Which lens mount works better?
 

Ok, I'm going to start building my adapter this week if some parts ever get here. Right now I am debating on how to work out the lens mount. I've decided to go with the Nikon f-mount (mainly because I have a Nikon SLR). I am deciding now between using an f-mount off an old parts camera on eBay or something like the Nikon BR-3 Mount. The reason I am considering using the BR-3 is because I can use a coupler to connect it directly to the 55mm tube I am using to hold my GG. This would also be helpful should I ever decide to change that mount.

My main point of concern is the locking mechanism. The BR-3 seems to have a straightforward locking mechanism. Having never taken a Nikon apart to see how the locking mechanism on an f-mount usually works, I don't know how that will work if I use an f-mount from an old camera. I know there is the little pin that locks the lens on. But if I use an old f-mount, how do I unlock the lens? Anyone dealt with this before? I'm sure many people have as it is a popular mount. Your thoughts would be most appreciated. And if you were me, which would you go with and why?

With the Nikon mount you will also need to use the spring which fits into a channel in back of the mount ring.

If you don't, your lens will be sloppy in the mount and not focus properly on the film plane, will turn in the mount too easily and eventually fall out. With the spring in place, there is enough friction to keep the lens there most times. I chose not to use the positive locking pin.

The curves on back of the spring which the wings of the bayonet mount on the lens slide over have to be able to exert pressure. So, you must also machine out of the face of the cover you screw the mount on to, shallow reliefs for the curves on the spring to have clearance.

The Nikon mount is adequate for most lenses on a Nikon camera which will be used in this application, but on a relay device there are more weights involved, this mount was not intended to deal with. The Nikon lens mount will bend if you are careless. Those tiny little screws are stronger than you think, even if tapped straight into a plastic case.

The Canon mount may have a bit of an edge for mechanical strength across the whole assembly once a lens is mounted and the ring snugged down.

In practical terms, I have a Nikon lens set, so I continue to use it. If I had Canon, I would use that.

The Nikon mount ring can be had as a replacement part plus the spring. I would be inclined to use this as a used one may have been damaged. I actually used one from the camera and fitted the new one to the camera so I contradict my own advice here.

I don't know why you would use the mount off an old parts camera when you can just get Nikon-mount macro tubes aka extension tubes, and use those. They are available in a variety of different lengths. This makes it even easier to dial in your registration distance (distance from GG to mounting flange of lens/mount).

Thanks for the detailed info Bob.

Crap Bill, I almost had my design finalized!! But what you are mentioning sounds a TON easier than what I had in mind. Might you have a link for these extension tubes with the lens mount already built in? If so that would be great. I'm off to search on my own. Thanks again for the info. If I could find a tube like that I'd be really excited.

Edit: Ok, I've found a ton of these: http://cgi.ebay.com/MACRO-EXTENSION-...QQcmdZViewItem . They seem to be the macro tubes you are suggesting. But my dillema is this. The "camera" end of the tube still seems to have an f-mount. But I am assuming that the first part of the extension tube screws into the f-mount piece. So, I'm thinking that if that first part is threaded then I can just screw it into whatever step down ring I need to attach it to my camera. I've asked one of the sellers what the thread diameter is. Anyone have other information about these types of tubes? I totally wasn't aware of these and they seem to be a much better option.

Check this guy out

http://cgi.ebay.com/Nikon-BR-3-Macro...QQcmdZViewItem

If the link doesn't work just search for Item # 7596410859
It's a lot cheaper than buying that extension tube. The ring is female threaded and 52mm in diamater. And he's a really cool guy to do business with.

RH.

Rich, thanks for the heads up. That's actually one of the pieces I was looking at before I found out about these extension tubes. I agree that BR-3 seems to be a viable option. The only thing that is keeping me from going that route is that the extension tube seems to be an easier way to adjust the distances involved (between the lens/GG and macro lens). Any thoughts on that? Right now I am using a 55mm spacer tube, but it is rather short.

Well, don't know about that much really. I've heard so many different opinions. I'm using a thorlabs tube which is 2inches long and have the BR3 adapter on it. So I guess it's really depends on your taste and how easy it is to use. With the thorlabs tube you can adjust the gg easily if you have a depth probe and a spanner wrench.

Rich,

Since that is a reverser, that's the "other end" of an F-mount. You need the opposite of this; you need the end of the mount that is on the camera or an extension tube.

Rich,

I thought about going with the Thorlabs as it seemed like such a compact and easy piece to use. Having the ability to thread your elements inside was also appealing. Ultimately I passed it up based on cost, but now I think maybe I should have got it. Have you experienced any light leakage with the BR-3 Rich? I've heard there is a bit of light spill through the locking mechanism, but I'd like to hear from you how things have worked. Also, is your adapter static or does the GG move at all? Mine will be static at this time, but maybe someday I'll take it to the next level.

Bill's right in a way. I can see why he is saying it is a reverser. In a way that is true Bill. But the f-mount is exactly like what is on a camera. It has 52mm threads on the other end, so to use it with a Thorlabs tube you just need a 52mm to 52mm coupler. I suppose a combination of step-up/step-down rings would also work.

I have managed to find a company that may or may not be the manufacturer of the extension tube I found on eBay. The company is named Fotodiox and I have emailed them in an attempt to clarify the construction of the extension tube. As I said before, if the individual extension pieces simply screw together then they should be able to screw into a step down ring and work. I'll post my results when I get them.

Mike, it is not what's on a camera. I think it is what's on the back end of a lens, which fits INTO a camera.

The way you use a reverser is, you turn the lens backward and screw the 52mm threads onto the front of the lens. This give the lens a "lens mount" and not a "camera mount." Then you pop the lens mount into your camera so you can do macro photography.

What he needs is a camera mount and an extension tube is the cheapest and easiest way I've found to get that.

Sorry Bill, but I still have to disagree. Hopefully Rich will come back and settle it once and for all. But the BR-3 does have the same f-mount as a Nikon camera.

I understand what you are saying about a reverser, but this is not a standard reverser. The 52mm threads do not screw into the lens, as they are female threads and they are on the inside of the BR-3. I have seen other macro reversers that work exactly as you are describing, but this is not one of those. Rich, come back and settle this. =) I don't like to argue, really I don't. I'm just continuing this for the sake of clarity, as others may want to use the BR-3.

Mike is correct, Its not for the connection between the lens and camera body in reverse. This is designed to attached to the nikon bayonet of the lens, not the camera body, so is perfect for what we need.

Thanks for weighing in Wayne. I've heard of others using these and they seem to work well. If the macro extension tubes I found on eBay and at Fotodiox.com don't work out then I'll most likely go with the BR-3. That's probably the easiest thing for me at this point actually.

Mike,

Let us know how it goes whatever route you go.

Sure thing. I plan to post up my plans and hopefully pictures if I can get my digital camera working again. It's based off the basic static adapter idea. Unfortunately I can't remember who that is attributed to, although I've heard your name thrown around quite a bit Wayne. It's amazing to be among all of these great people who have done so much to make this possible for the common man.

If I can ever get word back from one of the suppliers of this macro tube with the thread diameter, I think this might be a good/cheap alternative for those building their own adapters. One reason is that it takes the cost of your main tube and your lens mount and combines it into a nice $25 package. If I go the BR-3 route it will have cost me at least $30, after all of the shipping and that's assuming I can get a BR-3 for approximately $7-$8, which I most likely won't. But with the macro tube it's all there, nicely packaged. Plus having the removable segments is a plus if you need to alter the distances involved. Anyway, I'm through rambling. I'm just waiting for the thread diameter from these folks and then I'll decide how to proceed.