[pentax_amateur]

I would like to get a fast lens for my KP for those situations when it is getting dark, but I am still having am urge to continue shooting without a tripod. I am considering the two lenses above. I like the FA 50/1.4 better because it is faster, but I am eager to learn what others think. I am totally open to other suggestions. The requirements are a fast lens in 24-60mm range, autofocus only.

[reduno]

I don't know if you looked at the Pentax Forums 50mm prime shootout, which covered both of these models:
Pentax 50mm Prime Lens Shootout Review - Introduction | PentaxForums.com Reviews
There is also a separate in depth review of the FA 50mm F1.4:
https://www.pentaxforums.com/reviews/smc-pentax-fa-50mm-f14/introduction.html

[pentax_amateur]

Thanks a lot for the link to the comparison! It basically concludes that the three lenses are about the same

[pepperberry farm]

I would add a third lens for your consideration: a good, used DA* 55mm f1.4...

[pentax_amateur]

I would add a third lens for your consideration: a good, used DA* 55mm f1.4...

I have doubt this is a great lens, but the price is getting a little out of control I would like to keep it in the $250 budget for a used lens.

[ramseybuckeye]

Don’t forget the F 50 1.7, it can be found for considerably less.

[aslyfox]

lots of good choices for the " 50ish " Pentax

26 results 43mm - 55mm

https://www.pentaxforums.com/lenssearch/?minfl=41&maxfl=59&type=Prime&inproduction=0

be sure to check out the marketplace

it can be sorted by country

https://www.pentaxforums.com/forums/24-photographic-equipment-sale/?security...d+States&all=1

[Gerbermiester]

I've owned the da 50mm 1.8, the F 50mm 1.7, and the FA 50mm 1.4. I've also tried out a Da* 55mm 1.4 at my local camera store.


On Aps-c, the Da 50mm 1.8 is my favorite. It's light, well made, sharp wide open, has low ca, and pleasant bokeh. On full frame, I found the extreme edges to get very mushy and fairly dark unless stopped down until around 2.8 or so. Similarly, unless stopped down to around 2.8, the vignetting can be more prominent on one side or the other, if shake reduction is active. This makes fixing vignetting in post slightly more tedious.

On full frame, my favorite is the FA 50mm 1.4. In my experience it's not as sharp wide open and suffers from worse CA, but given the larger sensor size of FF, the CA is not as noticeable as it is when this lens is mounted to an Aps-c body. (Either way, CA is corrected easily in body or on your preferred editing programme). I generally treat this lens as a f/2 lens, rarely opening it up all the way. It performs beautifully at that aperture.

As for the F 50mm 1.7, I never fell in love. It's very sharp, but I find the bokeh to be the harshest of the three mentioned. The CA is also the poorest, at least in my samples.

The Da* seems to perform a lot like the FA 50 1.4, though l have admittedly had limited experience. The copy I was looking at had rather sleepy AF response, needing a few taps on the AF button to make it start focusing. I suspect the SDM motor was on the fritz.

That's been my experience in a nut shell, I hope it's been helpful to you.
In the end, each of the 50's are more than capable of capturing stunning images when placed in the right hands.

[hcc]

You already some good advice. I will share my own experience on fast primes.

I have three fast primes: Pentax FA50mm f1.7, Pentax A50mm f1.2 and Voigtlander Nokton 58mm f1.14. The first is AF and the other two are AF. All are FF.

The FA50mm f1.7 is sharp. Small. The A50mm f1.2 is fast. Solid construction. The VL58mm is fast, great IQ, all metal and very solid. Honestly, I do like the outputs from the FA50mm f1.7. The A50mm f1.2 is OK, but the IQ of the VL58mm f1.4 is mind-blowing. The other two lenses compare poorly because of the superb image quality of the VL58mm. I wrote more on the VL58mm at : FA31mm f1.8 vs VL Nokton 58mm f1.4 - PentaxForums.com.


I have also the FA31mm f1.8. A great Lens with outstanding IQ, but I would not qualify it as a fast prime IMHO,

Hope that the comment may help.

[Cerebum]

I bought the DA 50mm f1.8 and it is excellent, especially for the price. Have a look at MPB. When I got mine there was a DA f1.8 for £40 and an fa f1.4 for £114 serious bargains with warranty

[savoche]

I like the FA 50/1.4 better

If f/1.4 is what you want, then you should buy an f/1.4. If you buy the f/1.8 you will still want the f/1.4 and probably end up byuing both in the end.

That said, I don't think there is much practical difference between the two. Half a stop can let you get away with ISO 1600 rather than ISO 2500, true, but the depth of field will also be narrower and focusing will be easier to miss.

[pschlute]

I would like to get a fast lens for my KP for those situations when it is getting dark, but I am still having am urge to continue shooting without a tripod.

Just remember a fast lens has a very narrow depth of field at wide open apertures. While hand-holding with a fast lens may give you the "exposure" you want, it may not give you the "picture" you want. Fill-flash and tripods are options to consider, as may be upgrading your processing software and using higher ISO.

[Kwong]

I have doubt this is a great lens, but the price is getting a little out of control I would like to keep it in the $250 budget for a used lens.

Another consideration may be the Sigma EX 50 f1.4. They show up used time to time in your budget range.

[JensE]

Between the two in the original request, I would choose the DA 50/1.8 on APS-C, irrespective of price differences. I kept the F50/1.7, which is virtually identical except for the aperture blades, because of use on the K-1. Due to better contrast wide open, the AF precision with the DA is better, especially in low contrast situations, than with the FA50/1.4. The FA50/1.4 reaches 1.4 only with compromises and up to f/2.0, the DA50 will render cleaner and sharper. Bokeh depends on the subject, distance and aperture - the DA's round blades render smoother highlights, overall the FA'c optics may be a bit less 'busy' in the background. My DA50's focus ring was a lot better than my FA50/1.4's. Despite being made of plastic, it felt rather smooth and well damped - no play, no scratching.

[pres589]

Based on my personal experience with the DA 50 1.8, M 50 1.4 (supposed to be same optics as the FA 50 1.4 but take large grains of salt with that), F 50 1.7, and M 50 1.7 I would suggest the DA 50 1.8 or step up a class to the DA*55 or perhaps a used copy of the Sigma 50mm f1.4 EX DG (no direct experience with either, both seem quite good from reviews and samples). The differences in these lenses are just too hard for me to see to justify spending 2x as much and I agree that the F 50 1.7's out of focus rendering can seem a bit harsh where the DA 50's is not. Oddly I do not see that sort of behavior with the M 50 1.7 which is my favorite out of all of the lenses listed (but it is manual focus and I don't like that much on my digital Pentax camera).