Jupiter Oct 15th, 2 scopes & 2 cameras

[Space Cowboy]

Just going through avis from last night, seeing was not great with a stiff breeze. Decided to compare the DFK with spc webcam. Also took a shot with the Skymax 127 and DFK.

3 images below One using DFK & Auto Dob 250, one using spc webcam and Dob and the other is DFK with Skymax....but which is which???

Exhibit A

B

C

[AztecastroMcJ]

1st is dob n spc

2nd is mak n dbk

3rd dob n dfk ?? i think

nice comparison

[todd8137]

looks like you hit the nail on the head with those

great stuff

[neil phillips]

Aha some new ones. wondered where you was. good captures stuart. Its weird i thought seeing was going to be good, but my images were quite soft. think i overpowered, untill it was too late. Must resist massive power lol. Work on the contrast. You do what i do. but as Luis said without contrast they can look pale. Anyway you got some to be playing with now and your best yet i think. good stuff

[Space Cowboy]

1st is dob n spc

2nd is mak n dbk

3rd dob n dfk ?? i think

nice comparison

Yep spot on James! Not much in it though I was surprised how the webcam shot compared though after going through most of the avis I think seeing did improve when the webcam shot was taken.

[Space Cowboy]

Aha some new ones. wondered where you was. good captures stuart. Its weird i thought seeing was going to be good, but my images were quite soft. think i overpowered, untill it was too late. Must resist massive power lol. Work on the contrast. You do what i do. but as Luis said without contrast they can look pale. Anyway you got some to be playing with now and your best yet i think. good stuff

Cheers Neil! Yes it was difficult last night with a stiff breeze. I was not expecting anything to shout about but there are a few decent shots. The seeing had gone worse for the DFK shot here so i guess that's why the webcam image compares so well as that was taken just after the best DFK shots (on other thread).

Thanks Todd!

[bigal1]

Nice collecton of images Stuart and a very interesting comparison , i'm suprised how well the little mak does compared to your big dob although i guess the conditions didn't help too much . Thanks for posting

[Clayton]

Nice shots Stuart. You must have been a busy boy!

[Space Cowboy]

Nice collecton of images Stuart and a very interesting comparison , i'm suprised how well the little mak does compared to your big dob although i guess the conditions didn't help too much . Thanks for posting

Thanks Alan, yes the mak is a super little scope as you keep proving. I used a 3x tal and then upscaled the image 130% to match the 2 Dob shots.

[Space Cowboy]

Nice shots Stuart. You must have been a busy boy!

Cheers Clayton. First time I've imaged with 2 scopes on the same night lol Was curious to see a direct comparison.

[neil phillips]

Its a interesting test, and yes your right the spc seems to have done better than it should, all i can say is i know if i had only a spc i would not have been able to produce the results i have recently. Not only does 60 fps often out perform 30 fps ( not always granted ) with the same camera. But pushing the focal length to a point where i have about 5mm either side of the imaging chip would be impossible with the standard spc 900.

The histogram would be so dim the blue channel would be almost completely dimmed out. Indeed i have had to switch to using 30 fps on the blue channel at these focal lengths because even this more sensetive ccd can not cope. the spc under these conditions would die a horrible death. Dont forget Stuart your test involved single shot colour camera where all the channels are working in tandem the bright red, and slightly less bright green. Doing mono work, and pushing the cameras to there very limits would reveal a different result, mainly because the blue would almost certainly pull the image quality down.

Even though the red and green would fair probably ok. And there would be little point in getting good reds and greens when the blue would be so hard to see. its histogram would likely not even be trackable by stacking software. Of course one could Go down to 15 fps on the blue to raise the histo, but on a night of jittery seeing like i had on the 15th. would affect the quality of the blue, because at these focal lengths and with the jittery seeing described. The shutter speed would just not be fast enough to pull anything out other than a very blurry and soft blue. Even at 1/30th secs exposure my blues suffer this effect of not having a fast enough shutter speed to really beat seeing as well as the 60 fps 1/61 secs red and greens.

So i know this to be true from past and present experiance. So i agree your test shows how good this little camera is, I got good results with it for years. But when some one is trying to raise there game to new heights. dont think for one second that these things do not matter. If anyone is not convinced and has a mono spc 900 that they would like me to run these tests on showing side by comparison of the seperate channels and colour combined final result, then i would certainly give it a go. Having a spc 900 mono with the new 618 chip mode. would change the result dramatically. with this camera probably getting much closer to what im describing.

But again even though the levels problem could be sorted using this chip as a comparison. the abillity to shoot at only 10 fps would again severly effect the final stacked colour result, At 60 fps capturing for 45 secs ( my focal length must be at least 12 meters i think ) so fast capture times become important, though agreed winjupos changes this situation a little. But even then the more frames versus less frames problem would still apply

I would get 2700 frames for 45 secs, At 60 fps recently because its been jittery, ive been stacking about 1500 of those on the red. The spc 900 mono 618 on the other hand at 10 fps ( some say 5 is better because of compression, i prefered 10 ) would capture 450 frames, so going by the amount i lost recently 2700, down to 1500, thats nearly half the frames in bin, due to blurring of fine details.

Do that with the spc 900 mono 618 at 10 fps. i would be stacking about 250 frames a channel. I can say the images would be lacking detail. and badly noisy. It would not allow any kind of decent sharpening routines ( 250 frames is way way to low) so as mentioned i would run the tests if anyone is not convinced, After i agree this test almost suggests otherwise.

But i wanted to point these things out stuart to others reading this, as begginers wanting to go foward may well think theres little point in getting a better planetary camera. Thats not the case. I hope ive explained my reasoning for beliveing this. Theres likely reasons why its done so well Stuart, as you mention seeing for starters. but that is not the only reason i dont think. All 3 channels combined is also relevant here. And if the two cameras are pushed to there limits i belive other differences would start to show. Meaning say 12 meters ( or higher not sure what im at ? ) the more you push the focal length, the dimmer the histogrames become. The more difference you would start to see with the spc 900 ( old chip ) and the more sensetive new 618 ccd. Take the older spc 900 out of its comfort zone pushing harder and harder. More differences would start to show i think.

[beamish]

Great pics Stuart and a very interesting comparison!

[cgarry]

I am not going to try and guess which is which, but I do want to congratulate you on your skills with the humble little SPC webcam. This shows that those without lots of spare cash to spend on cameras can still produce great images.

Cheers,

Chris

[Space Cowboy]

Thanks Karlo & Chris.

Don't worry Neil I'm not suggesting we bin our IS cams ;-) Here is a better comparison I was a little unfair to the DFK as that shot was in poorer seeing than the spc and have used a DFK shot taken closer to the spc (15-20 mins).

DFK shot:

Spc 900:

[Space Cowboy]

What does concern me about the DFK is the high level of noise compared to the Spc webcam. That spc image is only 500 frames stacked compared to 3800 for the DFK shot. A 500 frame stacked DFK shot would be far too noisy and even 1500 frame stacks have noise. I assume its because of the 60fps speed but it kinda looses its advantage taking 6 times the amount of frames if you need to stack 6 times as many to produce an image with the same noise level as a spc shot.

Having said all that I'm still learning with the DFK and the Oct 15th avis were too dark (still not using histogram only judging brightness by eye) The spc frames were much brighter (1/61 sec exposure DFK and 1/50 sec for SPC). Might try 1/50 sec with the DFK next time.

[Gina]

Very interesting, thank you