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Extension tube vs teleconverter
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PostPosted: Wed Sep 14, 2011 8:49 pm    Post subject: Extension tube vs teleconverter Reply with quote

Experiment

1. This is a shot taken with a Canon FD 50mm 1:2 macro @ max magnification.







2. Same lens with a 25mm extension tube for 1:1 magnification.







3. Same lens with a Soligor 2x telconverter for 1:1 magnification.





The telconverter gave me more working distance than did the tube but as you can see it also degraded the image in comparison. Unfortunately, I did not think to measure the end of lens distance to the subject when I did this.

All shots were @ f16.


PostPosted: Thu Sep 15, 2011 6:36 am    Post subject: Reply with quote

Interesting.

I see little image degradation, if any


PostPosted: Thu Sep 15, 2011 1:47 pm    Post subject: Reply with quote

I think 100% corner crops will clearly (or not so clearly Laughing) show the difference!


PostPosted: Thu Sep 15, 2011 2:31 pm    Post subject: Reply with quote

Luis wrote:
I see little image degradation, if any

I don't see any image, I see only degradation Razz


PostPosted: Thu Sep 15, 2011 4:37 pm    Post subject: Reply with quote

At this size I see no degradation. The converter shot actually shows more detail then the tube


PostPosted: Thu Sep 15, 2011 7:16 pm    Post subject: Reply with quote

The tube shot does not have as much noise as the TC, however. That said, the TC seems to perform better in this scenario.


PostPosted: Thu Sep 15, 2011 8:41 pm    Post subject: Reply with quote

I too couldn't tell the difference, but then I noticed that the flare on the specular highlights is significantly different.

Do you happen to remember the exposure settings (ISO and aperture in particular) for the two shots?


PostPosted: Thu Sep 15, 2011 9:26 pm    Post subject: Reply with quote

Scheimpflug wrote:
I too couldn't tell the difference, but then I noticed that the flare on the specular highlights is significantly different.

Do you happen to remember the exposure settings (ISO and aperture in particular) for the two shots?



ISO 200
f16 for all shots.


PostPosted: Thu Sep 15, 2011 9:31 pm    Post subject: Reply with quote

revers wrote:
ISO 200
f16 for all shots.


Interesting... not what I would have guessed!

Do you see the star-shaped "twinkles" on the shots with the teleconverter, particularly on the lower right side of the knob? I wonder why this is more pronounced with the TC? Question


PostPosted: Thu Sep 15, 2011 9:36 pm    Post subject: Reply with quote

I think the extension tube is sharper. It might look soft all over, but notice where the focus is, then compare.

The teleconverter gives a greater depth of field, so it might look sharper overall, but the actual point of focus isn't sharper than that with extension tube.


PostPosted: Thu Sep 15, 2011 10:35 pm    Post subject: Reply with quote

My focus was the top of the dome.

Interesting, the diverse opinion on which is best. If it is this close, then I suggest we go with the telconverter for greater working distance.


PostPosted: Fri Sep 16, 2011 1:58 pm    Post subject: Reply with quote

Here is another combination, 25mm tube pluss a Raynox DCR-150 close-up lens clipped out front.




Razz


PostPosted: Fri Sep 16, 2011 2:14 pm    Post subject: Reply with quote

ah, the last one look more like a photo Very Happy


PostPosted: Fri Sep 16, 2011 4:39 pm    Post subject: Reply with quote

For fun how about trying the T/C with Raynox DCR-150 close-up lens clipped out front.


PostPosted: Fri Sep 16, 2011 5:48 pm    Post subject: Reply with quote

Would like to see 100% corner crops. Wink Of course center is sharpest, differences not so much.


PostPosted: Fri Sep 16, 2011 8:27 pm    Post subject: Reply with quote

visualopsins wrote:
Would like to see 100% corner crops. Wink Of course center is sharpest, differences not so much.


In every case, you are seeing the full frame, there is not much left in the corners.


PostPosted: Fri Sep 16, 2011 10:01 pm    Post subject: Reply with quote

revers wrote:
visualopsins wrote:
Would like to see 100% corner crops. Wink Of course center is sharpest, differences not so much.


In every case, you are seeing the full frame, there is not much left in the corners.


The camera produces images larger than 800x600 pixel shown here, more like 4000x3000 pixels for G1/GH1.

The corner 640x480 pixels of the full 4000x3000 image will better show the differences between lenses (at the corners). Also easier to see center differences if 640x480 pixels are cropped from center of 4000x3000 pixel image.

Images made using TC can be better in the center, but worse in the corners. Same with attachment lenses like the Raynox.


PostPosted: Fri Sep 16, 2011 11:00 pm    Post subject: Reply with quote

visualopsins wrote:


The camera produces images larger than 800x600 pixel shown here, more like 4000x3000 pixels for G1/GH1.

The corner 640x480 pixels of the full 4000x3000 image will better show the differences between lenses (at the corners). Also easier to see center differences if 640x480 pixels are cropped from center of 4000x3000 pixel image.

Images made using TC can be better in the center, but worse in the corners. Same with attachment lenses like the Raynox.


I agree with what you are saying. However, it is my opinion, that in macro work the subject is foremost centered & the corners of of no consequence. We can expect the corners not to be sharp because the DoF is dropping off from the subject.


PostPosted: Sat Sep 17, 2011 2:53 am    Post subject: Reply with quote

The frame-filling macro subject