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DBK 21AU618.AS vs Mallincam

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#76 Chris A

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Posted 14 April 2013 - 05:51 PM

Yes of course now you are talking about focal ratios like I have explained "What I am saying is for e.g. if you have an APC DSLR size sensor with 9um microns pixels and your 1/4" CCD sensor with 9um micron pixels there will be no boost in sensitivity when dealing with the same focal ratio." The lens is at F1.4 and the refractor at F6.

I think what Andy just posted to you is very valid and you should think about what he said. I am not too sure if you are the one on NSN under the name Luc, but if so then maybe go on NSN and show us the results please.

Chris

#77 budman1961

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Posted 14 April 2013 - 08:02 PM

Thanks Chris!

#78 GlennLeDrew

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Posted 14 April 2013 - 11:11 PM

Certainly, an f/1.4 lens will provide a quite bright image. With most scopes it's not at all hard to achieve f/4; compared to this, f/1.4 is 8X (3 stops) brighter. The question is, will this make up for the lower sensitivity?

#79 Moromete

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Posted 15 April 2013 - 04:35 AM

"What I am saying is for e.g. if you have an APC DSLR size sensor with 9um microns pixels and your 1/4" CCD sensor with 9um micron pixels there will be no boost in sensitivity when dealing with the same focal ratio." The lens is at F1.4 and the refractor at F6.

I think what Andy just posted to you is very valid and you should think about what he said. I am not too sure if you are the one on NSN under the name Luc, but if so then maybe go on NSN and show us the results please.

Chris


I agree with you that equal pixel size means quite similar sensitivity BUT with one amendment: after playing with a Canon 550D and a CCTV with 1/3" Sony SuperHAD II sensor I concluded that if I keep the cctv with AGC on Low and SenseUp x1024 than image brightness/light sources and detail is quite similar to the one obtained with Canon 550D at ISO1600 after 20s exposure. If raise the AGC on High the Canon remains behind. So a Mallincam/DBK/any Sony sensor cctv beats a Canon 550D especially due to increased Gain. Maybe I'm wrong but that's what I observed.

I'm considering the DBK21 because I don't have the money for a Mallincam (not because DBK21 is more sensitive/better than Mallincam because it isn't) and I don't even want to pay for Mallincam especially due to the old sensor and because it has Amp Glow. But I like the images obtained with Mallincam in spite the fact I don't want to expose for longer than 60s.

So you can think about using a Samyang 85mm F/1.4 lens with Mallincam too but it will give a smaller image scale. This way you don't have to go longer than 30s because the Samyang is a super fast lens which beats even a Hyperstar system regarding photon acquisition speed.
My only concern is image scale with a Samyang and a 1/3" or 1/4" Sony sensor which will be almost equal to the one obtained with a Canon 550D + ED80.

What makes me super happy is that with a Samyang 85mm + CCTV/DBK21/Mallincam/QHY IMG0H you can see in only [b]15s[/b] what you see with a Canon 550D + ED80 after a single [b]300s[/b] exposure! At such high photographic speed even a CCTV with SenseUp x1024 will be enough to view DSOs with low brightness. Look here too http://scantips.com/lights/fstop.html

Here is my question: how many DSOs (especially galaxies) can you discern/see some pleasing detail or structure in pictures made with Canon 550D + ED80 WITHOUT image cropping? (because the same image scale will be a 1/3" or 1/4" Sony sensor + Samyang 85mm F/1.4)

#80 jujumaster

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Posted 11 May 2013 - 01:37 AM

That was funny Lawrence.... Thanks. I know I'm late to the party but your earlier reference to narrow minded viewing habits struck a cord with me.






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