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.
- 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.