Lens quality information

[@imagesBV]

Before I buy I have found it difficult to deduce which lenses are good and bad, particularly from the Canon mtf charts.
I'm not daft....so if I find it difficult I assume others must do too.....if only because they are just too busy to fully research the info.
The data used by photozone and dpreview are much easier to use and compare but they don't cover every lens.

It would be nice if Canon or EOS magazine (if thats not against their remit) could offer a standard approach that we can all use.
I find it incredible that there is such a disparity between quality, cost and supposed grade (budget, L etc) across the Canon range.
i.e. the nifty 50 at £90 is better than some much higher costing glass, and the 28-135 at £370 is worse than lots of cheaper lenses.

If manufacturers want to continue to make a range of grades then surely they should be honest about what they are making.

Clarity and transparency is what I want.....and no chromic aberation in the prices!

Any comments? Do we need a campaign for clearer data?

[Millie]

Re: Lens quality information

If manufacturers want to continue to make a range of grades then surely they should be honest about what they are making.

They do Brian, the problem is that they like to use words like "affordable", when somtimes they really mean cheap 'n' nasty.

When you see manufacturers using phrases like, "ideal for capturing those family memories" you need to be a bit wary.

Millie

[@imagesBV]

Re: Lens quality information

Maybe I'm a bit myopic but numbers say more to me than weaselly words from the marketing department.
I've been saved twice by checking for comments on this website from buying cheap n nasty - its just so tempting to buy new glass at an attractive price.
It says something about the manufacturer when they cant be up front.

[MX5]

Re: Lens quality information

... how about these IMATEST ... gives optical quality ... but not build quality.

[Woolley]

Re: Lens quality information

Clarity and transparency is what I want

Transparency is the absolute minimum I expect from a lens!

You have a good point, although I'm not sure how acheivable it is, since the real test of a lens is how you use it, and the cost depends on what went into it. A lens can be brilliant on the test charts, but useless for what you want to use it for and vice versa. I've found the best trick is to ignore the charts and research the reviews and people's opinions. That's no guarantee of success either, of course.

[@imagesBV]

Re: Lens quality information

I'm not sure I understand that....if a lens is brilliantly sharp then in what circumstances can it be said to be useless?

[colin C]

Re: Lens quality information

Say, for example you want a lens to shoot sport. You buy a zoom lens that will go to 300mm, but wide open it is f5.6. You want to shoot wide open to isolate the sport from the background, but the resultant background isn't very blurred and the subject is a touch soft. That lens may well be bitingly sharp from f8 onwards, but it doesn't help you.

A 300mm f2.8 prime is bitingly sharp at all apertures and wide open, will throw the background into a complete blur. So the zoom may be completely useless to you, but very good for other users, whose requirements are more general.

Colin

[@imagesBV]

Re: Lens quality information

Colin
Ok, I see that; but I want the ultimate - sharp wide open and closed down - the depth of field should be chosen by the f stop selected - wide open to blur the backround or stopped down for front to back sharpness - obviously we are compromised by available light and shutter speed needed but thats my starting point.
Then its down to what you are prepared to pay for. In your example above you can still close the 300mm f2.8 prime down to f16 for front to back sharpness although at 300mm you might need to stop down more than that of course.
Brian

[colin C]

Re: Lens quality information

You can have two more stops Brian ........ it goes down to F32.

Colin

[Millie]

Re: Lens quality information

It’s not only manufacturers and retailers who “guild the Lilly” when selling lenses.
People who bought lenses primarily on price, focal length, and/or out of newness to 'the game', often use the manufacturers blurb when they subsequently flog their unwanted lenses to upgrade.

I don’t like variable aperture zoom lenses,
Using the 75-300 F4-5.6 zoom lens as an example.
Look at the max apertures at the various focal lengths.
75-94mm = f/4.0
95-139mm = f/5.0
140-239mm = f/5.0
240-300mm = f/5.6
The variable max aperture just gives you another thing to ‘worry’ about imho.

wide open to blur the backround or stopped down for front to back sharpness

Yes that's the general rule.
Focal length and subject distance has a visible impact on DOF
Using an EFS 18-55 2.8 lens as an example, try this experiment:
Take two images of a person’s face, approx 2 metres from subject, same location.
1.@ 55mm F2.8
2.@ 18mm F2.8

Observe the visible difference in DOF

'My truth' is that you need to study a bit before buying lenses (if you only want to buy once).
Other people's experiences or 'truth' may be different.

Millie

[MX5]

Re: Lens quality information

I agree with Millie (don't I always ;-)) ... it's just another reason to foster a relationship with a Canon (Pro) dealer. You can often get them to lend before you buy. I've done this a few times and no money has departed my wallet. Then when you actually purchase the lens ... jobs a good 'un as we say up here. Yes I could save money by searching out the cheapest price on t'Internet ... but having a dealer onside has more than made up for that over the years.

[briansquibb]

Re: Lens quality information

I don’t like variable aperture zoom lenses,
Using the 75-300 F4-5.6 zoom lens as an example.
Look at the max apertures at the various focal lengths.
75-94mm = f/4.0
95-139mm = f/5.0
140-239mm = f/5.0
240-300mm = f/5.6
The variable max aperture just gives you another thing to ‘worry’ about imho.





Millie

Does this mean you dont like the 100-400L then ?

[Millie]

Re: Lens quality information

Does this mean you dont like the 100-400L then ?

I prefer to talk in general terms about the charactistics of lenses I like or dislike.
Are you thinking of buying a 100-400 ? Is that why you're asking this question ?

[briansquibb]

Re: Lens quality information

It is on my list for sure - after seeing the quality of those planes... cant make up my mind between that and the 300 f4l

[Millie]

Re: Lens quality information

It is on my list for sure - after seeing the quality of those planes... cant make up my mind between that and the 300 f4l

You could try asking someone who's got both; to help with your decision