W7MEV

Question concerning astro cameras. I had a Meade DSI which was a CCD camera early on. It eventually died and I replaced it with an uncooled ZWO 178C. I used the Meade software with the DSI and am using SharpCap with the ZWO. I expected the ZWO, being years and years newer, to have much better sensitivity and less noise than the DSI did, but it really doesn't seem to be that way. In addition, comparing old pictures from the DSI and new ones from the ZWO, the DSI pictures seem to be sharper and with tighter focus. Perhaps the ZWO shows more of a tendency to bloom with longer exposures. Night before last I tried for Orion, but when I got enough exposure to get a really good nebula the stars bloomed to huge fuzzy balls. Tried various combinations of exposure times and camera sensitivities, but nothing was really good.

Can someone give me a short rundown on the practical differences between the two technologies and what kind of results I should expect for sensitivity and focus from the ZWO.

Also, recommendation for a camera that will show really tight focus and maybe minimum blooming on bright stars with longer exposures?

I would appreciate all efforts!!!

DJO

Nikon D200.

amfoto1 Loc: San Jose, Calif. USA

I am not familiar with the specialized cameras you mention....

But all DSLRs, all "mirrorless" and most of the mid to high-end compact point n shoot digital cameras now use CMOS.

The Nikon D200 mentioned was the last Nikon to use a CCD sensor. A friend who I worked with a lot was using a pair of those and was always reluctant to use ISO above 400. I was shooting alongside her with a pair of Canon 30D with CMOS sensors and was able to use two stop higher ISO with less noise problems (Canon was the first DSLR manufacturer to convert to CMOS in all their DSLRs, beginning in 2001.... all others have followed since). When she used her D200s at higher ISOs, she had to apply heavy noise reduction that made for significant loss of fine detail. When the Nikon D300 with CMOS sensors were introduced in 2007, she was one of the first in line to trade up from her D200s!

Now every Nikon, Canon, Sony, Olympus, Pentax, etc. DSLRs and most of their other types of cameras are using CMOS, which has continued to improve. Canon and Nikon both have made some "astrophotography" models over the years, too.... which were essentially CMOS sensor cameras with weakened or "cancelled" low pass or anti-alias filters (Canon 20Da and 60Da, for example). Today there are a number of DLSRs that have weakened or cancelled AA filters anyway (such as the 50MP Canon 5DS-R, 46MP Nikon D850, 42MP Sony a7R III), so AFAIK they no longer make specialized models for astrophotography.

Low pass filters were used over both CCD and CMOS sensors to reduce moire in images. That's an optical issue that can occur when photographing anything with a repetitive pattern. Moire is caused by the "Bayer array" of pixel sites used with both types of image sensors. The AA or low pass filter deliberately blurs the image slightly, so it needed to be re-sharpened in post-processing (either in-camera or in computer). This also cost some fine detail. The cameras now being made without those filters - to gather every last little bit of detail possible - use other methods of minimizing moire, or leave it up to the user to remove it from images if necessary.

I don't know if this helps or not... It's not a direct answer about the specialized cameras you're consider. But it's fair to say that among DSLRs and many other types of digital, CMOS has proven superior and won out over CCD. Medium format digital continued to use CCD for some time longer, too... but also have largely converted to CMOS now, too. At the other extreme, even many camera phones are now using tiny CMOS sensors. Her'es more detailed info about CMOS (also called "CIS"), it works, is manufactured, and has supplanted CCD: https://semiengineering.com/cmos-image-sensors-cis-past-present-future/

rehess Loc: South Bend, Indiana, USA

non sequitur

n3eg Loc: West coast USA

Watch out for the Sony A7R II and III though - I've heard that they are "star eaters" and their noise reduction also reduces stars.

rmalarz Loc: Tempe, Arizona

If I guess correctly, these cameras are for astronomy purposes. If so, you might want to post this question to the Astronomy group, http://www.uglyhedgehog.com/s-109-1.html .
--Bob

Bobspez Loc: Southern NJ, USA

...see next post..

Bobspez Loc: Southern NJ, USA

Regarding the suggestion for the Nikon D200 .... The ZWO is a 6 MP astronomy camera, with a 1/1.8" cmos sensor. It has the advantage of being used through a laptop with no controls on the camera. The D200 is a 10MP dslr with an APS CCD sensor, with more than 8 times the surface area of the ZWO sensor, and can be bought used on ebay for $200. The Nikon dslr adapter for a telescope is about $10 new on ebay. However the D200 does not shoot video. Depending on the type of shots being taken it might be an option for long exposure shots with a self timer. In the days of film, astrophotography was done as long exposures. Members of the UHH astronomy section use both dedicated astronomy cameras and dslr's, and would have advice on equipment for specific types of shots being attempted.

rehess Loc: South Bend, Indiana, USA

Yeah, you have to watch that kind of automation. The digital ICE on my Plustek scanner was cleaning small writing, as well as scratches and other true defects.