rmpsrpms Loc: Santa Clara, CA

I received my Venus 2x Super Macro 60-mm lens in the mail today and have done some initial shots to see how it performs. I bought the lens in Nikon mount for more flexibility, though all my first tests are using the Canon HRT2i with Nikon-EOS adapter. I did not test it yet at low magnifications, though I can say it seems to focus out to infinity, which is very nice. I bought the lens to use for walkaround macro on my D7000, and am hoping it works well for that. Review in this mode will come later.

First, the lens seems well-built. The helicoid is pretty smooth, though it goes from infinity to 1:2 in maybe 15-deg of helicoid rotation. It might be difficult to get critical focus at f/2.8 for medium subject distances. The full range of infinity to 2:1 happens in only around 180-deg (!!) so this lens focuses very fast indeed. Manually, of course.

Aperture is fully manual. This is great for studio situations with continuous lighting, which is my preference, so I am happy. Some folks might prefer automatic mode, but oh well.

The thing that I found most interesting is the lens is "internal focusing" It does not extend at all when focused. The front lens group sits deep inside the body of the lens at infinity, and moves to the front at 2:1, so it has a built-in lens hood for lower magnifications and best working distance at max mag. Seems a very good design. The result of this is the lens is very compact and easy to use.

The working distance at 2:1 is a bit over 2", which is enough for good lighting flexibility. I had no issues with lighting using this lens.

Now for the images.

The subject is a 1955-S Lincoln Cent RPM #4 in BU condition. I shot in Aperture Priority mode, with -1EV to avoid any hotspotting.

I took overall shots at around M=0.7. This nearly fills the sensor with a 19mm Lincoln Cent. See attached for an example shot at f/4, 6-shot stack.

I did an aperture sweep at f/2.8, f/4, f/5.6, and f/8 at M=0.7 and cropped near the center. I like to use Lincoln's beard as the subject for comparisons.

f/2.8
http://i943.photobucket.com/albums/ad273/rparkhurst/Lens%20Comparisons/Venus2x/M0p7f2p8_1.jpg

f/4
http://i943.photobucket.com/albums/ad273/rparkhurst/Lens%20Comparisons/Venus2x/M0p7f4p0_1.jpg

f/5.6
http://i943.photobucket.com/albums/ad273/rparkhurst/Lens%20Comparisons/Venus2x/M0p7f5p6_1.jpg

f/8
http://i943.photobucket.com/albums/ad273/rparkhurst/Lens%20Comparisons/Venus2x/M0p7f8p0_1.jpg

The f/5.6 looks sharpest to me, so this would be around f/9.5 effective.

I then took shots at 2:1 magnification with the S mintmark centered on the sensor, and in the lower left corner. I used both f/2.8 and f/4. See attached for example centered and corner shots.

Here are the Centered and Corner crops at f/2.8 and f/4 for comparison:

Centered and Corner, f/2.8:
http://i943.photobucket.com/albums/ad273/rparkhurst/Lens%20Comparisons/Venus2x/M2p0f2p8Center_1.jpg http://i943.photobucket.com/albums/ad273/rparkhurst/Lens%20Comparisons/Venus2x/M2p0f2p8Corner_1.jpg

Centered and Corner, f/4:
http://i943.photobucket.com/albums/ad273/rparkhurst/Lens%20Comparisons/Venus2x/M2p0f4p0Center_1.jpg http://i943.photobucket.com/albums/ad273/rparkhurst/Lens%20Comparisons/Venus2x/M2p0f4p0Corner_1.jpg

There is significant distortion of image in the corner, more than I've seen on any other lens I've tested. This will keep the lens from being useful for stitching.

f/4 is sharper in the center and significantly sharper in the corner versus f/2.8.

I saw a fair amount of longitudinal chromatic aberration during my testing. There is a greenish shift focused high, and reddish shift focused low. Here are two example crops from a center shot stack at 2:1 to show this effect:

Focused High and Low
http://i943.photobucket.com/albums/ad273/rparkhurst/Lens%20Comparisons/Venus2x/M0p7f4p0High.jpg http://i943.photobucket.com/albums/ad273/rparkhurst/Lens%20Comparisons/Venus2x/M0p7f4p0Low.jpg

This LongCA is mostly removed by stacking since the in-focus planes are true-color, but single images will suffer from color shifts on out of focus areas. This changes the apparent color and can be particularly noticeable and annoying on silver coins. Copper is not as big a deal.

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Nikonian72 Loc: Chico CA

Damn! What ever happened to just a simple initial test? This is gonna take me a bit of time to digest.
Nice job!

rmpsrpms Loc: Santa Clara, CA

I did an animation of the center vs corner distortion I see in with this lens. I am not sure what type of distortion causes this problem. One interesting thing is that this lens seems to be telecentric. I see almost no change in scaling through the stack, as evidenced by the stuck red pixel of my HRT2i rendering as pretty much a single dot. Normally I see a locus of points as the scaling changes through the stack.

http://i943.photobucket.com/albums/ad273/rparkhurst/Lens%20Comparisons/Venus2x/Distortion.gif

LoneRangeFinder Loc: Left field

Nice test, Ray. I hope you saw the reviews by OrionMystery and Thomas Shahan....

rmpsrpms Loc: Santa Clara, CA

I did see those reviews but they didn't really tell me if the lens would be good for studio macro. Indeed the one review where I read that diffraction is only showing up at f/22 got me very worried that the lens would be low quality. Another review said that the Venus2x had shallower depth of field versus the MPE65 at the same magnification and aperture. This told me 3 things:

1) The lens may be higher quality than the MPE65 at 2:1, which I can't imagine is the case, or it could be much lower quality, which I also can't imagine is the case.

2) The lens is shortening focal length more than the MPE65 at same magnification and thus has a larger effective aperture. This actually seems likely since 2:1 is at the end of the Venus' range and max focal length shortening would probably occur here. It also seems likely since in another review (or maybe same one) the working distances were compared, and the Venus' was significantly shorter.

3) The reviewer doesn't understand the technical aspects of depth of field. As we all know, depth of field is the same for all lenses at same magnification and aperture, so different lenses can't have different depths of field. That said, a bad lens will look worse at critical focus plane, so will APPEAR to have better depth of field, hence the lens quality considerations.

LoneRangeFinder Loc: Left field

My thoughts: I cannot imagine that diffraction only sets in at f/22. It may be that it wasn't noticeable (to the reviewer)-- but diffraction is a technical given. I would expect it to begin between f/8 and f/11 on this lens. I would also question that the lens quality and design is superior to the MPE65. There is another factor in DOF which is sensor size-- but that is irrelevant in this example unless testing one on a FF body and the Venus on a DSLR with a cropped sensor. I appreciate your attention to detail, specifically with your lab applications.
Thanks, Allen

Lighting

rmpsrmps, you did the type of test with photos that is extremely helpful. Good job :thumbup: