Celestron94175 Focal Reducer & Field Corrector Imaging Accessory, Reduces Focal Length & Ratio 37% – f/10 to f/6.3. For Schmidt-Cassegrain Telescopes

I have Celestron C8, this has a focal ratio of F/10. You don't necessarily need to know what that means but Astrophotographers would describe this as a "slow" ratio.Great for planetary obsevation.For nebulae, star clusters etc, still a great all-rounder, but some nebulae are quite large and/or diffuse.The focal reducer gives F/6.3. (faster).This means a wider and brighter field, though magnification can be applied to it, as normal.The Pleiades are almost all available in a low powered eyepiece, the moon is fully observable.When I went comet hunting, it gave me a better all-around view, before zooming in for the Nucleus and Coma.This may be classed as a luxury item, but it Does enrich the brightness and gives wider angle vistas.There are comments that it flattens the field. This means that at the margins of the view, in an SCT, the stellar points of light, can become slightly elongated. This is corrected with this lens.A good purchase for me, I would recomend, a good astronomer's tool, gives options.Is easy to add and take off the Telescope tube, in low light, thanks to the solid/well spaced screw thread.

This seems to work well on my 1970s celestron classic orange tube c8. From what I have seen weather permitting it’s seems to work well. But the weather in the uk has been mixed back over the months and not had a good long time to test the item. But in a short test it’s working well.

Improves the field of view of my 8SE, allowing decent photography of larger DSOs (particularly M42), when using a large sensor (APS-C), stars toward the edge are much smaller, rounder and more point like, but not perfect, there is also some strong vignetting, but this can be dealt with using calibration frames.

Good price including postage and packaging. I am yet to use it however. I needed the item to increase field of view for larger field images such as galaxies etc. The item arrived on time and was well packaged (and sealed) and all is as expected.

A must have for anyone with a scope. You don’t realise how much you need it until you have it.

If you tighten too much - impossible to get off. I can’t shift mine and worried I’ll break it now. But does the job.

Helps get more of the planets and moons in one picture.Used with a Celestron 8SE

Purchased for 5SE telescope in order to be able to use eyepieces set 3,5 - 14mm. In particular to be able to use 3,5 and 5mm lenses which without the reducer produce too big magnification fore the f/10 scope. It did work and for a 'made in China' product it is an exceptional quality item. The glass is spotless and the paint is of the highest standard. No engravings etc. but for the price - no issues with the quality at all. So? What is the problem? Well, I am not an expert in optical field but there seem to be an internal reflection issue when looking at bright objects. In particular, when the moon goes into the field of view a light glare appears and it only goes away when the moon is in the very centre of the view. Moving away from the centre, an irregular shape appears again and it is very disturbing. My scope may be slightly out of collimation but without the reduced this effect is negligible. With the reducer - very strong. It may be a very good product but I would not recommend it for a 5 inch scope.