Final Atik 460 sanity check please

[Nathan_Pembs]

When I was on holidays with parents (and sister) we always had the first two weeks in August and went to Pembrokeshire, West Wales and it usually rained most of the time

Not much has changed Gina lol

[AlistairHowie]

The 460EX with it's larger pixels also has greater dynamic range (larger pixels hold more electrons). The difference is in the region of 25-50%. This means you can achieve 25-50% longer exposures without burning out the highlights.

...

PS: Please feel free to disagree

Is that really correct? The 460EX has a full well capacity of 20,000e, and the 490EX 18,000e. On a single pixel, that would be about a 10% difference, wouldn't it? Of course, photons would hit more than a single pixel. So I've done a basic calculation based on an imaging area of, say 59um, which would represent a collection of 16 pixels on the 490EX and 13 pixels on the 460EX ...

Aik 490EX pixel size = 3.69um

An area of 16 pixels = 59.04um

Each pixel holds 18k electrons

So 16 pixels = 288,000 electrons capacity

Atik 460EX pixel size = 4.54um

An area of 13 pixels = 59.02um (essentially the same as 16 pixels on the 490EX)

Each pixel holds 20k electrons

So 13 pixels = 260,000 electrons capacity

The above implies that the 490 actually has greater dynamic range than the 460, doesn't it? Where am I going wrong with my numbers, and is it really a difference of 25-50%??

My head hurts ....

[Jessun]

Alistair, isn't the pixel size quoted in width, rather than square? I mean 3.69 for instance is the width, meaning you need to square this to get the area. 20.6um vs 13.6um.

Then the example above misses the target in terms of actual numbers, but the thinking may still be valid.

/Jesper

[FLO]

Unfortunately I can't help you with your figures Alistair and we don't have the test equipment necessary to confirm Atik's advice. To be fair, Atik's comments regarding dynamic range tally with our own understanding of pixel size and performance so we would not normally question them.

[AlistairHowie]

Alistair, isn't the pixel size quoted in width, rather than square? I mean 3.69 for instance is the width, meaning you need to square this to get the area. 20.6um vs 13.6um.

Then the example above misses the target in terms of actual numbers, but the thinking may still be valid.

/Jesper

Doh! Yes, of course it is. So re-doing the numbers for the entire chips, since they are the same size, gives a full well capacity of 164 billion electrons on the 490EX versus 121bn electrons on the 460EX. Which just goes to prove that I can do basic arithmetic but haven't actually got a clue what I'm talking about!

Unfortunately I can't help you with your figures Alistair and we don't have the test equipment necessary to confirm Atik's advice. To be fair, Atik's comments regarding dynamic range tally with our own understanding of pixel size and performance so we would not normally question them.

Fair enough. They know their products better than anyone else. I just wish they would give clearer information to help purchasers with their buying decision. You said the 460 has lower noise and higher sensitivity than the 490. That's really important to know, but it's not knowledge that Atik tells its customers. I just wish they would provide more technical specs so that people in the know (not me, I hasten to add), can do some proper comparisons. Rant over!

Perhaps it's time to talk caravans again.

[davew]

If Atik told you ALL you wanted to know about the chip, Sony would kill them

[AlistairHowie]

Well, Starlight Xpress give PLENTY of worthwhile data .... http://www.sxccd.com/products ... makes Atik look positively secretive by comparison!

[Davey-T]

When I was on holidays with parents (and sister) we always had the first two weeks in August and went to Pembrokeshire, West Wales and it usually rained most of the time

You must have been there the same time as us Gina mind I was born at Broadhaven so should be used to it.

Dave

[davew]

Well, Starlight Xpress give PLENTY of worthwhile data .... http://www.sxccd.com/products ... makes Atik look positively secretive by comparison!

If you're referring to just the Atik site then yes, it is a bit short. The manual isn't correct for the 460 yet, just the four series in general. An email to them to update their user manual may sort that. If you look at the FLO site then it gives all you need to know. ( I think )

What information were you after ? Don't look at the specs of one camera against another and think it means a great deal.

Dave.

[AlistairHowie]

If you're referring to just the Atik site then yes, it is a bit short. The manual isn't correct for the 460 yet, just the four series in general. An email to them to update their user manual may sort that. If you look at the FLO site then it gives all you need to know. ( I think )

What information were you after ? Don't look at the specs of one camera against another and think it means a great deal.

Dave.

For the 460EX, for example, FLO provide exactly the same information as the Atik site, although to be fair FLO has at least done the maths that Atik haven't to tell us the sensor horizontal, vertical and diagonal dimensions. Other than that, below is the ADDITIONAL information that Starlight Xpress provide for their 460EX equivalent CCD ...

• CCD quality: Grade 1 or better - No bad columns, no dead pixels, no more than 50 'hot' pixels (saturated in <10 seconds).
  
• Spectral Response: QE max at 580nM (~77%), 50% roll-off at 360nM and 770nM.
  
• Full-well capacity: Greater than 20,000 e- (unbinned)
  
• Anti-blooming: Overload margin greater than 800x.
  
• Dark current: Less than 0.002 electrons/second @ - 10C CCD temperature.
  
• System gain: 0.3 electrons per ADU
  
• Image download time: Typically 5 seconds at full resolution
  

And they provide a nice, absolute QE graph ...

Don't get me wrong, I really like my Atik 4000 and Titan, as well as Artemis Capture. But when you're spending £2k plus is it too much to expect to be presented with the sensor size (I know I can work it out myself, but I'd prefer not to), the full well capacity, a graph of absolute QE, level of dark current and image download time, etc ... and as you say, an up to date manual?

[davew]

Alistair, you've convinced me. You are quite right and I'm wrong.

Perhaps they should take a look at the Moravian site and learn - http://ccd.mii.cz/art?id=374〈=409 as an example.

With all that information you would imagine a headlong rush to buy from a manufacturer who informs their public and even writes articles on things like RBI mitigation. But they don't.

Contact Atik and let them know. They don't necessarily read all these pages.

On the other hand, remember when the 8300 chip came out and some were laughing at the full well depth of 25000e- ? The Sony chips appear worse 20,000e- and 18000e-. Where would that leave your analysis ?

Dave.

[AlistairHowie]

Perhaps they should take a look at the Moravian site and learn - http://ccd.mii.cz/ar...id=374〈=409 as an example.

Not just Moravian, but also QSi, SBIG and FLI too! Even when you look at their OEM targeted Artemis branded CCDs http://www.artemisccd.com/artemis-ccd-brochures-and-data-sheets.html their data sheets don't provide as much information as the consumer web sites of the above vendors. Interestingly, they don't provide the full well capacity for their Sony chipped CCDs, only their Kodak ones where these numbers are 40-60k electrons. Hmmmm ... I wonder why that is??? Oh well, I guess you can't blame them for highlighting a CCDs good points and downplaying less desireable attributes.

So why doesn't Atik provide as much information as others? Laziness? Arrogance? With the exception of at least providing us with damn basic chip measurements, perhaps it's just a desire to simplify things for purchasers ... a sort of "trust us that we've put together a great product with fantastic QE that will work for you" type attitude. They are certainly more mass market/mainstream than, say Moravian or FLI. Perhaps the more techy purchasers migrate to the other manufacturers where you can see all the spec of what you're actually buying.

The thing that I've never done is actually write to Atik to ask them specifics ... for the QE graph, or the dark current, etc. They may well hand that sort of information out when requested.

All I would say is that from a personal point of view, they could do with providing a bit more information along the lines of what SX provide, which would surely cover 95% of all consumer queries anyway. Oh yes, and an up to date manual would be nice

Apologies if this thread has gone off topic again - not as bad as talking caravans - and I'm not an Atik basher, honestly. I'm just personally trying to decide whether to go for a 460 or 490 for my Tak FSQ85, if I decide to come over to the dark size of mono imaging from OSC. The 490 gives better image scale (1.7 versus 2.1) for my Tak at native FL, or 2.3 versus 2.85 when it's reduced. At the end of the day, though, it's 460 higher sensitivity and lower noise versus the 490 higher resolution. For those with time on their hands, there's a good discussion on the two CCDs here ... http://www.progressiveastroimaging.com/viewtopic.php?p=63001&sid=9d12040ab60761d702588d6cd20f92f6

Perhaps I'll wait until those of you with 460s, 490s and FSQ85s have visited Les Granges so Olly can check them out and give us all his verdict!

[Gina]

You must have been there the same time as us Gina :clouds2: mind I was born at Broadhaven so should be used to it.

Dave

I remember Broadhaven - very nice place In those days caravans and tents were spread around the edge of farmers' fields and we had a standpipe for fresh water, bought milk from the farm etc. No electricity laid on or all the mod cons they have nowadays

[swag72]

Perhaps I'll wait until those of you with 460s, 490s and FSQ85s have visited Les Granges so Olly can check them out and give us all his verdict!

I know that Olly has said in the past that a visitors 460EX and his FSQ85 (I think it was) produced the best data that he'd ever seen. There are a few people using the 460EX and FSQ85 so there's certainly enough examples there. X6gas has an FSQ85 and a 460EX and a 490EX - Perhaps he'll do some comparisons if you ask him very nicely. Although, based on the UK weather, maybe not!

[Nathan_Pembs]

You must have been there the same time as us Gina :clouds2: mind I was born at Broadhaven so should be used to it.

Dave

Haverfordwest here, a mere stones throw from Broadhaven

[Davey-T]

Haverfordwest here, a mere stones throw from Broadhaven

Many "happy " memories of holidays at Porthclais (forgive spelling) one time our large bungalow tent blew over the cliff and nearly took my mother with it, spent the rest of holiday in a caravan at Whitesands.

Dave

[Gina]

The tent I was sleeping in was blown away in a storm when we were holidaying on the hill above Saundersfoot (near Tenby)! Torrential rain at the time too! Happy days!

[Davey-T]

And here I was, thinking I caused a thread creep :grin:

/Jesper

I think we can definatley say its crept

Dave

[IanL]

The tent I was sleeping in was blown away in a storm when we were holidaying on the hill above Saundersfoot (near Tenby)! Torrential rain at the time too! Happy days!

The only time we didn't end up in a caravan somewhere in west Wales for holidays was a when the whole family rented a flat over a restaurant in Tenby. Best caravan ever had to be at Kidwelly one year. Railway line was right behind us and the 4:30am mail train got the day off to a great start. Then for the rest of the first week we had the RAF in Hawk trainers circling overhead and strafing/ bombing the range across the estuary for 8 hours solid. Fortunately for my dad's blood pressure (but not the pilot) they managed to stick one in a hill in mid-Wales so the second week was a bit quieter as they were all grounded. Happy days.

[ollypenrice]

Perhaps I'll wait until those of you with 460s, 490s and FSQ85s have visited Les Granges so Olly can check them out and give us all his verdict!

You know, I'm a bit stone age. I have what I have and I take pictures with it. Then I process the data very laboriously... To be quite honest, if anyone thinks that the biggest obstacle between themselves and a great picture is their choice of 460 or 490 or 4000 then... they need to do more imaging! Because all this guff plays only a small role in the big picture. Or so I believe.

Olly

[AlistairHowie]

Amen! The voice of reason as always. Thanks Olly!

[kirkster501]

Amen! The voice of reason as always. Thanks Olly!

+1

Sent from my iPhone using Tapatalk

[kirkster501]

I have gone for it :-) 460EX/EFW2/filters :-) NB filters are the next purchase in a couple of months.

[AlistairHowie]

There goes the summer weather ...

[kirkster501]

There goes the summer weather ...

Lol. Indeed, blown it now. Not been out for three weeks anyway due to weather.....