[Jinnax]

I do believe this is my first post, so hello!

I've got an opportunity to get a Pentax-K 55mm F1.8 or a Pentax-A 50mm 1.7 - but I can't get both without buying a whole film package of legacy stuff that would be mostly dupes of my existing equipment.

I just got back into more serious photography via my new K-50 and a couple of survivors from my 35mm SLR days. My 50mm Pentax-M F2 seems quite nice as it is, but the forum here suggests one of the best 50s of them all was the Pentax-A F1.7. However, the reviews of the older Pentax-K 55mm F1.8 suggest it is also a very nice & sharp lens. I've read the -A's were largely well built, but perhaps not as well as the -M's or -K's. I haven't seen that there's any kind of pecking order, as in -M > -A > -K etc ... is there a decided difference? It seems the 50mm 1.7 A's are more common than the 55mm K is, but I haven't been around here long enough to find out.

Old hands, please feel free to point out the obvious to me.

And hi again!

[boriscleto]

If you intend to use the aperture ring, get the K. If want the body to set the aperture get the A. The A 50/1.7 is well known for it's poor aperture ring that often breaks in use. If it is left set on the A position it is not a problem.

[northcoastgreg]

The advantage of the A 50 1.7 is that it is compatible with all the automated exposure modes on Pentax cameras (and p-TTL flash and matrix metering). With the K 55 1.8, you'll have to shoot in manual, using the green button for setting exposure.

Even so, I would personally take the K 55 1.8, as I shoot in manual most of the time in any case. But you can't really go wrong with either. They're both well built lenses featuring excellent optical quality. Just pick the one that best fits your shooting style.

[TER-OR]

Yes, the A will be more convenient for your use. You'll just need to manually focus. The camera will be able to meter on its own, so that's nice.

[mattt]

A is plasticky compared to the K.

[pepperberry farm]

I have the A 50mm f1.7 - and the aperture ring is finicky... thankfully, I just leave it on 'A' and don't worry about...

I have bumped it occasionally when putting the lense on the camera, and then just have to wriggle the ring back to 'A'....

but the pictures it takes! worth the wriggling.....

[Jinnax]

The A 50/1.7 is well known for it's poor aperture ring that often breaks in use. If it is left set on the A position it is not a problem.

Yes, I'd noticed that in the Lens Reviews section, and even a nice Guide thread to CLA-ing the aperture ring for that particular lens. Since that was the first thing you mentioned about it, it's making me lean more to the 55.

Just pick the one that best fits your shooting style.

The meter in my K-50 seems competent, and I'm noticing much better results a) shooting in manual and b) shooting with primes. I like the complete control that manual metering and focusing provide so Manual it is. My reason for also leaning to the 55mm K is ... I don't already have one. That's the start of this LBA thing, isn't it? ;-)

[monochrome]

In my opinion the K is better built and has a more sublime feel to the focusing helicoid on a good copy; is probably sharper wide open but the difference isn't really distinguishable in practice (especialy from f/2 on); and renders somewhat warmer than the A due to coating distinctions.

The A is generally thought to have more flare resistance (again due to coatings differences); as well as a rumored tweak to the lens formula from the 'M' version; and, of course, has the great benefit of automatic (if imperfect) open-aperture metering in the 'A' position and eDial aperture control on the camera body.

The 'A' deal-breaker for me (aside from my K lens fetish) is the cheap aperture click detent assembly, which is a plastic spot weld that breaks easily. Not a challenging repair, but at the prices of these lenses it can be more than the lens cost to buy.

Your preference which combination of strengths and weaknesses is more suitable for your style.

[johnyates]

I once owned both and decided to sell one. I did some testing to compare them to help in my decision making. I ended up keeping the K55 as it was a teeny tiny little bit sharper towards the edges of the frame. Both really good lenses otherwise.

[gofour3]

Get the K55/1.8, it will last a lifetime with no aperture ring issues like on the A50/1.7. The K55/1.8 is also a bit bigger and easier to manually focus.

Phil.

[TedW]

I have them both and they are both excellent. The K55 is probably a bit sharper on the edges but I love the way the A 1.7 renders. If could only keep one it would probably be the A50 1.7.

[jjdgti]

I do believe this is my first post, so hello!

I've got an opportunity to get a Pentax-K 55mm F1.8 or a Pentax-A 50mm 1.7 - but I can't get both without buying a whole film package of legacy stuff that would be mostly dupes of my existing equipment.

I just got back into more serious photography via my new K-50 and a couple of survivors from my 35mm SLR days. My 50mm Pentax-M F2 seems quite nice as it is, but the forum here suggests one of the best 50s of them all was the Pentax-A F1.7. However, the reviews of the older Pentax-K 55mm F1.8 suggest it is also a very nice & sharp lens. I've read the -A's were largely well built, but perhaps not as well as the -M's or -K's. I haven't seen that there's any kind of pecking order, as in -M > -A > -K etc ... is there a decided difference? It seems the 50mm 1.7 A's are more common than the 55mm K is, but I haven't been around here long enough to find out.

Old hands, please feel free to point out the obvious to me.

And hi again!

I had both, each are great in its own way. I sold them because I no longer able to use manual lenses due to my eyes condition.

I would get/keep the k 55mm 1.8. The build construction is excellent. As other member said, it will last a lifetime. It is more rare and difficult to find.

Tha A 50mm 1.7 is more common in case later on you want to get it.

This is my humble opinion.

[Jinnax]

Thanks to everyone, great information especially from those with anecdotal experience with those exact lenses. I'm going with the K-55mm as most suggested - there's plenty of 50A's in the sea! I believe the future holds a place for a F1.7 50mm, just not right now.

Although....

Maybe I should mention the whole deal instead:

KX 35mm body with orig manual, the F1.7 50 and the F1.8 55, a Pentax-A 70-210 F4, and a Hanimex/Hanimar 80-200 F4, about a dozen 49 & 52mm filters (1A, CPL, and UV), Chinon 2x Teleconvertor, a closeup kit and few odds and sods. CAD $200 (under $160 US).

I don't need either zoom; I have a DA 50-200mm that I think is marvelous, and I have no plans to return to film. Seen on resale terms it's a good deal, esp the A zoom, but I prefer to get more into photography and less into selling lenses.

[RMabo]

Many of the A-lenses are optical the same as the M-lenses, just with the added benefit of electronic aperture so they can be used in all the auto and semi-auto modes on a Pentax SLR and DSLR - even multisegment metering works with aperture ring set at 'A'. K-series has a simpler coating formula (less resistant to flare), but optically they were very good - if a bit large compared to the M's and A's. A few M's got new optics when they were made in an A-version. Oh, and many of the F had the same optics as the A, and many of the FA were simply re-designed F's...

[pepperberry farm]

Thanks to everyone, great information especially from those with anecdotal experience with those exact lenses. I'm going with the K-55mm as most suggested - there's plenty of 50A's in the sea! I believe the future holds a place for a F1.7 50mm, just not right now.

Although....

Maybe I should mention the whole deal instead:

KX 35mm body with orig manual, the F1.7 50 and the F1.8 55, a Pentax-A 70-210 F4, and a Hanimex/Hanimar 80-200 F4, about a dozen 49 & 52mm filters (1A, CPL, and UV), Chinon 2x Teleconvertor, a closeup kit and few odds and sods. CAD $200 (under $160 US).

I don't need either zoom; I have a DA 50-200mm that I think is marvelous, and I have no plans to return to film. Seen on resale terms it's a good deal, esp the A zoom, but I prefer to get more into photography and less into selling lenses.

I have an A 70-210mm f4 lense and it takes very nice pictures, especially compared to the DA50-200

it is a manual focus/zoom lense, and is a single touch lense and that can take a little to get used to, but it renders colors amazingly well....