[PenPusher]

What has always puzzled me is the difference between FA series Primes and Zooms.

Nearly every prime is well regarded and some are thought of as having the best optics Pentax have ever produced with a few well know models still in production.

There is an equally wide range of zooms but with a few exceptions most have very low optical ratings.

I am well aware that designing a zoom is nowhere as straightforward as designing a prime but went wrong ?

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Last edited by PenPusher; 06-16-2020 at 02:05 AM. Reason: spelling

[Alex645]

Nearly every prime is well regarded and some are thought of as having the best optics Pentax have ever produced with a few well know models still in production.
I am well aware that designing a zoom is nowhere as straightforward as designing a prime but went wrong ?

It always comes down to 'Jack of all trades; master of none'. Optical designers given the task to optimize one focal length are given a much simpler task than an optical engineer trying to get 3x optical zoom as good as any prime. In general, you'll see the 2x zooms like the Pentax 20-40mm have better results vs. something like an 18-300mm zoom.

If a zoom were optically superior other than convenience, primes would be extinct. And it's not just resolution, but also distortion, chromatic aberration, vignetting, transmission, speed, and size/weight.

Or am I misunderstanding your question?

[Serkevan]

What has always puzzled me is the difference between FA series Primes and Zooms.

Nearly every prime is well regarded and some are thought of as having the best optics Pentax have ever produced with a few well know models still in production.

There is an equally wide range of zooms but with a few exceptions most have very low optical ratings.

I am well aware that designing a zoom is nowhere as straightforward as designing a prime but went wrong ?

Most of the FA primes are Star, Limited, or very "efficient" designs like the 50mm designs that had been excellent for decades.
Most of the FA zooms are cheap consumer level stuff - and it shows. The FA* 28-70 and 80-200 f/2.8 zooms are very good lenses so I really think it's an issue of Pentax deciding that entry-level photographers would only pay for cheap zooms, and that more discerning customers would either use primes or go for the monstrous zooms; no real "light but still good" option for, say, hikers

[Jonathan Mac]

A lot of the FA zooms were built to be really cheap, so it's no surprise that they're not the best quality. The corresponding camera series is the MZ - lightweight and almost entirely plastic with a design/build fault across the entire range that makes them very prone to failure.

I think Pentax mainly thought that pros would stick with primes and the zooms were for for amateurs who didn't demand too much. That whole time was a race to the bottom price-wise, and quality was very much secondary. You can feel it in the gear.

[RICHARD L.]

FA 20 mm f/2.8

FA 28 mm f/2.8

FA 35 mm f/2

FA 50 mm f/1.4

FA* 300 mm f/4.5

I have the FA* 28-70 mm f/2.8 and FA* 80-200 mm f/2.8 zooms. Both are very good performing lenses and their weight indicates a choice of quality, durable materials. I also had an FA 80-320 mm that was "so-so" and that died on me last winter (easily replaced without a huge heartbreak) and I still use an FA 20-35 mm f/4 which is quite good on APS-C.

OTOH, I have a quartet of fixed FA lenses (FA 20 mm f/2.8, FA 28 mm f/2.8, FA 35 mm f/2 and FA 50 mm f/1.4) that I wouldn't exchange for anything else. I also use an FA* 300 mm f/4.5 with great succes.

Regards

I think that the negative remarks about zooms are a bit "racist". Especially from people that talk about primes being superior. Ever since the zoom was introduced zoomlenses were thought of being inferior. They are not. They may be different. And yes there are some (Pentax) zooms that show a cheap build, but not all of them show a cheap IQ. But if I look at those lenses they were mostly from the time that Pentax decided to have lenses produced outside Japan. If I read about decentered Limited or * lenses, than I think that you pay a lot of money for a "cheaply" build lens (where the quality control is left to the customer instead of the manufacturer). I agree there are some bad zooms, but there are also bad primes. If you really want, you can always find fault with any lens (or camera). But zooms are very convenient and if it was true that the quality is sub par, then the zooms would already have perished. That is why, as you will notice if you look at Ricoh/Pentax's lens roadmap, there are more zooms being produced and introduced than primes. Old primes get an update from SMC to HD. Development of zooms is still going on whereas with most primes the old recipe is still followed so there is actually no need for R&D but still you pay a lot for such a prime that has seen little or no modernisation except for a new coating. It is also a complaint from some users of this forum that there is a shortage of primes in the collection that Pentax offers and that some limited primes like the 31mm and 77mm are the same as in the film era and that have seen little modernisation to adjust to the digital era.

[zapp]

Basically all FA glass is old and outdated. Primes were more mature at the time, zoom designs have a lot more trouble to compete against today’s glass.
There is more to a lens than simple ratings. Size, weight, image drawing capabilities... define the price and the value.

[northcoastgreg]

The main issues with the non-star FA zooms are (1) they tend not to be all that sharp wide-open; (2) they suffer from inconsistent performance through entire zoom range; (3) they don't feature as good anti-reflective coating technology as modern glass (i.e., HD coatings are the real deal, especially for zooms). But if you take some of the FA zooms, especially the mid-range offerings (FA 20-35, FA 24-90, FA 80-320), and you stop the lenses down they can very impressive. The problem is a lot of photographers buy these lenses and use them at their worst focal lengths and apertures and then complain about how bad they are. The FA 80-320 is a bad lens wide open at 320mm, but it's a great lens between 80mm and 135mm stopped down a bit. Alas, very few photographers use this lens where it's at its best and therefore have no idea how good it can be.

[house]

The main issues with the non-star FA zooms are (1) they tend not to be all that sharp wide-open; (2) they suffer from inconsistent performance through entire zoom range; (3) they don't feature as good anti-reflective coating technology as modern glass

Those are all true for the primes as well wouldn't you say? Alright perhaps not no 2

[ChristianRock]

Primes are much easier to design so we have had great prime lenses for decades now.

In the days of FA lenses, zooms were not a new thing, but today we've come a long way since. Back in the FA days, special glass like ED (Extra low dispersion) SD (Super low dispersion), and asphericals were expensive to make so only premium lenses would have them like the FA*28-70mm f/2.8, for example. Consumer lenses didn't have any special glass while today they do - even the older DA 55-300mm f/4-5.8 has a bunch of ED and aspherical elements in it, and most lenses have now at least one aspherical element. Once they started making the cheaper hybrid asphericals they started putting them on everything... but bokeh is still best if you have less of those special elements, usually, so that's one aspect of the appeal of older lenses.

[CarlJF]

Primes are much easier to design so we have had great prime lenses for decades now.

In the days of FA lenses, zooms were not a new thing, but today we've come a long way since. Back in the FA days, special glass like ED (Extra low dispersion) SD (Super low dispersion), and asphericals were expensive to make so only premium lenses would have them like the FA*28-70mm f/2.8, for example. Consumer lenses didn't have any special glass while today they do - even the older DA 55-300mm f/4-5.8 has a bunch of ED and aspherical elements in it, and most lenses have now at least one aspherical element. Once they started making the cheaper hybrid asphericals they started putting them on everything... but bokeh is still best if you have less of those special elements, usually, so that's one aspect of the appeal of older lenses.

This!

Prime lenses designs have been optimized many decades ago. Today, they mainly benefit from new manufacturing technologies but optically aren't much differents than decades old primes. On the other hand, zoom designs have improved tremendously since the FA days. So, an older prime lens could still hold very well optically when compared to a modern one, but most zoom lenses will not, their modern equivalents being way better.

[btnapa]

There is an equally wide range of zooms but with a few exceptions most have very low optical ratings.

I'll take zooms for overall convenience albeit at the expense of some image quality. In a totally non scientific test I did, I shot the same subject on a K3 with my Tamron 70-200 f2.8 and my FA Limited 77. Both lenses were set at f4. The center sharpness was equal but in the corners, Tamron zoom was noticeably sharper. To this they I cannot figure why. The FA Limited is a sublime lens but on that particular day the Tamron beat the mighty FA77 in the corners!!

Zooms are not what they used to be. I am old enough to remember terrible zooms we had back in the early 80's. It is not the same anymore in 2020. In my experience, pro class zooms can match or come very close to matching primes. When you consider the flexibility of a zoom vs. a prime lens, the zoom wins in most situations.

[normhead]

There is an equally wide range of zooms but with a few exceptions most have very low optical ratings.

Look at the original cost of the lens the tells you everything you need to know.

At one point Pentax was the same as everyone else. They made really cheap low end gear to draw people to the brand, and enough high end gear to satisfy people who wanted more. They don't make as much cheaper stuff these days.

In fact looking at the DFA lenses and recent releases, in Canadian dollars, they aren't designing and manufacturing anything under $1500 these days. That is departure from standard FA glass.

[vector]

Roger Cicala at Lensrentals.com has been testing all kinds of things lately and he has a great post about this that demonstrates the multiple personalities of zoom lenses at different focal lengths. They really are a mixed bag of tradeoffs vs even budget prime lenses.

Lens Rentals | Blog

[normhead]

Roger Cicala at Lensrentals.com has been testing all kinds of things lately and he has a great post about this that demonstrates the multiple personalities of zoom lenses at different focal lengths. They really are a mixed bag of tradeoffs vs even budget prime lenses.

Lens Rentals | Blog

Seriously?

That's because zooms have an infinite number of "bags." Primes have only one.
There is simply no lens made you don't have to get to know. But the pay off in zooms is when you do that you have many different shooting possibilities, more with one zoom than with camera a bag of 10 primes.

If you have a DA*18-135, you may not like it at 135mm... but you may find it acceptable from 20mm to 45mm. At least you have something. I bought the cheap 35 2.4 and don't like it. I got nothing for my money. At least with my 18-135 I got a walk around lens I love to use that's stellar at some focal lengths.

This can be spun more than one way.


SO I ask you, which is the preferable mixed bag? A range of 20-45 that's excellent in many categories... or a 35 prime that's excellent in one category, that you don't like?

Not only that Roger's post doesn't refer to "primes vs zooms".
It refers to "bargain primes vs bargain zooms."
I've taken comparison images with my DA* 60-250 against the DA*200 and Tamron 90. The DA*60-250 images hold up very well, at every focal length. When you get into quality zooms, the whole article is not relevant.

Even if only one area of zooms is prime quality, it still gives you more than a prime does in the big picture.

And for lenses like the 18-135.... not only does it give you prime quality through good range, it gives you access to things like 29mm, 32mm, 33mm 34mm 36mm etc that aren't even available in primes.

Bottom line, zooms should be your work horses, primes for when you have total control of the situation, as in studio or in the case of birders, where any zoom you can get will be too short or too slow, and you're going to crop extensively in any case.

Zooms vs primes is another one of those black holes people more intelligent than me avoid.

Every lens deserves it's own evaluation. Prime vs zoom has nothing to do with that.

There are great zooms, there are great primes. There are poor zooms, there are poor primes (although not so many lately). What works for one, doesn't work for everybody. There's no free lunch. Work with your lenses, get to know them. Zooms are more work to get to know. But the pay off is infinitely more FLs to shoot. For establishing your shooting preferences it doesn't matter what Roger or anyone else says. That's up to you.

In my polls a zoom has to be really really cheap, like FAJ 18-35 cheap, before nobody likes it. I paid $100 CDN for mine. Even kit lenses will get a few votes in blind tests, although many wouldn't have voted for them if they knew it was an 18-55, just on principle. It seems to be fashionable to deny the worth of cheaper zooms in some circles.