ASI 294 or ASI071

[Aidan]

Having done a lot of reading with regards to OSC cameras, i have narrowed it down to two cameras which take my fancy and by my calcuations the most suitable for my scope (f7 @ 840mm) which

The 294 gives me a pixel scale of 1.14
The 071 gives me a pixel scale of 1.17

What i am finding difficult is why i should chose one over the other..   With £400 difference between the two cameras, is the 071 really worth the extra money?    From all my reading it seems to be a 50/50 split.

Is the 071 the better bet?  Or, do i save some £££ and just get the 294?

Would really appreciate your comments or experiences.

[vlaiv]

There is more to sensor than pixel scale.

Surface area of 071 is much larger - 294 is 23.4mm diagonal and has surface of 258.36mm2, and 071 is 28.4mm diagonal and surface of 368.16mm2

That is surface increase of ~42.5% for price increase of about 49% price increase - don't know if one should expect exact match in price difference given that sensor is just a part of camera and the rest is the same. I think price is justified.

Question is of course, does your scope support that large imaging circle (corrected field) and do you have the need for such large field?

If that is one of your top considerations - than choice is obvious. Other params are in 294 favor - lower read noise (be careful about read noise jump in 294 - use it with gain above 120) and higher peak QE - estimated to be around 75% while that of 071 is estimated to be around 50%

 

[Adam J]

My big worry about the 294 is calibration as it's not perfect. The newer qhy268c might be a better option than both when they release it. 

[vlaiv]

1 minute ago, Adam J said:

My big worry about the 294 is calibration as it's not perfect. The newer qhy268c might be a better option than both when they release it. 

I was not aware that there is issue with 294 calibration. What is it?

[Adam J]

30 minutes ago, vlaiv said:

I was not aware that there is issue with 294 calibration. What is it?

It's mostly an issue with going deep on galaxy imaging. You see odd gradients in the background sky and they can't be calibrated out using darks. The thinking is that the type of packaging used in the sensor and its size leads to non uniformity in the cooling and results in a interaction with ambient temperature meaning that dark frames taken at different ambient temperature don't calibrate lights. It's a problem that won't always show up though, it can be burried under. Light pollution and won't show up in wide field nebula shots as it will be burried under the signal for the nebula. Hence you see it when going deep in low light pollution. So at the high end it's a limitation. 

Edited June 4, 2019 by Adam J

[Aidan]

It would seem both have their quirks, bit like anything really.

a bit of rational thinking on my part before decision time

[alan potts]

I asked more or less the same question about 2 month back and whilst the two above answered and are well worth taking note of someone said the 294 had some issues with condensation in the cooling, can't recall who it was though. I elected to carry on saving for the 071, which took a hit this weekend as I had to use 300 quid of my saving pot to buy a guitar for my son, so I may now be looking at the 183MC🙃.

[Davey-T]

6 minutes ago, alan potts said:

took a hit this weekend as I had to use 300 quid of my saving pot to buy a guitar for my son, so I may now be looking at to 183MC

My saving pot for a Mesu took a bit of a hit this week as I had to spend £15000.0 on my wifes new car 

Dave

[alan potts]

Dave, but surely 15K is enough to have bought it, and then restart saving for the car.

 

[Davey-T]

47 minutes ago, alan potts said:

Dave, but surely 15K is enough to have bought it, and then restart saving for the car.

 

This has been an ongoing thing, I've manged to stall her for 2 years while I " wasted " money on astro' gear but with another MOT looming it had to be done 

Dave

[Adam J]

2 hours ago, alan potts said:

I asked more or less the same question about 2 month back and whilst the two above answered and are well worth taking note of someone said the 294 had some issues with condensation in the cooling, can't recall who it was though. I elected to carry on saving for the 071, which took a hit this weekend as I had to use 300 quid of my saving pot to buy a guitar for my son, so I may now be looking at the 183MC🙃.

I really don't like the osc version of that sensor. I feel that the tiny pixels combined with bayer matrix leave it lacking in sensitivity. The 294 really is not that much more and despite what I said above it's still a better option for all but the shortest focal lengths. Of course a mono version is a different matter. 

 

[Paul73]

5 hours ago, Davey-T said:

My saving pot for a Mesu took a bit of a hit this week as I had to spend £15000.0 on my wifes new car 

Dave

Ouch!! Dangerous pecedent......

If blessed with a family, never never leave money in a savings account. They have a sixth sense. Spend it before they do.

Paul