Pentax PF-65ED and Pentax PF-65ED II (1 Viewer)

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Sout Fork

Well-known member

• Jan 9, 2008

• #21

eitanaltman said:

Matt is correct, a barlow isn't an eyepiece per se, but an eyepiece adapter that changes the effective focal length of an eyepiece.

Click to expand...

Sort of.
A barlow is what is called a negative focus lens. A barlow intercepts the steep light cone coming off the objectives of the scope and makes this light cone less steep thus extending the focal length of the scope's objectives not the eyepiece.

The typical barlow is often a 2x which means it doubles the focal length of a scope's objectives. Because magnification is computed by dividing focal length of scope by the focal length of the eyepiece and a 2x barlow doubles the focal length of a scope's objectives it also doubles the magnification for any given focal length eyepiece. This gives the impression that the barlow is actiing on the eps optics rather than on the scopes optics which is what's really happening.

SF

 

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young ian

Well-known member

• Jan 9, 2008

• #22

young ian said:

Good-day to all,

I'm feeling a little silly asking this question
but here goes:-

What's a 'Barlow' eyepiece used for?

Kindest regards,
young Ian.

Click to expand...

Good day to everybody.

I would like to thank all contributors
for explaining the 'Barlow' for me.

Many thanks,
young Ian.

 

Tero

Retired

• Jan 12, 2008

• #23

I have some attempts at pictures. Yes, I can focus through the zoom lens at 16x, and the camera I have sort of works. But it is a video camera, not enough pixels to blow up details of this. So, I am waiting for a 32x fixed Pentax eye piece, then need new camera. Or borrow one of my kids point and shoots. The two large birds are pelicans. There are older pictures in my gallery of them.

The zoom eye piece I have may fit some adapters, but I am shooting for Pentax adaper to come out this Feb.

 

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Last edited: Jan 13, 2008

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young ian

Well-known member

• Jan 13, 2008

• #24

I would like to thank all contributors
for explaining the 'Barlow' for me.

Many thanks,
young Ian.[/QUOTE]


Good day to everybody.
I know that I'm not the brightest kid
on the block. But could anyone please help
me with this question.

a) Why do 31mm and 36mm Hyperion
eyepieces cost twice the price of the 8mm
through to the 24mm eyepieces? As in
8,13,17,21 and 24mm are all £65. The 31 and
36mm are £155 and £169 respectively,for less
power!

In microscopy we would expect to pay a
higher price for a more powerful objective lens
or eyepiece.

Kindest regards to all,
young Ian.

 

Can Popper

Well-known member

• Jan 14, 2008

• #25

The 31mm and 36m Hyperions are 2" eyepieces versus the mid and higher power ones who are 1.25" eyepieces.

Wider aperture = more glass = more cost

 

Y

young ian

Well-known member

• Jan 14, 2008

• #26

Can Popper said:

The 31mm and 36m Hyperions are 2" eyepieces versus the mid and higher power ones who are 1.25" eyepieces.

Wider aperture = more glass = more cost

Click to expand...

Hello Can Popper,
Thank you for that explanation. I
thought that the Hyperions were modular i.e.
1.25 or 2" whatever one wanted.

I already have an Hyperion 21mm with which I'm
highly delighted. Thought I would extend my choice
each side of this (21mm) by 36mm and 13 or 8mm
to cover all situations. But,alas,its not to be!

Thanking you again,
young Ian.

 

Can Popper

Well-known member

• Jan 15, 2008

• #27

If you like a 1.25" eyepiece in the 30mm+ power range, go for the Siebert Performance. I recently attached Scopetronix T-rings to it and hooked up my high definition camcorder to it. It is extremely good. And I say this as an owner of the Pentax 10, 14, and 20 XW eyepieces.

Maybe I'll convert my bird video it to mpeg from ATSC and post it on YouTube for you to check out the results.

 

Tero

Retired

• Jan 25, 2008

• #28

I have the 65mm scope, XF12 32x eye piece and Nikon Coolpix camera, I think L11 , have not opened the box. It takes 6MP pictures. Any suggestions on an adapter? I would like a cable release.

 

Last edited: Jan 25, 2008

Tero

Retired

• Jan 26, 2008

• #29

OK, no tips, so I will try the Radian universal, large, adapter. Comes in two sizes, they give you a list of scopes.

 

Tero

Retired

• Jan 30, 2008

• #30

I ordered a Radian, the store, I will not say who, did a bait and switch, sent me a Vortex universal adapter. It seems to work. I tried my wife's camera, see book cover picture from about 30 feet. I will use my own camera outdoors. This one was confused, it used a flash, so will have to turn that off.

The Nikon Coolpix gave lens error easily, so I left a small gap even when the lens was out. Good eye relief with Vixen 16-49x zoom. I have a 32x eye piece on order.

 

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