Shortening the eyepiece holder?

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vikeljay

Shortening the eyepiece holder?

Post by vikeljay »

Has anyone shortened the eyepiece holder to gain more in travel for focusing? A local machine shop can do it and even add another hole for the screw to hold the eyepiece. I was thinking about 10mm shorter.


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Re: Shortening the eyepiece holder?

Post by Merlin66 »

Yes, this has been done many times. Usually less than the 10mm you suggest.
The nosepiece of your camera may also need to be shortened, and your eyepieces may "bottom out"


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vikeljay

Re: Shortening the eyepiece holder?

Post by vikeljay »

What would be ideal would be to reduce the size of the part below the eyepiece holder to really increase focus travel. No problem with the cut but reproducing the threads for the eyepiece holder is the problem. Anyone know of a machine shop that can reporduce those threads? Thanks.
Jim


peter drew

Re: Shortening the eyepiece holder?

Post by peter drew »

You can cut out a portion of the eyepiece holder and then make an outer sleeve to rejoin the two parts at the new shorter length. :)


vikeljay

Re: Shortening the eyepiece holder?

Post by vikeljay »

That is a good idea. I would make the cut myself but don't want to mess it up. You say the eyepiece holder. I hope you meant the part that screws into the black box. Will this affect anything else except focusing? Thanks.
Jim


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Re: Shortening the eyepiece holder?

Post by Allcart »

I just took 5mm off the top of my ep holder with a hacksaw. Then drill and tapped a small hole for a new screw. It was a fairly painless procedure and allowed focus with my DMK cameras.


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vikeljay

Re: Shortening the eyepiece holder?

Post by vikeljay »

Thanks. That makes me feel better but I have tried to cut stuff before and I can never get a straight cut so off to the machine shop it goes. What about cutting down the ERF holder? I would think that would be even better.
Jim


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Re: Shortening the eyepiece holder?

Post by JohnM »

This is the mini ERF holder that screws into the black box.



Leave it alone.

This is the eye piece holder, it's what holds the eye piece, it screws into the tube that holds the mini ERF.



This one has been shortened and a second lock screw added.

I read where you had ordered a short nose piece for your camera. It doesn't work?


vikeljay

Re: Shortening the eyepiece holder?

Post by vikeljay »

I have ordered it but it has not arrived yet. Can you explain why I should leave the mini ERF alone? Thanks.
Jim


peter drew

Re: Shortening the eyepiece holder?

Post by peter drew »

Jim. If you use the external sleeve method the cuts don't have to be particularly accurate. Provided that the sleeve is a reasonable fit and the ends are square then it will hold your cut pieces square, no rethreading or new drilled holes. ;)


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Re: Shortening the eyepiece holder?

Post by vikeljay »

Can I do the same thing with the mini ERF?


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Re: Shortening the eyepiece holder?

Post by JohnM »

There's only about 18mm between the cell holding the mini ERF and the threads needed to make the connection to the EP holder.
You go cutting that part to shorten it and try to make a sleeve to joint the parts together again you get into some limited operating room. A "sleeve" would have to be machined to close tolerances plus drilled and tapped with holes at both ends for set screws to lock everything together.
Then you are changing a design dimension in the optical train which has been advised against over and over.
There's nothing to be gained by such a project and much to lose.


vikeljay

Re: Shortening the eyepiece holder?

Post by vikeljay »

What I had planned to do was have a machine shop make 2 cuts and then join the screw parts together - thus shortening it. I would keep the middle piece in case I have to add it back on.
Jim


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Re: Shortening the eyepiece holder?

Post by JohnM »

Give up on all those wild ideas and just stick a barlow in it.
Generally a PST can handle 2-2.5X without a problem.
I used a TV2.5XPM 99% of the time, even after I built the mini stage 2.
Or look at the special camera adapters Siebert Optics offers.


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Re: Shortening the eyepiece holder?

Post by marktownley »

I have ordered it but it has not arrived yet.

Why not just wait and see if this works first ;)


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Re: Shortening the eyepiece holder?

Post by vikeljay »

The mini ERF looks like it can unscrew from its holder. Has anyone done this before? I cannot get it started turning.
Jim


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Re: Shortening the eyepiece holder?

Post by marktownley »

Yes, i've removed several. Use a lens spanner, makes the job easy.


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Re: Shortening the eyepiece holder?

Post by swisswalter »

Hi Jim


yes, I highly recommend a lenspanner, makes modding that much easier ;)


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