Camera conumdrum

[bomberbaz]

Hello all.

I have recently acquired a 650 FL reflector and I already have a camera which was actually purchased to be used with another scope which didn't work out.

So problem being is it is the ASI 183MM, px size is 2.4 which potentially leads to oversampling at 0.75"/px

I have been offered a loan camera, the ASI 174MM, px 5.86 which gives under sampling at 1.86.

So clearly neither are ideal but rather than rush out and buy a new camera, I want to test out the rest of the setup for balancing, tracking etc, you get the drift before doing so.

Given the above, I am swinging towards the 174 given most of what I do is from a heavily light polluted garden but anyone else have any pointers as to which may be best suited to test out until I am ready to make a decision on a more permanent solution.

Edited June 26, 2023 by bomberbaz

[ONIKKINEN]

You can bin the 183MM images to get a more reasonable sampling, either x2 or x3. Hardly a point in changing a camera especially since the 174MM has a smaller sensor than your current one.

And by the way, its not really possible to just say that one is oversampled and one is undersampled without knowing the aperture of the scope, the quality of the used flattener/corrector, the typical seeing conditions and so on. But for almost all imagers out there a sampling of 0.75" per pixel is severely oversampled (you got over and undersampling mixed up here, a small arcsec/pix value is typically oversampled not undersampled). Bin x2 with the 183MM might be ideal, or very close to ideal depending on what exact scope the 650mm fl refractor is and what kind of seeing you typically get. If not, bin x3 to 2.25'' is still very good and would consider it "high resolution" if the data supports this resolution.

[bomberbaz]

6 minutes ago, ONIKKINEN said:

You can bin the 183MM images to get a more reasonable sampling, either x2 or x3. Hardly a point in changing a camera especially since the 174MM has a smaller sensor than your current one.

Cheers @ONIKKINEN, After I posted I thought idiot, just bin it. But I had already made post so left it. However I altered the sampling error now, always get that mixed up. It took me 17 years to figure out my twin nephews names for goodness sake.

Anyway, the Data I will be taking will be mainly for spectroscopy. I have devoted quite a lot of time to it, it's been a steep curve but I am slowly getting there and really want to get it right.

I realise with a 130, anything I do manage (spectroscopy wise)  it isn't going to be scientific quality data yet but getting the basics right is important before I am ready to move on to another level. 

Anyway, thanks for the reply. You confirmed my belated thoughts and so bed this side of things. 

Steve

[ONIKKINEN]

14 minutes ago, bomberbaz said:

Cheers @ONIKKINEN, After I posted I thought idiot, just bin it. But I had already made post so left it. However I altered the sampling error now, always get that mixed up. It took me 17 years to figure out my twin nephews names for goodness sake.

Anyway, the Data I will be taking will be mainly for spectroscopy. I have devoted quite a lot of time to it, it's been a steep curve but I am slowly getting there and really want to get it right.

I realise with a 130, anything I do manage (spectroscopy wise)  it isn't going to be scientific quality data yet but getting the basics right is important before I am ready to move on to another level. 

Anyway, thanks for the reply. You confirmed my belated thoughts and so bed this side of things. 

Steve

Actually i mixed up something too, i thought you wrote refractor, but it was a reflector . Anyway with a newtonian your coma corrector will most likely be the weakest link in terms of what kind of resolution you get out of the thing (coupled with seeing of course, but this you cant help really).

[Adam J]

13 hours ago, bomberbaz said:

Hello all.

I have recently acquired a 650 FL reflector and I already have a camera which was actually purchased to be used with another scope which didn't work out.

So problem being is it is the ASI 183MM, px size is 2.4 which potentially leads to oversampling at 0.75"/px

I have been offered a loan camera, the ASI 174MM, px 5.86 which gives under sampling at 1.86.

So clearly neither are ideal but rather than rush out and buy a new camera, I want to test out the rest of the setup for balancing, tracking etc, you get the drift before doing so.

Given the above, I am swinging towards the 174 given most of what I do is from a heavily light polluted garden but anyone else have any pointers as to which may be best suited to test out until I am ready to make a decision on a more permanent solution.

Since when is 1.86 under-sampled and why don't you just software bin the 183 in processing?

Adam

 

[powerlord]

I've never been convinced about the point tbh. I'm pretty much always oversampled - I'd much rather that than blocking stars. And these days with the AI tools available, it seems to me that deconvolution on an oversampled image gets better results than shooting with the 'correct' sampling to begin with.

Plus, certainly where I am, 1.5" seeing is pretty common so even when I'm using something like the 300pds and asi2600 giving me 0.5"/pixel, I don't feel I'm getting soft blurry results after spending time deconvoluting. I've found that when the seeing is rubbish, the results with the 300pds are no better than with my 200pds, but when it's good, they are a LOT better.

however, I am also not a pixel peeper, nor one who typically takes much notice of what I'm 'supposed' to be doing tbh. If I was you, stick to the 174mm unless the seeing is really good, then give the 183mm a try ? I use meteoblue for seeing forecasts and find it pretty accurate.

stu

[bomberbaz]

7 hours ago, Adam J said:

Since when is 1.86 under-sampled and why don't you just software bin the 183 in processing?

Adam

 

It's meant to read potentially, only going of what I have heard/read or been told. If I am honest, I really don't understand these things beyond a given parameter so just go with them.

I had already confirmed in the second post of mine above that I realised binning would work with the 183mm. However it now transpires that the 183mm isn't suitable for other reasons not being discussed here.

So given this I think I will give the 174mm a bash as suggested by @powerlord and see how things work out. I have nothing to lose except a few hours under the stars.

Cheers

Steve