In a fairly length blog post back in May, I talked a lot about the different types of lens mounts, the differences between the manufacturers and some considerations when using those lenses on your camera body. At the end I mentioned I would follow up with a separate post about adapting lenses, with a particular focus on a combination that I have come to enjoy, the M42 lens on a Nikon camera body. I am going to focus on this combination as it takes into account several of the factors you would need to consider when adapting lenses. And even though I am talking primarily about the M42/Nikon combination, these aspects apply to adapting other types of lenses to other types of camera bodies, so please read on even if you use Canon and want to use a Nikon lens on your camera or any other combination.
Before I go on to specifics about adapting the M42 lens to a Nikon body, I am going to re-post the section with a bit of history and details on the M42 and M39 lenses below:
“M42 and M39 Universal Mounts – Although M42 and M39 mounts are different and were used by different companies, I grouped them together because they shared similar properties. The M## designation reflected the metric 42 or 39mm screw thread. Both used a thread pitch of 1mm. T-Mounts (see below) also have a 42mm diameter, however it uses a 0.75mm thread pitch and is not compatible with M42 cameras and vice versa. The M42 mount was first developed by Carl Zeiss back in the 1930s, and was adopted by many European, and particularly Russian camera and lens manufacturers. The M42 standard utilized a 45.46mm registration distance. As I mentioned above in the Pentax section, the Pentax camera company utilized the M42 mount as well. In the United States became known as the Pentax Universal Screw mount. The same occurred with the Praktica camera brand outside the US, however both are M42 universal screw mounts. The M39 screw mount was developed by Leica prior to the development of the Leica R bayonet mount and had a registration of only 28.8mm which is too short for many other cameras. Early Canon cameras used it (but called the J-mount) as did several of the Russian camera brands. The Zenit camera brand adopted the M39 configuration but extended the registration to 45.2mm. There is no visual difference between the mounts with different registration distances, so you must know for which one your particular M39 lens was designed.”
So know you have been refreshed on what an M42 mount is and a bit of the technical details. As you can tell by the description, a 42mm screw is not going to connect with the bayonet style receiving flange on a Nikon body, so an adapter must be used. Not all that surprisingly, the major camera manufacturer’s who also make lenses, do not make adapters to attach a different type of lens on their camera body. They want you to buy the equivalent type of lens from them with their mount. And, that’s a good business practice, but for the consumer and photographer it limits your world to lenses made from just one manufacturer. Now if I were limited to just using Nikon lenses, I would certainly get over it quickly, but knowing that there are some many different brands and types of lenses out there, I don’t want to be limited. For example, I have a Helios 44-2 58mm f/2 lens at home which uses an M42 lens mount. What is so special about it? It’s just a fast, normal prime lens. I could easily get the 50mm f/1.8D from Nikon (and I own that as well). So why would I want to attach this old lens to my new DSLR? Simple. The bokeh on this lens (a term for the quality of the out of focus area in front of and behind the subject that is in focus) has an awesome swirling pattern to it which I really like for some of my more artistic shots. The smooth bokeh on the Nikkor 50mm f/1.8 is great, but it doesn’t have the same effect. As an added bonus, because there are a lot of these old Russian lenses out there no new cameras today that accept M42 lenses, I was able to pick one up for cheap ($20) on Ebay and it is in flawless condition.
But what good is a fantastic lens for $20, if you can’t natively attach it to your camera, and your camera manufacturer doesn’t make an adapter to attach it? This is where general 3rd party manufacturers come in. There a slew of these 3rd party manufacturers who make adapters for just about any lens/camera combination where the connection is possible (for example Canon EOS lenses, due to their diameter, cannot be adapted to a Nikon body so no reputable manufacturer will make this type of adapter). These lens adapters are very simple in nature, being cut from aluminum, and consisting of the female attachment for the lens on one side and the male flange for the camera body on the other. Some manufacturers that are popular are Bower in the U.S. and Kood in the U.K., but there are many out there including some store brands which are just fine for simple adapters. They are usually sold for just a few dollars so if you get one brand and find there is some aspect that you don’t like about it (for example I have one adapter that does not lock into to the camera body properly) then there is not a whole lot lost and you can try another brand. Again, this is for the simple metal adapters (more on what is not a simple adapter in a minute).
Many lens combinations work really well with a simple adapter, for example mounting a Nikon lens on a Canon camera body. As the throat of the lens on the Nikon is smaller than the opening on the Canon there is no issue there. Additionally as the registration distance (for more on this see this post) for Nikon is longer than that for Canon, there is no issue with not being able to focus to infinity, however you may lose a little, but of focusing power on the shorter end. One thing to be weary of is the distance that the lens protrudes into the camera body. If one camera system is designed for a lens where the back element is deep in the body and you attach that lens to body where the system does not require the lens to stick into the body very deeply, you may end up with issues. The most common of these is that the reflex mirror actually hits the end of the lens which can do damage to the lens, but more likely could break the mirror in the camera (not something you want to fix). To avoid this, do your research online and look for groups on photography forums where these are discussed (such as Flickr or Photo.net). A few simple web searches will avoid you a whole lot of hassle before spending money on a lens that may end up breaking your camera.
Nikon, is actually one o the more challenging camera bodies to adapt lens to, but it also one of the safest. How so? First off, the opening or throat diameter on the Nikon body, is fairly narrow. As I mentioned in the earlier posts, Nikon has made very few changes to their mount since it came out in the 1950s and this “narrow” throat is one of the features that has been maintained. Why is this an issue? Most lenses with different mounts will still work as the throat is very similar to that of the Nikon. However some manufacturers, Canon with their EOS mount being the most recognizable of these brands, have a throat opening which is much wider than that of Nikon. As such, the end of the lens is too large to fit into the throat on a Nikon body. This is great for Canon users as they can use their Canon lenses and also use the narrower Nikon lenses which will mount deep enough in the body to make up the difference in registration distance with just a simple adapter. However, as you may be able ot tell from the other direction, Nikon users cannot use Canon EOS lenses on their bodies. The physics of it just don’t mix. A very complex adapter with lens elements would need to be developed, and the cost and headache of this type of adapter would not be worth the effort. As such, Nikon users are a little more limited in what lenses they can choose from when venturing outside of their brand. As noted by me, a Nikon user, this is very disappointing as Canon does have some great lenses I would like to try (although not enough to want to switch brands). I do not fault Canon or Nikon for this as it is just a product of the difference in design (at least I’ll be optimistic and say that this was not the intention of making the difference in design larger than any other two brands).
The second challenging part about adapting lenses to Nikon bodies is that the registration distance on a Nikon is 46.5mm and is longer than most other major camera manufacturers. By putting a lens on that is designed for a system with a shorter distance, you can be certain that you will not run into issues with the mirror hitting the lens. However, on the other side as the lenses were designed with a shorter registration distance in mind, you may actually lose the ability to focus to infinity (the lens is physically further away from the sensor and the stop that the manufacturer puts in the lens at infinity, will not allow the lens to be focused far enough to make up for that difference. This is exactly the issue of adapting my M42 lenses to my Nikon bodies. There are three main options when you run into this situation. You can use the lens as-is with a simple adapter without being able to focus to infinity, you can use a more complex adapter that uses an optical element to correct for the distance and allow for infinity focusing, or you can modify the stop in the lens to achieve infinity. There are advantages and disadvantages to each of these options. To explore these options, I will let you know what I have done on a few of my lenses.
The main advantage to using a lens as-is is that you do not need to modify any part of the lens, or add additional glass between the lens and the image sensor. By adding in more glass you risk the potential for degrading the quality of the image produced by the lens as every time you pass light through another element, you take this risk. Also, as the adapters are made by 3rd party manufacturers, you risk that the glass used does not have the same quality as the glass in the lens itself. Just as a chain is only as good as its weakest link, a lens is only as good as its worst element. I have a Pentax 50mm f/4 macro lens with an M42 mount, which I picked up for $50 on EBay. It is a fantastic lens with some great bokeh. As it is used for macro work, I use it with a simple adapter and no additional glass element as all of my work involves focusing close and rarely want to use it to focus to infinity. This maintains the optical quality I want for the fine details of macro work while sacrificing a function of the lens that I do not use often for macro work. For this situation this was the best option for me.
The second option is to use an adapter that uses a correcting element to achieve infinity focus. The advantage here is obviously you do not need to modify anything and you can have infinity focus. The drawback is that you are introducing an additional piece of glass between the lens and the sensor. Depending on the adapter you get, this may be just fine, but is also may cause degradation in the image quality of the lens. Often these elements do not have the same quality or coatings as the elements used in the lens. This type of adapter is more expensive than the simple adapters, so going by trial and error as mentioned above can become costly. By doing a little research you can find some that work well. I have actually had pretty good success with my Helios 44-2 58mm f/2 lens using an adapter from Bower. This Helios lens is hard to modify but because I wanted to used it for walking around for different landscapes and scenes, I wanted to have infinity focus available to me. This is also true for a Pentax 50mm f/1.4 that I picked up. It is super sharp and I wanted infinity focus, but Pentax lenses are designed with fairly tight tolerances so the lens was not really an option to modify to obtain the focus I wanted.
Lastly, the most brave and daring option is to modify the lens to allow you turn the lens far enough to obtain infinity focus. As mentioned with my Pentax 50mm lens above, this may not be possible for all lenses. It is most likely not an option, although it may be so do some research, if your lens uses and internal focusing mechanism rather than changing physical the length of the lens to focus, the latter being more common on less expensive lenses which are the best ones to try this option on (I wouldn’t do it on a high end lens, but I also probably would not have spent money on a high end lens with a different mount…see below for more). This type of focusing mechanism where the lens screws and unscrews to change the length of the lens is more common and cheaper. Functionally it is essentially that; a screw that you turn to move the elements closer and further apart from eachother to focus the light. To ensure that when you reach the longest extension of the lens, infinity focus, the lens does not actually unscrew from itself, the manufacturer installs what is known as a “stop” (this one has nothing to do with light though). It is a physical piece of metal or plastic on the inner and outer parts of the screw that hit each other preventing the screw from doing turned any further. Without it, you would just unscrew the lens from itself, and likely damage the lens. As an aside, there is also a stop on the other end of focusing ot prevent the screw from over-tightening, but more importantly to prevent elements of the lens from contacting each other by being moved to close together. You should never modify this stop. Other types of lenses with user a set screw as a stop. I have lenses of both types.
Before embarking on modifying a lens, you should do some research. It is quite possible someone else out there has already tried this and could save you a lot of time and headache before you embark on a modification that is either very challenging or not possible. If you do decide to modify your lens, it is also possible someone has already done it and provided step-by-step instructions on some forums out there which will save you some time as well. There are a few different types of modifications, but the two I have encountered are described in brief here (this is not a tutorial on it some I’m not going to go step-by-step on these lenses). The easier of the two lenses, and the one I successfully modified, was my MTO-1100A, which is a Russian-made 1000mm reflex mirror lens. The particularly lens was probably made in the 1960s and is an absolute beast made of metal. It has a set screw, which prevents the outer housing from being unscrewed from the inner part of the lens. It should be noted that you do have to take off some other simple housing parts to access the screw, but not any parts that could affect the function of the lens. Once you get to the screw, you just loosen it, and physically turn the focusing ring hard enough to have it move a little bit further to reach infinity (thankfully there is quite a bit of room before the screw reaches the end of the thread in the design to do this). Before re-assembling the lens, attach it to a camera after the adjustment to confirm you have hit infinity. Then once confirmed, you can retighten the screw and reassemble the outer housing.
The second adjustment I tried on my Helios 44-2 as I was not sure if it used the same set screw as on my MTO. Unfortunately it requires dissembling the lens, including parts that could cause issues if not put back together properly, and it uses a hard metal stop which is order to modify would require cutting away at the stop to adjust the focus. I did not feel that adventurous, so I did not make the adjustment and instead use a correcting adapter with this lens. It is personal choice to see if this type of adjustment is worth it to you. I have had great success with some of my adapters and did not find the effort and risk worth trying, but you may, so do some research and make the choice for yourself.
So now you know about how to adapt lenses, and what I have done for some of my M42 mount lenses to use them successfully on my Nikon camera bodies. But what types of lenses should you consider adapting? You can adapt most lenses, but because of the adapter you may lose some functionality whether it is ability to use autofocus, or the ability to reach infinity focus. As such, I typically stick with 4 rules when picking a lens to adapt. The first rule is, pick a lens because you like the features and would want it even if it came in the camera mount for your particular system. Don’t pick a lens just because you can adapt it, or because it was cheap. My second rule is to do some research on the type of mount to make sure it is possible to adapt the lens to your camera system and what considerations you might need to take into account. The third rule is don’t bother with lenses that have a whole bunch of electronic features, such as autofocus, image stabilization or chips for distance because likely they will not work when using an adapter and because they were designed for a different camera system. I typically stick with older manual focus lenses and focus more on their image quality than newer features.
Lastly, and this may vary depend on you budget and how the lens will be adapted, but don’t spend a ton on the lens. Look for good quality at a low price, and shop used whenever possible. Often times these older lenses are great optically, but because they are older, people are getting rid of them for pretty low prices. If you want a high end lens for your camera, find a lens that is designed for your camera system as often times the reason for the high quality and price are the newer electronic/automatic features in addition to the quality of the glass and construction. You can just ask yourself, if you didn’t have those features and especially if you need to use a correcting adapter or modify the lens, is it still worth the high price. My guess is a pretty strong “no.” If you really want the highest quality and have the budget, just buy the lens made for you camera system as it is much easier as you know it was designed for and will work with your camera. As you could see I spent $20-$50 on most of my older Pentax and Russian-made lenses and they work great optically. They are only that cheap because they are old and the person selling it has no value in it (maybe they stopped taking photos or inherited it from a family member). Plus, by spending less, you may have more of your budget for additional lenses to adapt to expand your toolbox. Again these are my rules when buying lenses to adapt.
Adapting lenses can be simple or a bit more challenging, but if you successfully do it you will have more tools at your fingertips. So far I mostly stick with old M42 mount lenses as I don’t want to go down the path of having a whole bunch of difference adapters for different lenses. There are a ton of great older lenses out there with plenty of quality life left in them. You can make them work with your camera fairly simply and potentially save some money. Go out and find them and capture the world around you.
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