# Tele-converter (1.7x) math

Discussion in 'Digital Photography' started by eNo, Jun 9, 2004.

1. ### eNoGuest

So... I have a camera with a 5x, 38mm-190mm equivalent lens. Now, I add a
1.7x. Do I have an effective 6.7x (additive) or 5*1.7x=8.5x
(multiplicative)? I'm thinking "x" means the latter, for an equivalent zoom
range of 65mm-323mm, but that sounds too good to be true. Can someone set me
straight on my math?

--
ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø¤º°`°º¤ø,,,,ø¤º
eNo
"If you can't go fast, go long."
ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø¤º°`°º¤ø,,,,ø¤º

eNo, Jun 9, 2004

2. ### David SommersGuest

It multiplies, so you are getting 65mm to 323mm. It should be obvious from
your shots taken with it in place.

Bye.

"eNo" <> wrote in message
news:uXtxc.1597\$...
> So... I have a camera with a 5x, 38mm-190mm equivalent lens. Now, I add a
> 1.7x. Do I have an effective 6.7x (additive) or 5*1.7x=8.5x
> (multiplicative)? I'm thinking "x" means the latter, for an equivalent

zoom
> range of 65mm-323mm, but that sounds too good to be true. Can someone set

me
> straight on my math?
>
> --
> ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø¤º°`°º¤ø,,,,ø¤º
> eNo
> "If you can't go fast, go long."
> ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø¤º°`°º¤ø,,,,ø¤º
>
>

David Sommers, Jun 9, 2004

3. ### Bay Area DaveGuest

sounds correct!

dave

eNo wrote:

> So... I have a camera with a 5x, 38mm-190mm equivalent lens. Now, I add a
> 1.7x. Do I have an effective 6.7x (additive) or 5*1.7x=8.5x
> (multiplicative)? I'm thinking "x" means the latter, for an equivalent zoom
> range of 65mm-323mm, but that sounds too good to be true. Can someone set me
> straight on my math?
>

Bay Area Dave, Jun 9, 2004
4. ### easGuest

it's still a "5x" zoom..... the range has just changed- i.e.the maximum
focal length is 5 times the minimum... right?

eNo wrote:
> So... I have a camera with a 5x, 38mm-190mm equivalent lens. Now, I add a
> 1.7x. Do I have an effective 6.7x (additive) or 5*1.7x=8.5x
> (multiplicative)? I'm thinking "x" means the latter, for an equivalent zoom
> range of 65mm-323mm, but that sounds too good to be true. Can someone set me
> straight on my math?
>

eas, Jun 9, 2004
5. ### Gene PalmiterGuest

No......its not done like that. The 5x means that your short wide angle
times 5 equals your long or telephoto. Now forget that for the next step
because its not related. Your wide is 38x1.7 and your tele is 190x1.7....and

"eNo" <> wrote in message
news:uXtxc.1597\$...
> So... I have a camera with a 5x, 38mm-190mm equivalent lens. Now, I add a
> 1.7x. Do I have an effective 6.7x (additive) or 5*1.7x=8.5x
> (multiplicative)? I'm thinking "x" means the latter, for an equivalent

zoom
> range of 65mm-323mm, but that sounds too good to be true. Can someone set

me
> straight on my math?
>
> --
> ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø¤º°`°º¤ø,,,,ø¤º
> eNo
> "If you can't go fast, go long."
> ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø¤º°`°º¤ø,,,,ø¤º
>
>

Gene Palmiter, Jun 9, 2004
6. ### DiVenZGuest

"Gene Palmiter" <> schreef in bericht
news:Owuxc.19897\$...
> No......its not done like that. The 5x means that your short wide angle
> times 5 equals your long or telephoto. Now forget that for the next step
> because its not related. Your wide is 38x1.7 and your tele is

190x1.7....and

But he cannot use the wide side anymore because of the "big black circle"
arround his picture.
I think it starts at 100x1.7 til 190x1.7 (so thats about 2x)
Regards
Div

>
>
> "eNo" <> wrote in message
> news:uXtxc.1597\$...
> > So... I have a camera with a 5x, 38mm-190mm equivalent lens. Now, I add

a
> > 1.7x. Do I have an effective 6.7x (additive) or 5*1.7x=8.5x
> > (multiplicative)? I'm thinking "x" means the latter, for an equivalent

> zoom
> > range of 65mm-323mm, but that sounds too good to be true. Can someone

set
> me
> > straight on my math?
> >
> > --
> > ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø¤º°`°º¤ø,,,,ø¤º
> > eNo
> > "If you can't go fast, go long."
> > ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø¤º°`°º¤ø,,,,ø¤º
> >
> >

>
>

DiVenZ, Jun 9, 2004
7. ### DiVenZGuest

"DiVenZ" <> schreef in bericht
news:40c6c9bf\$0\$92963\$...
>
> "Gene Palmiter" <> schreef in bericht
> news:Owuxc.19897\$...
> > No......its not done like that. The 5x means that your short wide angle
> > times 5 equals your long or telephoto. Now forget that for the next step
> > because its not related. Your wide is 38x1.7 and your tele is

> 190x1.7....and
> > still 5x your wide.

>
> But he cannot use the wide side anymore because of the "big black circle"
> arround his picture.
> I think it starts at 100x1.7 til 190x1.7 (so thats about 2x)
> Regards
> Div

PS to eNo
If this about the 717 and the Sony Converter I can show you some samples.

>
> >
> >
> > "eNo" <> wrote in message
> > news:uXtxc.1597\$...
> > > So... I have a camera with a 5x, 38mm-190mm equivalent lens. Now, I

> a
> > > 1.7x. Do I have an effective 6.7x (additive) or 5*1.7x=8.5x
> > > (multiplicative)? I'm thinking "x" means the latter, for an equivalent

> > zoom
> > > range of 65mm-323mm, but that sounds too good to be true. Can someone

> set
> > me
> > > straight on my math?
> > >
> > > --
> > > ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø¤º°`°º¤ø,,,,ø¤º
> > > eNo
> > > "If you can't go fast, go long."
> > > ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø¤º°`°º¤ø,,,,ø¤º
> > >
> > >

> >
> >

>
>

DiVenZ, Jun 9, 2004
8. ### Don StaufferGuest

There are two ways of looking at it.

If you are talking about the range with the teleconverter attached, it
goes to a 5X zoom from 65-323. However, if you consider the whole range
you have available (removing or adding the converter when needed), then
you do have a range of 38 - 323.

eNo wrote:
>
> So... I have a camera with a 5x, 38mm-190mm equivalent lens. Now, I add a
> 1.7x. Do I have an effective 6.7x (additive) or 5*1.7x=8.5x
> (multiplicative)? I'm thinking "x" means the latter, for an equivalent zoom
> range of 65mm-323mm, but that sounds too good to be true. Can someone set me
> straight on my math?
>
> --
> ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø¤º°`°º¤ø,,,,ø¤º
> eNo
> "If you can't go fast, go long."
> ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø,,,,ø¤º°`°º¤ø¤º°`°º¤ø,,,,ø¤º

--
Don Stauffer in Minnesota

webpage- http://www.usfamily.net/web/stauffer

Don Stauffer, Jun 9, 2004
9. ### TheNewsGuyGuest

On Wed, 09 Jun 2004 01:43:54 GMT, "eNo" <> wrote:

>So... I have a camera with a 5x, 38mm-190mm equivalent lens. Now, I add a
>1.7x. Do I have an effective 6.7x (additive) or 5*1.7x=8.5x
>(multiplicative)? I'm thinking "x" means the latter, for an equivalent zoom
>range of 65mm-323mm, but that sounds too good to be true. Can someone set me
>straight on my math?

I think you have to read the manufacturer's recommendations - from
what I understand the manufacturer matches the optics of the
teleconverter to LONG focal lengths of the camera's lens. So shots
taken at the wide angle setting of 38mm would not be of good quality,
even if the camera could mechanically zoom back far enough with the
teleconverter attached anyway.

The logic of the optics design is that you already have a 65mm setting
in your original lens - it is the 191mm to 323mm that you want to add.

+++++++++++++++++++++++++++++++++++
+ The News Guy(Mike) - Seinfeld Lists
+ (two mirrored sites)
+ http://membres.lycos.fr/tnguym
+ http://waveprohosting.com/tnguym
+ All things Seinfeld; scripts, trivia, lists,
+++++++++++++++++++++++++++++++++++

TheNewsGuy, Jun 9, 2004

On Wed, 09 Jun 2004 01:43:54 GMT, "eNo" <> wrote:

>So... I have a camera with a 5x, 38mm-190mm equivalent lens. Now, I add a
>1.7x. Do I have an effective 6.7x (additive) or 5*1.7x=8.5x
>(multiplicative)? I'm thinking "x" means the latter, for an equivalent zoom
>range of 65mm-323mm, but that sounds too good to be true. Can someone set me
>straight on my math?

Neither.

You still have a 5X zoom. The difference is with the 1.7X in place
you have a 64.6 to 323 equivelant. The focal length is multiplied by
1.7.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)

11. ### Jack-of-the-DustGuest

"Roger Halstead" <> wrote in message
news:...
> On Wed, 09 Jun 2004 01:43:54 GMT, "eNo" <> wrote:
>
> >So... I have a camera with a 5x, 38mm-190mm equivalent lens. Now, I add a
> >1.7x. Do I have an effective 6.7x (additive) or 5*1.7x=8.5x
> >(multiplicative)? I'm thinking "x" means the latter, for an equivalent

zoom
> >range of 65mm-323mm, but that sounds too good to be true. Can someone set

me
> >straight on my math?

>
> Neither.
>
> You still have a 5X zoom. The difference is with the 1.7X in place
> you have a 64.6 to 323 equivelant. The focal length is multiplied by
> 1.7.

This is not totally true. You will find that the converter more than likely
not work well at the 38mm equiv. end of the lens. And will also provide
vignetting until you are almost to the tele end of the lens. They do not
give a true zoom as many think. This causes much consternation to buyers who
think the range is 65mm - 323mm which you will find is not all useable.

Ed

Jack-of-the-Dust, Jun 11, 2004
12. ### RonGuest

"Jack-of-the-Dust" <> wrote in message
newsqcyc.44018\$...
>
> "Roger Halstead" <> wrote in message
> news:...
> > On Wed, 09 Jun 2004 01:43:54 GMT, "eNo" <> wrote:
> >
> > >So... I have a camera with a 5x, 38mm-190mm equivalent lens. Now, I add

a
> > >1.7x. Do I have an effective 6.7x (additive) or 5*1.7x=8.5x
> > >(multiplicative)? I'm thinking "x" means the latter, for an equivalent

> zoom
> > >range of 65mm-323mm, but that sounds too good to be true. Can someone

set
> me
> > >straight on my math?

> >
> > Neither.
> >
> > You still have a 5X zoom. The difference is with the 1.7X in place
> > you have a 64.6 to 323 equivelant. The focal length is multiplied by
> > 1.7.

> This is not totally true. You will find that the converter more than

likely
> not work well at the 38mm equiv. end of the lens. And will also provide
> vignetting until you are almost to the tele end of the lens. They do not
> give a true zoom as many think. This causes much consternation to buyers

who
> think the range is 65mm - 323mm which you will find is not all useable.
>
> Ed
>
>

Ed, would you say that is also true about wide-angle lenses? I'm thinking of
getting one or the other and if what you say is true about the teleys, then
I'm thinking the wide angle lens may be more useful. You ARE saying that
tele is NOT useful unless at the extreme end of the zoom, aren't you? And
I'm not talking about artsy effects either. For basic close-up shooting,
you're saying a tele is not useful unless fully zoomed. Is that correct?

Ron

Ron, Jun 11, 2004
13. ### Jack-of-the-DustGuest

"Ron" <> wrote in message
news:40c98691\$0\$2986\$...
>
> "Jack-of-the-Dust" <> wrote in message
> newsqcyc.44018\$...
> >
> > "Roger Halstead" <> wrote in message
> > news:...
> > > On Wed, 09 Jun 2004 01:43:54 GMT, "eNo" <> wrote:
> > >
> > > >So... I have a camera with a 5x, 38mm-190mm equivalent lens. Now, I

> a
> > > >1.7x. Do I have an effective 6.7x (additive) or 5*1.7x=8.5x
> > > >(multiplicative)? I'm thinking "x" means the latter, for an

equivalent
> > zoom
> > > >range of 65mm-323mm, but that sounds too good to be true. Can someone

> set
> > me
> > > >straight on my math?
> > >
> > > Neither.
> > >
> > > You still have a 5X zoom. The difference is with the 1.7X in place
> > > you have a 64.6 to 323 equivelant. The focal length is multiplied by
> > > 1.7.

> > This is not totally true. You will find that the converter more than

> likely
> > not work well at the 38mm equiv. end of the lens. And will also provide
> > vignetting until you are almost to the tele end of the lens. They do not
> > give a true zoom as many think. This causes much consternation to buyers

> who
> > think the range is 65mm - 323mm which you will find is not all useable.
> >
> > Ed
> >
> >

>
> Ed, would you say that is also true about wide-angle lenses? I'm thinking

of
> getting one or the other and if what you say is true about the teleys,

then
> I'm thinking the wide angle lens may be more useful. You ARE saying that
> tele is NOT useful unless at the extreme end of the zoom, aren't you? And
> I'm not talking about artsy effects either. For basic close-up shooting,
> you're saying a tele is not useful unless fully zoomed. Is that correct?
>
> Ron
>
>

HI Ron,

Yes this is correct. Many people believe that they end up with a true zoom
which is just not true. Kodak for many years with their Retina line of 35mm
cameras utilized Schneider lenses with front elements that would
interchange. Giving quite a respectable line of focal lengths, and today
some of the most collectable cameras.
You will also get the same tunnel effect with the wide angle converter if
you zoom out towards tele.
However I like having the extreme wide end of my Canon, and while there is a
lot of distortion when used with building shots this can be corrected using
software.

Ed

Jack-of-the-Dust, Jun 11, 2004

On Fri, 11 Jun 2004 06:37:23 GMT, "Jack-of-the-Dust"
<> wrote:

>
>"Roger Halstead" <> wrote in message
>news:...
>> On Wed, 09 Jun 2004 01:43:54 GMT, "eNo" <> wrote:
>>
>> >So... I have a camera with a 5x, 38mm-190mm equivalent lens. Now, I add a
>> >1.7x. Do I have an effective 6.7x (additive) or 5*1.7x=8.5x
>> >(multiplicative)? I'm thinking "x" means the latter, for an equivalent

>zoom
>> >range of 65mm-323mm, but that sounds too good to be true. Can someone set

>me
>> >straight on my math?

>>
>> Neither.
>>
>> You still have a 5X zoom. The difference is with the 1.7X in place
>> you have a 64.6 to 323 equivelant. The focal length is multiplied by
>> 1.7.

>This is not totally true. You will find that the converter more than likely
>not work well at the 38mm equiv. end of the lens. And will also provide
>vignetting until you are almost to the tele end of the lens. They do not
>give a true zoom as many think. This causes much consternation to buyers who
>think the range is 65mm - 323mm which you will find is not all useable.

You are correct. Normally the teleconverter that fits on the end of a
zoom lens pretty much only works at the longer focal length. Well...
the multiplication factor does work over the entire range, but as you
stay, the corners get chopped off through probably more than half the
bottom range of the zoom.

OTOH, I have used negative teleconverters. I have a 0.5 for my E20N
and it works well across the entire range.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
>
>Ed
>

On Fri, 11 Jun 2004 15:15:00 GMT, "Jack-of-the-Dust"
<> wrote:

>
>"Ron" <> wrote in message
>news:40c98691\$0\$2986\$...
>>
>> "Jack-of-the-Dust" <> wrote in message
>> newsqcyc.44018\$...
>> >
>> > "Roger Halstead" <> wrote in message
>> > news:...
>> > > On Wed, 09 Jun 2004 01:43:54 GMT, "eNo" <> wrote:
>> > >
>> > > >So... I have a camera with a 5x, 38mm-190mm equivalent lens. Now, I

>> a
>> > > >1.7x. Do I have an effective 6.7x (additive) or 5*1.7x=8.5x
>> > > >(multiplicative)? I'm thinking "x" means the latter, for an

>equivalent
>> > zoom
>> > > >range of 65mm-323mm, but that sounds too good to be true. Can someone

>> set
>> > me
>> > > >straight on my math?
>> > >
>> > > Neither.
>> > >
>> > > You still have a 5X zoom. The difference is with the 1.7X in place
>> > > you have a 64.6 to 323 equivelant. The focal length is multiplied by
>> > > 1.7.
>> > This is not totally true. You will find that the converter more than

>> likely
>> > not work well at the 38mm equiv. end of the lens. And will also provide
>> > vignetting until you are almost to the tele end of the lens. They do not
>> > give a true zoom as many think. This causes much consternation to buyers

>> who
>> > think the range is 65mm - 323mm which you will find is not all useable.
>> >
>> > Ed
>> >
>> >

>>
>> Ed, would you say that is also true about wide-angle lenses? I'm thinking

>of
>> getting one or the other and if what you say is true about the teleys,

>then
>> I'm thinking the wide angle lens may be more useful. You ARE saying that
>> tele is NOT useful unless at the extreme end of the zoom, aren't you? And
>> I'm not talking about artsy effects either. For basic close-up shooting,
>> you're saying a tele is not useful unless fully zoomed. Is that correct?
>>
>> Ron
>>
>>

>HI Ron,
>
>Yes this is correct. Many people believe that they end up with a true zoom
>which is just not true. Kodak for many years with their Retina line of 35mm
>cameras utilized Schneider lenses with front elements that would
>interchange. Giving quite a respectable line of focal lengths, and today
>some of the most collectable cameras.
>You will also get the same tunnel effect with the wide angle converter if
>you zoom out towards tele.

I have a 0.5 X on my E20 N and it works well across the entire range.
No such tunneling effect is visible. However I can speak only for that
particular lens and converter combination.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)

>However I like having the extreme wide end of my Canon, and while there is a
>lot of distortion when used with building shots this can be corrected using
>software.
>
>Ed
>