10 replies to this topic

[Astrojedi]

Captures and observations from SX Ultrastar mono first light last night.

 

Setup: C8@f4 using Meade 3.3FR (Japan), SX Ultrastar Mono (Sony 825 sensor), AVX EQ Mount, Orion SkyGlow Astrophotography Filter and Starlight Live software v1.1

 

Conditions: Heavily Light Polluted Location (visually only mag 3.5 and brighter stars visible), seeing and transparency both were average but struggled with high humidity later in the evening as the battery powering the dew strip died (forgot to charge it).

 

Initial observations:

• As expected the 825 sensor at a high FR works best for larger DSOs. Overall really enjoyed the larger FOV on nebulae and supernovae remnants but missed the perfect image scale X2 provides for smaller galaxies
• In my view the 825 at x1 bin mode is at least 1.5 - 2 stops slower than the X2 but still is an acceptable compromise between my ‘need for speed’ and ‘need for resolution’
• Starlight Live (lodestar live) SW does not yet have a bin option so could not try it out but I think at x2 bin 825 should provide similar speed as the X2.
• The sensor is very ‘clean’ – very few hot pixels. Very viable for traditional style imaging as well after using darks
• I was surprised by how well the Meade 3.3 performed. There was some vignetting at the corners of the frame and some coma but overall the image was very good (at least for EAA)
• Stacking with Starlight Live SW was much slower and it really struggled to stack frames for objects in rich star fields. It refused to stack 11/15 perfectly good frames with pin point stars for the Wizard Nebula. I don’t this this is a big issue to fix – just need to optimize the registration process a little bit when there are too many stars.

 

You can find the images here: http://stargazerslou...no-first-light/

 

[Dom543]

Hiten,

 

Congratulation to your new camera !

 

Are you sure you mean 1.5-2 stop slower, i.e 3-4 times longer integrations?

Or you wanted to say that it needs 1.5-2 times longer integrations?

My experience was approximately one stop slower, i.e. requiring 2x longer integrations.

 

Paul is working on the stacking issue when there are many (>200) matched stars.

That came up during beta testing last summer.

Until the new optimized algorithm is released, use an H-alpha filter. That takes care of the issue very efficiently..

 

Clear Skies!

--Dom

Edited by Dom543, 08 October 2015 - 03:14 PM.

[Astrojedi]

Thanks Dom.

 

So far I am having to do exposures ~2.5-3x of what I did with the X2 to get the same SNR hence the comment on 1.5 stops slower. Your estimate of 1 stop makes sense given the specs. Of course some subjectivity is inherent in my evaluation hence I may be off.

 

I will try to do a more direct comparison next time I am viewing to ensure conditions are similar. Ultimately at the end of the day I am really enjoying viewing with this camera. Next stop is multi-spectral viewing : ) another great tool to deal with light pollution

 

Hiten

[Astrojedi]

Dom,

So I accounted for the viewing conditions on that night and I think I came out closer to a 1 stop difference. Still need to do a head to head comparison on the same night but I think we are close.

 

Hiten

[nytecam]

Well done - some very nice images:-)  

 

Corner vignetting can be resolved with suitable 'flats' but strangely EAA doesn't seen to be bothered or use them (except me!). Have recently found that chance images of LP cloud base make excellent 'flats' removing both dust bunnies and vignetting :-) 

Nytecam

[Astrojedi]

Thanks Nytecam. I do sometimes use flats but mostly don't bother. But may have to consider it more seriously when using the new larger sensors.

[jonbosley]

Interesting, as I am looking at replacing my old lodestar with either the x2 or the ultrastar. I am surprised that the X2 has that amount of better sensitivity over the ultrastar, I guess it's related to its larger pixel size. I like the idea of a 2/3rds chip over a 1/2" for better Goto's for placement on the ccd and wider field for more guide stars when being used as a guider but the loss in sensitivity over the X2 could be a deal breaker for me. It looks as if the Ultrastar has the same sensitivity as the original Lodestar?

[Astrojedi]

The Ultrastar is more sensitive than the original Lodestar (the QE is much higher). I think the difference vs. the X2 is primarily attributable to pixel size. You can always bin x2 to achieve similar sensitivity to the X2... of course you lose the resolution.

 

In actual use I have not felt the difference in sensitivity. At no point have I said to myself that I should get my X2 out. Also in my subjective experience the Ultrastar produces better detail at full resolution.

 

Having said that if you don't care about the extra resolution I would recommend you go for the X2. It puts less stress on the optics and is $350 cheaper.

[OsirisRA]

I have been playing around with different scope setups with the Ultrastar colour and so far the 825 chip is performing quite well. I don't have a X2 to compare but it seems to be quite sensitive.

 

Some pics here for those interested.

 

https://www.facebook...909921105724539

https://www.facebook...911228178927165

Edited by OsirisRA, 25 October 2015 - 01:50 AM.

[nytecam]

Welcome Ken of G-town to CN EAA and well  done with the SX Ultrastar-C - very nice images.  Didn't manage to get to G-town when we visited Perth awhile back but some of our party's family from G-town joined us briefly in Perth :-) 

Keep up the good work :-) 

Nytecam

[OsirisRA]

Welcome Ken of G-town to CN EAA and well  done with the SX Ultrastar-C - very nice images.  Didn't manage to get to G-town when we visited Perth awhile back but some of our party's family from G-town joined us briefly in Perth :-) 

Keep up the good work :-) 

Nytecam

 

Cheers