Roxsen Focal Reducer Crooked?

[tjdean01]

I bought a PK-m43s focal reducer from "Roxen" (both seller and maker) on Ebay. Works well and I was very happy until I noticed that the lenses spin 5-degrees past the center point. I emailed the seller and got something I don't understand:

"The mount may be little bit poor made, we can offer 15% discount for it."

"The lens is Contax RF mount, but CRF adapter is not recommended because its mount is too deep to fit on digital cameras"

What does that mean? Does it mean they're all like that? I could try to fix it myself with a drill but I don't know how to thread the brass for new holes (I could use the old holes but they might not line up. I could glue, but I don't want to go through all that.




Listing: http://www.ebay.com/itm/Focal-Reduc...3-/400689103350?ssPageName=ADME:X:RTQ:US:1123

 

[OzRay]

That problem is only cosmetic, given that all other aspects are OK ie, both flanges are parallel and the thickness is correct. You'll find these sorts of issues with many of the cheaper products, as they don't have quite the same quality controls as the more expensive brands. I wouldn't bother trying to fix what is not an optical issue, you might end up with a paperweight.

 

[tjdean01]

That problem is only cosmetic, given that all other aspects are OK ie, both flanges are parallel and the thickness is correct. You'll find these sorts of issues with many of the cheaper products, as they don't have quite the same quality controls as the more expensive brands. I wouldn't bother trying to fix what is not an optical issue, you might end up with a paperweight.

True, but square hoods don't look too cool being crooked. And my 200 and I think a couple of the 135s even have a rectangular baffle on the back of the lenses that wouldn't align with my sensor (which luckily is small).

 

[Cruzan80]

You should be able to unscrew the top mounting plate, and then drill and "tap" new threads. A new tap usually only costs less than $5, and you can find one that works with a drill, if you are at all handy.

 

[HarryS]

For a 5 degree misalignment, would there be enough room to put in new holes?

 

[Cruzan80]

Depends on how big the screws are. If it were me, I would take the lens and hold it against the adapter with it at the position I wanted, and mark the adapter with a grease pencil. I would also mark it when it was locked (mis-aligned). Carry the mark from the misalignment down into the chrome, unscrew the three screws, and then rotate the adapter to where it lines up with the second mark. Take your grease pencil and mark the new holes. Then take out the chrome piece and see how much room you have to work with. Generally, since the adapters are black, I would use a red (also shows up well on chrome). If there isnt enough rooom, just re-screw in the existing holes and wipe off the grease pencil.

When tapping holes, it is highly recommended to drill first on a drill press (to ensure it is perpendicular and the correct depth), but DO NOT use the tap in the drill press! Most taps will tell you how much extra needs to be drilled out for a given length of screw (1.5" screw may need 1.625" drilled to accomodate the tip of the tap). If you think you will be doing stuff like this occasionally, Harbor Freight sells a SAE and a SAE/Metric tap and die kit for not too much. IIRC, the SAE/Metric kit is on sale now for ~$30, and comes with a lifetime warranty (useful if you break taps). It will also let you thread rods for screws (dies). Remember to use cutting fluid.

And all the cool kids wear their square hoods at an angle...

 

[stargate]

I am sorry but the making new holes solution will not work for this adaptor. As I see in the picture from ebay there is an additional hole on the side through which the lens release button enters the adaptor. You would have to make another hole for that too and then fill the old one (with epoxy maybe?) and everything will be too messy even if possible. I would grin and bear it. As you mentioned, the square baffle at the back of your lenses should not pose any problem but the rectangular lens hoods will definitely look odd.

 

[Cruzan80]

Or you could do the same on the m43 side, since it is just mechanical.

Sent from my LG-P769 using Mu-43 mobile app

 

[stargate]

Or you could do the same on the m43 side, since it is just mechanical.

Sent from my LG-P769 using Mu-43 mobile app

This is a good idea. If the back of the adaptor is also screwed down and not machined out of the body of the adaptor then if there is enough clearance it would be doable.

 

[Cruzan80]

So tried to write this on my phone several times, and it kept throwing errors at me.

Looking at a generic adapter I have (MD mount) the release lever on the side engages about .25-.375" into the adapter. So depending on how much the top mount needs to rotate, there still could be room to release the lens with pivoting the mount. Without disassembling mine, it looks like the release lever is not connected to the top plate in any way. So depending on how handy you are, you could always unscrew the top mount, rotate the lens enough to correctly line it up, and then see if the release lever still contacts the pin enough. If it doesn't have enough slack, just rescrew the top mount on, and decide to live with it.

 

[HarryS]

I am sorry but the making new holes solution will not work for this adaptor. A.

I missed stargate's original point. but now I see what is meant. The alignment pin on a Pentax lens is what sets the lens orientation. You have to shift the pin 5 degrees or whatever it takes in the adapter body, Moving the pin is not simple. The design of the Roxsen adapter requires the whole assembly to be moved.

Take the 15% discount.

 

[tjdean01]

Thanks for the advice, guys. I ran through all the various options:

1. I simply ordered another focal reducer adapter from Roxen. Still crooked--though not as much. And seems worse optically. So, I planned to return it
   
2. I decided to fix the the first one, but after looking into getting a very tap and chamfer tool to change front of the adapter, I realized that as Stargate said, the locking pin will need to be moved!
   
3. I'm using this mainly on my Pentax 50/1.7, so I could technically simply drill a new locking hole into the rear lens mount. But then I'd have to do the same for my Rokinon 85/1.4, 135/2.8, etc.
   
4. There is a very tiny screw on the m4/3s body side of all of my adapters. It looks like you can remove the screew and turn the lens mount. Unfortunately, you can't. It's once piece. What is that little screw for for then?
   
5. You know how the original Olympus body cap or a lens will 'click' into place but the $2 Chinese body caps won't? On the same note, you can put any lens/adapter on the camera and stop 3mm before the hole reaches the pin so it won't click into place. What if I simply do as Cruzan80 suggested and add another hole in the camera-side of the Roxen adapter 3mm before the first one? I know it would lock into place and be secure. The writing on the adapter would be crooked but that's better than a crooked lens. But, would it damage anything on my body's mount, such as weaken the springy things or anything?

 

[Ulfric M Douglas]

This thread would work better with pictures,
but this ;

What if I simply do as Cruzan80 suggested and add another hole in the camera-side of the Roxen adapter 3mm before the first one? I know it would lock into place and be secure. The writing on the adapter would be crooked ...

Surely that would be obvious and a five minute job?
Was there some complication stopping this being the obvious fix?
(3mm sounds more than 5 degrees though...)

 

[Petrochemist]

Thanks for the advice, guys. I ran through all the various options:

1. I simply ordered another focal reducer adapter from Roxen. Still crooked--though not as much. And seems worse optically. So, I planned to return it
2. I decided to fix the the first one, but after looking into getting a very tap and chamfer tool to change front of the adapter, I realized that as Stargate said, the locking pin will need to be moved!
3. I'm using this mainly on my Pentax 50/1.7, so I could technically simply drill a new locking hole into the rear lens mount. But then I'd have to do the same for my Rokinon 85/1.4, 135/2.8, etc.
4. There is a very tiny screw on the m4/3s body side of all of my adapters. It looks like you can remove the screew and turn the lens mount. Unfortunately, you can't. It's once piece. What is that little screw for for then?
5. You know how the original Olympus body cap or a lens will 'click' into place but the $2 Chinese body caps won't? On the same note, you can put any lens/adapter on the camera and stop 3mm before the hole reaches the pin so it won't click into place. What if I simply do as Cruzan80 suggested and add another hole in the camera-side of the Roxen adapter 3mm before the first one? I know it would lock into place and be secure. The writing on the adapter would be crooked but that's better than a crooked lens. But, would it damage anything on my body's mount, such as weaken the springy things or anything?

The little screw on the µ4/3 is a stop. It fell out & got lost from my tilt adapter, which means the bayonet goes too far & tends to jamb onto the camera!
Changing the µ4/3 mount on the adapter is definitely the better way to go. Might consider it on my RJ reducer (which has the same offset problem) - I don't have any square hoods so the offset hasn't bothered me too much.