Pentax or Sigma

[Arun]

Hi,

Are there any benefits of using Pentax branded lenses over Sigma or Tamron?

I currently have the 18-55mm and 70-300mm Sigma lenses and find that the 70-300 is a little soft at 300mm. I was thinking of swapping them for the Pentax ones if it would make a difference in the quality of the images.

Cheers

[Mr Guy]

As far as true advantages, the only one I'd really call a pure advantage by brand is that Pentax will promise their lens will work and continue to work and will support their lens if they make some kinda change to the camera body. Since Pentax is the king of backwards compatibility, I don't really know how much of a problem that'd really be anyway.

In general, Pentax is known for having extremely good lenses, but it's been my experience (probably due to my limited budget) that Pentax and the off brands just don't have the same choices available at the same price points. Because of that, I don't that a sweeping generalization of which lenses are better is all that helpful; I think you'd be much better off determining what function you want the lens to serve and your price point, and then reading reviews of those specific lenses to choose.

I don't know if there really is a good general rule.

[MikeM]

I'll agree that there is no general rule. The more you pay, usually the better the lens you get.

If you're disappointed with the Sigma at 300mm, you could get the Pentax DA* 300m f/4, but it'll cost you >$1000.

For comparing lenses of similar focal length and price, I'd recommend reading reviews of the individual lenses and checking out sites like photodo.com.

pentaxforums.com also has a lens review section.

There are some lenses that are only made by 3rd party manufacturers. There's currently no fast telephoto zoom from Pentax, but Sigma and Tamron both offer a 70-200 f/2.8. DPReview.com recently reviewed both those lenses and found them to be quite good.

[inkista]

Accepted wisdom is simply that third-parties are at a slight disadvantage because they're reverse-engineering the mount system. If the manufacturer introduces a change to the mount (or more specifically, the electronic signals communicated between the body and the lens), they can make sure all their old lenses work with it, but they don't have to make sure third-party offerings do the same. There are known cases where third-party lenses have had to be rechipped to work with new digital bodies. Typically, third-party manufacturers will offer to do the conversion for free for specific lenses for a limited time, but there's never a guarantee they will offer it for your specific situation.

OTOH, third-party lenses will also fill in holes in a manufacturer's lineup, have decent-to-great optics, and better price tags, so there's definitely a tradeoff to taking the risk.

[Arun]

Thank you all for comments. I will read the reviews mentioned and see if my local camera guy has the different lenses to test.

Cheers

[Usuqa]

from what i hear the pentax 55-300mm lens is ment to be pretty dam nice, f4 upto around 200mm, it could be a lens to look into if you feal your 70-300 isnt so good.

[MalD]

Here is just one more consideration. The rotation of the front element when focusing. Cheaper lenses will do this. Normally this isn't an issue unless you are using a creative filter system like Cokin. As they attach to the front element. You will need to keep a weather eye on the filter glass/insert and if you are using a graduated filter you might have to adjust the orientation to ensure correct alignment. Nothing worse than a 45 degree graduated angle effect on the filter to the 180 degree (Flat) horizon. . The same applies to circular grad and polerising filters on these types of lenses.