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ASI294 MC Pro or ASI 2600 MC Pro / QHY268C


smr
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Hi all,

I'm just wondering, given that the retail price is around £1k let's say, for the 294, and double that for the forthcoming 2600/268C, how are they worth 1k more? If they're worth 1k more at all?

 

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I like Richard have the 071 and not long since bought. One never knows when new gear will come along. As much as I feel the new 2600 model will be better, I personally am always reluctant to buy anything right at the beginning of a production run, there always seems to be some issues, no matter what, even cars. I rather fancy the full frame model though not so keen on the price tag. I have seen some very nice shots taken with the ASI 294 though, and 1000 is a fairly large amount in any language.

Alan

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13 hours ago, smr said:

Hi all,

I'm just wondering, given that the retail price is around £1k let's say, for the 294, and double that for the forthcoming 2600/268C, how are they worth 1k more? If they're worth 1k more at all?

 

Well its about double the sensor area and a little more sensitive with no amp glow. So I would say that its actually a bargain for only twice the price as normally prices are not linear with sensor area for a given performance level. The 071 falls outside of that pricing as its a much older sensor generation. 

Adam 

Edited by Adam J
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Yes I saw that beta testing was available. I don't meet the criteria for testing one though.

Here are some charts released today by QHY for their 268C... Not sure I really understand them, what do they mean and are they good results?

79752251_2072673362835936_68350315234527

 

78850081_2072673349502604_83619896567151

79727510_2072673369502602_26760105208756

 

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I think that above are decent results.

For comparison to other models, I would consider blue line to be interesting - that is mode #1 (not sure if there will be modes with other vendors - that looks like it is QHY thing).

It can operate in two distinct regimes, and selection of regime should be based on sky LP levels and how good your guiding / tracking is (exposure duration is the key).

"Low gain" regime (for mode #1) at gain 0: ~60000e FW, ~3e read noise, 0.925e/ADU

(that is quite a bit of full well capacity and very decent read noise for such capacity - dynamic range is about 14.3 in this mode)

"High gain" regime (again for mode #1) at gain 75: FW is ~16384e, read noise is 1.466e and e/ADU is 0.252 (or about 1/4 - which means that 14 out of 16 bits is used in practice).

with these settings we have something like 13.45 dynamic range (not bad at all).

I think we can conclude that in these parameters we have equal or better option with this sensor than other current OSC offerings. Size is of course important - and APS-C size is very nice. What remains to be seen is how well it calibrates.

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It looks like ZWO decided to go somewhere in "between" of my two suggested regimes as their gain 0 setting.

According to specs on ZWO website and this is chart for their ASI2600:

graph-of-2600mc-pro.png

Now if you look at the read noise line for ZWO and above for QHY - blue line (mode #1) - you will see some similarity both are around 3e (ZWO one a bit more) and then fall of below 1.5e (around 1.45 or something like that).

This means that ZWO is using mode #1 for their camera and they don't let user change it to other modes (which is fine if you ask me as mode #1 seems to be the best for AP applications).

At gain 0, ZWO states that their e/ADU is -0.77 - but that is just their lowest gain setting. This corresponds to gain setting of about 19 with QHY model - just look at graph for gain and blue line - 0.77 e/ADU is at about gain 19.

Now look at FW part of QHY graph - again blue line and gain 19:

image.png.d53a05f1f8d5bd81a4eef84b59617b99.png

Same sensor - same values, it is just that ZWO opted to put gain 0 at e/ADU value of 0.77 and at that point sensor has FW of about 50K - hence ZWO claim that their model has FW of about 50K.

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20 hours ago, vlaiv said:

It looks like ZWO decided to go somewhere in "between" of my two suggested regimes as their gain 0 setting.

According to specs on ZWO website and this is chart for their ASI2600:

graph-of-2600mc-pro.png

Now if you look at the read noise line for ZWO and above for QHY - blue line (mode #1) - you will see some similarity both are around 3e (ZWO one a bit more) and then fall of below 1.5e (around 1.45 or something like that).

This means that ZWO is using mode #1 for their camera and they don't let user change it to other modes (which is fine if you ask me as mode #1 seems to be the best for AP applications).

At gain 0, ZWO states that their e/ADU is -0.77 - but that is just their lowest gain setting. This corresponds to gain setting of about 19 with QHY model - just look at graph for gain and blue line - 0.77 e/ADU is at about gain 19.

Now look at FW part of QHY graph - again blue line and gain 19:

image.png.d53a05f1f8d5bd81a4eef84b59617b99.png

Same sensor - same values, it is just that ZWO opted to put gain 0 at e/ADU value of 0.77 and at that point sensor has FW of about 50K - hence ZWO claim that their model has FW of about 50K.

Nice detective work Vlaiv.

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30 minutes ago, tooth_dr said:

This might make a real nice camera for the 180ed? @Allinthehead

If it lives up to the specs, then yes definitely. A Osc camera and an Epsilon are made for each other especially with your dark sky. 

The only concern about the Epsilon with a largish sensor like this makes spacing, collimation and focus even more critical.

I never managed nice round stars all the way to the edges with mine, in fact i don't think i've ever seen an image taken with one and a large sensor which doesn't have some sort of star distortion.

 

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  • 4 weeks later...
12 minutes ago, Allinthehead said:

Took a chance on the Asi2600. Arrives tomorrow. Forecast showing clear all weekend. Surely that can't be right can it?😁

Looks amazing Richard, I'm sure it will produce excellent images in your capable hands.

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59 minutes ago, Allinthehead said:

Took a chance on the Asi2600. Arrives tomorrow. Forecast showing clear all weekend. Surely that can't be right can it?😁

Should be an excellent choice of sensor at the very least. I just wish that they produced a mono version. 

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On 15/01/2020 at 18:46, Allinthehead said:

Hopefully i made the right choice of manufacturer.

I may be buying this camera either this or next month. Looking forward to seeing how you get on with it this weekend, hope you have clear skies and enjoy your new Camera. Keep us posted.

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Will do. Gathering subs on Orion at the moment. All worked as expected, all i had to do was unscrew the 071 and replace with the new camera. Same back focus so no messing around. One thing i've noticed is that my HFR has shot up, i assume that's because of the smaller pixels.

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2 hours ago, Allinthehead said:

I managed to get about 5 hours on Orion. Forecast is clear for tonight so i think I'll keep going. No calibration data yet hopefully get some today.

Great stuff, you had a good night then. I got two hours on M45 but the clouds then rolled in. Looks like it should be crystal clear from 10pm tonight. 

Have you got your new camera on your star 71? Similar focal length to my scope I think if so. Are you using any filters with it ?

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1 hour ago, smr said:

Great stuff, you had a good night then. I got two hours on M45 but the clouds then rolled in. Looks like it should be crystal clear from 10pm tonight. 

Have you got your new camera on your star 71? Similar focal length to my scope I think if so. Are you using any filters with it ?

Yes good night, hopefully fog stays away tonight too. 

I image with an Esprit 100, all that gear in my sig has been sold apart from the AzEq6. I've tried to update it but i can't some error due to the badges i think.

5 hours 240 second subs gain 0 -10 Autostretch in APP. No processing done or calibration

Orion_Auto_stretch.thumb.jpg.256017c0a34104446be455638b5f9b38.jpg

Unstretched to show dynamic range

Orion_no_stretch.thumb.jpg.d13a0c4404c568d0b55c3fbb5d59a42b.jpg

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