Lens Variation- good/ bad copies

[Dr_O]

Couldn't see it posted, just came across this interesting article from Roger Cicala. Have read a lot of the stuff he blogs and it can be quite interesting- this seems to be a bit of a summary/ update of articles he's covered before.

His conclusion is that Sigma can't make lenses properly and should focus on that (no pun intended) before making ridiculously expensive cameras

Ok, so I made that up -essentially he thinks trying to get the sharpest copy is a pointless task and that variation due to machine tolerances is mainly negligible in practice.
He goes onto to say that really bad lenses are easy to spot but are fairly rare and that if your camera body allows proper micro-adjustment he would recommend it.

From my own experience I have had some obvious duffers which were returned but most have been fine and not put me up nor down- rarely felt the need to micro-adjust. I would say I might look into it but I think I know there's nothing wrong with my kit the way it is and that any bad pics are my responsibility alone

 

[Bristolian]

When I was looking for a Tamron 28-75 f/2.8 I had to try 3 lenses in my local camera store before finding one that would focus properly at short, mid and long focal lengths. The first 2 were fine at the short end and at 50mm but back focussed at 75mm.

The search was well worth while because the one I ended up buying is beautifully sharp throughout the focal length range and aperture range too It was one of those times when the service and help I received in the store (Clifton Cameras) was worth the extra money

My only issue with making corrections using micro-adjust (at least on a Nikon body) is that it applies the same correction at everry focal length where it might not actually need it.

Sadly, I've never found a Sigma lens that I have been happy with in terms of focus accuracy which is why there aren't any in my gear bag :thumbsdown:

 

[Moos3h]

In terms of sharpness, I think we do tend to obsess over things a little - if it were like the (good? bad?) old days of things being printed from 35mm negatives, high levels of sharpness would never have been noticed and tolerances could have been a lot wider - no-one would have been any the wiser.

Given we are now all able to pixel peep at 100%, it can make us paranoid about always having the absolute sharpest copy possible - its just the way of things.

Interestingly - I recently shot a load of stuff for a client and there were some where I had missed focus oh-so-slightly - it wasn't dreadful, but just not quite nailed. Anyway, those shots went in with the rest and the client picked all the ones that (for me) were the least sharp of the bunch. Having seen them printed, they look great and you'd never know!

A good pic is a good pic, I suppose and relative sharpness is only one factor out of many.

 

[viewfromthenorth]

I used to have a sigma 24-70 which i thought was fine. Then I sold it and bought a nikon 28-70, and realised just how soft the sigma was.

To be honest there's no excuse for product to product variation in this day and age, especially from japanese products, heck they taught the rest of the world about reducing variation and total quality control.

 

[Oggy]

I am not sure where this is coming from. I have two Sigmas - the 150-500 and the 10-20 and both are remarkably good for the money. They may not quite hold their own against "own brand" lenses costing twice as much, but what would you expect?

 

[LongLensPhotography]

There are defects that can't be cured by AF microadjust. The tolerance levels for these are really huge. Some of the more complex lenses, like wideangles, or very fast ones seem to be more prone to be defective, as they are harder to make, contain more and bigger glass elements.
The combination of lens+camera does seem to make a difference sometimes though, as both can be inperfect in different ways

 

[scottthehat]

I have had one and i mean one awfull siggma 150-500mm and it was naff, it went back to siggma 4 times and even with my bodies and still come back naff, i ended up with a new one(thanks to srs microsystems and chris), so when i brought my 50-500mm os i went and tried 5 different copies in 2 shops and ended up buying the one that i thought was sharpest(and im very happy).

 

[hollis_f]

I really like this article by Roger.

It’s pretty obvious that the spread of sharpness of one lens focused many times is pretty similar to the spread of sharpness of all the different copies tested once each.

 

[LongLensPhotography]

I really like this article by Roger.

I really don't think the article looks deep enough.

The article didn't state what camera they used. Pro bodies can achieve much better accuracy and more consistently than entry level DSLRs.

Secondly, they only appear to have tested the centre of the lenses. Far greater variation will come in the corners, and they have failed to address it. Bad corners can also have a knock off effect to central focus accuracy, that some falsely believe can be cured by microadjusting.

Thirdly, they provide their evidence based on long macro lenses, that are fairly simple in design and easier to manufacture. Why didn't they check the more challenging fast wideangle zooms for example?