Originally posted by semaca Just with a K3 and a 300mm lens can I shoot what kind of stars?
Basically with a K3 and a propper 300 mm lens you can shoot the main (bigger and brighter) deep sky objects like Andromeda, Orion Nebula, Plejades in stunnig quality - wether you have OGPS-1 or not. I have attached some reduced examples of Andromeda, the North America Nebula and Orion Nebula. They are not my best but may give an idea.
OGPS-1 compensates earth's rotation for a while by moving the sensor adequately so that more light gets onto the sensor in one shot without stars making trails. My OPS gives me 10-20 x more exposure time without star trails.
Without OGPS-1 you can shoot the same objects but the exposure time is limited to approx. (500/(focus length x crop factor)) what is about a second time for a 300 mm lens depending on the direction you shoot. Because in this one second you catch only few photons the single picture would be to dim. The technique is to shoot a series of single shots in RAW at high ISO and open aperture (20 to >100 interval shots) and stack the photos, preferebly in a freeware like DeepSkyStacker or another Software that rotates and registers the photos. Stacking also reduces noise and there are several techniques to get the maximum out of your raw data in post processing software. Sounds complicated but is not - to fix a propper dinner in the kitchen is more difficult.
Stacking photos improves also the quality of photos that are shot with OGPS dramatically!