Speak to me of teleconverters
After Paul's comment about using the 2x on the 150-450 I looked into
them a bit.
It seems as if the Pentax 2x will crop on FF, but that Tamron has one
that won't.
Also, after looking at some posts by folks who pixel peep, that when it
comes to fine detail, the teleconverter doesn't actually gain you
anything in detail in the final image over cropping. In short, when the
sensor is outresolving the lens, a 2x TC will give you four times as
many pixels, but each pixel is only 1/4 as good.
It seems to me, that if you are shooting professionally, where post
processing time is of the essence, then if the detail in the final image
is about the same, then the TC is definitely worth it, particularly if
you aren't shooting wide open anyways, and the loss of a stop or two
doesn't matter.
My only real experience with this was many years ago, I did some tests,
photographing the moon, and the final images, cropped to the size of the
moon and processed to the same number of pixels, if anything the TC
images were degraded over the cropped images. Back in the days of film,
where film, particularly tri-X, didn't out resolve the lens, then the
TCs would make a significant improvement.
So, do TCs help? If so when? Thoughts? Experience?
If so, which ones do the best?
I can definitely understand that even if a TC isn't a full 24x36, when I
actually would use one, I'd go to a crop sensor first, so that doesn't
really matter.
--
Larry Colen LRC@red4est.com http://red4est.com/lrc
I don't recall where this was much discussed, but wherever, it was
between people who know far more than I about the finer things in
photography.
The general consensus was that most teleconverters do degrade the image
somewhat, 2x converters being quite a bit worse than 1.4 converters, and
that one is better off to shoot without one and crop the image as part
of processing it.
This was prior to the vast improvements we've seen in AI driven image
resizing, so my own opinion, which is probably not worth much, is to
forget about the 2x converter and if you have enough pixels to crop, do
it, and if you have to use an AI resizing tool to give you enough pixels
to crop with, resize and then crop.
Obviously this gives some limitations. For example, with the 2x
converter you will bring a very distant subject close enough that
resizing will give a more usable image, and this is a consideration that
must be accounted for.
Matched multipliers seem to be the exception to this as do the higher
end units. I have the Rear Converter A 1.4X-L which I use from time to
time with my A*600/5.6 and it seems fine. It is well matched to the lens
though.
When I went on my Fuji buying spree a couple of years back I purchased
their 1.4 teleconverter to stretch out my 50-140/2.8 and it also seems
quite good, but when I was researching it I was told to definitely stay
away from their 2x converter. Apparently it isn't up to the red badge
Fuji lenses and degrades them quite a bit.
HTH
bill
On 6/26/2025 1:39 PM, Larry Colen wrote:
After Paul's comment about using the 2x on the 150-450 I looked into
them a bit.
It seems as if the Pentax 2x will crop on FF, but that Tamron has one
that won't.
Also, after looking at some posts by folks who pixel peep, that when
it comes to fine detail, the teleconverter doesn't actually gain you
anything in detail in the final image over cropping. In short, when
the sensor is outresolving the lens, a 2x TC will give you four times
as many pixels, but each pixel is only 1/4 as good.
It seems to me, that if you are shooting professionally, where post
processing time is of the essence, then if the detail in the final
image is about the same, then the TC is definitely worth it,
particularly if you aren't shooting wide open anyways, and the loss of
a stop or two doesn't matter.
My only real experience with this was many years ago, I did some
tests, photographing the moon, and the final images, cropped to the
size of the moon and processed to the same number of pixels, if
anything the TC images were degraded over the cropped images. Back in
the days of film, where film, particularly tri-X, didn't out resolve
the lens, then the TCs would make a significant improvement.
So, do TCs help? If so when? Thoughts? Experience?
If so, which ones do the best?
I can definitely understand that even if a TC isn't a full 24x36, when
I actually would use one, I'd go to a crop sensor first, so that
doesn't really matter.
Thanks Bill,
That pretty much confirms my thoughts.
LRC
On 2025-06-26 13:53, Bill wrote:
I don't recall where this was much discussed, but wherever, it was
between people who know far more than I about the finer things in
photography.
The general consensus was that most teleconverters do degrade the
image somewhat, 2x converters being quite a bit worse than 1.4
converters, and that one is better off to shoot without one and crop
the image as part of processing it.
This was prior to the vast improvements we've seen in AI driven image
resizing, so my own opinion, which is probably not worth much, is to
forget about the 2x converter and if you have enough pixels to crop,
do it, and if you have to use an AI resizing tool to give you enough
pixels to crop with, resize and then crop.
Obviously this gives some limitations. For example, with the 2x
converter you will bring a very distant subject close enough that
resizing will give a more usable image, and this is a consideration
that must be accounted for.
Matched multipliers seem to be the exception to this as do the higher
end units. I have the Rear Converter A 1.4X-L which I use from time to
time with my A*600/5.6 and it seems fine. It is well matched to the
lens though.
When I went on my Fuji buying spree a couple of years back I purchased
their 1.4 teleconverter to stretch out my 50-140/2.8 and it also seems
quite good, but when I was researching it I was told to definitely
stay away from their 2x converter. Apparently it isn't up to the red
badge Fuji lenses and degrades them quite a bit.
HTH
bill
On 6/26/2025 1:39 PM, Larry Colen wrote:
After Paul's comment about using the 2x on the 150-450 I looked into
them a bit.
It seems as if the Pentax 2x will crop on FF, but that Tamron has one
that won't.
Also, after looking at some posts by folks who pixel peep, that when
it comes to fine detail, the teleconverter doesn't actually gain you
anything in detail in the final image over cropping. In short, when
the sensor is outresolving the lens, a 2x TC will give you four times
as many pixels, but each pixel is only 1/4 as good.
It seems to me, that if you are shooting professionally, where post
processing time is of the essence, then if the detail in the final
image is about the same, then the TC is definitely worth it,
particularly if you aren't shooting wide open anyways, and the loss of
a stop or two doesn't matter.
My only real experience with this was many years ago, I did some
tests, photographing the moon, and the final images, cropped to the
size of the moon and processed to the same number of pixels, if
anything the TC images were degraded over the cropped images. Back in
the days of film, where film, particularly tri-X, didn't out resolve
the lens, then the TCs would make a significant improvement.
So, do TCs help? If so when? Thoughts? Experience?
If so, which ones do the best?
I can definitely understand that even if a TC isn't a full 24x36, when
I actually would use one, I'd go to a crop sensor first, so that
doesn't really matter.
--
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follow the directions.
--
Larry Colen LRC@red4est.com http://red4est.com/lrc
On Thu, Jun 26, 2025 at 4:53 PM Bill anotherdrunkensot@gmail.com wrote:
The general consensus was that most teleconverters do degrade the image
somewhat, 2x converters being quite a bit worse than 1.4 converters, and
that one is better off to shoot without one and crop the image as part
of processing it.
Is the text on teleconverters here reasonable? Or, for that matter,
the rest of the article?
https://en.wikivoyage.org/wiki/Travel_photography/Full_systems#Telephoto_lenses
This is a travel guide wiki run by the same foundation as Wikipedia. Anyone
can edit & I'd encourage anyone here who can improve the article to do so.
On Sun, Jul 27, 2025 at 06:25:56PM -0400, Sandy Harris wrote:
Is the text on teleconverters here reasonable? Or, for that matter,
the rest of the article?
https://en.wikivoyage.org/wiki/Travel_photography/Full_systems#Telephoto_lenses
Most of the article is reasonable (although there's nothing really
said there that any experienced photographer wouldn't already know).
But there is one 'suggestion' there that I find totally ridiculous; that
one way to get a narrower field of view is to purchase a small-sensor
body (with the same lens mount) to use alongside your full-frame body.
Almost all the small-sensor bodies I know have no more pixels in total
than the same area of the larger sensors in the full-frame body, so all
you get by adding a different body is more weight to carry around;
simply cropping the full-frame image to the area of interest will yield
an image at least as good as the one you would get from a smaller sensor.
I've almost always had TCs in my camera bag, but very rarely used them;
probably the combination I used most often was a 1.4x converter and my
old Pentax 300/2.8 (back in the days when I was shooting film).
On 2025-07-28 09:51, John Francis wrote:
On Sun, Jul 27, 2025 at 06:25:56PM -0400, Sandy Harris wrote:
Is the text on teleconverters here reasonable? Or, for that matter,
the rest of the article?
https://en.wikivoyage.org/wiki/Travel_photography/Full_systems#Telephoto_lenses
Most of the article is reasonable (although there's nothing really
said there that any experienced photographer wouldn't already know).
It pretty much matches my experience.
But there is one 'suggestion' there that I find totally ridiculous;
that
one way to get a narrower field of view is to purchase a small-sensor
body (with the same lens mount) to use alongside your full-frame body.
Almost all the small-sensor bodies I know have no more pixels in total
than the same area of the larger sensors in the full-frame body, so all
you get by adding a different body is more weight to carry around;
simply cropping the full-frame image to the area of interest will yield
an image at least as good as the one you would get from a smaller
sensor.
The per pixel resolution of the K-3 is a little higher than the K-1, but
not
dramatically so. I.e. the K-3 III will have more pixels than the K-1 in
crop
mode.
Here are my thoughts:
Note what the diffraction limit is on different sensors. TL;DR for the
most part it seems that most modern sensors are pretty close to
out-resolving
most lenses. This is the reason that anti-aliasing filters are going
away.
At one end of the spectrum, you have people doing things like
astrophotography,
where the absolute resolution of the final image is critical. If they
are already
using a high resolution sensor (as opposed to Tri-X film), and
processing the
raw files using a teleconverter doesn't seem to improve final image
quality,
and could degrade it.
On the other hand, if someone is just taking the jpegs out of their
camera,
and not doing any post processing, or they are using film, or a low
resolution
sensor, then a teleconverter could help.
A lot of image quality does come down to how many photons hit the image
area
of the sensor, or the pixel. Adding a TC can't put any photons there
that weren't
there with the base lens.
--
Larry Colen LRC@red4est.com http://red4est.com/lrc
The Pentax 1.4x DA AF converter yields excellent results on my K3 with the DFA 150 -450 or on the K-1 cropped. On the K3 I get the reach of a 960mm lens, razor sharp.
Paul
On Jul 28, 2025, at 3:20 PM, Larry Colen lrc@red4est.com wrote:
On 2025-07-28 09:51, John Francis wrote:
On Sun, Jul 27, 2025 at 06:25:56PM -0400, Sandy Harris wrote:
Is the text on teleconverters here reasonable? Or, for that matter,
the rest of the article?
https://en.wikivoyage.org/wiki/Travel_photography/Full_systems#Telephoto_lenses
Most of the article is reasonable (although there's nothing really
said there that any experienced photographer wouldn't already know).
It pretty much matches my experience.
But there is one 'suggestion' there that I find totally ridiculous; that
one way to get a narrower field of view is to purchase a small-sensor
body (with the same lens mount) to use alongside your full-frame body.
Almost all the small-sensor bodies I know have no more pixels in total
than the same area of the larger sensors in the full-frame body, so all
you get by adding a different body is more weight to carry around;
simply cropping the full-frame image to the area of interest will yield
an image at least as good as the one you would get from a smaller sensor.
The per pixel resolution of the K-3 is a little higher than the K-1, but not
dramatically so. I.e. the K-3 III will have more pixels than the K-1 in crop
mode.
Here are my thoughts:
Note what the diffraction limit is on different sensors. TL;DR for the
most part it seems that most modern sensors are pretty close to out-resolving
most lenses. This is the reason that anti-aliasing filters are going away.
At one end of the spectrum, you have people doing things like astrophotography,
where the absolute resolution of the final image is critical. If they are already
using a high resolution sensor (as opposed to Tri-X film), and processing the
raw files using a teleconverter doesn't seem to improve final image quality,
and could degrade it.
On the other hand, if someone is just taking the jpegs out of their camera,
and not doing any post processing, or they are using film, or a low resolution
sensor, then a teleconverter could help.
A lot of image quality does come down to how many photons hit the image area
of the sensor, or the pixel. Adding a TC can't put any photons there that weren't
there with the base lens.
--
Larry Colen LRC@red4est.com http://red4est.com/lrc
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