Pentax 105 SDP refractor apokromatski focal length of 670mm and 105mm diameter. It consists of 4 elements into two groups - version Petzval design. In front of the group, one element of SD, and the last of ED glass. This combination provides the image without chromatic aberrations and completely flat field of view with sharp stars to the edge. This refractor can easily shoot Astronomy at 6 × 7 medium format film!

Pentax 105 SDP I bought primarily for astrophotography. For visual observation, there are cheaper solutions, but if the goal is astrophotography, these telescopes have to add costly field-flatteneri, and if finances allow, I think it is better to start, get a telescope that is scheduled to astrofotografiju.

Visually, the 105 SDP is beautiful. It looks solid, and it is with its 6 kg. Unfortunately, the shade is fixed and can not be or unscrew. Fokuser at first sight "normal" rack & pinion, but very solid and can be seen that is designed to present a huge burden. I wish that was accurate or that has the ability finijeg shift, but I had no problems reaching focus or visual or photographic. During the shooting, or one thing has not moved (lost focus) after fixing screws located on the upper side.

Somewhere I pročiato to Pentax with their telescopes guarantees that focuses on stars within 5 micrometers. This requires a precise focus, so I bought this purpose Stiletto fokuser. After viewing photographs of my freshly modified Canon 20D, I noticed a mistake! Yes, the stars were very small and sharp, but - double! All the stars are on the right side had a somewhat darker reflection. After the initial despair to the telescope, something is wrong, it turned out the opposite - the Canon is the replacement filter in front of the CCDA was placed upside down! The telescope is actually so sharp that the error was easily visible.

Comparison of images of the same object (Flame Nebula) Pentax 105 SDP (left) and 10 "Newtonian (right, shot Matthew Pozojevic; click on picture for larger version).

Firstly, the comparison is not fair nor objective nor one nor the other telescope. Finishing operations are different, and the recording of the C10 is reduced to match that of the P105 since the C10 has a focal length of 1200mm compared to 670mm Pentaxovih (images from Pentax is 100% crop size). However, I put in a comparison of details which can be captured, and Pentax here very well compete with much larger diameter, because of the already specified a precise focus. The images created Pentax can also see the "twin stars", ie the reflection caused by wrong placing filters on Canon.

Shooting digital SLR-om, on the edges of the visual field there is absolutely no degradation in quality. Stars on the edges are just as sharp in the middle. So far I've only tried twice to take pictures at 6 × 7 format. Vinjeritanje the angle is expressed, which was expected, but here are the stars sharp enough not to see significant degradation of the image.

Bottom: Flame Nebula and Horsehead. Pentax 105 SDP, modified Canon 20D, Astronomik CLS filter 4 × 8 min exposures @ ISO 800th

Watching the Pentax is a fantastic experience. Although it is only 4 "in diameter, the details of which can be drawn are incredible, and immense contrast. Looking at the Moon with binoviewerom, feeling as though you are in orbit. The shadows are completely black. When I looked at the planets, Mars and Jupiter, the atmosphere is, unfortunately, was very turbulent, even for a 4 "telescope, but at times one could quite make out the details. Enough for detailed study, although the effect is not as impressive as the Moon. Uranus and Neptune are easily visible as a disk expressed colors.

Below: Preparations to observe the Pentax 105 SDP astronomy camp Letenka 2007 . Photo Bojan Markovic .

Deep sky objects also look great. Pentax has a very high-quality coatings on the lenses, and the contrast lets look at curve objects. Up with Peter I noticed no problems G1, a globular cluster galaxy M31, a magnitude 13.7. A view of M31 through a 35mm Panoptic (19x, 2.5 degree field of view) is the first time was better than in any telescope! North America Nebula is easily seen without the filter. It is fascinating how you can observe objects at low magnification, for example, and then put the 5x Powermate for details on the planet.

Pentax 105 SDP is a great visual and photographic instrument. If you are looking for visual APO refractor, there are less expensive telescope that will serve equally well, but when the equation included into astrophotography - here he is second to none.

Below: Pentax 105 SDP on HEQ-5 assembly, astronomy camp Letenka 2008 .

Pentax 105 SDP and 13mm Ethos

View of Lens