Cosmicar/Pentax C-mount 2X teleconverter (1 Viewer)

I won this on ebay this morning for just £1. These tend to be used on CCTV cameras, I already have a couple of Fujinon C-mount ones and have wanted the Pentax version for quite a while. They tend to be offered at much higher prices than the tiny amount I paid though.

I shall try it out on the scope once it arrives and then post up some images.

Paul.

Good for you ! If you try hard enough, there are gems to be had for a song on eBay.

The ones I have seen have been quite pricey! Keep us posted.

The Cosmicar/Pentax TC arrived over a week ago but there hasn't been a great deal of good weather for trying it out. These small c-mount teleconverters generally give around 3X to 4X mag on the scope, this is because the dslr sensor is much further away than the sensor on CCTV cameras. For that reason you really need good weather to get any sort of shutter speed.

Had a sunny day yesterday and you really need a sunny day with this much mag. The TC works fine but there's a bit of red and blue CA quite noticeable and contrast wasn't all that good.

The small Fujinon c-mount was much better with regards to CA and contrast, hardly any CA with that TC. It's slightly longer than the Pentax one so maybe it has more glass in it. The Fujinon one also has much nicer looking multicoatings ranging through various colours depending on how you tilt it to the light, the Pentax coatings were just blue.

The only other c-mount one worth a look at would be the Fujinon 1.5X extender and this would provide a more useful magnification.

Paul.