Wild M400 eyepiece question...

[Ux4]

...I am looking for eyepieces will maintain focus with an M400 throughout its zoom range. I have adapters for 23mm eyepieces, but so far, nothing that I have on hand seems to work. I have tried Meiji, B&L, AO, generic, and Leitz(Ortholux I -Periplan GF 12.5) so far. Any suggestions or tips?

[Conny Forsberg]

You just have to set the parfocality. It has nothing to do with the eye pieces. Just use the originals. Check out how, here. If this is no solution I suspect you need to get the Wild adjusted by professionals. I did like this and my M400 is keeping it's parfocality.

[Tim]

Conny, you have a set of original (short & stubby 30mm oculars) M400 eyepieces, right? These are the ones John is looking for. I just had a quick look around but there don't seem to be any for sale at the moment.

[Ux4]

Conny and Tim,

Thanks for your responses. I do have the Wild eyepieces with which I set parfocality. No optical or mechanical problems whatsoever. The problem arises with other (23mm) eyepieces. From Conny's response, I'll just twist the holders to the limit but I think the travel will be to great for what I have on hand. For 20x eyepieces, I have to move the whole assembly (or stage focus on the Aristophot}. I'll look for another pair of Wild's in any event.

[Lukeness]

Do you already have a 2x auxilliary lense?

[Ux4]

Hi lukeness! Yes, I have the jewel, a pristine one! I had no luck with the 23mm, 20x B&L eyepiece. I will try 10x and 15x B&L and other brands when I have time and will report back here. I have no problem adjusting parfocality with the stock Wilds andthe 2x in place.

[G4Lab]

John the reason your adapters are not working is that they are not placing the aerial image plane from the M400 in the exact location on the interior of the ocular.

You need to keep experimenting andt adjust the 23 to 30mm adapter to adjust the Z axis location of the ocular until you find the spot that works. This is exactly what is accomplished by the instructions which Conny linked to. But there may not be enough travel on the ocular tube focusing mounts to accommodate your ocular and adapter combinations.
Stand the oculars {Wild P10x and whatever type you are wanting to use} up next to one another and examine the relative heights/locations of their internal field diaphragms. Those need to be at the same Z axis location. If your 23>30 adapter has set screws lock them there. If not use some tape to hold them.)
If you do that Conny's procedure which I imagine you have known for decades, should work for you.

Its not working because the focus rings can't get the field diaphragm to the plane it needs to be because 1) the different brand oculars have a different "tube length" requirement than the Wild has and 2) where the field diaphragm lands with and adapter is anybody's guess. You have to run it down by experimentation and beat it into submission. It will work.

And using other brand 15x and 20x oculars is fine because their field numbers shrink so much that you don't loose much compared to 30mm OD. That is not the case at 10x where you can lose several mm.

Be careful to not use oculars that have a lot of chromatic aberation correction built in because you will get color fringing. Use oculars intended for stereos. (as opposed to Huyghens and Compensating oculars) or use Nikon CFoculars.

[Ux4]

Thanks Gene! I do have 10x and 15x Nikon CF's on hand.

[G4Lab]

I do have 10x and 15x Nikon CF's on hand.

[Ux4]

Thanks Gene! I do have 10x and 15x Nikon CF's on hand.

No luck with 1st pair of 10x CF's, 'cept they do render a fine image, flat to the edge, of the slightly smaller FOV compared to the Wilds - just as you said, Gene.