Hypercam 294C PRO TEC - Sharpcap HCG mode

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sebastien85
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Joined: Thu May 16, 2019 11:13 am

Hypercam 294C PRO TEC - Sharpcap HCG mode

#1

Post by sebastien85 »

Hello,

I have a Altair Hypercam 294C pro tec since few days.

I use Sharpcap and I have a question about triggering the HCG mode: HCG mode is activated at 450 or 900 gain settings ?

I just found this in the sharpcap release notes, and now I have a doubt... ? :
Download Version 3.2.5926.0
21 January 2019

• Altair 294C – switch from LCG to HCG at 900 gain not 450

Thank you in advance and clear sky,

Best regards, 
Sébastien.
Last edited by sebastien85 on Fri May 17, 2019 12:36 pm, edited 1 time in total.
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admin
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Re: Hypercam 294C PRO TEC - Sharpcap HCG mode

#2

Post by admin »

Hi,

In the most recent builds of SharpCap HCG mode enables when the gain is 900 or above.

Cheers, Robin
sebastien85
Posts: 5
Joined: Thu May 16, 2019 11:13 am

Re: Hypercam 294C PRO TEC - Sharpcap HCG mode

#3

Post by sebastien85 »

Thank you Robin :)
dilipsharan
Posts: 7
Joined: Tue Feb 14, 2017 7:00 pm

Re: Hypercam 294C PRO TEC - Sharpcap HCG mode

#4

Post by dilipsharan »

I use both SharpCap and N.I.N.A. with a Hypercam 294C. In this context I saw a NINA article [link below] which confused me! It was about the use of the HGC [High Conversion Gain] switch in NINA and also refer to the implementation in SharpCap. If I understand it correctly then when the HGC switch is set in NINA a gain of 200 in NINA will convert to a native gain of 900 (multiplier of x4.5) at which point the High Dynamic Range boost kicks in. But in SharpCap however there is no HCG switch and it automatically goes to HCG mode and applies the multiplier above 200.

https://nighttime-imaging.eu/docs/maste ... _dualgain/

Is this correct? Or should I be setting the gain to 900 in NINA as well and HCG switch is only set on to get the advantage of High Dynamic Range. I.e. SharpCap handles this better and more transparently from a user perspective.

An additional question regarding Sensor analysis. Why does the gain value jump from 400 to 890 and not go over 1000?

See attached image "Sensor analysis - Hypercam 294C - 14 Bit - 2020-09-23"

Regards,

Dilip
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Sensor analysis - Hypercam 294C - 14 Bit - 2020-09-23
Sensor analysis - Hypercam 294C - 14 Bit - 2020-09-23
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Re: Hypercam 294C PRO TEC - Sharpcap HCG mode

#5

Post by admin »

Hi Dilip,

First I'm going to describe the way the sensor works (and the controls as they are in NINA).

On the 294 sensor, switching from LCG to HCG gives you an extra gain of 4.5x - that is if you turn it on at any gain value your image will suddenly become 4.5 times brighter. There is an important gotcha with the 294 sensor though – if you switch on HCG and keep the basic gain anywhere between the minimum value (is that 100 in NINA?) and 2x (200?), then the image does not saturate properly. This means that you can be badly overexposed and the histogram still won't be hard up against the right hand side if you set HCG mode with a gain of less than 2x.

SharpCap combines the LCG/HCG switch into the gain control on all Altair cameras that have the LCG/HCG option. As soon as you get to the point where switching to HCG is beneficial, SharpCap will turn it on for you and adjust the normal gain appropriately.

For instance, with the 294, if you want a total gain of 10x brighter than minimum gain in LCG, you can (in NINA) either choose

LCG, Gain=1000, Read noise about 5e
HCG, Gain=222, Read noise about 1.5e

SharpCap automatically chooses the latter option for you when you move the gain slider to 1000.

On some other cameras the LCG/HCG brightness change is 2x. You can identify the cameras with HCG/LCG as the read noise graph will have a cliff edge fall in it at the point where the HCG mode is turned on.

Hope this helps, Robin
dilipsharan
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Joined: Tue Feb 14, 2017 7:00 pm

Re: Hypercam 294C PRO TEC - Sharpcap HCG mode

#6

Post by dilipsharan »

Hi Robin,

Thank you very much for the clear and concise explanation about how the LCG/ HCG and Gain work in SharpCap Vs other applications such as NINA. It now makes perfect sense and is what I though it would be but wanted validation.


Many Thanks and Best Regards

Dilip
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