Canon tele converter

[steve atkinson]

High new to this so be kind .My question is While using a 5d with 70 200 f2.8l and a canon 2 times converter i am getting a alarming amount of softening of my images some softening is expected but. Is this normal is there go and bad copy's of canon converters. should i just abandon converters and crop good sharp images and get as good a result .Have same result using with sigma 120 300 f2.8 ex

 

[Asher Kelman]

Hi Steve,

Yes, you can get significant softening with the x 2.0 converter. You can decrease the aperture but then you would need more light or slower shutter.

For the 70-200 2.8 IS L, the x 1.4 convertor is much better and you should get very sharp images. you need to practice with different apertures as the DOF becomes very limited especially close objects and wide open.

Asher

 

[steve atkinson]

thanks for the quick reply will try f stop hop it works or i have a small but expensive boat anchor

 

[Asher Kelman]

Not so fast, Steve!

This is a tad small for a boat anchor and would be better in a kerchief swung around your head as a missile to kill pirates! In the meanwhile, it might work better with prime lenses!

Asher

 

[John Sheehy]

High new to this so be kind .My question is While using a 5d with 70 200 f2.8l and a canon 2 times converter i am getting a alarming amount of softening of my images some softening is expected but. Is this normal is there go and bad copy's of canon converters. should i just abandon converters and crop good sharp images and get as good a result .Have same result using with sigma 120 300 f2.8 ex

A 2x converter will make images softer at the pixel level with just about any lens and camera. It's spreading what would be on the focal plane without it to 4x the area. Most lenses are a little soft, wide-open, and need to be stopped down about 2/3 stop or more to get the best results with a TC. This means about f/10 with the 2.8 lens.

A teleconverter does not magically give you more reach with the same quality as the lens alone; it just spreads what the lens can do over more pixels. Even though the image may look soft, a TC should give you more detail of the subject with a good lens, and that is why I use them. With Canon DSLRs, going to higher ISOs to compensate for the loss of light should not be a problem, a cropped image without a 2x TC at a lower ISO is actually less detailed and more noisy in the shadows than with the TC and at 4x the ISO, if you properly resize them and display them at the same subject size. It is only the image that loses light with a TC; the subject doesn't lose any significant amount of light.

 

[Marc Hankins]

As these guys have stated, you do loose sharpness with 2x teleconverters.

Having used that combination myself a fair bit, the loss of sharpness can be beyond what is required for a decent print. Having used that combination at airshows, a HUGE amount off photos were unworkable because of the sheer softness. I was expecting it, but hard times called for hard measures.

 

[Nill Toulme]

I don't even like the 1.4x on the 70-200. On the big white primes, in contrast, the converters work great.

Nill
~~
www.toulme.net

 

[John Sheehy]

I don't even like the 1.4x on the 70-200. On the big white primes, in contrast, the converters work great.

With my 70-200 f/4L IS, one 1.4x Kenko Pro 300 TC at f/8 allows almost the maximum pixel-to-pixel contrast allowable by the AA filter in my 30D.

 

[John Sheehy]

As these guys have stated, you do loose sharpness with 2x teleconverters.

Since I am being paraphrased, I would just like to point out that it is pixel sharpness or image sharpness that is lost; if the main lens is sharp enough, you can get greater subject sharpness with the TC.

IOW, what difference does it make if the image sharpness or pixel-to-pixel sharpness is better in the shot without the TC, if it gets softer when you crop for the same subject size? Subject quality (SQ) is the bottom line to me; not IQ or PQ (pixel quality).

 

[Nill Toulme]

Who wants to shoot long lenses at f/8? :-(

John the difference it makes is making you imagine that you don't really need a longer lens or to walk some steps closer. I consider the 2x utterly unusable on the 70-200 f/2.8L IS, and the 1.4x borderline usable at best.

Nill
~~
www.toulme.net

 

[Bart_van_der_Wolf]

IOW, what difference does it make if the image sharpness or pixel-to-pixel sharpness is better in the shot without the TC, if it gets softer when you crop for the same subject size?

Exactly. However, TCs also add their own aberrations on top of magnifying the aberrations of the lens they are used with. So finally it is the combined result versus the interpolated non-TC result that determines if it is worthwhile from a technical point of view. Some lens/TC combinations are a better match than others.

Overall softness, if 'well behaved', can be somewhat compensated for with appropriate (deconvolution based) software.

Subject quality (SQ) is the bottom line to me; not IQ or PQ (pixel quality).

Up to a point I'd agree, although poor image quality (often poor Chromatic aberration correction towards the corners, especially on Full-Frame sensor arrays) can distract from getting the 'SQ' across.

Bart

 

[John Sheehy]

Up to a point I'd agree, although poor image quality (often poor Chromatic aberration correction towards the corners, especially on Full-Frame sensor arrays) can distract from getting the 'SQ' across.

Then the SQ isn't there. Nothing to qualify, really. The aberration affects the SQ. The SQ is still the bottom line. It is far more relevant how aberrations affect SQ than IQ or PQ. The SQ is the IQ and PQ scaled into context.

 

[John Sheehy]

Who wants to shoot long lenses at f/8? :-(

John the difference it makes is making you imagine that you don't really need a longer lens or to walk some steps closer.

Not at all. You're reading too much into my statements. And I also made it quite clear in my previous post that I didn't think that a TC is a substitute for a longer lens; I said it was for spreading a smaller area over more pixels.

Use of a TC is basically an optical substitution for cropping. Whether or not it is possible (fences, walls, chasms, subject skittishness) or advantageous (perspective is a creative variable) to get closer is a separate issue.

I consider the 2x utterly unusable on the 70-200 f/2.8L IS, and the 1.4x borderline usable at best.

The f/4 is supposed to be sharper, and mine is very sharp.

Are you talking about autofocus quality? IMO, far too many evaluations of soft optics are based on AF issues. I prefer manual focus with telephoto lenses, especially with TCs.

 

[Nill Toulme]

Are you talking about autofocus quality? IMO, far too many evaluations of soft optics are based on AF issues. I prefer manual focus with telephoto lenses, especially with TCs.

Very good question. My only use of the TC's on the 70-200 has been in the occasional pinch for sports use when I've found myself without one of my long primes for some reason or other. It's entirely possible that the unacceptable results I always got that way were due to poor AF rather than some other factor(s).

Nill
~~
www.toulme.net

 

[steve atkinson]

Thanks for the input but it sounds to me like. Don't use it unless you are using it on a big white prime don't have enough spare cash for that so for the time being its a small but expensive boat anchor or ammo for killing pirates.

 

[John Sheehy]

Thanks for the input but it sounds to me like. Don't use it unless you are using it on a big white prime don't have enough spare cash for that so for the time being its a small but expensive boat anchor or ammo for killing pirates.

For the 70-200 f4/L IS, the sharpness is there for a TC; just don't expect the combo to be as sharp as good lens that is longer to begin with. For something like a 75-300, a TC doesn't gain much if anything.

 

[steve atkinson]

High been busy for a while. Thanks for the feedback again had a Chance to try using stopped down, found some improvement it worked OK? if every thing was going for you but not great when you are compromised ( sun angle harsh shadows etc) just have to think of a way to get a big white prime past the cheese and kisses. Got half an excuse.