Double Cluster Wide Field

[Chuck]

I was able to get out this past Saturday night to try out using a Canon Extender EF 1.4x II with my Canon EF 200mm f/2.8L II USM lens. Thought I'd try this combination on the Double Cluster, so nothing spectacular here. I was hoping for no distortion in star images to the edge of the field at F5.6. However, I wasn't satisfied with the results and will need to use at least F8 with this setup.

The results can be found in the following Astrobin link. There, I've got a little more detail in the description and where you can also click on the image to see at full resolution.

[bluemax]

Nice Chuck!~ I like the nice clean star field. Was the Canon mounted on the Ioptron? What caused the neat star spikes? I thought those usually came from diffraction from the spyder on dobsonian type scope.

[menardre]

Chuck

Very nice image of the double cluster. I like the wide star field.

I don't know what distortion you are referring too. Looks like nice pin-point stars throughout the image.

I assume the 1.4 extender makes the 200mm into 280mm and probably a F step loss. Dropping to F8 would mean one more F stop. That means doubling the exposure time for the same image.


Roger

[Chuck]

Nice Chuck!~ I like the nice clean star field. Was the Canon mounted on the Ioptron? What caused the neat star spikes? I thought those usually came from diffraction from the spyder on dobsonian type scope.

Thanks Frank. Yep, the Canon and lens was mounted on the iOptron. The spikes around the stars was just from the aperture diaphragm in the 200mm lens. I kind of like them myself but some don't.

[Chuck]

Chuck

Very nice image of the double cluster. I like the wide star field.

I don't know what distortion you are referring too. Looks like nice pin-point stars throughout the image.

I assume the 1.4 extender makes the 200mm into 280mm and probably a F step loss. Dropping to F8 would mean one more F stop. That means doubling the exposure time for the same image.


Roger

Thanks Roger. The distortion was found in the original image where I used all 38 frames taken that night (30 at F5.6 and 8 at F8). The original image is available in the Astrobin link. The Final image was processed with just the eight F8 frames. If you look at both, full resolution, you'll see what I was referring to with the original image (especially on the right hand edge of the image). I was hoping to get away with shooting at F5.6 with the extender but I think I'll have to go with F8. I realize I'd have to double the exposure time but I was only shooting at ISO800. I should be able to go to ISO1600 w/o any issues. I'll have to play around with this combo more to find out. I may try M45 as the next test.

[Bruce D]

Chuck that's an image I'd be proud of, very nice!

[Chuck]

Thanks Bruce.

[Pete]

Opened the full screen image and got sucked in. Oh my! Wonderful!

[Chuck]

Thanks Pete. Hopefully can get more time on it to eliminate/reduce the noise.