New Astronomy Tools Calculator

[FLO]

It's back! 

Earlier this year we announced we were working on a new CCD Suitability Calculator for the Astronomy Tools website. Our aim was to make it easy for someone to determine if a CCD camera and telescope are a good match. We included a link to the experimental calculator and invited comment. Thank-you to everyone who responded with suggestions 

This finished calculator includes many of the improvements you suggested, we hope you find it useful. 

CCD Suitability Calculator

Steve & the FLO team. 

[FLO]

A big thank-you to Grant (FLO's IT manager). Without his enthusiasm, patience and wizardry Astronomy Tools would not exist

[Garethr]

Thanks guys

A really useful tool.  Much appreciated

Gareth

[FLO]

Oops! We forgot the 'Add New Equipment to Database' button 

It is now there so if your telescope or camera isn't in the list please add it. 

HTH, 

Steve 

[FLO]

Reducers and barlows need to be added by us. Most are already listed but we have received a request for the the Takahashi 0.73x reducer and 1.6x extender, they will be added today. If there are others you would like included please ask. 

[Jimtom]

Great tool and very useful.I did not ever realise how much pixel size and "seeing" were related.  I've used the FOV calculator for ages not realising that FLO was responsible! That's a fantastic bit of kit, I've wasted hours playing with that and putting together my "Fantasy Observing " rigs.

[michaelmorris]

Another really useful tool, thanks.

[FLO]

Great tool and very useful.I did not ever realise how much pixel size and "seeing" were related.  I've used the FOV calculator for ages not realising that FLO was responsible! That's a fantastic bit of kit, I've wasted hours playing with that and putting together my "Fantasy Observing " rigs.

Thank-you Jimtown, it is good to hear you are finding it useful

We launched Astronomy Tools back in July 2014. We built it originally for our own use (to help our support people answer customer's questions) then decided to make it publicly available. Up until that point we were using a number of freely available online resources so keeping ours all to ourselves didn't feel right. 

Here is a link to the original thread. 

Steve

[Tim]

Thank you again for this toolset FLO, extremely useful when dealing with lots of variables!!

[FLO]

Thank-you Tim  

It was an interesting challenge but required less time than the FOV Calculator. I remember Grant worked especially hard on that one. 

Steve

[ollypenrice]

I like it, too, but I have a question.

I don't understand this:  but using more pixels than is necessary restricts the amount of sky you can fit onto the camera sensor. 

I'd have thought that the amount of sky which fitted onto the sensor was goverend by the size of the sensor, not the size of the pixels. In our tandem Tak we have two identical chips sizes next to each other (full format Kodaks) but one has 9 micron pixels and the other a larger number of 7.2 micron pixels. They cover exactly the same amount of sky.

Olly

[FLO]

I don't understand this:  but using more pixels than is necessary restricts the amount of sky you can fit onto the camera sensor. 

You can change the effective field of view of a CCD (the amount of sky covered by the sensor) by changing the focal length of the telescope. If your CCD and telescope combination results in oversampling (more pixels than is necessary) you can afford to reduce the telescope's effective focal length (use a focal reducer) which increases the amount of sky that will fit on your sensor. It also makes the image brighter, which is desirable.

Perhaps we should rewrite that part if it is ambiguous

Steve

[FLO]

Perhaps we should rewrite that part if it is ambiguous

Would it help if we use the following text instead?  

Over-sampled images actually look rather nice because the stars are round with smooth edges but if you have more pixels than are necessary why not use a reducer to reduce the telescope’s effective focal length, which makes the image brighter and enables you to fit more sky on your sensor. In affect, over-sampling reduces the sensor’s field of view. 

Steve 

[ollypenrice]

Ah, OK, I see where you are. You are treating the sampling rate as the definitive value and varying the focal length to adjust it. I don't think that's an intuitive approach (maybe just because it just isn't one I've taken!) but I guess you've taken it because sampling rate is your 'constant,' if you like, and the thrust of your discussion. It does make sense but it introduces an amibiguity in regard to sensor size which is highly variable in CCD. I prefer to base explanations on primary rather than derived values, so...

Pixel size and focal length (primary values) define arcseconds per pixel (the most useful derived value.) Too few "p/p and you starve the pixels of light and so slow down the capture in pursuit of a resolution you can't achieve anyway. Too many "p/p and you lose the resolution of which your seeing/guiding/optics might be capable. Once you have chosen a pixel size/focal length (and so a sampling rate) you can then consider chip size and corrected circle in your optics.

Someone coming to this for the first time might be confused when told that pixel size affects field of view.

Please ignore me entirely but, since I'm in the business of explanations, I'm always interested in ways to attack the problem of making them. It is darned difficult to give explanations, which is why it's interesting and worth talking about. 

Olly

[FLO]

Ah, OK, I see where you are. You are treating the sampling rate as the definitive value and varying the focal length to adjust it. I don't think that's an intuitive approach (maybe just because it just isn't one I've taken!) but I guess you've taken it because sampling rate is your 'constant,' if you like, and the thrust of your discussion. It does make sense but it introduces an amibiguity in regard to sensor size which is highly variable in CCD. I prefer to base explanations on primary rather than derived values, so...

We don't think pixel-scale is the 'definitive' value but that is what the calculator calculates so the text is there to support it. It isn't a 'how to choose' article but we have included this advice on the calculator page: 

Pixel-scale (the subject of this calculator) is arguably the most important factor to consider when choosing a camera for your telescope, but there are others: Sensitivity, dark current, read noise, anti blooming, etc. They all play a part. Please don’t base your purchase decision on pixel-scale alone. Most astronomy retailers understand the significance of pixel-scale so will consider it, together with other factors, before recommending a camera / telescope combination. 

Few people understand pixel-scale so instead they (not always, and not everyone) choose a camera according to it's perceived quality and who else owns it. Often I read how someone has this high-end camera to go with that high-end telescope and I am left scratching my head thinking - why!? 

This is only my personal preference but I feel it makes most sense to begin with a short-list of cameras that suit your telescope and seeing conditions, then consider other factors. This calculator makes it easy to do that. You don't need to understand the maths or theory. 

Someone coming to this for the first time might be confused when told that pixel size affects field of view.

I agree and am glad you mentioned it. My preference for short explanations has resulted in an ambiguous sentence. I will expand it

Please ignore me entirely but, since I'm in the business of explanations, I'm always interested in ways to attack the problem of making them. It is darned difficult to give explanations, which is why it's interesting and worth talking about. 

I never ignore you Olly, I am grateful for your feedback and admire your work. I am also watching your progress at SGL and at Les Granges with interest

Steve 

[ollypenrice]

We don't think pixel-scale is the 'definitive' value but that is what the calculator calculates so the text is there to support it. It isn't a 'how to choose' article. We have also included this advice on the calculator page: 

Pixel-scale (the subject of this calculator) is arguably the most important factor to consider when choosing a camera for your telescope, but there are others: Sensitivity, dark current, read noise, anti blooming, etc. They all play a part. Please don’t base your purchase decision on pixel-scale alone. Most astronomy retailers understand the significance of pixel-scale so will consider it, together with other factors, before recommending a camera / telescope combination. 

Few people understand pixel-scale, so often they (not always, and not everyone) choose a camera according to it's perceived quality and who else owns it. Often I read how someone has this high-end camera to go with that high-end telescope and I am left scratching my head thinking - why!? 

This is only my personal preference but I feel it makes most sense to begin with a short-list of cameras that suit your telescope and seeing conditions, then consider other factors. This calculator makes it easy to do that. You don't need to understand the maths or theory. 

I agree and am glad you mentioned it. My preference for short explanations has resulted in an ambiguous sentence. I will expand it

I never ignore you Olly, I am grateful for your feedback and admire your work. I am also watching your progress at SGL and at Les Granges with interest

Steve 

Yes, I see your point. Perhaps I came in a bit 'cold' with regard to your starting point and, also, a bit set in my explanatory ways!

As for progress, well, imaging is a funny game. I think it's made of tiny incremental improvements. At the beginning you can, for sure, make big gains in technique but, after that, it really slows down. We're in a golden age, though. I genuinely believe that.

Olly

[FLO]

Yes, I see your point. Perhaps I came in a bit 'cold' with regard to your starting point and, also, a bit set in my explanatory ways!

As for progress, well, imaging is a funny game. I think it's made of tiny incremental improvements. At the beginning you can, for sure, make big gains in technique but, after that, it really slows down. We're in a golden age, though. I genuinely believe that.

You are right, this is a wonderful time for anyone interested in astronomy. And you make another good point when you say "tiny incremental improvements". I wonder sometimes if you, Sara, Per and anyone else with night after night of clear dark sky realise how very fortunate you are. Because when 'you' make one of those small incremental advances you can apply what you learn the following night, and the next night, and so on. Here in the UK it could be days or even weeks before we can apply what we have learned! 

Steve

[FLO]

... we have received a request for the the Takahashi 0.73x reducer and 1.6x extender, they will be added today. 

Done  

[ollypenrice]

You are right, this is a wonderful time for anyone interested in astronomy. And you make another good point when you say "tiny incremental improvements". I wonder sometimes if you, Sara, Per, and anyone else with night after night of clear dark sky, realise how very fortunate you are. Because when 'you' make one of those small increments advances you can apply what you learn the following night, and the next night, and so on. Here in the UK it could be days or even weeks before we can apply what we have learned! 

Steve

Oh, I do realise this, every single day. I think the others do, too. In fact I often offer it as an explanation when asked how I learned the ropes. The other thing, and I make no bones about this, is that in the early days I knew precious little about it and learned a vast amount from those guests who were already engaged in imaging. Tom was about six months ahead of me and taught me a huge amount, as did many others. And they still do. AP is a kind of self-help society since, so far as I know, you can't sign up for a degree course (or even an 'A' level) in it. The whole thing is based on a constructive exchange between practitioners, retailers, providers, journalists and manufacturers. It's maybe interesting to reflect on the fact that digital AP and the internet revolution are not very different in age. Digital AP and the internet are pretty well inseparable and your resource under discussion plays a part in that. To quote Python, 'I think this is good!'

Olly

[FLO]

That line of text has been updated, hopefully it is now less ambiguous. 

Since we revealed the CCD Suitability calculator (nearly two weeks ago) 206 people have used it a total of 379x, which is nice 

If you are reading this and can see how we might improve any of the astronomy tools calculators, or if would like us to build a new one, please contact us. 

Steve & the FLO team

[Bovski]

Seems Like a bit of a missed opportunity adding some information from telescopes to the Field of View Calculator why not create a database of all the specs into a database then just pull out the information needed for use on any of the calculators It would also make a great reference for OTA's, Eyepiece's, Mounts...

 

[Grant]

31 minutes ago, Bovski said:

Seems Like a bit of a missed opportunity adding some information from telescopes to the Field of View Calculator why not create a database of all the specs into a database then just pull out the information needed for use on any of the calculators It would also make a great reference for OTA's, Eyepiece's, Mounts...

 

That's how it works ?

We don’t ask for data that isn’t used by the calculators though like weight and dimensions etc.. because that data isn’t always readily available and it would create a huge administrative burden to collate and check it plus, if we required people to put that level of detail it would cause a big barrier to actually get people to submit equipment.

[Stub Mandrel]

On 14/12/2015 at 16:44, FLO said:

That line of text has been updated, hopefully it is now less ambiguous. 

Since we revealed the CCD Suitability calculator (nearly two weeks ago) 206 people have used it a total of 379x, which is nice 

If you are reading this and can see how we might improve any of the astronomy tools calculators, or if would like us to build a new one, please contact us. 

Steve & the FLO team

How about a planetary imaging calculator, or just a button on the CCD calculator?

The 'simple' calculation being that ideal planetary imaging scale with oversampled 'lucky imaging' is about 1/3 of that for DSOs.