Tuesday, July 18, 2017

Lenses for Twin Samsung NX camera rigs


In today's digital and phone photography, lenses are neglected. Most compact cameras use a zoom lens and the photographer, using the camera in auto-everything mode, is often unaware of the focal length or aperture selected by the lens. In many cases, maybe this is a good thing: The photographer can focus on the composition and not have to worry about technical details. But there are cases where it pays to know what the focal length and aperture is (or could or should be).

The Samsung NX1000 twin camera stereo system takes interchangeable lenses and also has a variable stereo base from normal to hyperstereo. It is a good system to experiment with different lenses.

There are three sources of lenses for the Samsung NX cameras:
  • Lenses made by Samsung
  • Third party lenses with NX mount
  • Vintage lenses adapted to fit the NX mount
This link describes the NX mount and lists all Samsung NX lenses from Samsung and also third party manufacturers: https://en.wikipedia.org/wiki/Samsung_NX-mount

Crop Factor

One thing to remember is that the Samsung NX system has a “crop factor” of 1.5x. If you do not know what this means, google to learn more. Here is a good starting point: http://www.photographymad.com/pages/view/crop-factor-explained
In summary, because the sensor of the NX is smaller than full size (24x36mm), the image is cropped (compared to the full size sensor). The end result is that the field of view of a lens when used on an NX camera is more narrow, as if the focal length of the lens is multiplied by 1.5x. The focal length of the lens does not change. This is just a way to compare the field of view of the lens. Since a lot of people are used to focal lengths from full frame 35mm film photography, this helps understand what the sensor sees.

So when you see focal lengths for the NX system, multiply the values by 1.5x to get a value comparable to a full frame camera lens. For example, the standard 20-50mm zoom lens is equivalent to a 35-75mm lens, which is a fairly standard and not very exciting focal length range.
Zoom Lenses by Samsung
These are some zoom lenses that I have tried:
  • Standard 20-50mm f3.5-5.6 (kit) zoom lens. A solid zoom lens that has received good reviews. You need to match the zooms, or find some way to link the lenses. The zoom control rig is easy to rotate. StereoPhoto Maker (SPM) will align images with differences in focal length (just a matter of scale difference), but within limits.
  • 16-50mm f3.5-5.6: This was standard I believe with the NX500. It is a compact lens (see picture below) and attractive for its wider end (16mm) and also because it offers image stabilization (turned ON through the menu, one of the few lenses with this ability). However, it is a motorized zoom lens and does not show the focal length outside or on the screen of the NX1000 cameras, so there is no easy way to match the focal lengths from each camera, other than the two ends. Another kit zoom lens is the 18-55mm lens that came standard with the NX300 cameras, I believe.
  •  50-200mm f3.5-5.6: The longest lens by Samsung, useful for wildlife, long distance action, etc. Does not fit the 68mm spaced camera but most likely it will be used with side-by-side cameras. Here is a picture of me with these lenses. I took some nice bird shots and pictures at a baseball game with these lenses.

The picture below shows the zoom lenses discussed above.  One last comment is that the 20-50mm is the only lens that locks (manually) and needs to be unlocked to use.

Other zoom lenses that I have not tried include the 15-50mm f2-2.8 (note wider maximum aperture than the standard zoom lens), 18-200mm f3.5-6.3, 50-150mm f2.8 (fast fixed aperture).

Matching Focal Lengths: With the 20-50mm lenses, one has to match the focal lengths, if using anything other than the two ends (20mm, 50mm). This is usually done by matching the focal length markings on each lens. This is a bit of a problem in the z-configuration where the left lens is upside down and you cannot see the markings. I have used a marker to mark the back side of upside down lens. Another option is to use some kind of mechanical method to link the zooms. I know a couple of people are working on this. I will update this section when I see an interesting solution.

Zoom vs. Fixed FL Lenses
After using the standard 20-50mm lenses, I decided that I prefer to shoot with fixed focal length lenses, for three reasons:
  1. Fixed focal length lenses are more compact.
  2. They are faster (have a large and fixed maximum aperture)
  3. The focal length cannot be changed accidentally. This is easy to do with the 20-50mm lenses.
 For those who find themselves using the wide and of the 20-50mm lens 99% of the time, why not use the 20mm lenses to get a faster (f2.8 vs. 3.5) and more compact/lighter rig, without worrying about accidentally mismatching the focal length?

An interesting side-effect of using fixed focal length lenses: If I happen to have the 45mm lenses, I change my composition and subject framing, to match the lenses. It is a bit of a challenge to use the lenses that I have on the cameras for any situation I find myself into, and the results are often rewarding (unusual composition, different point of view).

One last comment: I survived 30 years of fixed focal length lenses with my Stereo Realist and RBT S1 stereo camera. Yes, I did try zoom lenses with RBT SLR-type cameras, but soon switched to fixed focal length lenses there too. Zoom lenses are a convenience (carry less weigh, be able to change the focal length to compose better) but at the expense of quality, in my opinion.
Fixed Focal Length Lenses by Samsung
Samsung makes a wide range of compact pancake type fixed focal length lenses:
  • 10mm f3.5 Fisheye: Very tiny!
  • 16mm f2.4, a fine performer
  • 20mm f2.8, has now become my standard lens
  • 30mm f2.0, has received good reviews
  • 45mm f1.8, hands down my favorite lens
These lenses (except for the 30mm lens that I do not own, it is similar in appearance to the 20mm lens) are shown in the picture below.

It is interesting to note that all NX lenses come several colors. The most common are black and white. But there is also pink and silver (the 20mm lens above is silver). The camera bodies also come in different colors (black and white are the most common but I have seen pink too). Some people like to use a different color so they can immediately tell which is the R and which is the L camera/lens. I used to do this too, but not any more. My color of choice for the camera bodies now is white, and black for the lenses.
All these lenses above fit in the cameras separated by 68mm. Two more specialized lenses that I own (these are not pancake, they are both large and heavy):
  • 60mm f2.8 macro
  • 85mm f1.4, great portrait lens but too large and heavy

  [The 20-50mm lens is shown for comparison]
My first two pairs of lenses were the 20-50mm and 50-200mm. My next pair was the 16mm. I found the 16mm too wide for general use, so now I use the 20mm lenses as my standard wide angle lenses.
The Samsung NX 45mm f1.8 Lens

The 45mm f1.8 lens gives me excellent results even wide open. I have several examples on my Phereo account. Here are some advantages of the large maximum aperture (f1.8):
·           Can throw the background out of focus, which is useful for available light portraits: http://phereo.com/image/59258532e7e5649c4600024b
·           Can be cropped without grain or much image quality loss because of the low ISO and sharp image. This picture was taken at a show at night. It has been cropped a lot and still looks sharp. The fast aperture helped me use a fast shutter speed to stop action, at a reasonable ISO:

·           If you shoot through wires with wide open aperture, the wires disappear. This is what happened in this picture: http://phereo.com/image/592585f1e7e5647e63000185  I took this at the local museum of Natural History. I was shooting behind a wire link chain fence, not between the openings (which were too small). There are wires in front of the lenses but using the wide f1.8 aperture, makes them disappear. Also, this picture is cropped quite a bit, I was a lot farther than it appears.
2D/3D: An interesting thing about the 45mm lens is that it comes in 2D and 3D versions. The 3D function does not work with the NX1000 cameras (the lens behaves exactly as the 2D version, as a matter of fact my pair consists of a 2D and a 3D lens) but it works with all later models. The lens has an aperture with two openings and the camera takes a sequential pair using a rather small (8mm) stereo base. The settings in 3D are very limited, so this lens as 3D is not of much use for stereo photographers.
Non-moving Front: Another unusual feature of the 45mm f1.8 lens is that the front element does not move when the lens focuses. This is useful when you flush the lens on a glass, or when using polarizers or any graduated filters in the front. If the front element moves, focusing is impaired when the front if flushed on glass and the lenses might not be able to focus. No problem with this lens. For other lenses I use a rubber shade to block reflections and avoid touching the glass.

A Tip for Carrying/Storing Lens Pairs

I used to throw all the lenses inside my camera bag. They would bang each other and get nicked. I have dropped lenses as I pulled them out of my bag. Now I am trying to be more careful and better organized. Here is what I have done:

I have glued together two back lens caps, using superglue (an alternative to superglue is to use double-sided foam tape, which allows you to separate the caps later). I use generic caps. Some of them do not hold the lens well, so make sure you find one that does.

I then attach the matched lens pair to the twin cap. I then use an OP/TECH foldover pouch to store the pair. These are soft, durable, neoprene pouches, that protect the lenses.

For the 10, 16, 20, and 30mm lenses, also 16-50mm zoom, the size pouch is 253 (2.5x3 inches)
For the 45mm lenses (also, the 20-50mm zooms), the size needed is 2.5x4 inches.
For longer lenses (50-200mm, for example), I do not bother.They are too long to keep like that.

Another useful accessory is rubber shades. I prefer foldable rubber shades which work better when I flush the lenses to glass (airplane window, for example). Finally, I use generic lens caps (about $1 each) so I do not worry about losing the original lens caps. 

Here are all the parts taken apart:

It helps that ALL pancake Samsung lenses use the same filter size: 43mm.
Third Party Lenses with NX Mount
Samyang Optics (a Korean company) has made lenses with the NX mount. These also come under different names, such as Bower and Rokinon. Here are some lenses that I have owned and tried:
  • 8mm f2.8
  • 12mm f2.0
  • 85mm f1.4
These lenses have the correct NX mount but are manual focus only. I tried to get lenses not covered by Samsung. The plan was to use the 8mm or 12mm for night/star photography. They are both faster than the Samsung 10mm f3.5 and focusing is not important.  The 85mm was a lot cheaper than the Samsung one but without AF. Unfortunately, unlike the wider lenses, focus does matter for the 85mm especially for portraits, etc.
Here is a picture of some fixed focal length lenses, from left to right:  Lensbaby 5.8mm f3.5 circular fisheye lens,10mm f3.5 Samsung, 8mm f2.8 Rokinon, and 12mm f2.0 Rokinon lens. The Samsung stands out as being the smallest of the bunch.
Vintage Lenses
Most vintage lenses by Nikon, Canon, Olympus , Pentax, Minolta, etc., can be used with the NX cameras using the appropriate adapter. These adapters are inexpensive (often as low as $10). They are basically hollow tubes (no lenses) that serve two purposes:
  1. Adapt the mount (Nikon, etc., on the front, Samsung NX on the back).
  2. Take care of the infinity focus.
Here is how the MD to NX adapter looks. This picture shows three adapters at different angles. The black end goes to the camera. The Minolta lens attaches to the silver end.

Infinity focus should be preserved, but you need to check this. I have found some variations, so I always focus by looking at the screen, not the lens focus markings.
Because of the 1.5x crop factor wider lenses are not very useful (they are heavy and expensive and Samsung has plenty of those). But Samsung  lacks in long lenses so I am using Minolta lenses (with the appropriate MD to NX lens adapter) to cover these longer focal lengths. Here is what I have:
  • 50mm f3.5 macro
  • 85mm f2.0
  • 100mm f2.5
  • 100mm f4 macro
  • 135mm f2.8 and f3.5
  • 200mm f4
All these lenses above fit with the cameras at 68mm separation.
I also have these lenses that I have used for bird photography:
  • 300mm f4.5 and f5.6
  • 500mm f8 (mirror)
Here is a picture of some lenses from my collection:

The 500mm is a mirror type, so it is compact by design. The 300mm lens has a mounting collar which helps ease the tension from the camera. The 200mm lens is about the length and weight of the 50-200mm Samsung lens, but it this thinner and also faster (f4 vs. f5.6).  The 135mm f3.5 lens is really lightweight and a bargain at about $20 used.

These Minolta lenses need to be focused manually (the aperture is also set manually).  Because they are longer lenses, focusing is rather critical. It would be nice to have a system that links the focusing rings of the lenses. One feature I use a lot for critical focus is to magnify the image by pressing the center button in the back - see also:http://drt3d.blogspot.com/2017/07/tips-for-using-twin-nx1000-cameras.html
Here is an example taken with the 500mm mirror lens:

In Summary

Even though the NX system is dead, there are plenty of lenses to use. This includes lenses from Samsung, third party lenses with NX mount, and vintage/legacy lenses with an adapter. I have accumulated a large number of lenses. Come to think about it, after investing a lot of money on lenses and accessories (mounts, remotes, etc.) the price of the camera body has become almost irrelevant. The investment is in the lenses and accessories. The camera bodies are disposable.

My own personal shooting style favors fixed focal length lenses. I like the pancake lenses by Samsung because they are compact, lightweight, of good quality, and can auto focus. The 20mm lens (35mm equivalent) is my standard wide angle lens. The 16mm is used for indoor shots or when a wider angle of view is needed. The 45mm f1.8 lens is used any time that I do not need a wide angle.

If, in a previous life, you used a different system (Canon, Nikon, Pentax, Minolta) and still have the lenses, you can use these lenses with the Samsung NX camera and an inexpensive adapter. For example, if you do not want to invest in the (rather expensive) 45mm f1.8 lenses, an alternative is to use normal 45-50mm f1.7 lenses found used for maybe $20 for most camera systems. You will lose auto focus.

As I was organizing my lens collection, my wife asked me: “Why do you need all these lenses? Don’t you miss shots as you switch lenses?” Yes, that’s true, and that’s one reason to use zoom lenses. But different focal lengths allow you to take different pictures. And the wider maximum aperture allows you to use faster shutter speeds and/or lower ISO.

We are really fortunate to we have access a variety of lenses that we can use with cameras with normal stereo base (Samsung NX1000 cameras in the z-configuration) and I am taking full advantage of it.

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