Teleconverter sharpness issue.

Mack

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Been using the MC-14 teleconverter on my 300mm f/4 lens but was having issues in low light with the AF so I took it off to gain a stop which helped. I've held off buying the MC-20 for fear of even worse performance in dim light.

While looking at the images without the TC I noticed they seemed a lot sharper. I first thought it was because I read in the Imaging Resources website review of the lens where they recommend just using the "Silent Shutter" mode instead of the mechanical. I liked to hear the shutter knowing it fired, but did take some time to get used to Silent Shutter mode and not hearing it (Add a "beep" maybe someplace in menu?). Doing that, I noticed in the EVF the feather detail was much better and contrasty. Still with the TC mounted, I struggled with the fine feather detail and had more missed shots where FastRawViewer failed to show the fine detail in red on their bodies.

Back to Imaging Resources I noticed a small "1.4x TC" in their "Lab Test Results" window. Clicked on that to find that using it drops the 300mm sharpness down one full Blur Unit, from 1 to 2 as shown in the photo below. Doesn't mention using the TC in their 300mm review though but they show it in the "Lab Test Results" window. Personally, I'm not a fan of buying lenses where they show a Blur Unit of 2 or more like my Nikon lenses (ahem!).

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It does seem to work better for me on the 40-150mm f/2.8 lens though. Maybe being one stop faster for the AF and maybe better optical performance on that lens than the 300mm f/4. :(
 

ArizonaMike

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It has always been my experience that using a TC reduces the sharpness of the images. The question I have always asked was if the added focal length was worth the cost in image sharpness and I generally think it is not.

In some of the testing I have done I have taken a standard raw image, upscaled it to 140%, cropped it 1:1 and compared the crop with one taken of the same image with the 1.4TC and found the upscaled image sharper, at least to my eyes. I also found the difference less with the 40-150 Pro than on the 300 Pro but am not sure why.

Mostly I have stopped using the TC as being a waste of money and effort. Some of the new upscaling apps like Topaz's Gigapixel do such a good job of upscaling that I am not sure there is not need for a TC even if it did not cause a loss of image sharpness.
 

Phocal

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I prefer Lenstip testing and they have the MTF50 of the 300/4 at just under 70lpmm and with MC-14 at 56lpmm. So yes, it does lose some sharpness with the TC...................all lenses will lose sharpness when you add a TC. I have done a ton of testing with TC's and have found that if all you are going to do is post to the internet/social media or view on a computer you are are better off just cropping. But if you are going to print big you are better off using the TC, if printing small (under 20" on long side) you can just crop. By the way, it is still sharper with the TC than the Panny 100-400 at 400mm.

This image was taken using the MC-14 from a drifting kayak and I have it printed 40x30 hanging in my living room and you can walk right up to it and the detail holds up from a foot away view. It may hold up when closer but my eyes are bad and I can't focus when closer to say if it is true or not.

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Tricolored Heron 006 by Phocal Art, on Flickr
 

ArizonaMike

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view on a computer you are are better off just cropping.
This is what we do and it is the only testing we have done so I am reassured that it corresponds to your testing as well. And with some of today's advanced sharpening tools cropping and resizing and then sharpening can produce very good results if you make sure you do not overdo it.
 

Mack

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Fwiw, Topaz is having a "Sharpening AI webinar by Joel Wolfson" on March 31 at 4PM CT.

You might get the email from Topaz today if you are on their user list.
 

ArizonaMike

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Fwiw, Topaz is having a "Sharpening AI webinar by Joel Wolfson" on March 31 at 4PM CT.
It is not at a convenient time for me to watch as it is right in the middle of our dinner but I will watch it when they post it for general viewing. I do want to see it as it will probably answer some of my basic questions. I use the software and think it is quite good but I am never sure which module is best for any particular image. And it takes forever if you try to sharpen an entire image. The new version with masking is a big improvement for me.
 

Phocal

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This is what we do and it is the only testing we have done so I am reassured that it corresponds to your testing as well. And with some of today's advanced sharpening tools cropping and resizing and then sharpening can produce very good results if you make sure you do not overdo it.
maybe for web/computer viewing. for printing large all that stuff will never produce as good of an image if you used a TC, even with the slight hit to image quality.
 

Carbonman

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It may hold up when closer but my eyes are bad and I can't focus when closer to say if it is true or not.
+1.5 diopter reading glasses, sir! I have a collapsing pair in my pants pocket, plus a pair in the livingroom, bedroom and office. I also have a pair of +4.00 diopter glasses for really high magnification work but can only wear them for a few minutes.
 
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