[Boydmaine]

Is there any advantage to using an FA lens on an APS-C body so far as image quality is concerned?
Thanks

[timw4mail]

Not really.

If the lens has really soft edges those are 'cropped' away, but that doesn't really lead to increased image quality.

[normhead]

Is there any advantage to using an FA lens on an APS-C body so far as image quality is concerned?
Thanks

Only the extra reach you get using a long lens on a K-3. Otherwise, it's just a smaller image. Even that is misleading as opposed to film. In film every image was enlarged meaning the smaller image had less resolution and larger grain. In digital 99 % of the image taken are reduced from their native size to a smaller size. Less reduction is not the same as more enlargement. Most images are identical in most practical applications. The inner part of the projected image circle does tend to be the sharpest part of the image and some have suggested that the edges will be better, but that's something I've never seen in the field.

The biggest drawback to FA lenses on APS-c is the odd focal lengths. I love my FA 35-80 cheap and plastic feeling as it is, but on APS_c it's just a weird focal length. On FF it's a nice walk around lens.

My advice would be, if you have it use it.

[pathdoc]

Slap it on and shoot with it. Don't fret.

The big advantage to having FA lenses is if you buy a K-1 down the road or start dabbling in film cameras. Then the FA lenses will practically all work at a pinch on any K-mount camera (except for the FA-J series because they didn't have aperture rings), though they are not optimised for manual focus and some are actually pretty bad at it (e.g. FA28-90 3.5-5.6). But few are so bad that they will actually turn out awful pictures in and of themselves, and it depends at the end of the day what the pictures are actually for. I wouldn't bring my FA28-90 to a serious event on my K-1, for example, but for Facebook and happy snaps it's just fine.

[Na Horuk]

A good lens is a good lens, and a bad lens is a bad lens. FA or DA doesn't mean much.
It can only be a problem if you try using a lens for a larger format, like using an APSC lens on FF might give you poor quality edges, or even completely black edges.

[normhead]

except for the FA-J series because they didn't have aperture rings

Thats' not an issue on digital. My FA-J 18-35 isn't a great lens, any 18-xx lens is going to be better. But it works on all of them for test shots, where it inevitably proves to be inferior to anything else. But it works fine on a K-1. Fine as in OK but not exceptional.

[pathdoc]

Thats' not an issue on digital.

Yeah, I know - that caveat was intended to be in regard to film bodies only. From time to time I've considered picking up an FA-J-18-35 to have that ultra-wide option on full frame in an AF lens, but I anticipate that 99% of what I'm going to use a lens that wide for on full frame is going to be carefully chosen and deliberately shot, and I have a 17/3.5 Tokina for that. Hardly used, not all that usable in a fairly flat rural environment I don't get out much in (would be wonderful in big city back alleys), but occasionally I have a shot that needs taking for which nothing else I have will do. The same goes for the DA15 on my APS-C cameras, oddly enough - I took it on my most recent holiday because there was ONE thing I took my kids to where I knew it was the only conceivable option - and it shone brilliantly.

[photoptimist]

As others have mentioned, FA on APS-C does offer a minor advantage of more uniform sharpness and less vignetting by avoiding the corners of the FA lens.

One minor disadvantage of FA on APS-C is flare. The large image circle of an FA lens pulls in a lot of extra light from the scene that does not fall on the sensor but just bounces around inside the mirror box and contributes to a bit of fogging of the shadows. And sometimes you might get serious flare from the sun or other light source in which those bright lights aren't in the APS-C frame but they are in the FF frame.

But it's a minor disadvantage because it's easy to fix with the right lens hood.

[climit]

No specific advantage, just that there are two good FA lenses, the FA 35/2 and 50/1.7 and the limiteds. But the DA 35 and 50 have come to replace them on aps-c.

[normhead]

One minor disadvantage of FA on APS-C is flare

If flare isn't a problem on an FF sensor, why would it be a problem on an APS-c lens, or are you saying there are more problems with flare on FF lenses?

[stevebrot]

Put it on and forget about it...simple as that.

I have two crop-format lenses and shoot freely with a few dozen more FF lenses on my K-3 and confidently report that the extra image circle with the FF lenses is not a handicap.


Steve

[photoptimist]

If flare isn't a problem on an FF sensor, why would it be a problem on an APS-c lens, or are you saying there are more problems with flare on FF lenses?

Flare from an FA on FF can be a problem although that doesn't seem to be the OP's question.

Boydmaine seemed to be asking about FA on APS-C versus DA on APS-C. I've noticed on the K-10D and K-5 that lenses such as the Sigma 12-24 DG and the Pentax 28/3.5 shift lens can be very prone to colored flare bubbles from sunlight that comes from outside of the APS-C frame (that is, one does not realize the sun in shining into the lens from the viewfinder) but the sun is inside the image circles of those lenses. Any dust inside or on the lens elements as well as imperfect blacking of rings and spacers inside a lens will scatter light. An FA lens admits more total light to cover the larger image circle so it is likely to have more internal scattering unless one puts a good hood that is sized for the APS-C image circle. And if one can get a petal hood, that's even better.

[stevebrot]

No specific advantage, just that there are two good FA lenses, the FA 35/2 and 50/1.7 and the limiteds. But the DA 35 and 50 have come to replace them on aps-c.

Hmmmm...That is a pretty brash statement. I own the FA 35/2 and have never shot with the DA 35/2.4 or DA 35/2.8 Limited, so I can't comment beyond saying that the the owners of both DA versions seem pretty happy. I have not heard of anyone replacing their FA 35/2 with either DA lens.

I also own several examples from the 50/1.7 lineage (all from M through FA series share the same optical formula) as well as the DA 50/1.8. (I assume that is the "50" you are referring to.) The DA 50/1.8 is a very decent lens and the value queen at its current price point. However, given the choice between an FA 50/1.7 and DA 50/1.8 for the same money*, I can only think of one reason to go with the DA 50/1.8; that being that it has a much nicer focus ring. I strongly prefer the optical behavior of the older design.** Again, I have not heard of anyone replacing their FA 50/1.7 with the DA 50/1.8. I do know of at least one PF user who replaced their DA 50/1.8 with the FA 50/1.7 for use on APS-C (@dcpropilot).

there are two good FA lenses, the FA 35/2 and 50/1.7 and the limiteds

Those two lenses (and the Limiteds) aside, there are few other FA-series lenses that are highly regarded and might be considered "good":

• FA 20/2.8
• FA* 24/2
• FA 100/2.8 Macro
• FA* 200/2.8
• FA* 200/4
• FA* 300/2.8
• FA* 300/4.5
• FA* 400/5.6
• FA* 600/4
• FA 20-34/4
• FA* 28-70/2.8
• FA* 80-200/2.8
• FA* 250-600/5.6

Steve

* The FA 50/1.7 is sort of a cult classic and usually demands a fairly high price.

** A full discussion would require many words. While I enjoy shooting with my copy of the DA 50/1.8, I have found that it imparts a "glow" (no, not flare) at wider apertures that tempers my enthusiasm for the lens.

[luftfluss]

I do know of at least one PF user who replaced their DA 50/1.8 with the FA 50/1.7 for use on APS-C (@dcpropilot).

In similar vein, I returned my DA 50/1.8 in favor of my F 50/1.7 because I preferred the F's OOF rendering (except for rounded highlights) and color signature.

[hcc]

A good lens is a good lens, and a bad lens is a bad lens.

+1. Most definitely.