Help!? Which of these two CCDs?

[Jezphil]

I am looking at buying a new CCD camera and can’t figure out which of two cameras is technically more suitable, despite reading up on this subject. Would really appreciate any pointers you could give me and thanks in advance…

I’m imaging DSOs with a SkyWatcher Evostar 120 ED, using a x0.8 reducer, so reducing 900mm at f7.5 to 720mm at f6. Seeing conditions mostly not great. Field of view just a bit larger than North America in the North America Nebula, and just about the length of the Andromeda galaxy, so not a big FoV and not an especially small f number. I’m choosing between the Atik 490EX and the Atik 460x. 

460EX

• Sensor Type: CCD - Sony ICX694 /5
• Horizontal Resolution: 2749 pixels
• Vertical Resolution: 2199 pixels
• Pixel Size: 4.54 µm x 4.54 µm
• 490EX
• Sensor Type: CCD - Sony ICX814 /5
• Horizontal Resolution: 3379 pixels
• Vertical Resolution: 2703 pixels
• Pixel Size: 3.69 µm x 3.69 µm

Given the middling f-number, lack of need for a sensor to suit a big FoV, not great seeing conditions, which one should I go for? The 490 has better resolution, but wider field of view with smaller pixels. Any thoughts?

 

 

Edited September 1, 2020 by Jezphil

[wimvb]

The zwo asi 183 and 533 have a similar fov at less than half the price. So the question is, why expensive ccd when much cheaper cmos is an alternative?

[alacant]

On 01/09/2020 at 23:13, Jezphil said:

the length of the Andromeda galaxy,

Hi

If you wish to keep your current telescope and fit in the whole galaxy in one go in a ccd, then you're going to need something like this. 

I don't to think your telescope will cover that size camera though. You could do a mosaic instead however, with either of your choices.

HTH

Edited September 5, 2020 by alacant

[MarkAR]

Using the CCD Suitability calculator the 490EX gives you  a resolution of 1.06 "/px and the 460EX gives 1.3 "/px. Either will be suitable for your set up but bear in mind that the lower the "/px the better your guiding has to be. I think the guiding RMS has to be half or better than the resolution in ideal circumstances.

Edited September 5, 2020 by MarkAR

[david_taurus83]

At longer focal lengths bigger pixels are better but you can bin CCD anyway. Just bear in mind if your buying new the current resale value of those 2 cameras can be less than 50% as CMOS is surging in popularity.

[ollypenrice]

1 hour ago, alacant said:

Hi

If you wish to keep your current telescope and fit in the whole galaxy in one go in a ccd, then you're going to need something like this. 

I don't to think your telescope will cover that size camera though. You could do a mosaic instead however, with either of your choices.

HTH

Even that won't get anywhere near covering the Andromeda galaxy at a FL of 720mm. I used the same chip at only 530mm and still needed a 2-panel mosaic.

(You link to the supplier 'Robtics.' I'll be happy to receive PMs on that subject and to reply to them.)

12 hours ago, wimvb said:

The zwo asi 183 and 533 have a similar fov at less than half the price. So the question is, why expensive ccd when much cheaper cmos is an alternative?

Fair point.

On 01/09/2020 at 23:13, Jezphil said:

 

Given the middling f-number, lack of need for a sensor to suit a big FoV, not great seeing conditions, which one should I go for? The 490 has better resolution, but wider field of view with smaller pixels. Any thoughts?

 

I'm not sure what you feel the F-number has to do with the choice. Uncooled cameras thrive on fast F ratios but with cooled ones you just increase the exposure time.

Will you be able to see a difference in fine detail between 1.06"PP and 1.3? You'd need very good, stable seeing and if you don't have it go for the bigger pixels.

As far as I can see the field of view is identical in both cameras because the chip size is the same.

It would be incredibly helpful if camera manufacturers would stop using the term 'resolution' to say how many pixels per side their camera has. This has precisely nothing to do with resolution which is determined exclusively by pixel size and focal length. GRRRR. What we want to know is chip size in mm per side and pixel size. The rest is 'removed word.'

Am I ranting? Oops!!

🤣lly

[wimvb]

On 01/09/2020 at 23:13, Jezphil said:

The 490 has better resolution, but wider field of view

Actually, both cameras have exactly the same sensor size in mm, so they will also have an identical field of view.

(Olly beat me to it. He's faster on the 'submit' button.)

Edited September 5, 2020 by wimvb

[Alien 13]

4 minutes ago, ollypenrice said:

Even that won't get anywhere near covering the Andromeda galaxy at a FL of 720mm. I used the same chip at only 530mm and still needed a 2-panel mosaic.

 

🤣lly

Not sure you got it all even on that excellent image 

Alan

[Miguel1983]

Can't speak for CCD, never had or used one, but i think the zwo ASI 1600 has to be one of the most popular camera's for AP, but even the 1600 won't get M31 fully covered.

You would need a full frame camera for that, but you Evostar 120 + 2"reducer won't have a image circle large enough to cover that sensor.

Objects like M31, M42, NGC7000, .... ask for a short FL scope or a full frame rig if you can afford it. (if you wan't to shoot them in 1 go, there's always mozaik...)

Edited September 5, 2020 by Miguel1983