Mitakon 20mm f/2 4.5X super macro

[Nordentro]

Good performance vs price, but very narrow usage area

[rockycarter]

Nordentro i have been thinking about getting one of these lens. i was wondering would you mind photographing a coin straight on meaning flat to the lens. what i am wondering is what what is the depth of field on a letter on a coin. thank you

[Nordentro]

I have many samples that you might find interesting rockycarter.

Rice

[rockycarter]

Nordentro thank you so much. yes that has showed me enough. i see what i was looking for great depth of field for coins no doubt. again thank you.

[rockycarter]

excellent

[Nordentro]

But, you can't really fit a coin, the magnification is too great

[kds315*]

but very limited use due to the very limited 4-4x magnification range

[Nordentro]

[Nordentro]

Pepper

[Nordentro]

Gillette

[Nordentro]

Rose

[Nordentro]

Snow

[Nordentro]

This is more or less what you see of a one cent

[SonicScot]

[TrueLoveOne]

interesting shots! great work, i love it! indeed a lens with very limited use, but it sure gives a quite different view on very normal day-to-day items!

[buerokratiehasser]

4.5x? 20mm?

Does it come with a depression in the front lens for the specimen perhaps?

When I did some experimental reversed lens mag 2.?? shots with SD cards and coins it was VERY hard to get anything into focus. Razor sharp DOF. I longed for an optical bench.

It is probably better with a real macro lens which you can stop down, too, but there is this "implicit stopping down with macro lenses" issue which limits your gains due to diffraction. I would have thought for magnifications larger than about 2 or so it would be better to acquire an actual microscope, which includes an optical bench.

One pixel at 2:1 APS-C ~= 3µm. Thats how many atoms, 30,000?

[Ray Parkhurst]

How much working distance did you have when taking the Cent shot?

The clarity of the Cent image is pretty good, but it appears you had to come in pretty much sideways with lighting. I assume this is due to the very short working distance. Would be much better if they provided a ring light of just larger diameter than the objective element.

In general, this is a very useful magnification. 4x is around the point where microscope objectives are the clear winners vs other types (bellows lenses, stacked lenses, reversed enlarging lenses, etc).

I find the way they market the lens as odd. If I were making it, I'd call it a 4:1 macro lens with focusing helicoid. It's true that the action of the focusing helicoid changes the magnification, but who really cares? Unless you're trying to measure something you don't really care what the exact magnification is.

Now, what would really be helpful in reviewing this lens is an aperture sweep. How about the same coin photo, but with aperture at f2, f2.8, f3.3, f4, f4.7, f5.6? This would correspond to effective apertures of f10, f14, f16, f24, f28. I expect we'd see a slight improvement from f2 to f2.8, then degradation due to diffraction limitations. If we only see degradation from f2 to f2.8, I will be favorably impressed. If we see improvement from f2.8 to f3.3, I will be very unimpressed. Of course you need to show us 100% crops, not the whole image. And if you really want to review the lens, show us crops both at the center and one corner...

[Nordentro]

Well, I guess 2-4 cm working distance (pretty close)
The angle on the coin picture make it blur a little at right edge...
Most of the shots where taken at f8-f16

It is basically a reversed lens scheme with focusing helicoid. Marketing name is probably to also reach younger photograpers without any experience with focusing helicoids.

I'm not really up to making a bunch of aperture tests in 100% at the moment, I just thought I could share some results I got with it. It's only three blades in the iris so bokeh shots have triangular OOF highlights.

Could possibly be a interesting lens for insect closeups...