How to find Macro magnification of picture (1:1 or 2:1)?

[commonjunks]

Hi,

Trying kenko with TC and 50mm.
Not sure how to find what is macro magnification? Let say the picture below

7D, EF50mm f/1.8 II, f/8.0, 1/250, ISO 640, 3 Kenko Tube, 1.4x TC, Handheld

Taken with 50mm f1.8II with out kenko and TC

 

[wwooaahh]

Shoot a ruler and check the width your image can cover. Divide the width of your sensor to that, you get the macro magnification of the lens. For instance, APS-C sensor size: 22.3x14.9 mm, the width (on ruler) you capture is 22.3 mm, then it's 1:1 (22.3:22.3), if it's 11.15 mm then it's 2:1 (22.3:11.15).

 

[commonjunks]

Hi mate thanks for your reply.
I took snap with setup

7D, 50mmII, 3 Kenko Tube, 1.4TC

seems it is 11 points from start. is it 11mm?

Here for reference what is the exact size
7D, 50mmII, 1.4TC

 

[sinned79]

there is a formula to calculate.

http://photography-on-the.net/forum/showpost.php?p=104627&postcount=5

 

[commonjunks]

there is a formula to calculate.

http://photography-on-the.net/forum/showpost.php?p=104627&postcount=5

Thanks mate.
Looking at this formula magnification is
((12+20+36+7.5)/50)*1.4=2.114 (around 2x)
12+20+36 = extension tubes
1.4 = TC

Also would like to acknowledge on wwooaahh comment, using his rule it is also 2:1 Magnification.

 

[UncleFai]

Did some tests this evening using the ruler setup:



I used a Nikon D7000 and a SB600 flash in remote for lighting. I set the flash at -2EV and did not bother to tweak it... so some of the photos underexposed. (And sorry... the ruler is old and dirty...)

Baseline setup: Micro-Nikkor 105mm at 1:1. The focusing distance was 15cm. The ruler says its 24mm - though the Nikon APS-C sensor is suppose to be 23.1mm... may be I am the lucky one who got a bigger sensor for free Nah... more likely, the ruler was not completely perpenticular. Anyway, I will take 23.1mm as the baseline.


Setup 2: Micro-Nikkor 105mm + 12mm Kenko Extension Tube. Measured 20mm, magnification 1.15x, focusing distance 14cm (there was some difficulty in measuring the focusing distance... so it is an approximation)

 

[UncleFai]

Contd...

Setup 3: Micro-Nikkor 105mm + 20mm Kenko Extension Tube. Measured 19mm, magnification 1.21x, focusing distance 13.5cm


Setup 4: Micro-Nikkor 105mm + 36mm Kenko Extension Tube. Measured 16mm, magnification 1.44x, focusing distance 12.5cm


Setup 5: Micro-Nikkor 105mm + 12+20+36mm(68mm) Kenko Extension Tube. Measured 13mm, magnification 1.78x, focusing distance 11.5cm


Setup 6: 35mm f1.8G DX reverse mounted. Measured 12.5mm, magnification 1.85x, focusing distance 6cm (Trick: use Blu Tac to hold the aperture wide open)

 

[UncleFai]

Cont'd...

Setup 7: 20mm f3.5 AI-S reverse mounted. Measured 8mm, magnification 2.88x, focusing distance 4.5cm


Setup 8: Cheapee 18-55mm f3.5G reverse mounted, zoomed out at 18mm. Measured 6mm, magnification 3.85x, focusing distance 3.5cm


Setup 9: Cheapee 18-55mm f3.5G reverse mounted, zoomed out at 18mm + 12+20+36mm Kenko Extension Tube. Measured 3mm, magnification 7.7x, focusing distance 3.5cm


Final Setup: Cheapee 18-55mm f3.5G reverse mounted, zoomed out at 18mm + 12+20+36mm Kenko Extension Tube + 2x Kenko TC. Measured 1.5mm, magnification 15.4x, focusing distance 3cm

 

[UncleFai]

Cont'd...

All focusing done via live view... this is the winner of the magnification contest:



The cheapee 18-55mm kit lens reversed mounted using a BR-2A + all three Kenko extension tube in the set + the 2x TC... > 15x.

Really happy with this lens... I bought second hand at $100... it is great for IR photography, and when reverse mounted gives great magnification. However, I must say that at f3.5, the amount of light loss was very significant and it took me more than 10mins to get the ruler lined up (and not quite focused in the end).

Anyway, I hope folks will find this useful.

... the end ...

 

[UncleFai]

PS: All my photos were *NOT* cropped but down-sampled.

 

[commonjunks]

UncleFai, how usable is this 15X setup?
I did have a reverse ring but while using 50mm reverse i didn't got that clear result as compare to when i use 3xKenko tubes + 1.4TC + 50mm (2X).

 

[UncleFai]

More experimenting... this time with better lighting:


The target is a 1mmx1mm graph paper generated by http://incompetech.com/graphpaper/.

First... 1.4TC + all 3xKenko tubes + 50mm (f1.4G)

Indeed around 2x magnification. But the focusing distance was a mere 3.5cm.

Here's the 100% crop (captured using Win7 snipping tool from Photoshop):

 

[UncleFai]

Next, 1.4TC + all 3 tubes + Micro-Nikkor 105mm (set at 1:1 distance):

1.15x magnification. Image a bit OOF coz only after the whole thing did I realized that I forgot to turn the VR off, causing some lens motion during the experiments. The good news is that the focusing distance is 11.5cm.

Here's the 100% crop:


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

Next, 1.4TC + all 3 tubes + reverse mounted 20mm manual focus lens (sorry, my 50mm is 58mm filter size and I only have the 52mm reverse mounting ring - so can't test 50mm)


Here's the 100% crop:

 

[UncleFai]

Next, what the heck... 2xTC + all 3 tubes + reverse mounted 20mm (at f3.5)

More than 10x magnification.

The 100% crop:

I can see the fibre of the A4 paper.

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

I also tried 2xTC + all 3 tubes + 105mm at 1:1

About 3.55x magnification. Focusing distance still around 11cm.

The 100% crop:

VR caused some motion.

 

[UncleFai]

Final setup, my "KAWABUNGA" setup for the evening... 2xTC + 1.4xTC + 3x Kenko tubes + reverse mounted 20mm manual focus lens opened wide at f3.5

I stunned myself... 19.25x magnification! At a working distance of about 4.5cm

Here's the 100% crop:

With my setup, I think this is the best focusing I can hope for... the slightest tweak and it went OOF.

 

[UncleFai]

Next, the $50 bill setup:


Point of focus is President Yusof Ishak portrait's left eye.

First, 2xTC + tubes + 105mm:


The 100% crop:

Again, the VR boo-boo cost me IQ.

 

[UncleFai]

Next, 2xTC + tubes + 50mm


The 100% crop:


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

Next, 2xTC + tubes + reverse mounted 20mm


The 100% crop:

Can see the ridges of the ink! OK... chromatic aberration is kicking in...

 

[UncleFai]

Finally, the KAWABUNGA setup - 2xTC + 1.4xTC + 3 tubes + reverse mounted 20mm

This is the region near the white of the eye.

The 100% crop:


In conclusion, I should thank commonjunks' posting for triggering me to experiment with this. It was very fun - though I still have much to learn esp. about macro photography. None of this will work on things that move. At a focusing distance of 3cm, getting sufficient light, as well as focusing was an issue. And the irritating VR boo-boo also taught me to be careful the next time. Further, with one extension after another, the setup felt fragile.

 

[Cowseye]

Next up, portrait photo of germs and virus on that $50 note. whahaha

 

[kei1309]

wah uncle fai you're really too free! haha