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Pentax VM 6x21 WP Monocular/ 18x Microscope (1 Viewer)

John A Roberts

Well-known member
Australia
This is one of 2 new V series products recently released by Pentax (there is also a 3-in-1 4x20 binocular/ monocular pair/ 16x monocular)
see at: http://www.ricoh-imaging.co.jp/english/products/binoculars/v-series/

And see more at: https://pentax.com.au/products/63621/pentax-vm-6x21-wp-monocular---complete-kit

It's a 6x21 roof prism monocular that has a close focus to 70 cm (27.6”) in regular mode
and it is also an 18x microscope when mounted on a stand
There is also a smartphone adaptor


John
 

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henry link

Well-known member
The oddest thing about this device is surely the use of a Schmidt-Pechan prism configured to produce the same off-set as a Porro. Why didn't they just use a Porro, since it would have been cheaper and optically superior? I can't think of another example of an off-set S-P prism used in any modern optic.
 

Binastro

Well-known member
At least the phase coating suppresses goose, which should be a good thing?

What type of goose, I wonder?

What about a duck?

Regards,
B.
 

Binastro

Well-known member
The Canon 15x45 IS binocular may have used roof prisms with some offset.

But 20 years old now.

Regards,
B.
 

John A Roberts

Well-known member
Australia
Hi Henry and David,

The reorientation and elongation of the Schmidt-Pechan prism pair - to produce the significantly offset objective and ocular axes - was presumedly to meet the particular design brief
i.e. the combination of both significant vertical offset and minimum width, to work with the hand hold and top mounted rocker focuser

The simpler Porro prism option was perhaps not chosen due to its greater width when vertically orientated. Though considering the VM's price (B&H Photo lists it for US $200),
it must have been long considered

And it would seem that a simpler roof prism option was also dismissed: the 4 reflection Sprenger-Leman design of 1895


John


p.s. for some more information about various types of roof prisms used in binoculars, see posts #32 to #34 at: https://www.birdforum.net/showthread.php?p=3935264
 

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John A Roberts

Well-known member
Australia
Hi Henry,

If I correctly understand your image, the two transmission faces are vertically in line? If so, the image will be neither inverted nor reversed

As indicated in the first image, each prism flips the image about its apex, so:
- the first vertically orientated prism inverts the image top-to-bottom, then
- the horizontally orientated prism reverses the image side-to-side

The classic Noblex (nee Turmon) monocular helps make the point: it folds flat for storage and carry, but the 2 prisms need to be at 90 degrees to correctly function


John
 

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jring

Well-known member
The oddest thing about this device is surely the use of a Schmidt-Pechan prism configured to produce the same off-set as a Porro. Why didn't they just use a Porro, since it would have been cheaper and optically superior? I can't think of another example of an off-set S-P prism used in any modern optic.

Hi,

when I saw this I was quite sure it must be a porro until I found the design drawing... most peculiar. Phase coated roof prisms seem to a big selling point - regardless whether they are useful or not.

The other item in the series, a 4x20 IF roof pair is even stranger... you can take the two tubes apart and use individually as two monoculars to share and also mount them behind one another as a 16x telescope...

The mechanics to allow this and not loose collimation is a bit mind-boggling...

https://pentax.com.au/products/63600/pentax-vd-4x20-wp-binoculars

Joachim
 

Alexis Powell

Natural history enthusiast.
United States
I preordered the Pentax VM 6x21 WP Monocular. It seems very interesting...

I think it is interesting that Pentax chose to produce the product because I don't find it a compelling choice for any practical purpose. What is the purpose of this monocular? It seems excessively large for a 6x21 compared to Nikon or Zeiss monoculars. It seems to me that the performance of the 6.5x21 Papilio binoculars should blow it away with their binocular viewing and much closer and likely more precise focus.

--AP
 

PeterPS

MEMBER
I preordered the Pentax VM 6x21 WP Monocular. It seems very interesting.
Why would you think it is very interesting? I had my "monocular period" some years ago and tried many of them---some were reasonably good (the best was a Zen Ray 10x40) but none was really satisfactory.
 

[email protected]

Well-known member
Supporter
Why would you think it is very interesting? I had my "monocular period" some years ago and tried many of them---some were reasonably good (the best was a Zen Ray 10x40) but none was really satisfactory.
Just for the fact that it is roof prism design and I like the ergonomics and the way it is focused so you can use it with only one hand. It is also much smaller than the 6.5x21 Papilio and 1/2 the weight and has a bigger FOV of 8.2 degrees @430 feet versus the Papilio's 7.5 degrees @ 393 feet. The best monocular I have used is the Leica Monovid 8x20.
 
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fazalmajid

Well-known member
Hmmm. Looks bigger than even the Minox Makroscop 8x25. The main draw would seem to me to be the 18x microscope function.
 

[email protected]

Well-known member
Supporter
Hmmm. Looks bigger than even the Minox Makroscop 8x25. The main draw would seem to me to be the 18x microscope function.
Yes, but the Minox Macro scope 8x25 is essentially a two handed optic, whereas, the Pentax VM 6x21 WP Monocular can be used in one hand. That for me is the big draw. Also, the Minox Macro scope 8x25 only has a 6.5 degree FOV and 12 mm of eye relief, whereas, the Pentax VM 6x21 WP Monocular has an 8.2 degree FOV and 17.8 mm of eye relief.
 

dries1

Member
Pentax

Hmmm. Looks bigger than even the Minox Makroscop 8x25. The main draw would seem to me to be the 18x microscope function.

I agree with this, I would use the microscope in the field, the other feature not so much. Perhaps for someone at an art exhibit?... when they have to leave those 8X56 Dialyts at home.

Andy W.
 

[email protected]

Well-known member
Supporter
I got a Pentax VM 6x21 WP Monocular from Amazon.com. They are very cool because you can use them with one hand. The optics are very good being sharp to the edge and having a very wide FOV and the focuser is the bomb. It is one of the best and handiest monoculars I have ever used. I highly recommend it.
 

PeterPS

MEMBER
I got a Pentax VM 6x21 WP Monocular from Amazon.com. They are very cool because you can use them with one hand. The optics are very good being sharp to the edge and having a very wide FOV and the focuser is the bomb. It is one of the best and handiest monoculars I have ever used. I highly recommend it.

My experience tells me to stay away from monoculars but I have to agree with you that this little Pentax is interesting, especially its seesaw focuser--Can you describe how it works?
 

[email protected]

Well-known member
Supporter
My experience tells me to stay away from monoculars but I have to agree with you that this little Pentax is interesting, especially its seesaw focuser--Can you describe how it works?
It fits your hand perfectly and you just push down on either end of it to focus. It is really fast and easy and the focusing is accurate. Much faster and easier than a knob rotating focuser. It almost makes me wish binoculars had a focuser like this monocular does. Very cool!
 

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