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04-17-2016, 06:06 AM - 1 Like   #31
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QuoteOriginally posted by kh1234567890 Quote
Probably because it is not exotic enough ...

Flickriver: kh1234567890's photos tagged with smcpda1645mmf40edal
I can't recall a16-45 image on the forum. I don't think a lot of people have any experience with them.

I look at the 16-45 and think, I don't own a single lens that doesn't open to at least 3.5, if it has 21mm as an focal length ƒ3.5 at 21mm. That lens is just weird. In general, fixed aperture lenses are a waste of glass. They have to waste a host of real estate in front element glass, at the wide end. The front element of my 60-250 could probably support 60mm ƒ2, if you used the same front element in a 60mm prime. Fixed aperture is always much heavier than it needs to be for any but it's longest focal length. That's a function of the designs I really don't get. I trust they are cheaper to manufacture, they certainly aren't better for the photographer in terms of what he gets for what he carries.

But I digress. I look at what my F 70-210 gives me at 70mm and ƒ4, and set my 60-250 to 70mm and ƒ4 and think, look at all that wasted glass. They could have done better.


Last edited by normhead; 04-23-2016 at 04:52 PM.
04-17-2016, 06:49 AM   #32
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QuoteOriginally posted by hal55 Quote
... hence I'm just after a good walkaround lens, capable of good quality shots, that won't be taxing to use. It won't be my standard lens, that tends to be the Rikenon 28-100, but it must be capable of magazine quality work. I have been published in "Camera for Enthusiast" magazine in Australia and write occasional travel pieces, which is the reason I'm after a step up from the kit lens without breaking the bank. Some excellent recommendations, but so far they are panning out more expensive than the Sigma barring a good second hand example coming up, which is something I'll keep my eye out for.

Hal55
,
Another relatively inexpensive option would be the Tamron 28-75.
Tamron 28-75mm F2.8 AF XR Di LD Macro SP Lens Reviews - Tamron Lenses - Pentax Lens Review Database

Full disclosure: I'm selling one on the Marketplace but that's not the reason I'm suggesting it. It's simply a very good not-too-heavy walkaround capable of rendering excellent images.
04-17-2016, 07:31 AM   #33
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Yes, I love my Tammy 28-75 f2.8...nearly as much as the 70-200
But as a general walkaround the extra width and length of the 18-135 is very useful. On the other hand the relatively narrow aperture is a hindrence in some circumstances.

There are some K-50 kit bundles with the 18-135 for only a little more than the usual DAL kit. If you can find one, it's well worth the extra bit of cash compared to buying a separate retail lens.
04-17-2016, 08:13 AM   #34
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QuoteOriginally posted by normhead Quote
I can't recall a16-45 image on the forum. I don't think a lot of people have any experience with them.
They hide here

04-17-2016, 06:40 PM   #35
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QuoteOriginally posted by normhead Quote
I can't recall a16-45 image on the forum. I don't think a lot of people have any experience with them.

I look at the 16-45 and think, I don't own a single lens that doesn't open to at least if it has 21mm as an focal length 3.5 at 21mm. That lens is just weird. IN general, fixed aperture lenses are a waste of glass. They have to waste a host of real estate in front element glass, at the wide end. The front element of my 60-250 could probably support 60mm 2, if you used the same front element in a 60mm prime. Fixed aperture is alway much heavier than it needs to be for any but it' longest focal length. That's a function of the designs I really don't get. I trust they are cheaper to manufacture, they certainly aren't better for the photographer in terms of what he gets for what he carries.

But I digress. I look at what my F 70-210 gives me at 70mm and 4, and set my 60-250 to 70mm and 4 and think, look at all that wasted glass. They could have done better.
There isn't a Pentax prime or zoom at 20-21mm f/4 that will touch the sharpness of the 16-45. While the DA 21 is interesting and adequate wide open, the 16-45 simply is sharper (although with more CA and less overall character). Pentax would do very well to improve the build and provide WR, releasing it with a DC motor, HD coatings and simply re-release in the same optical design. Ultimately, the lens is at least as fast as the other midrange variable aperture zooms on the long end - where the lens speed counts. You also get more consistent exposures with a constant aperture lens.
04-17-2016, 06:58 PM   #36
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QuoteOriginally posted by ScooterMaxi Jim Quote
There isn't a Pentax prime or zoom at 20-21mm f/4 that will touch the sharpness of the 16-45. While the DA 21 is interesting and adequate wide open, the 16-45 simply is sharper (although with more CA and less overall character). Pentax would do very well to improve the build and provide WR, releasing it with a DC motor, HD coatings and simply re-release in the same optical design. Ultimately, the lens is at least as fast as the other midrange variable aperture zooms on the long end - where the lens speed counts. You also get more consistent exposures with a constant aperture lens.
Do you have other zooms that you can post pictures to show this?
04-18-2016, 05:08 AM   #37
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QuoteOriginally posted by ScooterMaxi Jim Quote
There isn't a Pentax prime or zoom at 20-21mm f/4 that will touch the sharpness of the 16-45. While the DA 21 is interesting and adequate wide open, the 16-45 simply is sharper (although with more CA and less overall character).
My 16-45mm was sharper across the frame than my 18-135 and DA 15mm Limited at their widest angles and any aperture. This is a set of full resolution images comparing them:
https://picasaweb.google.com/100586096103361553535/Comparo?authkey=Gv1sRgCLOD9LjmoOKTlAE

The 16-45mm is an excellent lens due to its sharpness, flat field and low distortion, but I was not using it much due to the lack of WR and short reach. I replaced it with a Sigma 17-50 f2.8 for shooting indoors when I want the flexibility of a zoom. At the price of a used 16-45, it is an untouchable bargain, IMO, but I wouldn't buy without return rights. Some have a wobbly barrel, which can spoil photos. Mine was quite tight and extremely reliable.
04-18-2016, 05:28 AM   #38
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QuoteQuote:
While the DA 21 is interesting and adequate wide open, the 16-45 simply is sharper (although with more CA and less overall character).
The 21ltd is equal too this lens at every focal length, in the classic Pentax ltd. design way. Soft edges (for smooth out of focus areas, for portraits wide open and ƒ4, and sharp everywhere stopped down to F5.6 or more,

Personally , I simply won't pay the big bucks for a lens with CA. A good lens puts the light where it's supposed to go. CA is light that belongs somewhere other than where it ended up. Eliminating the wavelengths the CA occurs in is not correction and those images are not as good as image taken with a good lens.

I can't condone the idea of paying money for an upgraded lens with those CA numbers. In our tests , the biggest contributor to good micro contrast in a lens are the CA values. CA correction gets rid of visible CA, but it doesn't restore micro-contrast. The only lens that I have that competes with these kinds of values would be my Sigma 70-300.

For me at least, the first thing I look at in a lens is what the CA values are. My DA*60-250 hangs out somewhere around .7 pixels, and the difference between it and my Tamron 90 at .4 pixels is observable in a blind test. CA values of 2 pixels are simply off the charts in my opinion. This is a lens I wouldn't use if it was offered to me. And before you ask, one was offered to me, and I turned it down.

DA 18-55 CA values are half what this lens's are.

But as I don't own the lens I'm willing to entertain the notion that Klaus over at photozone just got a bad copy. After all, his copy of the 18-135 exhibited characteristics mine doesn't. It can happen. As for the 16-45 being sharper, than the 21. Wide open, that's different design criteria, not one is better than the other. Where it counts for landscape the 21 is simply better. And in creating soft smooth out of focus areas at the edges wide open, it's probably better as well.


Last edited by normhead; 04-23-2016 at 04:53 PM.
04-18-2016, 05:35 AM   #39
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QuoteOriginally posted by normhead Quote
I can't recall a 16-45 image on the forum. I don't think a lot of people have any experience with them.
Tsuken used one in the single-in challenge in both January and February if memory serves me correctly.

QuoteOriginally posted by ScooterMaxi Jim Quote
Pentax would do very well to improve the build and provide WR, releasing it with a DC motor, HD coatings and simply re-release in the same optical design.
What they need to do is change the SDM motor in the 16-50*/2.8 out and re-release it as an HD DC edition, to bury the SDM legacy and end the stigma attached to that lens. Either that or downgrade it to DA or offer screwdrive reversion as a service recall, because nobody's going to buy a * lens they think will fail on them.
04-18-2016, 07:13 AM   #40
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QuoteOriginally posted by normhead Quote
I can't recall a16-45 image on the forum. I don't think a lot of people have any experience with them.

I look at the 16-45 and think, I don't own a single lens that doesn't open to at least if it has 21mm as an focal length 3.5 at 21mm. That lens is just weird. IN general, fixed aperture lenses are a waste of glass. They have to waste a host of real estate in front element glass, at the wide end. The front element of my 60-250 could probably support 60mm 2, if you used the same front element in a 60mm prime. Fixed aperture is alway much heavier than it needs to be for any but it' longest focal length. That's a function of the designs I really don't get. I trust they are cheaper to manufacture, they certainly aren't better for the photographer in terms of what he gets for what he carries.

But I digress. I look at what my F 70-210 gives me at 70mm and 4, and set my 60-250 to 70mm and 4 and think, look at all that wasted glass. They could have done better.
A small point but those who are using flash, especially in manual mode, likely benefit from a fixed aperture zoom. Also, exposure accuracy is slightly improved with fixed aperture but this would matter more for film when some of these lenses were designed. DSLRs always round to the nearest 1/2 or 1/3 stop (depending on how you set them up) even though a variable aperture zoom has a continuously variable max aperture throughout its zoom range. In the digital age, you can easily adjust in PP.
04-18-2016, 07:24 AM   #41
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QuoteQuote:
A small point but those who are using flash, especially in manual mode, likely benefit from a fixed aperture zoom.
So, ƒ4 like the 16-45 is better than ƒ2.8 on the 16-85?

When you say that you have to remember, you're not getting wider on the long end, you're getting a smaller aperture on the wide end.

The Pentax 17-70 is constant ƒ4 and 485 grams. filter size 67mm

The Sigma 17-70 is 470 grams, filter size 72mm and is faster than ƒ4 right up to almost 70mm.

In what possible circumstance is not having ƒ2.8 available at the wide end, not a good thing? I don't get it.

If you don't want to use it you can set your camera to ƒ4, if you want it, it's there.
04-18-2016, 07:31 AM   #42
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QuoteOriginally posted by normhead Quote
Personally , I simply won't pay the big bucks for a lens with CA. A good lens puts the light where it's supposed to go. CA is light that belongs somewhere other than where it ended up. Eliminating the wavelengths the CA occurs in is not correction and those images are not as good as image taken with a good lens.
It depends on how and when you do the correction. If you do it before demosaicing - rather that trying to hide the colour fringes afterwards - then in my experience it makes little, if any, difference to microcontrast.

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/268733-help...ml#post3429293
04-18-2016, 08:50 AM   #43
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QuoteOriginally posted by normhead Quote
So, 4 like the 16-45 is better than 2.8 on the 16-85?

When you say that you have to remember, you're not getting wider on the long end, you're getting a smaller aperture on the wide end.

The Pentax 17-70 is constant 4 and 485 grams. filter size 67mm

The Sigma 17-70 is 470 grams, filter size 72mm and is faster than 4 right up to almost 70mm.

In what possible circumstance is not having 2.8 available at the wide end, not a good thing? I don't get it.

If you don't want to use it you can set your camera to 4, if you want it, it's there.
I wasn't commenting on the DA 16-45. If you're trying to shoot wide open with a flash, your aperture changes when you zoom in with a variable aperture zoom. If the flash is in manual, you're changed your exposure.
04-18-2016, 09:15 AM   #44
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If, if , if....

If you set your camera to ƒ4, and your camera's best is ƒ2.8, it stays at ƒ4, even if you have an ƒ2.8 lens. The above would only apply if your camera was set to ƒ2.8 then zoomed out to f4 and then zoomed back in again. So, you'd actually have to use a procedure that tried to fail to make that happen. Manuel exposure and manual flash, camera set to f4 it won't happen. You can use settings that will use an ƒ2.8 variable focus lens exactly the same as a fixed aperture lens. Of course, if you don't think of it, or don't know your camera I guess it could be a problem.

Last edited by normhead; 04-18-2016 at 09:36 AM.
04-18-2016, 09:40 AM   #45
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QuoteOriginally posted by normhead Quote
If, if , if....

If you set your camera to 4, and your camera's best is 2.8, it stays at 4, even if you have an 2.8 lens. The above would only apply if your camera was set to 2.8 then zoomed out to f4 and then zoomed back in again. So, you'd actually have to use a procedure that tried to fail to make that happen. Manuel exposure and manual flash, camera set to f4 it won't happen. You can use settings that will use an 2.8 variable focus lens exactly the same as a fixed aperture lens. Of course, if you don't think of it, or don't know your camera I guess it could be a problem.
Try setting the DA 16-85 or DA 18-135 to f/4 and then zooming. It won't be f/4 for long.
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