caused me to look forward to the day when I could own one.

The A77 meets my long held expectations. It could be better in various ways, but the compromises are worth the gains. The area I most wish for improvement in is low light performance. The pellicle mirror takes 1/2 an f stop off performance.

  • DxO optics gives the A77 / A77-II "low light ISO" scores of 801 / 1013. With the half stop affect of the pellicle mirror allowed for that would be 1.414 x 801/1013 = 1132 / 1430. That puts the A77-II sensor a full stop lower than the leading FF cameras (not surprisingly for an APSC) and 1.5 stops behind when the pellicle mirror is included.
    Q: Is this really noticeable in real world situations?
    A: Alas, yes. My Nikon D700 with a DxO 2400 ISO low light rating is noticeably superior.

But, just restoring the 1/2 f stop taken by the mirror would not be a vast gain.

I have read comments by people who have tried the A77 EVF and say that it is unacceptable compared to using an OVF. Personal preferences vary - I notice the difference, but for me what differences there are are a small price to pay for what is gained instead.

Things like
- the ability to see white balance effects as they will be (in "journey record" mode I often shoot high resolution JPG & swap to RAW for specific occasions. I am increasingly shooting RAW + JPG and still value this), and
- the effect of changes in exposure compensation being visible as they are made.
- "Focus peaking" in manual focus mode. Utterly superb - a "wave of colour coats areas which are in focus - you can eg focus on a leaf at say 10 metres away in the middle of a thicket of branches. Or on a face and see graphically which areas are in focus. Those blessed with younger eyes may be able to do this directly with an OVF - but it is quick easy and accurate with focus peaking. - And quite a lot more ...

Several years ago I bought a Nikon D700 due mainly to its low light performance, with the expectation of moving to all Nikon equipment over time. I still own the D700 and love its low light capabilities, but my intended expansion path includes A77-II as a second camera and an A99 when I can afford it (or persuade Sony to give me one (still working on that :-) )).

In March this year I spent 3 months in India. Practicalities made taking only one DSLR "sensible" - I took the A77, and regretted not having the D700 only in a very few night-time situations.

I've owned several film SLRs and 4 DSLRs prior to acquiring the A77. Overall I am extremely happy with the abilities of the A77 as a "picture making system" an prefer it to a conventional OVF DSLR.


Following Hugo's link from above I see I've commented on this extensively about 18 months ago. As my material was all in comments and not in an answer I'll edit it and add it here. Some overlap with my answer above (as you'd hope :-)).:

Observation only: I've owned 5 x DSLRs (4 x Sony/Minolta, 1 x Nikon D700) and have a Sony A77. For me the advantages of the EVF and permanent "electronic image" with phase focusing, no mirror madness, WYSIWYG, focus peaking good frame rate and much more are so great that I can't imagine going back to an OVF. The disadvantages are real, but the gains are stunning. The term "live view" is meaningless - it's just "view" permanently - viewable either on EVF or back LCD as suits. Response time for any action is bearable - eye and brain can do well enough.

Terrible EVF performance in extremely low light (Moonlight on down) is my biggest complaint. Dynamic range I can live with. The half a stop sensitivity loss to pellicle mirror is sad but acceptable. I'm wondering how to afford an A99 and also wondering what Sony's 36 Mp sensor FF is going to look like and cost when it finally arrives.

TRY a Sony with EVF and see if it suits. If it does you'll love it. My D700 is a better camera and takes better hi ISO photos - BUT the A77's always View system makes it an integrated photo making system and as such is superior in most cases to "just a camera".

I have not tested effect of EVF on battery life. I can see no reason why it has to be major despite what others said. BUT the exposures per battery under std conditions are available for all good DSLRs - check and see how they compare. The BIG life affector on the A77 is GPS - when it is on the sleep current is high and it is unwise to "walk around all day" with the camera in standby. Other than that I have not noted that the A77 is terrible. The Sony battery used by A700/A77/A99 and some others (NP-FM500H) is 1400-2000 mAh @ 7.2V and substantially larger than some - Sony or others.

I have 5 batteries - 2 original and 5 aftermarket. Aftermarket batteries have lower mAh usually (and claim higher) and may not give as many cycles BUT are much better value/$. I have had no problems with then. They are not a vast cost compared to body, lenses etc. On a very long day I charge on the fly, where possible, either from car 12V charger or mains. Seldom necessary but nice to be safe. DPReview A77 test says 470 shots with EVF, 530 live view (ie LCD) CIPA standard. I probably get more than that when VERY busy.

Again, "Live View" has no meaning for an A77. It is ALWAYS in live view - you just choose to look at EVF or LCD at rear. There is essentially no difference. Sony pellicle mirror cameras have removed the distinction. Buy one! :-).

Hmmm 2 + 5 = 5? / Make that 2 + 3 = 5.

  • \$\begingroup\$ Just a note since you mention aftermarket batteries: I have used cheap aftermarket batteries in my current Sony a200 and they are down to almost no capacity within months, not claiming that all aftermarket batteries are bad. \$\endgroup\$ Aug 30, 2014 at 16:02
  • \$\begingroup\$ @AndreasHartmann - Yes. Quality varies. If buying in my country I ask if there is a warranty - usually there is even on an auction site - but I've had good luck and all have lasted acceptably well. If buying from or in China in small volume its pot luck. I bought a number in Hong Kong (for A200 or A700) and they were all acceptable. \$\endgroup\$ Aug 31, 2014 at 11:40
  • \$\begingroup\$ So I did pick up an A77 and I'm mostly happy. It's a great overall camera, and the EVF is generally decent, the only thing I'm annoyed with is that when it gets too dark, one only sees some noise through it, while with an OVF I could still recognize shapes and small light sources. Thus, it's very difficult to focus on a tree at night for example, as I did try for a long exposure photo. Next time I better bring a maglite for that. \$\endgroup\$ Sep 4, 2014 at 21:08
  • \$\begingroup\$ In Menu item *2 / Live view display/ Setting Effect [on/off] try Off. This MAY help somewhat. When on the EVF tracks WYSIWYG alterations for eg White Balance May help with brightness level. More desperate but useful is to wind exposure compensation up - a max of 5 EVs. THEN store the correct setting to say memory 1 and bright setting to memory 2. Leave LH rotary selector on MR. To change memories rotate selector 1 click one way and back, select one step right or left for desired memory with rear thumbwheel and press selector centre button. Takes very little time indeed once burned into brain. \$\endgroup\$ Sep 5, 2014 at 2:32

SLT is the designation of sony cameras employing a pellicle mirror, an electronic viewfinder as well as a phase-detection autofocus system.

The pellicle mirror causes about one-third of an F-stop's worth of light to get lost to the AF system. This is of course something you don't want, but the gain is a phase detection even when recording movies.

The EVF has both its pros and cons (there is another question about its disadvantages here) and saying that there are just disadvantages with using them compared to an OVF is wrong. One of the problems mentioned in the answers to the question (about the cons of an EVF) linked to above is the frame rate. This answer suggests that the frame rate of the A77 is quite how though.

The SLT camera offers a unique design and their disadvantages are weighted carefully by sone against the very snappy, full time AF system and having no mirror movement or black out while taking a picture. Also, as you see what the sensor records you see the effects of exposure compensation etc in real time, potentially increasing the keeper ratio. If you're an JPEG only shooter you can fiddle around with the settings that affects what is lost in the RAW to JPEG conversion.

  • \$\begingroup\$ The pellicle loss is actually ~= 1/3 of the light but ~= 1/2 of an f stop loss due to logarithmic nature of the calculation. eg 2/3 x 2/3 = 4/9 = 0.444 of original = > 1 stop so 1/3 loss is > 1/2 stop. 1/2 a stop is (1-1/sqrt2) loss = 1-0.7071 =~ 29.3% loss. The difference between 1/2 and 1/3 of a stop is almost indistinguishable to mere mortals. Even a full 1/2 stop loss is relatively minimal as it reflects not in exposure, which is the same with an equal metering in both cases, but in aperture and/or shutter speed used. eg 1/100th of a second would become 1/70th, all else being equal. \$\endgroup\$ Aug 30, 2014 at 11:47
  • \$\begingroup\$ @RussellMcMahon I'm well aware of the logarithmic nature of the f stops. I don't know, however, where you got the 1/3 of the light lost due to the pellicle mirror from. Both the wikipedia article about pellicle mirrors as well as the source I included in the article (that refers to measurements by DxO Labs) states the loss is 1/3 of an f stop. I could very well be 1/2 a stop, perhaps the sources I cited got it wrong. \$\endgroup\$
    – Hugo
    Aug 30, 2014 at 12:08
  • \$\begingroup\$ @RussellMcMahon Of course the light loss from the pellicle mmirror does not give you an underexposed image as long as you compensate for it by other means. i don't think I made the impression that the light loss has a significant impact. Regardless the light loss is not unimportant when comparing an SLT with a camera using a flipping mirror sharing the same sensor, as the latter will always perform better in low light situations. \$\endgroup\$
    – Hugo
    Aug 30, 2014 at 12:17
  • \$\begingroup\$ Hugo - Sorry if I seemed to be criticising - I've had various people misunderstand the 1/3 light vs 1/2 stop claim and thought I'd spell it out so people knew what I was saying. Actual loss is a little hard to come by formally - but here is a site by a man who seems to know his stuff which **measures mirror loss and examines mirror distortion. He says the mirror gives 1/2 f stop and also causes noticeable quality degradation. Examples shown with and without mirror. I've read of someone using plastic wrap as a mirror ... \$\endgroup\$ Aug 30, 2014 at 12:40
  • \$\begingroup\$ .... replacement with, he said, 100% success. \$\endgroup\$ Aug 30, 2014 at 12:41

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