[Recovered Thread: 82624]

[fmoore]

stnkline wrote:

I am hoping someone will post the off-set of the two rings, 55/62 step-up and 62/55 thread converter for the application of the WCON 07 to the FZ30!

Why not just use a 55mm uv filter? Remove the glass if need be.

[stnkline]

fmoore wrote:

stnkline wrote:

Why not just use a 55mm uv filter? Remove the glass if need be.

I understand from LoveLife and CK that there is a finite distance the WCON 07 has to be offset from the FZ30 to reduce the center softness of this lens. A glassless filter may well have the correct offset. But till one knows what is correct one will never know without a lot of experimenting. Easier to know the correct offset. I have in my notes 0.186 inches but did not record where I saw that offset. I am trying to verify the 0.186 is correct.

Thanks

Stan

[shene]

stnkline wrote:

But till one knows what is correct one will never know without a lot of experimenting. Easier to know the correct offset. I have in my notes 0.186 inches but did not record where I saw that offset. I am trying to verify the 0.186 is correct.

Youhave been fooled by this meaninglessnumber 0.186 inches (or approximately 4.72mm). As a scientist and engineer for many years, if someone quotes this number tome saying thatis the "best" gap, I would justask that person to go back and retake the Physics 101 or Engineering 101 courses. Here is a list of reasons.

First,tools for making consumer productsin general do nothave a 0.001 inch accuracy. Yes, there are computer controlled machines that can produce a surface of thickness accurate to 0.001 inch for sure; but, these tools are for advanced engineering purposes mostly forhigh tech applications rather than for step ring making. One certainly can use those tools to make rings of thickness of 0.186 inch, but just think how much you are going to pay for the machining and material that can provide a constant 0.186 inch thickness.

Second, even though you have a ring that was manufactured with the 0.001 inch accuracy, can a human being mount that ring on a camera lens with a 0.001 inch accuracy? What if the ring is screwed onto the lens cannot maintain that 0.001 inch accuracy? I don't thinkthe hands of a human being can manipulate a ring that requires 0.186 inch accuracy onto a camera lens. So, the "optimal" 0.186 inch is not reachable.

Third, the making of the camera lens and converter lens also subject to manufacturing error. It may be and very likely belarger than 0.001 inch. This means even though you have a 0.186 inch ring, the camera lens and converter lens may not be up to the expectation of using that space age accurate ring. Therefore, the 0.186 inch ring does not make sense.

Fourth, I have never seen a careful and correct derivation of the 0.186 inch number. Nobody published the reasoning behind it. Some one kept saying the same thing here and elsewhere; but, that person was not able to provide any convincing argument to justify his/her result. As a result, I don't even consider this 0.186 inch number a valid one.

Fifth, due to the optical theory of converter lenses, this 0.186 does not make any sense. The theory is too complex to be discussed here; but, if you like, the why 1.5X is 1.5X page of my FZ-30 user guide may offer you some clue.

Given the above reasons, I would suggest just forget this meaninglessnumber. Use whatever ring that can remove the center blur spot. The WCON-07 warning page of my FZ-30 user guide has the details.

CK

http://www.cs.mtu.edu/~shene/DigiCam

Nikon Coolpix 950/990/995/2500/4500/5700, Panasonic FZ-10/FZ-30, and Canon A95 User Guides

[stnkline]

shene wrote:

Given the above reasons, I would suggest just forget this meaninglessnumber. Use whatever ring that can remove the center blur spot. The WCON-07 warning page of my FZ-30 user guide has the details.

CK

OK. If the .186 is wrong what is the offset you used to mount the WCON 07 when you made your tests ofyour lens on your camera.That is if you measured it.The optimum offset may be different with my camera/lens stack.

Granted there will be a tolerance build up of the camera threads plus that of the step up ring and the thread converter one would get .xxx +/- .yyy but I have to start somewhere. . To me that is very simple.No 101 required!

If I had given the offset to one of my machinists in the past it would be a measurement plus or minus some specified tolerance. I could not tell them I did not know the dimension/ tolerance and get a part machined. Precision gearing and mounting in mechanical air data computers in the 50's were in tolerances of +/- 0.0001 inches. Re J4 air data platform for the B58 A shaft size might have been 0.0625+0.0000 -0.0002" Yes: Not a consumer product.The parts would be segregated by measuring to 0.000050" Measuring equipment to 1/10 of that. The bearings were manufactured and inspected and sized in the same manner. Run-out too! But I would get the part machined and inspected to Mil standards and hand assembled in a white room. Granted this is not possible with the consumer camera as you mentioned.

From reading and printing out your reviews you did mention a step up ring and a thread converter. Then: there are nominal dimensions and their tolerances. I.E. the real world. I was trying not to reinvent the wheel by buying various rings and converters and attendant assemblies in order to reduce the soft spot..If this information is propriety informationI can and will live with that.

I have read and printed out all of your reviews thatrelated tomy interests in photography. In this instance I was hoping to benefit from your experience from mounting the WCON 07 on the FZ30. Extremely informative. I salute you.

Thanks

Stan