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05-23-2016, 06:12 PM   #16
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Here is how bad the 150-450 vignettes with the DA 1.4 tc on it.

---------- Post added 05-23-16 at 07:13 PM ----------

Ohh, sorry about the lack of sharpness. I had the shutter speed down at 1/100 and was through a not too clean window.

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05-23-2016, 06:29 PM   #17
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concurrent threads about this apparently.

my 5 minute backyard test from today:

https://www.pentaxforums.com/forums/190-pentax-k-1/321600-ff-teleconverter-k-...ml#post3654072
05-23-2016, 06:31 PM   #18
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Please try the DA* 50-135mm lens with the DA 1.4 if you can on a K-1 in FF mode!
05-23-2016, 06:39 PM   #19
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QuoteOriginally posted by mee Quote
Please try the DA* 50-135mm lens with the DA 1.4 if you can on a K-1 in FF mode!
so you can have a 189mm f4 lens?

Between the little gain in focal length and the ungodly slow AF performance of the 50-135, better off getting a real 200 f2.8 or even a 70-200. You're already halfway there cost wise just picking up the TC. Sell off the 50-135 and it's almost a zero sum trade.

05-23-2016, 06:44 PM - 1 Like   #20
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QuoteOriginally posted by ybo1 Quote
To my knowledge, a TC never adds detail, just increases FL.
Thank you, thank you. I have been asserting without finding kindred company that: 1) TC's were invented to provide frame-filling during the era of chrome (slide) film, especially for nature photography; 2) the very best a TC can do is avoid degrading the image; they cannot improve the resolution of the lens; 3) because no TC is perfect, all will degrade IQ at least slightly; 4) using a TC is basically "pre-cropping." The only potential advantage of using a TC is to get greater pixel density relative to cropping in PP from an image taken at the same distance, same subject, with the same camera + lens but without a TC.
05-23-2016, 06:50 PM   #21
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QuoteOriginally posted by nomadkng Quote
so you can have a 189mm f4 lens?

Between the little gain in focal length and the ungodly slow AF performance of the 50-135, better off getting a real 200 f2.8 or even a 70-200. You're already halfway there cost wise just picking up the TC. Sell off the 50-135 and it's almost a zero sum trade.
I'd be ok with an 189mm f/4 lens. And thus I'm asking how it specifically works, not for other options. So, if anyone has the HD 1.4x and the DA* 50-135mm, please let me know how it works on the ends.
05-23-2016, 07:25 PM - 3 Likes   #22
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Just a brief clarification here..... the TC magnifies the image from the first lens. In itself it ads no new information.

However two other things happen. Detail too fine for the sensor to resolve, can be magnified to the point where they are accurately portrayed using the given sensor density. Same as thing that are invisible to the human eye become visible under a microscope, the 1.4 converter has the ability to make details invisible to the sensor, viable, through magnification.

So more detail in the magnified image is possible based on he resolving power of the lens and the quality of the sensor.

For example, say your sensor is 10 lines. It will portray accurately 5 black and 5 white lines. But what if you have 14 black and white lines, 7 black-7 white. Your 10 line sensor can't resolve that, it doesn't have enough resolution. Put the 1.4 TC on your lens and the sensor now sees only 10 lines. The sensor is capable of resolving 5 black and 5 white ones. You actually can get an accurate image of a reduced section of the target, because you used the TC. The information was always supplied by the lens. But with a 10 line sensor, 14 black and white lines cannot be accurately portrayed, 10 can.

This is I know horribly over simplified. But it should give you some understanding of how a TC can provide a clearer image, than simply blowing up the original target to the same size. Any detail that could be resolved by the sensor with the TC, that is small enough to be unresolvable by the sensor without the TC will be lost if the TC isn't used. It's possible wo use picture for your comparison that have no unresolved detail without the TC. But in my own tests, I have never seen that happen. IN my test, so long ago I can't find it, Resolving power was in keeping with the focal length of the lens. Whether or not a TC was used, made no difference. The above explains why I think that happens.

The other way these details could theoretically be picked up could be by using smaller pixels. The example would be putting my A-400 on Q to give myself the equivalent of 1800 mm. Would I resolve things that couldn't be seen using the same lens on my K-5. Of course I would.... would the picture be as crisp? I don't know, but looking at the best of the Q images I've seen using long lenses, they are as good a s APS-c

HeInrich Lohman's Ground Squirrel... 200mm lens on a Q
https://www.pentaxforums.com/forums/12-post-your-photos/321606-nature-just-so...e-gophers.html



AN image from a Panasonic FZ1000 1 inches sensor..


If you calculate the size of these pixels and realize that the FZ1000 is 20 MP on a one inch sensor that's 1/4 the size of an APS-c cranks out this kind of detail, you quickly realize, it's going to be a long time before good 1.4 or even 2x converters don't ad detail. This FZ1000 camera can produce 2700 lw/ph on a 20 MP sensor, the K-3 produces 2800 on an APS-c sensor. The average lens can be magnified quite a lot, before it stops providing new information.

IN fact if you think of microscopic dust and stuff, there is simply no point at which more magnification doesn't produce more detail. Magnification makes things visible which were previously invisible. This is not a magic class of product that renders magnification meaningless, and to argue against a TC is pretty much to argue against magnification.

Last edited by normhead; 05-23-2016 at 07:51 PM.
05-23-2016, 08:12 PM   #23
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QuoteOriginally posted by mee Quote
I'd be ok with an 189mm f/4 lens. And thus I'm asking how it specifically works, not for other options. So, if anyone has the HD 1.4x and the DA* 50-135mm, please let me know how it works on the ends.
Me too, especially with the specific pixie dust of the DA* 50-135, a Tamron just won't cut it.
johnc sent me a couple of samples done with the DA* 50-135 and the DA 1.4x Rear converter - the results are not good imo. It covers full frame at 50mm, with slight vignette, but 135mm looks like the same amount of vignette as without a TC (heavy). Corner resolution is very poor.
I've got a Kenko 1.4X Teleplus MC4 DG on the way, and I'll test it on arrival.

05-23-2016, 08:33 PM   #24
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QuoteOriginally posted by Mock Quote
Me too, especially with the specific pixie dust of the DA* 50-135, a Tamron just won't cut it.
johnc sent me a couple of samples done with the DA* 50-135 and the DA 1.4x Rear converter - the results are not good imo. It covers full frame at 50mm, with slight vignette, but 135mm looks like the same amount of vignette as without a TC (heavy). Corner resolution is very poor.
I've got a Kenko 1.4X Teleplus MC4 DG on the way, and I'll test it on arrival.
Ok thank you. Next question is if it vigenettes heavy on the long end.. I wonder where in the focal length range the vignetting stops? Oh I'm so difficult
05-23-2016, 09:16 PM   #25
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QuoteOriginally posted by mee Quote
I'd be ok with an 189mm f/4 lens. And thus I'm asking how it specifically works, not for other options. So, if anyone has the HD 1.4x and the DA* 50-135mm, please let me know how it works on the ends.
Well, you can get a really good full frame 200mm f/4 lens for about 1/10 the cost of the teleconverter!

SMC Pentax-A 200mm F4 Reviews - A Prime Lenses - Pentax Lens Reviews & Lens Database

https://www.pentaxforums.com/lensreviews/SMC-Pentax-M-200mm-F4-Lens.html
05-24-2016, 02:22 AM   #26
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Just guessing Pentax had no plans to release a full frame when the current 1.4 was designed/released. I am also guessing Pentax will need to add a FF 1.4 TC to the road map in the fast lane so it appears in the rear view mirror quickly.
05-24-2016, 02:40 AM   #27
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Scotty - I just looked at your image... Do you have a UV filter on that lens? I notice a diagonal banding in the bokeh which is very reminiscent of a problem I had with a Kenko filter some time ago...
05-24-2016, 09:41 AM   #28
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QuoteOriginally posted by BigMackCam Quote
Scotty - I just looked at your image... Do you have a UV filter on that lens? I notice a diagonal banding in the bokeh which is very reminiscent of a problem I had with a Kenko filter some time ago...
No filter at all, just movement because I had the shutter speed too low and was shooting through a window that has loads of oak pollen stuck to it in a raindrop pattern.
05-24-2016, 10:02 AM   #29
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QuoteOriginally posted by normhead Quote
Just a brief clarification here..... the TC magnifies the image from the first lens. In itself it ads no new information.

However two other things happen. Detail too fine for the sensor to resolve, can be magnified to the point where they are accurately portrayed using the given sensor density. Same as thing that are invisible to the human eye become visible under a microscope, the 1.4 converter has the ability to make details invisible to the sensor, viable, through magnification...to argue against a TC is pretty much to argue against magnification.
In other words, the middle bit of your 36MP sensor becomes in effect the middle bit of a 72MP sensor so if you are only interested in the middle bit (moon shots, distant planes, birds... and squirrels), and if your prime lens and the TC combination are up to the job, you can see more detail. In the middle bit.
05-24-2016, 10:45 AM   #30
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QuoteOriginally posted by VoiceOfReason Quote
Here is how bad the 150-450 vignettes with the DA 1.4 tc on it.

---------- Post added 05-23-16 at 07:13 PM ----------

Ohh, sorry about the lack of sharpness. I had the shutter speed down at 1/100 and was through a not too clean window.
So what size does that crop to to avoid the vignetting? Bigger than 5000x3000 approximately the size of the crop seņor...more or less. If more, the TC will ad detail, if not he images will be close to the same.

QuoteOriginally posted by Dave L Quote
In other words, the middle bit of your 36MP sensor becomes in effect the middle bit of a 72MP sensor so if you are only interested in the middle bit (moon shots, distant planes, birds... and squirrels), and if your prime lens and the TC combination are up to the job, you can see more detail. In the middle bit.
I'm not sure what you're saying here.

----------------

Anyway, more on TC use.

Better here than tying up this thread.
https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/321890-unde...ml#post3654825

Last edited by normhead; 05-24-2016 at 10:52 AM.
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