Portrait lens...

[al_dunwood]

I just can't believe it, someone told me he's used a 1.4x TC on a 50

mm, since this guy owns a 70-200/4, he must have been drunk, I never

heard of anyone using a TC on a 50 mm...

[jimstrutz]

<I>"I never heard of anyone using a TC on a 50 mm..."</I>

<P>

That's hard to believe. I'm not doubting you, but... ...where have you been? There has been some discussion of it here in the recent past. I have done this in the distant past, and with decent results. I have seen several other do it as well, so I know it's not THAT uncommon.

<P>

TC's are primarily designed for long lenses and work best with very good long lenses, but that doesn't mean you CAN'T use them with normal lenses. If you had a 50mm f/1.4 with a 1.4x TC, it would act like a 70mm f/2. That would be a usable portrait lens. That's how I used mine.

[jonathan_wang]

Also, the reduction in sharpness when using a teleconverter could improve the quality of the portrait.

[al_dunwood]

OK, that possibly means that using a 50mm with a 1.4x tc for portrait is not as insane as one would think, I guess the resulting min aperture is still near 2.0, right? I'm just trying to figure out if this is worth the try when you own a 70-200/4L, given that the only drawback of the 70-200 is that you may have to use it wide open for portrait...

[ron c sunshine coast,qld,a]

I've used a cheap TC on a great pentax 50mm/1.8 lens.It was so bad i threw that tc away after awhile....

<br>in other words,use a good one!

[john_c.2]

I heard somewhere TC only works on long lenses.

[citizensmith1664875108]

TC's may be optimized for certain focal lengths, generally telephoto. That's not to say you can't use them, just that the image degradation is greater on normal or wide lenses than on a tele. Unless you find somewhere a TC optimized for normal/short tele lenses.

[citizensmith1664875108]

Oh, and the other thing you may be thinking. Canon TCs will only work on pro zooms and primes of 135mm or longer. They are made to physically be incompatible with other lenses.

[peter_kim2]

Actually I have a followup question, sorry for butting in.

 

I have a Canon A-1 with a 50mm 1.8 lens and a 2x teleconverter. If I were to use the TC what effect would it have on the apreture. Would the TC merely cut down the amount of light requiring a slower shutter speed or, something I am curious about, will the TC actually reduce the 1.8 to a 2.8 apreture-with all the resulting consequences to depth of field.

 

To put it another way. Will using a 2x TC on a 50mm 1.8 make it a 2.8 or will it still be a 1.8 with just less light reaching the film?

[sam_mahmoud]

It sounds to me like a nice portrait lens.

 

Adding a 1.4 teleconverter to a 50mm f/1.4 or a

50mm f/1.8 creates a 70mm lens at f/2.0 or f/2.54

respectively. That's still a faster lens than the

70-200/4 you are comparing it against, so it will

blur the background more if used wide open. Just

the thing for portraits. I have actually done this,

but for nature shots, not portraits. I was happy

with the results. These lenses have both sharpness

and speed enough to spare for the teleconverter.

 

To answer Peter's question, a 50/1.8 with a

2x teleconverter is a 100/3.6 lens in every

way. (well, it may actually be 3.5, but that's

a matter of whether the f/1.8 on your lens

really means exactly 1.8). It has the depth

of field one would expect of any 100/3.6 lens.

If the manufacturer had welded on the telconverter

and then hidden it cosmetically so you couldn't

tell, that would be just a different way to

design a 100/3.6 lens.

 

You can think of it as narrowing the max aperture

if you like. Actually, it is neither light

loss nor narrowing the aperture. It'a an artifact

of the fact that f-numbers are not the absolute

aperture, they are a ratio of focal length to

aperture. Change the focal length, and the

f-number changes. To take an example, that

f/1.8 printed on your lens is literally the

focal length f, which is 50mm, divided by 1.8,

So the real aperture is 50/1.8, which is

<punching calculator> 27.78mm. Your actual

aperture is 27.78mm wide or an optical equivalent

at this setting. If the telconverter doubles the

focal length, the aperture is still 27.78mm,

but now the focal length is 100mm. That means

the f number is 100mm/27.78, which is f/3.6.

Your f number just got smaller even though the

aperture didn't change its size in absolute mm.

 

All of these calculations are even true for

a perfect, theoretically ideal teleconverter that

doesn't lose any light. Any real teleconverter

will lose some slight amount of light, so there is

also a reduction of light on top of the apparent

reduction in aperture. It's usually not enough

to worry about.

[peter_kim2]

Sam thank you for that great explaination. I understand now, its the focal length that is the determining factor. Just to make sure I got it. I have my 2x TC on a 50mm 1.8 so I just go ahead and set the camera to f/1.8 with apreture priority...The apreture is still 1.8 but because of the doubling of the focal length it will, for all intents and purposes, be as if it was a f/3.5 even though the lens is on 1.8 because of the doubling of the focal length from 50mm to 100mm...

 

Thanks again!

[ari_friedman1]

Many of the older Nikon TCs come in two versions, one for long lenses (>135mm) the other for short lenses (<135mm). I have used the TC-16a on a 50/1.8 (what it optimized for) and long lenses (300mm). It definitely produces nice results on the 50, almost indistinguishable from a prime. The results on my 300 are less spectacular, as one might expect using a TC in a less than ideal set-up.

 

Ciao,

Ari

[jim_larson1]

I am confused: Will the teleconverters physically fit on the 50? The "L" lenses are built very different on the camera end than the non-"L" lenses.

[tom_menegatos]

The canon TC's no. You need to get a third party tc. The tamron's are pretty good. I think. I forget which one I had and I just used it with my 100/2 and was thinking of useing it with a 50mm just to see what happens as a matter of fact.

 

The other nice thing about using a tc is that your minimum focussing distance is unchanged. So the 50/1.4's minimum focusing distance is 1.5 feet. The 70-200/4l is 3.9 feet. At 70mm you can fill the frame a lot more with the 50 and tc because you can get a lot closer. The 70-200/2.8's minimum focussing distance is a bit more I believe.

 

There's alos the weight to be concerned about.

[al_dunwood]

Thanks for all your answers, it does help, but sometimes it raises new questions too ;)

To summarize:

1) Using a tc on a 50 mm for portrait? Yes, provided good TC

2) Using a Canon TC? No (incompatible)

3) TC optimized for tele? Yes, but works fine on 50 mm

4) Vignetting with TC on a 50mm: ??? No answer

5) 70-200/4L or 50/1.8 with TC for portrait??? which is better???

Some seem to say the 50mm with TC cuz will it gets you a better aperture... anyone to say the 70-200 is better?

[jmublueduck aim]

look into Kenko's Teleplus Pro 300 TCs. 1.4x is $170 & I've only heard good things

about it. Plus, it WILL work with almost every EF lens.

[al_dunwood]

One more thing: while a 2x TC on a 50mm/1.8 would compare to a 100mm/3.6, it is not really true to say that it would be a better lens than my 70-200/4L given that the aperture is better than my L zoom lens. The 50/1.8 is very poor wide open and IMHO, 2.8 is where this lens begins to produce decent results, that would mean 5.6 with the TC