Description:

My INTES Mk-67 was a 1997-Model scope. The OTA (Optical Tube Assembly) is manufactured in Russia by INTES and features a solid metal construction without plastic parts. The quality of the paint job is ok but not exceptional as on some high-end products. The manufacturers name was applied just with blue gaffer tape. On the upper back side of the OTA is a very practical handle (mine was loose from the first day on). On the bottom there are 1/4 inch and 1/8 inch (two of them) holes for photo tripods. The corrector is protected by an aluminum cap. The scope comes with a black nylon bag.

The Mk-67 is a Maksutov-Cassegrain scope of 150mm ( ~6" ) aperture and 1800mm focal length ( f12 ). It is interesting to note, that the Russians described the optics for several years as f10 (1500mm focal length), the OTA is stamped also with this misinformation! The primary mirror is fixed and doesn't move for focusing. The inner side of the tube is covered with black felt, there are no baffles in the tube. Since the primary mirror is fixed, you won't experience "focus shift" with this scope however the crayford focuser is limited in range.

The secondary mirror is of 51 mm diameter. This works out to a 34% obstruction which means some contrast gets lost on planets. The secondary is not an aluminum spot on the corrector, but a standalone mirror with 3 screws to collimate if necessary.

The Mk-67 comes with a very smooth 2" Crayford-Focuser. A 2"-1,25" adapter is supplied.The two tandem screws you see on the lower side are for locking (left screw in the photo) and for setting the resistance (right).

The scope was delivered with a 7x35 straight through finder with a reticle (not illuminated). The finder is quite dark, so the uniluminated reticle is not very prominent. I think the finder is adequate but at times uncomfortable to look through.

Mount:

My scope was delivered with a Vixen Great Polaris Mounting (GP). I consider the GP adequate for this scope if there is no wind.

I also tried to mount the OTA on a Manfrotto 55C using a fluid head without success. I think the OTA is too heavy for observations anywhere but near the horizon.

Weights:

All together weighs some 18kg's,

OTA with finder, bag, accessories (no eyepieces):	6,5kg
Weight:	3,5 kg
Tripod:	3 kg
Mounting with one motor:	5 kg

Things I liked:

Good optical performance. At star parties it compared very favourably to other obstructed scopes of comparable size showing the planets. However, comparing the jovian moons on a recent star party, a 100mm Zeiss refractor (AS lens) showed them as tiny balls while in the Mk-67 they where a not as sharp on the border.

For deep-sky the scope is adequate but lacks the punch. The Mk-67 will show most bright NGC-objects and offer fine detail on some of the brighter ones.

I had also great success with the sun. With a Baader/Zeiss binoviewer in place, it is easy to see the granulation on the solar surface.

Things I liked less:

You got to deal with a long cool-down time of 1,5 to 2 hours. This reduces the usability if you decide to make use of a sudden break in the clouds or have no place to setup the scope in advance. Until the scope has cooled down to ambient temperature, a considerable amount of detail is lost on planets (and on high magnifications). Actually if you defocus, you see the air "boiling". Since the mirror is mounted firmly at the back and is coated with aluminum on the front (reflecting heat back), the heat probably can't escape easily. After the scope reaches equilibrium, the image improves (almost instantly) suddenly.

Because the primary mirror is fixed, the focusing range is restricted. The Crayford focuser will move only 38mm's, thus the use of ( 2") extension tubes became a necessity for me. Even though the Intes extension tubes are very well made when using heavy eyepieces, the whole construction slightly bends. The Baader-Zeiss bino reaches focus with the 1.7x corrector lens (which has to be installed in front of the prism in order to reach focus and according to Mr. Baader works out to a factor of 1.85 in this configuration). I use the bino viewer with great success and it really improves the views on planets and the sun.

On bright objects (such as the Moon or Jupiter) I noticed that the sky adjacent to the object is considerably brighter than what I saw in refractors.

For more detailed information on INTES scopes please refer to APM Markus Ludes

Jay Reynolds Freeman wrote several reviews of the scope in the late nineties. The set of reviews can be send by mail

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Tahir Saban, Baden Austria. ©2004