Canon L series not all its cracked up to be?

[Gidders]

Up until recently I've been doing my portrait work with my Canon 17-85 IS with ilumination by (battery powered) flash at f5.6-f8.0 For head & shoulders shots focusing distance has been ~1.5 mtrs.

I have now switched over to continuous lighting so I dont have to wait for the flashes to recycle, and also I'm wanting to move into baby & toddler portraiture and repeated flashes might become a problem. I have two Interfit cool lite 500w heads with soft boxes but these only give a shutter speed of ~1/60 @ f5.6 & ISO 800. While my 17-85 lens has IS so camera shake is not a problem at this speed, subject movement sometimes is.

So I've been looking at lenses with a faster maximum aperture and have a second hand Canon 28-70 f2.8 L series on approval. I've taken some test shots of a target using a tripod, cable release and mirror lock at 50mm & 70mm (the focal length range I'm most likely to be using) and compared against my 17-85 EF S lens. The target I've used is attached to this post and is about 30 x 45cm. I'll post the test result s in the next post.

[Gidders]

Here are the test results at 50mm centre & edge definition at f5.6 & f8.0 and similarly @ 70mm.

I so wanted this lens to shine, but now it may be my imagination, by my eyes tell me that my 17-85 is sharper than the L series lens

I did do some more tests outdoors with a landscape subject and then the L Series did outperform my lens, but I can't photograph portraits focused at infinity.

Is this short focusing performance differential typical, have I got a particularly good EF S lens or is the L series faulty

[Leif]

This might be of interest:

http://www.photozone.de/8Reviews/len...0_28/index.htm

Here is what Klaus has to say:

Quote: It took me 4 (f-o-u-r) samples of the lens to get a good one - please note: "good", not a "great" sample. The first three variants showed rather hefty centering defects which spoiled the results quite a bit.

As I understand it L means pro-build, but not necessarily premium optics. Nikon also have issues with quality control.

[Don Hoey]

Clive,

When I set up for with and without 2 x teleconverter shots in Robs TC Musings thread, I found my 28-105 zoom outperformed the older fixed focal at distances less than 15 ft. By 20 ft the prime wins. So I guess there are instances where some lenses will perform better at close distances.

Have you considered a fixed focal 85mm f1.8. As these were always favoured for portraiture I would guess the performance at 1.5mtrs would be very good.

Don

[paul0510]

L glass is QUALITY. Having said that, you should be aware of certain shortcomings one of which is a tendency to back focus. I love my 70-200 L F4, it goes everywhere with me but as long as I remember to focus slightly in front of my subject and stop-down to a 'sweet' F10-13 it produces spot-on results. When I first purchased this lense, I took it to my 'test-centre', a disused railway track, and setup a few (also disused) Marlboro fag packets(!) on the sleepers. At first I was slightly disenchanted with the results and had considered returning the glass to Canon. But, with a serious Death Valley trip in the offing, I decided to take into account this somewhat irritating feature together with the revealing performance results and have not looked back since. So take your time and do some proving at home with the simplest of tests.

Have a look at what Bob Atkins has to say:

http://photo.net/learn/focustest/

....and don't look back, er, forward?

[Nigel G]

Originally Posted by paul0510

L glass is QUALITY. .... a tendency to back focus. .....stop-down to a 'sweet' F10-13.

I don't own any L glass (or even an SLR for that matter) but given the price I would be seriously disappointed with comments like this.

Surely it should focus were you want it and whilst almost any lens will be sharper stopped down "a bit", to have to go to +f10 on an f4 lens seems to be giving away a lot of light.

Is this really a normal expectation of Canon's flagship glass ??

[Roy C]

Originally Posted by Nigel G

Is this really a normal expectation of Canon's flagship glass ??

I have three 'L's and they are all excellent lenses so I would say the answer is no.

[postcardcv]

Originally Posted by Roy C

I have three 'L's and they are all excellent lenses so I would say the answer is no.

I'd agree I've got two L lenses (I dream of others), both are excellent. Af is fast and acurate on them and they are useably sharp wide open. If either of my L lenses back focused I'd be sending them to Canon to get it corrected.

[Gidders]

Thanks all for your comments & input on this one. I'm with Nigel in that I expect that when I pay serious money for a pro spec lens I expect it to focus where I want and certainly require no more than 1 stop down to get the best.

It was encouraging to hear of other members being extreemly happy with their L series glass but after a week of experimenting with real life situations, I decided that this particular sample was not for me and sent it back. I also decided that I missed the IS of my 17-85 and the 70mm long end was also limiting for the kind of pictures I tend to take.

So.... I decided that the 24-105 f4 IS L series would be the one for me but I had read on some forums that there could be sample to sample variations with this as well. I decided I wanted the ability to easily exchange it if I was not happy so I went to Jessops (shock - horror) They were offering this lens at £680 but when I said that I had seen it in Bristol Camers for £639 (warehouseexpress £649) they agreed to match that and I got 12 months interest free credit

When I got it home and checked it out, I still didn't think that, at short focusing distances, it was as sharp as it should be I tried the "photographing a peice of newspaper at an angle test" and sure enough, the sharpest point was about 30/40mm behind the focus point. Again on landscapes it was excellent but I guess the DoF would take care of a small focusing error at infinity. Anyway I took it back and Jessops exchanged it no problem.

And..... this time the lens is super sharp even wide open edge to edge at all ranges

Clearly Canon have some quality control issues and the moral is to test your lens at a range of setting to make sure you are getting what you pay for.

[Canis Vulpes]

Glad it worked out for you now Clive.

Good for you in persevering to end up with a good copy.