Info on Canon's 300mm F4 L Is

John Mc · Feb 1, 2011

To be more exact, It's on my Wish list(my cheap one

) and my Fiance said i can have pick a lens upto £1000 for This Christmas and Birthday (She likes to be organised).
Anyway, im just looking for any good or bad experiences with said lens.
If you use a Tc,which one(s) as im considering getting a 1.4 to get a little longer focal length.

John

Overread · Feb 1, 2011

1.4TC and the 300mm f4 IS L is a solid combo that many use and image quality and AF speed should remain very usable - and it gives you 420mm with IS support for help when handholding.

The alternatives to this would be the 400mm f5.6 L and the 100-400mm IS L. If you feel you want more focal range all the time then the 400mm will give you faster AF and better image quality than the 300mm +1.4TC combo - of course it lacks IS.
Whilst the 100-400mm is going to give you the lower image quality, but has the zoom functionality which is a boon the other two don't have.

Also note whilst I'm taking about lower and higher image quality it should be noted that they are all performing at a very good grade to start with so its more a case of splitting hairs between good options than night and day differences.

I'll also add that the 100-400mm can suffer from poor copies or missaligned ones with your camera body so it can be a bit of a hit and miss lens in some respects. Those that get a good one (or calibrate to their camera body) like it and those that get bad ones hate it ;P

John Mc · Feb 1, 2011

Cheers overread,i had a shot of the 100-400mm in jessops the other day and i wasnt to pleased with the lens. didnt focus brilliantly and i had to boost the iso from 100-800 to get a shot of 1/60.the thing is,it wasnt even a dull day,it was really bright,i was using 50iso film and was able to shoot at f8 at 1/60th,so it was bright.
speaking to the bloke he did say it was calibrated to the 7d,which was convieniently out of battery when i asked to get a shot of it on that.

I dont mind a fixed focal length lens,and a 1.4 Tc,i would prefer the 300mm then the 400mm. If i need to use a wider aperture,i can walk closer to the subject,if i can.
I heard rumours of the Af not working if i use a 2x Teleconvertor, Is this true?

Overread · Feb 1, 2011

On canon camera bodies the AF will not work if the AF system detects that the lenses maximum aperture (smallest f number) is smaller than f5.6. Now 1D bodies don't have this limit and the 7D also avoids it when in live view mode only (I think they cap at f8) because they use a different AF system.

Now the important part is that some lenses lie - eg some zooms end at f6.3 and just lie to the camera's electronics not to see that fact; plus sometimes 3rd party teleconverters or taping the pins over teleconverters will trick the camera into not seeing a teleconverter.

When you use a 2*TC it robs 2 stops of light from your setup - so f4 becomes f8 whilst the 1.4TC only takes one stop of light - f4 becomes f5.6

However the limit is there for a reason - after f5.6 AF speed and accuracy drops of very fast, even in good lighting. For most it ends up almost unworkable for something like wildlife and manual mode can also be hit and miss (no MF focusing aids - dimmer viewfinder). When you add that to the image quality hit its often too much for most to consider shelling out on the TC for.
Note taped pins and a 400mm f5.6 and a 1.4TC tends to work ok from what I've read (I say ok which means some use it and others dislike it).

John Mc · Feb 1, 2011

Thanks soo much! i get it now,i think if i was going to use a 2xtc it would be for something static. i dont like the idea of buying gear then taping over circuits and pins :S. I'll just stick to the 1.4. Im just in a pickle to see if i should fork out for the new MkIII Tc's. or save abit and get a Sigma Tc

Overread · Feb 1, 2011

Sigma 1.4TC is pretty much identical image quality wise to the canon 1.4TC - about the only slight difference is a little bit more vignetting on fullframe sensors - for crop sensor you really can't tell them apart. The only other difference is that the canon does come with weather sealing; but for that to work fully it has to be part of a weathersealed setup (ie lens and camera both sealed as well).

As for the M3 TCs I've not really seen an indepth comparison review between them; however from shots and examples I've seen around there isn't a massive difference in the 1.4TCs - the 2*TC do show better edge performance in the M3 version. In short I think you'd be perfectly fine with either a canon 1.4TCM2 or a sigma 1.4TC