Originally posted by 6BQ5 First : Which body are you using?
Second : The lens sharpens up significantly as the aperture is stopped down. Check out the test data :
Pentax smc FA 31 mm f/1.8 AL review - Image resolution - Lenstip.com
Third : I have had worse luck with CDAF than PDAF on my K-3. Sometimes I feel like the CDAF overshoots the perfect AF point because the screw drive AF motor can't stop in time. After calibrating my lenses on my K-3 I can achieve better focus which occurs at f/1.8. As Ole said above, depth of field at f/1.8 is really thin, even at 31mm, and it's easy to miss focus if the K-3 is powering through the focus range.
Fourth : Make a few portrait shots before you dismiss the FA 31mm Limited and compare the out-of-focus areas between it and the DA 35mm. Compare the colors, contrast, and general rendering. A good test of resolution is photographing something dusty. Dust is very fine and small. Many camera sensors and lenses together have a hard time resolving details as small as that.
I'm using the K-3 which seems to be working fine and is consistent with my other lenses. I think i will need to do more tripod and real world tests again today to compare both, as if the 31 is sharper and more consistent I will keep it. I think the mis-focus point is what is bugging me, though in manual mode it's all of course perfectly fine. I 'm able to get it to AF on close subjects fine, but as the distance expands it gets worse. I may need to check my calibration again as I'll move from -6 to -2 depending on subject distance.
I've taken many portrait shots of my dog, and this is where the FA 31 has been failing me unless I shoot at 2.2+ my DA 70 and FA 43 are just fantastic here, but at 1.8 this lens just misses focus to easily I think without some further calibration. I will keep trying again as I feel that it should be fine, and I a mover analyzing, but since I have an option to return it and get something else I and scrutinizing it more. I will have to find someone other than my dog to pose for me. I have a husky and his hair is very fine and many cameras and lenses will easily blend his fur into a white blob instead of the fine -grained hairs which is why I like to photograph him. I'll post some samples later.
---------- Post added 06-04-15 at 01:40 PM ----------
Originally posted by DeadJohn The Sigma 10-20 might fill your indoor low-light requirement. Wide angles are more forgiving of camera shake as long as you don't crop heavily. Shake Reduction + slow shutter + high ISO might be adequate for your low light photos.
I agree, it might be ok but I feel the 20 mm is too wide for me a bit. I just don't shoot at that FL as often but can if I need to. Honestly, the lens is having a AF motor issue and I would get it fixed but I don't think I can get the lens repaired before m trip. I'm going to shoot it in manual mode or use the AF if I can, works half the time.
---------- Post added 06-04-15 at 01:45 PM ----------
Originally posted by seventysixersfan Thank you for the feedback on your experiences/opinion of the lens. I have thought a lot about getting the FA 31 to replace my FA 35 but I am doubtful that the benefits gained will be worth the huge cost.
I have the DA 20-40 and it's an excellent performer. I usually shoot at the wide end (20mm) when I'm indoors, in order to get the f/2.8 aperture. The lens handles beautifully and I'm very pleased with the sharpness of the images.
If the lens was $600, I would keep it without thought and it would justify the higher price. Maybe even $800 at the most. I paid $996 over the weekend sale and it's around that price at some retailer still. I've heard very good things about the 20-40, and I'm tempted to purchase it as well. It would fit well where I want a flexible prime but not the full 18-135 range and need a little better low light performance. Otherwise the 18-135 is a marvelous lens. I never used it much before but once I really started to use it and see how it should be used, it's truly a amazing lens and has made compromises where they make the most sense.
---------- Post added 06-04-15 at 01:47 PM ----------
Originally posted by savoche I don't think your 31 sounds very different from mine. That said, I prefer the results from the 31 over the 35. I prefer the size of the 35, though. And is the difference worth $800? Well, if you have the money...
I still like the 43 more, but as you say it's a tad long indoors. I like the DA21 a lot for use inside. Not blazingly fast, but 3.2 is just half a stop slower than the 2.8 of the 20-40.
Another good option is an F/FA28 if the 35 should be too long and the 21 doesn't fit the bill.
Or the FA*24/2, maybe?
Oh don't give me more lens choices! I may end up with the FA 31, FA 77, 20-40, and keep the HD 70 and 35 DAL. I guess it's only money in the end....