[lightbulb]

Yeah 16-85 f2.8-4 with dc motor and fast af. Better iq at wide end than 16 50, sold!

[DSims]

Would you prefer a constant f4 aperture versus a variable f2.8 to f4 aperture?

I would!

I would too! Constant aperture is not only easier to manage when zooming, it almost always provides a higher IQ lens, in my experience.

[Buschmaster]

I would too! Constant aperture is not only easier to manage when zooming, it almost always provides a higher IQ lens, in my experience.

Maybe because the highest IQ lenses are usually primes.

[DSims]

I dearly want a weather-sealed zoom to complement my 50-135, but the overall consensus on the DA* 16-50 is that the IQ is not worthy of it's high price (unlike the 50-135). So I guess it's a waiting game ... still.

I'm very interested in seeing what it is too, but I think the bottom line is if you really need one that badly you'll try something that's already on the market. I think this lens is one of the worst ones to wait for, since we don't even know what the actual focal length will be, what the aperture will be, and whether or not it will be designed for APS-C only (e.g. on the wide end). Oh, yeah, and it has the most ambiguous release date as well.

Plus, even if it comes out perfect in the above respects as well as price, if they put an SDM motor on it many people will be afraid to buy it - regardless of its merits.


Why wait for something that only has a 20% chance of meeting your criteria, when you can buy something that almost meets your criteria now?

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Last edited by DSims; 11-20-2012 at 05:55 PM.

[DSims]

Maybe because the highest IQ lenses are usually primes.

It sounds like you have a variable-aperture prime I should try out!

I think creating a constant-aperture zoom is more demanding and usually more expensive, and a desirable byproduct of this is higher IQ in the resulting end-product.

[enoxatnep]

Plus, even if it comes out perfect in the above respects as well as price, if they put an SDM motor on it many people will be afraid to buy it - regardless of its merits.

Why wait for something that only has a 20% chance of meeting your criteria, when you can buy something that almost meets your criteria now?

Thanks for trying to put things into perspective. However, I no longer have concerns about SDM issues now that new SDM lenses (2012 and on) apparently won't have them.

Why I am willing to wait is simply because there seems to be such a love-hate relationship with this lens. Some owners think it's the greatest whereas others loathe the day they bought it. I don't know of any other current DA or DA* lens that is so schizo in terms of quality-control. It's like you're rolling the dice by buying one, with the chances seeming to be only 50-50 that you'll get a good one. And if you do, you'll still suffer from not-so-great results at the wide end and when wide open compared with most other zooms wide open.

That said, if I get too impatient/desperate, I might look into the 16-50, but I'd have to get a pretty incredible deal on it because I feel a new one is about $300 over-priced given its limitations.

[bdery]

Constant aperture is not only easier to manage when zooming, it almost always provides a higher IQ lens, in my experience.

It provides higher IQ because the aperture is voluntarily limited...

Almost any lens that is constant aperture could be faster at the wide end. It's basic lens design. when the manufacturer decides to put in a constant aperture, he does so because he can avoid working on the IQ at wide ends and fast apertures, giving him more leevay. In short it makes his job easier, but it doesn't mean the lens couldn't be made great at larger apertures.

Just look at the Sigma 17-70 vs Pentax 17-70.

[snake]

What I look forward is seeing the aperture it offers. DA* lenses are usually pretty fast, but with such a range I have a hard time believing it will be f2.8 at 80mm. And DA* don't usually have varyable apertures, so maybe it will be f4.

Well, Fuji, for its x-series, which is expensive and supposedly "premium", put out a variable aperture zoom...

It's not inconceivable they'll do it.

Olympus had their 12-60 with a variable aperture, same for the 14-54.

It wouldn't surprise me if it was 2.8 only when at wide angle.

[DSims]

Just look at the Sigma 17-70 vs Pentax 17-70.

Are you suggesting the Sigma is great within the first stop? The Sigma's I've used have been weak until stopped down a bit - even primes. In my book a quality lens only needs to be stopped down 1/3 stop, or in some cases 2/3. What's the point otherwise - besides looking good on paper (and I don't mean photo paper)? I had the Pentax 17-70 and got good results at f/4.5 throughout the range. With Sigmas I feel like it's almost false advertising - promising something they can't deliver on with usable quality.

I later sold the DA17-70 and a while later got the DA*16-50, but I've been happy with both.

[DSims]

That said, if I get too impatient/desperate, I might look into the 16-50, but I'd have to get a pretty incredible deal on it because I feel a new one is about $300 over-priced given its limitations.

With the DA*16-50 I think you have to buy used, and make sure the seller will let you return it if you don't like it. I ended up returning the first one I tried (it was probably one of those "decentered" models) which was OK but not quite up to snuff. I purchased this second one a while later, and it's been good.

I can relate to you, because I put off this lens purchase far longer than any other. But my concerns were always about whether I actually "needed" this lens. It turned out I did. Between it and the DA*50-135 I now had the whole range covered, and I stopped buying lenses at that point, because it completed my kit. I hadn't even looked at the Marketplace for over a year. Finally I bought a few more lenses recently - 1 1/2 years later - picking up some of the more unique models. I still use mostly primes, but the DA* zooms are my "safety net," and are essential when I need them. If you need it, I'd encourage you to try one.

[7samurai]

Would you prefer a constant f4 aperture versus a variable f2.8 to f4 aperture?

My preference is for a constant aperture whenever possible. I've lived and learned on variable apertures. All of have them been satifying and less expensive. Size and cost are generally a positive aspect.
However, for a DA* lense, my preference would be for a constant aperture.

[snake]

Would you prefer a constant f4 aperture versus a variable f2.8 to f4 aperture?

Between the two, I'd lean towards the latter, but the problem is we have now newer variables in sharpness at any FL. The constant ones, in my observation, tend to be much better in sharpness throughout the range.

[bdery]

Are you suggesting the Sigma is great within the first stop?

It depends on your definition of "great". By reading your post, I doubt we would agree. I have absolutely no problem using the Sigma 17-70 at its widest aperture at any focal length. Of course it improves when stopped down.

Look at the comparative review of the various 17-70 lenses here on pentaxforums (written by yours truly). You'll see what I refer to.

In my book a quality lens only needs to be stopped down 1/3 stop, or in some cases 2/3.

Again, "need" might not mean the same thing for both of us. My new 60-250 will see action mostly wide open, my DA21 is often at f3.2 but I rarely use my F50 f1,7 wider than f2. It really depends on the lens. My DFA 100 macro is as good wide open as it is at f8.

I had the Pentax 17-70 and got good results at f/4.5 throughout the range

True, it's a sharp lens at most apertures. However, there is more to an image than sharpness, and I assume by "good" you mean "sharp". For instance, DOF will influence the final output more than sharpness in some cases.

With Sigmas I feel like it's almost false advertising - promising something they can't deliver on with usable quality.

I don't see how you can make that claim if you've never used the 17-70. My own experience, and reviews/user reports all around the web suggest otherwise. And it holds true for their other lenses I've used/seen reviews of.

[Rondec]

My experience is that no zoom lens is truly sharp wide open. Even the 50-135, which is reasonably sharp at f2.8 between 60mm and 100mm still benefits from being stopped down a stop. The same is true of a lens like the DA 55-300 where stopped down a stop varies throughout the focal length range.

The issue with variable speed primes is that they tend to be fastest at the short end, where you really don't need it as much and are slowest at the long end where you can use the extra speed. I think if it is a DA * prime, it will be decent wide open, whether it is variable or constant aperture, but will benefit from being stopped down.