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Anyone try high magnification in their 65mm (1 Viewer)

Dd61999

Well-known member
If so , ow what magnification and how was the view?

I’m more interested in hearing about eyepieces 80x or higher
 

Binastro

Well-known member
Hi Dd61999,
Welcome.

I don't actually own a 65mm Pentax, but if I did I would expect it to be good up to 130x with astro or Pentax eyepieces.
Others here would probably expect a cautious 100x.

I had the Pentax 100mm f/12 astro refractor, the importer's demonstrator, and it was fully useful on planets at 250x and 300x, and tested excellent at 400x.
But a spotting scope is more compromised.

If you have, or can borrow eyepieces from the local astro society, just try them.
 

jring

Well-known member

billb9430

Well-known member
Hello Dd61999,

Welcome to Birdforum!

I have a Pentax PF-65EDaII and occasionally use it with a Pentax XW 3.5mm eyepiece that normally serves for astronomical viewing with other telescopes. The combination gives 111x, a .63˚ true field of view, and an exit pupil of about .6mm. While images at this magnification are sharp and without false color thanks to the ED objective, the very small exit pupil means the image is pretty dim. This is fine for viewing the moon, since it is bright. The moon subtends a .5˚ angle so it nearly fills the field of view at this power. This magnification can also be used as a "long distance microscope" to view critters like garden spiders or insects at fairly close distances in bright sunlight. At short distance, like birds at a feeder, the images are sharp and close up detail is interesting. The problem for birding or other daytime terrestrial viewing at longer distances is the wavy refraction of non-uniformly sun-heated air near the ground. While this somewhat degrades the image at low powers, it makes higher magnifications (often well below 60x) completely unusable. This is why many spotting scopes with zoom eyepieces "max out" in the 50 to 60x range. The other drawback to high magnification is the trade-off in field of view. The higher the power, the smaller the field of view, and consequently, greater difficulty in finding and keeping a bird in the scope field.

Although the Pentax XW and XL eyepieces give nice views, my most-used eyepiece for the PF65 is an adapted 2" 26mm SWA giving just 15x, a 4.5˚ field, and a bright 4.3mm exit pupil. (My preferences here may not be typical of most birders, as I'm kind of a wide field, bright view nut!)

With easy interchangeability of 1.25" barrel diameter eyepieces in the Pentax, the suggestion of "trying out" various eyepieces at a local astronomy club is a great idea. Not all astronomy eyepieces will come to infinity focus in the PF-65, but you can try out or ask here on Birdforum if you find ones of interest. You can economize by buying used eyepieces on astro-classified listings like "Cloudy Nights" (free) and Astro-Mart (fee to join). Most of my eyepieces were purchased used.
Hope this helps. - Bill

If so , ow what magnification and how was the view?

I’m more interested in hearing about eyepieces 80x or higher
 

Dd61999

Well-known member
Hello Dd61999,

Welcome to Birdforum!

I have a Pentax PF-65EDaII and occasionally use it with a Pentax XW 3.5mm eyepiece that normally serves for astronomical viewing with other telescopes. The combination gives 111x, a .63˚ true field of view, and an exit pupil of about .6mm. While images at this magnification are sharp and without false color thanks to the ED objective, the very small exit pupil means the image is pretty dim. This is fine for viewing the moon, since it is bright. The moon subtends a .5˚ angle so it nearly fills the field of view at this power. This magnification can also be used as a "long distance microscope" to view critters like garden spiders or insects at fairly close distances in bright sunlight. At short distance, like birds at a feeder, the images are sharp and close up detail is interesting. The problem for birding or other daytime terrestrial viewing at longer distances is the wavy refraction of non-uniformly sun-heated air near the ground. While this somewhat degrades the image at low powers, it makes higher magnifications (often well below 60x) completely unusable. This is why many spotting scopes with zoom eyepieces "max out" in the 50 to 60x range. The other drawback to high magnification is the trade-off in field of view. The higher the power, the smaller the field of view, and consequently, greater difficulty in finding and keeping a bird in the scope field.

Although the Pentax XW and XL eyepieces give nice views, my most-used eyepiece for the PF65 is an adapted 2" 26mm SWA giving just 15x, a 4.5˚ field, and a bright 4.3mm exit pupil. (My preferences here may not be typical of most birders, as I'm kind of a wide field, bright view nut!)

With easy interchangeability of 1.25" barrel diameter eyepieces in the Pentax, the suggestion of "trying out" various eyepieces at a local astronomy club is a great idea. Not all astronomy eyepieces will come to infinity focus in the PF-65, but you can try out or ask here on Birdforum if you find ones of interest. You can economize by buying used eyepieces on astro-classified listings like "Cloudy Nights" (free) and Astro-Mart (fee to join). Most of my eyepieces were purchased used.
Hope this helps. - Bill

Thanks Bill!

This is what I was looking for. I was only considering high magnification for astronomy.

I was originally looking at a small 60mm apo telescope to use for traveling in my day bag and it was doing double duty for terrestrial views. I found an awesome telescope but I am really worried about it being weatherproof , since many places I go to are fair weather destinations. Hence the reason I’m looking at the Pentax spotting scope.

Like you I’m very big into wide field of views, the fact that I can use wide 1.25 eyepieces are very appealing to me. I’m even more impressed that you were able to fit a 2” eyepiece. Was the modification hard? Is it still weatherproof?

One more question how are the views with Deep space objects at higher magnification?...can you resolve globulars, nebulas, galaxies, etc...?

Thanks again, you were extremely helpful
 

Binastro

Well-known member
The most important thing regarding deep sky objects is how dark your viewing location is, rather than the scope being used.

Nebulas and galaxies won't be resolved except maybe the brightest such as the Orion nebula and M31, M81 and M82.
Planetary nebulae benefit from high power, such as the ring nebula
Globular clusters should be resolved at high power to some degree, although 65mm is a small aperture.

During the day viewing over water, especially if the air, water and ground are at nearly the same temperature, then high powers can be used.
Usually best in autumn and spring.
Especially if around 60F.
 

mayoayo

Well-known member
I had a couple of units of the original pentax pf65ed ,and non of then was well corrected enough to push magnification ,even to 60x ..at 45x with the old swaro 8-24 astro zoom,the image was starting to break down..If you want to use high power regularly, you need some better optics than the ,otherwise ,nice ,compact and rugged little pentax(a nice birding scope).My experience with the Regal 65 is a cherry unit out of one tested,with an incredibly well corrected scope,so i think favorably of the model.Another excellent scope would be the Nikon EDIII,an f:7 scope with extraordinary optics.Some astro eyepieces CAN be adapted to Nikon with excellent results ,but ultimately a good apo astro refractor of similar apertura should give better results at high power.Something like the Televue 60 being what i probably would like ,with the helicoidal draw tube focusser,more compact and field friendlyr
 
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