Pentax 16-45 vs Sigma 17-70 vs Tamron 17-50

[mtnman]

I also have the Pentax 16-45 and I'm very pleased with it. It was sharp and contrasty on my K100D and it is equally so on my K20D. The 16-45 is my regular, "walking around" lens, and I could not be happier with it.

One thing to keep in mind, though: it's a big, bulky lens: big enough that on my K100 it casts a distracting shadow if the pop-up flash is used. I only got my K20 a few months ago and I haven't tried the pop up flash with the 16-45, but I expect the lens casts a shadow on that camera as well. I'll try to find a sample photo to show you.

[mtnman]

Bpp -- Here's a very un-interesting, bland pic I took last summer with my K100D and pop-up flash. As you can see, the lens definitely casts a shadow, and it has a profound effect on the resulting image. If you use a flash mounted on the hot shoe, or simply don't do much flash shooting (which is my case) this won't be an issue.

[lesmore49]

Mtnman.



The shadow that is cast by the 16-45 is not due to the 'bulkiness' of the 16-45...but because the 16-45 is quite a wide angle at the 16-20 mm end of it's range.

The pop up flash, on the Pentax DSLR is like most, if not all in that a pop up flash on any DSLR is only good at moderate wide angle settings...say around 28 mm or so.

I have a Pentax 360 flash and a Vivitar 285 HV flash and both have a ''' Fresnel diffuser...that you fit when you are using wider angle lens.

A pop up flash on any camera (DSLR) I'm aware of does not have an additional flash diffuser which will diffuse the flash so that a wider angle lens can get complete flash coverage.

I'm not an expert on pop up flashes and I know Sarah knows a lot more than me on the subject...so Sarah and others, please correct me if I'm wrong.

Les

[mtnman]

Lesmore, I'm certainly not an expert on this issue either, but I do believe the dimensions of the lens are the cause of the shadow. According to that photo's exif data the lens was set to 23 mm, so it was nowhere near it widest setting. The kit lens, which is much smaller in physical dimensions, has never cast a shadow even when zoomed out all the way to 18 mm.

Having said that, I hope someone who knows more about this will correct me if anything I've put here is wrong.

[lesmore49]

Originally Posted by mtnman

Lesmore, I'm certainly not an expert on this issue either, but I do believe the dimensions of the lens are the cause of the shadow. According to that photo's exif data the lens was set to 23 mm, so it was nowhere near it widest setting. The kit lens, which is much smaller in physical dimensions, has never cast a shadow even when zoomed out all the way to 18 mm.

Having said that, I hope someone who knows more about this will correct me if anything I've put here is wrong.

After considering the issue some more, I think we're both right.

Some lenses don't cover the entire area with flash due to having lens hoods, or as you say they are bulky lens. Other lens...such as the wide angle 65 mm on my medium format Mamiya don't cover everything completely with flash as the standard flash unit is not able to throw sufficient flash without having a diffuser added to diffuse the flash for wider coverage.

[mtngal]

Originally Posted by Ballpointpenner

I am rather surprised how one lens can peform so differently on two cameras. Can someone explain to me why that might have happenned?

I was quite satisfied with the old version of the kit lens when I got it with a DS, and used it quite often until I got the K20. That camera can out-resolve the lens and all of a sudden, the pictures looked quite a bit less sharp than they did on the 6 mp K100. I also have the DA*50-135 and was amazed at how much more detail the K20 captured with it than even the K10.

[a200user]

Pentax forums has user reviews:
DA 16-45mm was a 8.72 out of 10 from 33 reviewers.
Sigma 17-70mm was a 8.32 from 19 reviewers.
Tamron 17-50mm was a 8.57 from 7 reviewers.
Not a fair comparison because the reviewers are only rating one lens, and probably not the other two, but it does indicate the DA 16-45mm may be the best pick.

I tried the Sigma 17-70mm in a local store a few years ago on my K100D and couldn't justify $319 in comparison to the kit lens. (Even considering that $319 is a great price and still selling for that now locally) The newer kit lenses version II and WR are supposed to be better than my original DA18-55mm. The DA18-55mm II got an 8.33 rating.

I wound up getting a Sigma 24-60mm constant f2.8 (8.93 rating on Pentax Forums) which I like because it was only $200 (New). It's a bit soft at f2.8 and front focuses on both my K100D and K20D but that can be adjusted on the K20D and also on the K100D by getting into the "debug" menu.

I keep looking at the DA16-45mm and may wind up with one. The reviewers on Pentax forums rate it higher than those reviewing the DA*16-50mm (8.57)

I find Pbase.com is a good place to compare photos from different lenses. Click on the "cameras" link on their home page and rest is pretty much self explanatory.

Good luck and let us know what you wind up with.

Jim

[Trojansoc]

Originally Posted by mtngal

P.S. - I'm still sort-of in the market for a kit lens replacement. I don't have anything between 24 and 50 except the kit lens at the moment and would rather like something better. I'm toying with the idea of the WR kit lens as I'd really like weather sealing.

Harriet,

I bought the WR kit lens a little while back, and I've been very pleased with it. It's a definite improvement over the one I got when I bought my K10d and I DO like the weather sealing. Here's a couple of sunset cloud shots I took with it--a pano and a straight shot.





Paul

[penolta]

Originally Posted by mtnman

Lesmore, I'm certainly not an expert on this issue either, but I do believe the dimensions of the lens are the cause of the shadow. According to that photo's exif data the lens was set to 23 mm, so it was nowhere near it widest setting. The kit lens, which is much smaller in physical dimensions, has never cast a shadow even when zoomed out all the way to 18 mm.

Having said that, I hope someone who knows more about this will correct me if anything I've put here is wrong.

Sometimes just removing the lens shade will remove the obstruction, or shortening the focal length if it extends too far into the light path. On some camera models the popup flash is taller than on others of the same make - the taller the better for clearing the lens.

[interested_observer]

I too have the 16-45 going on almost 4 years now. It has been out for quite a while, I would say about 6 years, and has been doing a good job. It is highly rated, as everyone has indicated. It does a much better job than the kit lens - and that is not to say that the kit is bad, its just that the 16-45 is so much better.

It is a reverse zoom, so that at 16mm the lens extends out and at 45mm it is pulled in. While using the on camera flash, you can get a "nose shadow" in the image - depending on your perspective.

The zoom range of the 16-45 is not that wide, its just 2.8 (45/16=2.8) and the recent lenses do have a wider focal length range. It is a constant f4 and thus the Sigma and Tamron are faster (depending on where you are at in their zoom range). So, depending on your needs - its a very good lens for what it does, however the others do have aspects that may appeal to your needs a bit better.

I'll go out on a limb here and try to address what DMJJR found. Some lenses either front or back focus (on various camera bodies), and thus can appear to be "soft". A number of the bodies offer adjustments - K20 and K7 - and I can't remember about the K10, where by the sensor is adjusted in its depth position very slightly, so as to remove the focus bias. I would think what DMJJR ran into was an extreme case of that. Like I said, I don't know for sure, but ..... That said, any make of lens on any vendor's body can have the same problem.

hope that helps....