Sensor Choice for Mallicam Xtreme

[Martyk22]

I'm about to purchase a Mallicam Xtreme but am having difficulty deciding to go for the Exview HD sensor or the regular one. I have spoken to both Rock and Jack about it and they seem to have differing opinions about it and encourage me to get others opinions online. So what do think? 

I will be imaging, at least for the time being exclusively on a fork mount 8 inch alt-az, which Rock seems to think is reason enough to go with the Exview HD.  Jack seems to think the better color saturation, less amp glow and fainter hot spots of the regular sensor outweighs the sensitivity advantage. I realize there's no correct answer, just looking for opinions from people who might have used both. 

Thanks,

Marty

[shirva]

Ken ..dragon man would be ideal guy to give you an independent view on what would be better

davy

[Astrogate]

Martyk22, on 08 Jul 2014 - 6:23 PM, said:

I'm about to purchase a Mallicam Xtreme but am having difficulty deciding to go for the Exview HD sensor or the regular one. I have spoken to both Rock and Jack about it and they seem to have differing opinions about it and encourage me to get others opinions online. So what do think? 

I will be imaging, at least for the time being exclusively on a fork mount 8 inch alt-az, which Rock seems to think is reason enough to go with the Exview HD.  Jack seems to think the better color saturation, less amp glow and fainter hot spots of the regular sensor outweighs the sensitivity advantage. I realize there's no correct answer, just looking for opinions from people who might have used both. 

Thanks,

Marty

Hi Marty

I have beta tested both CCD sensors for Rock Mallin and it all depends on certain factors. Here are my choices for which sensor to use for DSO's.

EXView HAD ICX428AKL CCD sensor

1) If you are going to be observing under dark skies magnitude 5 or better.

2) If you are using a very fast optical telescope like f/2 or faster.

3) If your tracking mount cannot go longer then 30 seconds

ICX418AKL CCD sensor

1) Observe under moderate to heavy light polluted skies (lower then magnitude 5).

2) Will require light pollution filters because of your location

3) Using a scope that is slower than f/3

4) You are using a well tracking mount such as a GEM which will allow for longer integrations providing more detail.

* If you notice the pattern you will see that the EXView HAD CCD sensor is best when your exposures are kept below 4o seconds. The reason for this is that the amp glow will become very dominant in your images plus you will notice more color noise since the saturation must be boosted in order to enhance the colors. In order to keep your exposures below 40 seconds to control the amp glow and color noise, you need to use fast optics and have nice darker skies so filters will not be required. Also since most Alt-Az mounts have tracking issues beyond 30 seconds (esp. when pointing straight up which happens to be the best place to observe), causing field rotation issues.

I honestly do not find that sensitivity that much more between both CCD sensors, but I will give the edge in the red spectrum to the ICX428AKL, but I also give the edge to the ICX418AKL when observing the Hb & OIII spectrum. I would strongly recommend that you spend the extra on a class 0 sensor if you choose the ICX418AKL for the extra benefit of less hot pixels and a smoother image.

Chris A

Astrogate

[Martyk22]

Hmm......if I understand you correctly, it seems like I'm dammed if I do and dammed if I don't:

I would say I fit the bill for the first 3 variables of the ICX418AKL sensor, but I'm using an Alt-Az mount necessitating exposures of 30 secs or less. 

I was thinking that the increased sensitivity of the EXView HAD would allow me to use shorter exposures but that's not your experience? 

[Astrogate]

Martyk22, on 08 Jul 2014 - 7:47 PM, said:

Hmm......if I understand you correctly, it seems like I'm dammed if I do and dammed if I don't:

I would say I fit the bill for the first 3 variables of the ICX418AKL sensor, but I'm using an Alt-Az mount necessitating exposures of 30 secs or less. 

I was thinking that the increased sensitivity of the EXView HAD would allow me to use shorter exposures but that's not your experience? 

Not if your in a light polluted location and need to use filters to cut out the light pollution. The filters will allow you to go longer and improve the contrast and detail but at the expense of more integration. Here is an example (only did the example using two different galaxies) of the two sensors which will provide you a better understanding of both sensors.

M64 with ICX418AKL on the left side and ICX428AKL on the right side

https://www.flickr.com/photos/47296963@N08/7489545478/

M51 with ICX418AKL on the left side and ICX428AKL on the right side

https://www.flickr.com/photos/47296963@N08/7489545974/in/photostream/

Chris A

Astrogate

[Astrogate]

Astrogate, on 08 Jul 2014 - 9:01 PM, said:

Not if your in a light polluted location and need to use filters to cut out the light pollution. The filters will allow you to go longer and improve the contrast and detail but at the expense of more integration. Here is an example (only did the example using two different galaxies) of the two sensors which will provide you a better understanding of both sensors.

M64 with ICX418AKL on the left side and ICX428AKL on the right side

https://www.flickr.com/photos/47296963@N08/7489545478/

M51 with ICX418AKL on the left side and ICX428AKL on the right side

https://www.flickr.com/photos/47296963@N08/7489545974/in/photostream/

Chris A

Astrogate

Marty

I was giving this some more thought and I know you mentioned that you will be in a light polluted area observing so if I were you I would try to get your C8 as fast as possible without any severe distortion by perhaps using a .5x reducer or better but more money an MFR-5 with a 5 & 10 mm spacer which will get you faster than the .5x reducer. If you have or can find a good Meade 3.3 reducer even better. You must keep your exposure times shorter due to the mount so do not use any filters and use the AGC at 3 or 4 and go for the EXView HAD ICX428AKL Xtreme. The Standard ICX418AKL is a great sensor but will require about 25 to 30% more exposure time and your mount probably will not allow for this.

Chris A 

[Martyk22]

Chris

Thanks for taking the time to help me out.  

[Astrogate]

Martyk22, on 08 Jul 2014 - 9:58 PM, said:

Chris

Thanks for taking the time to help me out.  

You are very welcome Marty. I would take your time and go on NSN to watch some live astro shows.

Chris A

Astrogate

[Dragon Man]

I can only speak from my own experience,

I have both Ex-view sensor and a Standard chip in my Mallincam Xtreme, and the results really are chalk and cheese.

Because I have VERY dark sky (zero light pollution, 6.7 mag naked eye) I can run at longer integration times without the worry of getting hot pixels and noise, which I do get with the Ex-View if I run at long integrations.

Fortunately because of the extra sensitivity of the Ex-view I can use shorter integration times, but the result still isn't as nice as the longer Standard results.

But if I lived near light pollution the Ex-view would win hands down. The standard would pick up too much light pollution doing a longer integration.

I hope all that makes sense