Are all mounts equal?

Apologies if this has been asked before, cannot find it on a search;
If I read a lens review on say a Sigma with a Cannon mount can I assume the lens characteristics would be the same on a Pentax mount?


Davex.

To a certain extent yes, but remember that all cameras are different so what may be a punchy, saturated photo on a Canon is probably more due to the characteristics of Canon than the lens, though the reviewer, not having tried the lens on a different mount, may not realise this. Also what may work well with a 10MP camera may not work with a 14MP camera as it could be out-resolved by the sensor.
Plus the difference in focus speed, different HSM workings and the like will possibly effect the review.

Thanks for that Gwyn.
Then probably reading comparisons between say Tamron and Sigma on a Canon mount would not have much relevance to how they perform in a Pentax set-up.

The only way we ever really get a proper assessment of a lens is to try it for ourselves - everything else is a guide unless it's a proper Lab Test that explores a lens's characteristics in some detail, and of course we are able to interpret the results.

So, for example, we can infer reasonably certainly that the Pentax Limited lenses are a bit above the norm, but whether or not they suit our photography is something we discover for ourselves.

Yes and no; using your example if the Tamron faired significantly better than the Sigma on the Canon mount then the chances are good that the same would be true on the Pentax mount. What you couldn't fairly compare would be a test where the Tamron was on a Canon and the Sigma on a Pentax (or vice versa) as the playing field isn't level.

If the differences between the Tamron and the Sigma were only slight on the Canon mount then there's an outside chance that the reverse may be true on a Pentax camera or there may be nothing between them at all.

In other words, where two lenses are closely matched then the only way of telling which is best is to try them on the camera *you* intend to use them on; where one lens is *much* better than the other in a particular mount then it's unlikely to give up its advantage on other mounts.

Hope that makes sense!

makes perfect sense.
thanks all.

Davex.

I think the question was an interesting one, even though the intent was slightly different. This has turned out to be a discussion as to whether lenses behave equally in all mount versions.

The question of the mount is interesting in another way as well, as the Pentax K bayonet mount has proved itself to be a very superior one that has been able to be developed as camera technology has demanded. Originally conceived as a high quality stainless steel mount of wide diameter (45mm) it has survived the test of time extremely well.

By comparison, the Nikon mount is narrower and the solutions to various demands have been possible but perhaps a bit strained...the external meter coupling of the original version was very crude, although AI and AI-S developments improved on that. Early Nikon lenses had to be returned to the factory to be upgraded, which was a major exercise.

Canon actually had a superb manual focus mount in the Breech Lock version, where no rotation of the lens was needed and hence there was no wear of the interface. This was simplifued at some point to a standard bayonet and then had to be abandoned completely to cater for AF.

I think mounts could make an interesting discussion of their own.

It could be argued that the K mount that we all know and love has become a bit of an albatross around the neck of Pentax.

Why, because the vast number of compatible lenses in the market that Pentax use as a selling point, actually harms them when it comes to selling new lenses. The DA designed for digital may be better on a DSLR, but it is not something that Pentax can push to much without compromising the advantage of the back catalogue.

Steve

Ot could, but I doubt that it has any effect on the bulk of buyers, who probably have no allegiance.

Targeting those moving up from compact and bridge cameras will bring in new photographers who have little knowledge of Pentax lenses, probably. This is potentially the expanding part of the market - established photographers don't change marque very much. I know it sometimes seems here as though they do, but we are not a representative sample.

I know quite a few K100 users who have no thought in their minds about upgrading. They've entered the DSLR world at a fixed point and that's where they expect to stay. So you get them at that point, or someone else does.

I take your point John, but more profit is made from lenses than cameras. Pentax make nothing from someone picking up an an old M series lens from a car boot sale. Pentax need to attract additional sales from new users beyond the initial camera and kit lenses.

Here is a thought, what about an exchange deal? Trade in your old lenses to Pentax for credit against a new DA. Pentax could then refurbish and sell back into the market with an OEM warranty to new entry level users.

You might want to limit the reselling to the old classic manual focus primes, for which there appears to be quite a strong demand.

Regards - Steve

Interesting idea, and it has been tried by retailers such as Jessops.

I wonder what they did with all the old cameras and lenses though - if they just destroyed them to remove their impact from the market, that would not be good.

I think the key is to retain the OEM link and warranty. There must be mountains of salvageable material out there that could be given a new lease of life.

Another benefit is a possible 'Green' angle. Why buying a Pentax is good for the environment

A nice up selling opportunity as well, you tried the kit lens, you tried the manual prime now be prepared to be blown away by the new DA Limiteds.

Regards - Steve

How about a service to put an A mount on an M or K lens? That would bring in a few punters.

G

George, I did that with a M series 28mm lens. It is easy enough to fool the camera into thinking you have a 'A' series lens fitted and it does bring some extra functionality, such as adjustment of aperture from the camera, but you still have the exposure issues.

I read an article on this, but cannot put my hands on it, but if I remember correctly aperture control in earlier lenses is non linear and this is the main reason for the exposure problems.

Link to a thread on Pentax Forums http://tinyurl.com/kv6w4g

I think there is merit in the original idea, just wish I had access to someone in Pentax marketing. It would be relatively easy to set up and provide some real differentiation for Pentax.

Steve

I was thinking that the base of the lens would be replaced with an A version. A proper job in other words.

G