Moon Surface via afocal technique

[callingrohit]

hello friends,

I re-attempted to capture good surface images of the moon using a AEPA (adjustable eyepiece projection adaptor) + 2x Barlow + 25mm Plossl EP + Canon 400D.

I have cropped both the moon surface images and also sharpened them in the photoshop.

I found a few difficulties photographying using the AEPA. The adjustable barrel was kept very close to the EP inside the AEPA....ie - it was under minimum eyepiece projection but still focussing was a bit problematic....I did try to adjust the barrel but the best focus was seen at the minimum eyepiece projection. Also, the weather was not quiet good, a lot of air turbulence, so not sure if that was the reason for improper focus a few times....

Using AEPA with a 9mm plossl EP was a pain.....it was just impossible to focus...so thats why I photographed with the 25mm plossl EP.

I would be really grateful if you all could give me suggestions in improving the focus and also let me know your comments on my snaps....

oh yeah i forgot to mention the third image...nothing flashy....i saw saturn and wanted to capture but as i said earlier the weather was very bad and I have no CCD ..... my version of saturn is a bit different from all the other saturn photos on this site....i know its bad but still...;)...

thanks

[iceman]

The first one is pretty good vivek. I'm not sure why they're so grainy?

What settings did you use? How high was the moon when you captured them?

[callingrohit]

Thanks for the comments mike. The 1st image was captured at ISO-400 with 1 sec exposure. I forgot what the focal length was but I think it would have been F/11 but since I had no lens on and just the AEPA, the image data has F/00.

In regards to how high the moon was, I can't say in degrees, but it was pretty high from the horizon in NE. The grainess I think was introduced by PS after I sharpened the image.

[callingrohit]

Mike, any suggestions on better focussing with an AEPA..... any tips would help ???

[iceman]

Are you using the 400D?

[callingrohit]

yeah....unfortunately i have no other camera - digital / CCD....I do have a canon 3000 SLR but thats film and its costly to use for practice....

[jjjnettie]

Hi Vivek,
One second is way too long an exposure when you use a Dob. You'll blur the image.
Try not to go any slower than 1/150 and your ISO under 200 to keep the noise away.
It's hard to find a good compromise when you're trying to keep the image bright but you also want to get in as close as possible.
When I photograph the moon through my Dob, I use ISO 80 and a shutter speed between 1/150 and 1/250.
I find it much easier to adjust focus using the telescope focuser, not through the camera.
Out of 20 photos taken, I might get 2 or 3 that are of good quality.
Good luck

[callingrohit]

Thanks Jeanette.

I'll keep that in mind. In my first attempt (posted a few days ago), I didn't have the AEPA and so I just kept my 400d very close to the EP and took the snap with ISO 400 & 1/125 and got some good results.

But with AEPA, photographying was a bit more difficult. The other problem was as the weight at the focusser increased the dob was just not able to balance itself and I had to put a chair below the tube just near the secondary mirror at the correct elevation to avoid the dob from going down....any suggestions on how to balance the dob. The 400d is heavy plus a 100gm wireless shutter receiver made the dob go down easily....so the chair was handy but that was just a workaround....I would be happy to get a solution.

Thanks

[jjjnettie]

Some counter weight ideas.
Fill a "Bum Bag" with weights/sand/marbles and clip it on to the mirror end of the Dob.
The magnets that you find in stereo speakers, they can get quite large and heavy. Wrap one in a pillow case, to protect your paint job, and stick it to the bottom of the Dob. Won't work on some tubes though.

[callingrohit]

hmmm....thats an interesting idea....now all i need to do is find some subwoofers and speakers .... ;)....I'll have lotsa fun ripping them apart.

thanks.