I didn't want to start a new thread, so this one looked to be the best to add my comments and tests.
I have the DA 50 f1.8. I don't have any other autofocus 50mm, but I do have an A50 f1.7 and M50 f1.7. I've done a bunch of testing. First, my methods:
- I've tried a number of different settings: adequately lighted scene, low-light interior, full light exteriors.
- I used tripod with timed release.
- For comparisons, I set ISO and shutter speed. I let the DA and A figure out their own exposure and used green button for the M.
- When trying to get the best shots w/ the A/M50s on my K-30, I used both the viewfinder indicator and the liveview with focus peaking and took the best result. The focus peaking consistently provided the better focused shots for me. In general, the A50 and M50 differences were more related to my accuracy of focus than anything. So, what goes for the A50 goes for the M50. (Very generally, the A tended to underexpose on its own and the M tended to overexpose using green button. I've made notes to myself to adjust when shooting.)
My conclusions:
- Build: The M50 f1.7 is my favorite lens in terms of engineering aesthetics. It is just a solid, beautiful, smooth piece of equipment. The A50 f1.7 is not far behind, but mine is just a bit 'looser' compared to the M50. The DA is light but tight. Yes, it doesn't have the heft of the M/A 50s, but its lightweight can be a good thing. It is more plastic, but it definitely is quality. I don't worry about the plastic mount. (Quick shift on the DA would be nice though.)
- The DA 50 f1.8 is really an excellent lens. At f1.8, I was getting sharper pics than the A/M at f1.7 and much less chromatic aberration.
- Chromatic aberration: The DA had the least wide open and mostly gone by 2.8. The A/M decreased from 1.7 > 2.8 and mostly gone by f4.
- Sharpness and f-stop: For all the lenses, there was a good jump in sharpness from open > 2.8 some improvement > 4 > slight improvement > 5.6 - 8 > slight decrease > f 11. Going to f16, the DA had a minor decrease but there was a noticeable decrease with the A/M.
- That is: they were all best at f5.6-8. Depending on focus accuracy, I could get mixed results, but the DA was best in most circumstances and very close in all others. At wide open where it can be hard to focus due to DOF, the DA's autofocus did a better job than I could manually with A/M.
- Sharpness across frame: In general, the DA consistently did better across the frame.
- Color / Contrast: This is related to exposure, and there was more inconsistency w/ the A/M in terms of exposure getting set correctly. Even when A/M exposure was right, the DA consistently did as well as better. Very nice Pentax color and great contrast.
- BUT: The one situation where the DA suffered a bit was in low light. I didn't notice that it was particularly slow, but it just had trouble getting the focus as well as I could do manually with the A/M. In low light settings, I'll try using manual focus with the DA.
OVERALL: I am really pleased with the excellence of the DA 50 f1.8. For getting photos at 50mm, there really is no reason to use anything other than the DA 50.
Ok, that last sentence makes me a little sad, since I so like the M50 f1.7. (So, no, for now I will not be selling the A/M 50 f1.7!)
Additionally, I compared the DA 50 with some zooms I have in the 50mm range, namely the F35-70, DA 18-135, and Tamron 24-135.
None of them were as good as the DA50, but the F35-70 came close. The Tamron 24-135 was also remarkably good. The 18-135 lagged behind a bit. If I'm not worried about top-rate sharpness, the 18-135 is still my primary lens due to its versatility and WR.
Originally posted by audiobomber 
Post #7 by johnnie518
Similar Threads 
