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UltravioletPhotography

Canon 40mm F2.8 Pancake is 370nm UV fast on m43rds


dabateman

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I was able to get a cheap Canon 40mm f2.8 with bag and useless hood for very cheap of the bay and decided to test it on my EM1 and EM5mk2 cameras.

 

The Canon 40mm can be used with AF adapters on micro four thirds cameras to get autofocus and aperture control. But even more interesting is the recent firmware update by Metabones, version 3.4 which came out August 23, 2019. If you have installed the firmware hack on your EM1, EM5mk2 or EM1mk2 camera, you can now do incamera focus stacking using the Metabones adapter and the Canon 40mm lens. This does not work with other adapters. My cheap chinese adapter will register in focus stacking, but is too slow to AF. But I do get an 8 image merge, which can be handy to eliminate the Noise in high ISO.

 

This focus stacking and AF also works with both the 10mm and 16mm extension tubes. So you can get macro with the Canon 40mm, just like the Sigma 30mm using the firmware hack.

 

So I did a quick 370nm test to see how the Canon compares and its faster than my Sigma 30mm.

 

Using two ZWB1 filtered 365nm LED bulbs on the subject flower and stacking first the 370bp15 filter on lens, followed by Baader Venus U to tighten the range. I got the following settings using my full spectrum EM1 camera.

 

Olympus 30mm Macro settings ISO 200, F4, 3.2 second shutter:

post-188-0-29711700-1570809619.jpg

 

Sigma 30mm, with 10mm extension tube, ISO 200, F4, 2.5 second shutter (Acts like 28/29mm):

post-188-0-04040700-1570809635.jpg

 

Canon 40mm, with 10mm extension tube on an Andoer EF to m43drs pass through adapter, ISO 200, F4, 2 second shutter:

post-188-0-08852800-1570809649.jpg

 

Canon 40mm with 10mm extension tube on Metabones Ultra speed boster, ISO 200, F4, 4 second shutter (Acts like 26/27mm):

post-188-0-90658400-1570809666.jpg

 

The Speed boster reduces the exposure of the Canon 40mm by 1 full stop, but allows for F2 like this (F2, ISO 200, 1.3 seconds):

post-188-0-60408500-1570809720.jpg

 

 

So order is:

Sigma 1/3rd stop faster than Olympus 30mm.

Canon 2/3rds stop faster than Olympus 30mm or 1/3rd faster than Sigma 30mm.

Canon on speed booster is 1/3rds slower than Olympus 30mm.

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Hard to tell if there is much bandpass with that flower, since chicory usually is a long-wave reflector anyhow. Have you tried it with other flowers yet?
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Yes,

The Canon was good as Jonathan has said previously.

What I was surprised by was the hit on UV at 370nm using the Metabones speed booster ultra. When I tested it with the UAT I didn't see an effect. The stop gained by the booster was lost in the added elements, at 370nm. Nothing transmits with lower filters.

But with the Canon the images are slightly bluer, and I loose a stop of UV light.

So using the booster on a lens where the transmission curve is dropping will show its effect. I may now need to test the Nikor 80mm EL on the booster to see if similarly effect. It drops below 370nm.

 

In this test though the Canon was sharper than the Olympus 30mm macro. Similar in sharpness to the Sigma 30mm f2.8 lens.

 

So if you want a general UV auto focus lens this Canon pancake seems good. Just the AF adapters maybe expensive depending on your camera. But I think there is a EF to everything AF adapter now.

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I think the Canon 40mm f2.8 pancake lens could be a great general AF UV lens for every camera, except a NIKON F-mount, were the Nikon 105mm f2.8 Macro D works and Sigma SA mount cameras where I am not sure yet the best AF lens.

 

I do seem to be excluding Pentax K-mount. But I think most have. Not sure of a good lens there either.

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