Crop?

[Shannon]

I notice a lot of you taking great close up shots through lenses that are up to 300mm in focal length. With a telescope at 600mm I'm still not getting that close, even if I crop in after it still looks grainy. So is it a Megapixel problem or am i shooting too high of an ISO.

[dgates]

Shannon, I don't know what the megapixels are with the telescope but I have a Cannon 7D and I can usually crop in pretty far until it gets grainy. Your ISO is also going to make a difference as well.

[Ira Runyan]

Your Canon T3i has a 18MP APS-C CMOS sensor, so you don't have a "Megapixel problem". You could be cropping too much or you could be using too high of an ISO. Another possibility is that the "grain" or "noise" is being caused by the editing software you are using.

I could be wrong, but I don't think that the image quality of a telescope will be anywhere near as good as a telephoto camera lens. 

[Ira Runyan]

Another point to think about.... You may be trying to photograph birds that are too far away.

Have you ever been driving down a highway on a hot day and looked at something far away? As hot air rises from the road, that air is a different density than cooler air, and when light travels through it, the light is bent causing the appearance of "ripples" above the highway. A telephoto lens causes an exaggeration of that effect which causes your background to be distorted and appear noisy.

With bird photography, your best photographs no matter what size lens you use are of birds that are 40 foot or closer away from you.