Lodestar + C14 + Hyperstar

[HiloDon]

Hi All,

As I had indicated in some other posts, I have been working with the Mauna Kea visitors Center here on the Big island of Hawaii, to bring EAA to their outreach program. It has given me the great opportunity to try the SX Lodestar and LL software with their C14 Edge equipped with Hyperstar. The system is really fast at F1.9. Many DSO's can be captured in 5 to 15 seconds giving the system a live view feeling. The most common question from visitors is, "Is this live?"

The admin has been very happy with the results and are buying their own equipment. I have informed them of the potential to use the higher res 825 cams that are just coming on the scene. I am reluctant to advise getting one without seeing some results from users. The Ultrastar would be easy to adapt, since the mounting is identical to the Lodestar. Has anyone seen results from either of the new 825 cams, the Atik Infinity or the SX Ultrastar? I'm still concerned about the increased exposure requirements and noise that comes with it, but they may be a good match with the faster Hyperstar setup. I would appreciate any feedback on experience with these new 825 cams.

I have attached an example of an image captured the other night using the MK system. The FR is 1.9, not F5 as indicated on the image. I forgot to change that from the night before. This is a single capture at 15 seconds. Also, here's a link to my gallery with some other captures from the same viewing session, all at 15 seconds and F1.9. I did do a stack of three on some to smooth them a bit.

http://stargazerslounge.com/gallery/album/3978-lodestar-c14-hyperstar/

Thanks,

Don

[aparker]

Hi Don,

Due to work and clouds I've only had one significant outing with the Ultrastar, but in that first light experience I found the increased FOV and resolution over the Lodestar to be noticeable improvements. I did not change my usual exposure paradigm from the Lodestar (stacking 10 sec subs) and saw no obvious reduction in sensitivity (judged as or time to desirable image detail and brightness). It must be there, given the smaller pixels, but it's not particularly noticeable for me. With a C14, especially at the 700mm FL offered by the Hyperstar, I can't imagine that you'll find sensitivity too much of a problem....

Alex

[Dom543]

Hi Don,

Apart from the shorter exposure times, I don't see much difference between these images and the ones you took earlier with your 8" SCT at f3.3. This is somewhat of a surprise. According to optics theory, the almost twice as large aperture should provide considerably higher resolution. And seeing cannot be blamed on MK. The only explanation I can come up with is that the resolution of the Lodestar is already maxed out with the 8" optics. Or that on diffuse nebulas resolving power doesn't really matter.

I posted my experience with the SX-825 in some detail in August. The short summary is that it appears one stop slower than the Lodestar. That means exposure times would double. But with more aggressive stretching one can stick with the Lodestar exposure times, at the cost of some loss of dynamic range. Exposure times are, of course, not really an issue in the magnitude of 10 seconds. The higher resolution of the 825 is noticeable on a good computer screen but not on internet size jpeg postings. To me the most important improvement is that stars are nicer, more pinpoint, even when no NB filter is used.

All this is just my personal, subjective opinion.

Clear Skies!

--Dom

[nytecam]

Hi Don,

Apart from the shorter exposure times, I don't see much difference between these images and the ones you took earlier with your 8" SCT at f3.3. This is somewhat of a surprise. According to optics theory, the almost twice as large aperture should provide considerably higher resolution.........

All this is just my personal, subjective opinion.

Clear Skies!

--Dom

Dom - I think optical theory takes into account the image scale as well for apparent improvement of resolution! This won't occur via the Hyperstar or heavy focal reduction on a regular scope. Theory and reality don't often work together but just my personal opinion :-)

Nytecam

[HiloDon]

Thanks, Alex, Dom and Nytecam for the feedback,

Alex, I look forward to seeing some results from you Ultrastar. I think you have the mono, but it would be good to see the resolution improvement. If you could, please do some longer exposure single frame captures for comparison.

Dom, you are correct. I don't see much, if any, improvement in image quality from captures with my 8" Meade with the same image scale. I took a close look at a capture of M20 with my Meade and compared it to this one. My subjective opinion is that they are close, but the C14 image shows more detail in the faint Nebulosity especially in the reflection portion. This could be difference in seeing as well. Both images looked much better in their full res format on my MacBook Pro. The one posted here is a reduced res JPEG. The C14 image also had smaller tighter stars with slightly better color. I was using a Baader UV/IR cut filter.

I agree with Nytecam that optics aren't going to mean much for the same image scale, unless you're doing visual. What aperture will do for EAA is give more light and thus shorter exposure to collect the same data. My Meade 8" needs about an F3.4 to get the same focal length as the C14 Hyperstar at F1.9.

Don

[Astrojedi]

Don,

Thank you for posting the captures. I do see more detail especially in the reflection parts of the nebula. I have not been able to capture that detail in 15s exposures with my X2C & C8 @ f2.8. LP may have been a factor in that but still the image does looks 'cleaner'. It is also is virtually free of coma or vignetting (which is what you would expect with a hyperstar.

Hiten

[Astrojedi]

Edit: (still getting used to the fact that I cannot edit posts on SGL)

Don, I am getting my SX Ultrastar mono this week and will post results this weekend (but may be less relevant if you are looking for feedback in the SX Ultrastar color).

Based on the images above in my view the Ultrastar color should not increase exposure times significantly on the setup you have.

Alex, I am interested in seeing some results from your viewing sessions with the Ultrastar.

[HiloDon]

Hiten,

I look forward to seeing results from your Ultrastar. We would prefer color, but the mono should still give us some idea on exposure and resolution.

Thanks,

Don

[nytecam]

Edit: (still getting used to the fact that I cannot edit posts on SGL. .....

You CAN edit SGL posts but only on a time scale of a few minutes !

CN, despite 'using' SGL format, edits up to a day or so (I think) are allowed :-)

Nytecam

[RobertI]

Edit: (still getting used to the fact that I cannot edit posts on SGL)

Don, I am getting my SX Ultrastar mono this week and will post results this weekend (but may be less relevant if you are looking for feedback in the SX Ultrastar color).

Based on the images above in my view the Ultrastar color should not increase exposure times significantly on the setup you have.

Alex, I am interested in seeing some results from your viewing sessions with the Ultrastar.

Hi Hiten,

Just to confirm, you need 50 posts before you can edit your posts. when you have this you can only edit during the 30 minutes after the post.

Rob

[Astrojedi]

Thanks Nytecam, Rob. That is good to know.

[Astrojedi]

Don,

You can find Ultrastar first light captures here: http://stargazerslounge.com/topic/254457-sx-ultrastar-mono-first-light/

Overall really enjoying the bigger field of view... I would say that at x1 bin the Ultrastar mono is maybe 1.5-2 stops slower than the X2 mono.

-Hiten

[HiloDon]

Thanks, Hiten.

I haven't had much time today to analyze your results and tonight and tomorrow I'm going back up to the VIS Center, so I'll respond this weekend.

Don

[Hibou]

I posted my experience with the SX-825 in some detail in August. The short summary is that it appears one stop slower than the Lodestar...

To me the most important improvement is that stars are nicer, more pinpoint, even when no NB filter is used.

Perhaps that's because the 825 has (more) smaller pixels than the 829 in the Lodestar X2 :-) The 825 has 1392 x 1040 pixels of 6.45µm while the 829 has 752 x 580 pixels of ~8.5µm so the pixel area is 74% larger, and if the QE is the same for these same generation chips, the 829 in the lodestar X2 will collect 74% more light.

Of course if you adjust your focal length to have the same FOV, and 2x2 bin the 825, this bigger chip will give you a brighter image. But then you would only have the same resolution, so the stars wouldn't be quite as nice :-) And the 825 is progressive scan readout, while the 829 is interlaced so the more expensive chip has an advantage there too. You do get something more than nicer stars for the extra money of the SX-825 or Ultrastar :-)

BTW, The lodestar X2 is a great camera, but of course it's not really twice as bright as the X1 despite the comparison images :-) If you download those images (unfortunately only 8-bit) and stretch (is that the word?) the X1 image in imageJ, it looks almost identical to that shown for the X2. However, from the distribution of intensities the X2 is apparently more efficient (though you really need to compare the full 16-bit images to make a reliable comparison).

[Hibou]

Has anyone seen results from either of the new 825 cams, the Atik Infinity or the SX Ultrastar? I'm still concerned about the increased exposure requirements and noise that comes with it

image.jpg

Don. Noise with the 825 cams will be much lower than with the 829 in the lodestar X2, if that even matters for exposures as short as yours. The 825 has similar noise to the older 285 equivalent. I don't have an 825 at the moment, but here is a comparison of a long dark field exposure (256s) with an 829 compared to an old 285. If you cool the 285/825 it is even better. I'm not trying to down the Lodestar, a great little camera for short exposures, or compare SX and Atik, just the CCDs they use. Click on the images to get the full frame.

Lodestar X2 256s dark

Atik 314L+ 256s dark

Atik 314L+ cold 256s dark

I'm puzzled why people, especially on CloudyNights, think that the new 825 cams are not much better than the 829 cams, and not worth the price premium. You get what you pay for, and the competition between SX and Atik means that the new UltraStar & Infinity are priced.... competitively.