Color or Mono... The age old question.

[tooth_dr]

Equipment is only a part of it, your ability to process the data can make the difference too. I’ve the mono QHY268M and the OSC ZWO2600MC and love both. If I had to choose only one, I honestly don’t know which one I’d choose. 

[ollypenrice]

I continue to insist that, contrary to popular belief, mono is faster because it can capture luminance (all three colours at once) which OSC cannot do. If this is not correct, please tell me why. The LRGB system was invented to save time. However, it doesn't save frustration if you're deprived by cloud of a critical filter's subs. 

As Dave says, mono is better for narrowband, better as in faster and having higher resolution, which makes it better at beating the moon and other severe LP.

However, the new CMOS OSC cameras have changed my mind about the usefulness of OSC. They are far better than OSC CCDs, of which I've had two and sold both. I'm now using an ASI 2600, which I certainly won't be selling, a) because it isn't mine  and b) because it is downright excellent!  The arrival of dual and tri-band filters for OSC also opens up a new world of exciting possibilities.

Conclusion: personally I would seriously consider OSC CMOS but not OSC CCD.

Olly

Edit.  Don't be fooled by the parfocality debate regarding filters. Most of them are parfocal, the non parfocality coming from the optics. These remain non-parfocal when you're using an OSC but you can't do anything about it. You have to choose the compromise focus.

Edited October 23, 2021 by ollypenrice
clarification

[tomato]

The very best images tend to be taken from premium locations, top end kit cannot fully compensate for turbulent, murky atmosphere, light pollution, or being forced to image when the moon is intrusive.

So for 95% of us, imaging is a compromise, and cost, simplicity and convenience of use are big factors. OSC is certainly a compromise, but with some of the best imagers on SGL now using CMOS OSC and getting stunning results, it looks to me like a compromise that is worth accepting.

[Stefek]

Well, it depends a bit what are you really after : many photos or good photos. 

It often gets somewhat forgotten that OSC has Bayer matrix and yes you collect all channels at the time, but just 25% per R and B and 50% per G, compared to mono. So, is OSC that much faster?

Not that much. Light pollution plays also important role. In light polluted area, mono camera will perform better. I do have both 2600 OSC and mono versions. L-Extreme or other dual or multi-band filters are great, they help with LP , but then again , they are much slower than without them and they are not in the same league with real narrowband filters combined with mono camera. 

Either way, buying 2600MC can't be wrong , especially if you get good dual band filter.

If you go with mono , think once more should it really be 1600  or something else in that price range . There were some reports about reflections from sensor cover glass. 

Clear sky, whatever you buy .

 

 

 

Edited October 23, 2021 by Stefek

[tooth_dr]

21 minutes ago, Stefek said:

Well, it depends a bit what are you really after : many photos or good photos

Definitely have a look around, there class leading photos on here with the OSC. You don’t have to compromise any more. 

[pete_l]

On 17/10/2021 at 01:14, 69boss302 said:

whats the general consensus?

Both can produce excellent results.

Leaving aside narrow band imaging, I would defy anyone to look at the final result from either and be able to say, without any further information, whether it came from a OSC or mono camera.

[pete_l]

duplicate

Edited October 23, 2021 by pete_l

[ONIKKINEN]

15 minutes ago, Stefek said:

Well, it depends a bit what are you really after : many photos or good photos. 

It often gets somewhat forgotten that OSC has Bayer matrix and yes you collect all channels at the time, but just 25% per R and B and 50% per G, compared to mono. So, is OSC that much faster?

Not that much. Light pollution plays also important role. In light polluted area, mono camera will perform better. I do have both 2600 OSC and mono versions. L-Extreme or other dual or multi-band filters are great, they help with LP , but then again , they are much slower than without them and they are not in the same league with real narrowband filters combined with mono camera. 

Either way, buying 2600MC can't be wrong , especially if you get good dual band filter.

If you go with mono , think once more should it really be 1600  or something else in that price range . There were some reports about reflections from sensor cover glass. 

Clear sky, whatever you buy .

 

 

 

This is an imaging target vs imaging camera issue in my opinion, if you're imaging broadband targets that are primarily star coloured (green wavelengths) then the difference between OSC and mono gets much smaller and i would say that the small gains are probably not worth the effort of having to refocus 4 times (possibly more, depending on thermals and filters) stack 4 times and take flats 4 times each session. If the goal from the beginning would be to capture emission nebulae then yes mono would be the obvious winner.

5 hours ago, ollypenrice said:

I continue to insist that, contrary to popular belief, mono is faster because it can capture luminance (all three colours at once) which OSC cannot do. If this is not correct, please tell me why. The LRGB system was invented to save time. However, it doesn't save frustration if you're deprived by cloud of a critical filter's subs. 

I couldn't tell you why, but i think you partly answered your own question why many perceive it as faster. Also, like you mentioned there can be issues with parfocality, whether filter or optics based. Taking time to focus after a filterchange is time off that precious clear dark sky. Shooting flats should also be taken into account since you would have to take 4x the amount. Or just don't retake flats and have a chance to get a bad calibration and either lose the dataset or have to result to trickery to salvage the data. If we assume time on site when imaging is 4 hours including setting up, taking flats and tearing down, is mono really faster?

[DaveS]

I have a calibration library of Dark, Flat, Dark Flat, and Bias frames, with Flats and Dark Flats for each filter, and for bin 1 and bin 2 that I reuse for images. May only redo them every 6 months to a year. Certainly don't do new Flats every session, waste of time and storage space.

On my ODK there's no need to refocus between filters, and on the TS apo I have a set of filter offsets so that the software can nudge the focus for each filter. Takes no more time than to rotate the wheel.

[ollypenrice]

2 hours ago, ONIKKINEN said:

This is an imaging target vs imaging camera issue in my opinion, if you're imaging broadband targets that are primarily star coloured (green wavelengths) then the difference between OSC and mono gets much smaller and i would say that the small gains are probably not worth the effort of having to refocus 4 times (possibly more, depending on thermals and filters) stack 4 times and take flats 4 times each session. If the goal from the beginning would be to capture emission nebulae then yes mono would be the obvious winner.

I couldn't tell you why, but i think you partly answered your own question why many perceive it as faster. Also, like you mentioned there can be issues with parfocality, whether filter or optics based. Taking time to focus after a filterchange is time off that precious clear dark sky. Shooting flats should also be taken into account since you would have to take 4x the amount. Or just don't retake flats and have a chance to get a bad calibration and either lose the dataset or have to result to trickery to salvage the data. If we assume time on site when imaging is 4 hours including setting up, taking flats and tearing down, is mono really faster?

You're assuming that non-parfocality comes from filters but I don't think it does. I think it comes from optics. If you don't refocus between filters with mono (and I usually don't) you are in the same focus situation as with OSC where you can't focus per colour. You need to refocus regularly anyway, so it's no big deal.

Flats: I use luminance flats for everything, 95% of the time. 

But, with the demise of CCD, I like OSC!

Olly

Edited October 23, 2021 by ollypenrice

[Clarkey]

I went down the mono route about 18 months ago based on the theory that mono would give better and faster results. I think this is probably right providing you can finish you imaging sequences before the clouds roll over. Many times I have got some channels completed but missed others and end up with 'half' an image. I am seriously considering going over to (or at least adding) OSC for this reason. In the event of a full night of imaging as planned I think the mono definitely has the edge. However, this seems to be such a rarity that at least if I set a OSC sequence to run for the night I will at least get something to show for it. Having seen some of the images from OSC camera's with only a few hours integration it does seem to be a practical proposition.

I have just got an F4 imaging scope to try and improve my data capture rate. Lets hope this helps over the F6.3 I was working with. (Having bought the scope I then needed a new coma corrector and focuser so I probably should have just got the OSC camera for the same cost!!)

Maybe I just need an F2 RASA and a new house in the middle of the Atacama🤣

[Allinthehead]

19 hours ago, DaveS said:

Remember that the biggest source of LP is the Devil's Lightbulb, AKA the Moon. Under moonlight H-alpha might be the only viable option, in which case mono wins. And given how many clear nights seem to coincide with a full moon...

I agree with Dave here, while you can shoot Ha with a colour cam the resolution and speed of a mono can't be beaten. I shoot ha with my 2600mc but not for stand alone images, only to add to rgb images. If I had the budget I'd compliment my 2600mc with the mono version. 

[dmki]

I am just starting to get into astronomy and I am currently at the stage of knowing how little i  know, so take what i am saying with a pinch of salt.

There's a budget issue here. that filter wheel and filter set is going to set back the best part of 700+ GBP, add this to the cost of a mono sensor and its going to come close to taking you into a new class of sensor when your buying osc. I suspect that unless you have a lot of clear nights and an observatory to capture them, that your going to get best value from the osc.

the one thing can say with experience, going from a Pentax DSLR aps-c to a secondhand 183 osc; is that the loss of fov is more than made up for by the huge improvement in sensitivity, noise and general image quality. which ever way you go, the only regret you will have is not doing it sooner.

Edited October 23, 2021 by dmki

[69boss302]

22 hours ago, Stefek said:

Either way, buying 2600MC can't be wrong , especially if you get good dual band filter.

Thank you, That is great information. Do you have a good filter recommendation for dual band? I see a ton of them out there.

bob

[ONIKKINEN]

22 hours ago, DaveS said:

Certainly don't do new Flats every session, waste of time and storage space.

Im curious as to how this can work. Do you rebuild and tear down everything for each session? I would imagine you dont, and in that case yes probably dont need flats every time.

I notice very small but still visible changes in my flats every time. Maybe collimation was different due to temperature or bumping the OTA in transportation, maybe the focuser sagged at a slightly different fraction of a degree of an angle that night, maybe there was a new dust particle somewhere. My flats have a good 50% chance of not being good if i just reuse old ones. Maybe its a newtonian and traveling astrophotograher issue?

Edited October 24, 2021 by ONIKKINEN

[DaveS]

My main instrument is on a pier in an obsy, my secondary is on a pier under a TG cover on a raised platform. I've not seen shifts in any dust bunnies between sessions.

Even when I was setting up each session I never broke down the imaging train unless I was making major changes, in which case, yes new Flats and Dark Flats were needed.

[Lee_P]

6 hours ago, 69boss302 said:

Thank you, That is great information. Do you have a good filter recommendation for dual band? I see a ton of them out there.

bob

Optolong L-eXtreme is great.

[gorann]

18 minutes ago, Lee_P said:

Optolong L-eXtreme is great.

Or IDAS NBZ, you cannot go wrong with it.

[Icesheet]

I went from 1600MM to 2600MC and no regrets yet. I think most of it has been covered already but one thing I haven’t seen mentioned is sensor size (apologies if it has). The 2600MC’s APS-C is going to give you a lot more real estate than the 4/3rd of the 1600MM. Can make all the difference depending on the targets you are going for. 

Edited October 24, 2021 by Icesheet

[Adam J]

The physics of mono Vs OSC has not changed. Both have gotten better equally. It's just OSC has now improved to the point when people are willing to settle for the results, nothing wrong with that I may get one on that basis at some point. But if I want to get the very best image I can it's going to be using a mono camera. 

[Lee_P]

8 hours ago, Adam J said:

The physics of mono Vs OSC has not changed. Both have gotten better equally. It's just OSC has now improved to the point when people are willing to settle for the results, nothing wrong with that I may get one on that basis at some point. But if I want to get the very best image I can it's going to be using a mono camera. 

I think it's more specifically that the development of dual and tri-band filters have increased the versatility of OSC cameras, rather than OSC sensors simply getting better in quality in-step with their Mono equivalents.

[vlaiv]

4 hours ago, Lee_P said:

I think it's more specifically that the development of dual and tri-band filters have increased the versatility of OSC cameras, rather than OSC sensors simply getting better in quality in-step with their Mono equivalents.

Interestingly enough - dual and tri-band filters are better suited for use with Mono cameras - yet not much people use them that way.

They are in fact equivalent of Lum filter for NB imaging.

People also don't use mono + filters in most effective way to really show biggest difference between mono + OSC. They shoot LRGB instead of LRG. Later requires somewhat special processing - but not different processing to what should also be done with LRGB and OSC data alike.

 

[vineyard]

18 minutes ago, vlaiv said:

Interestingly enough - dual and tri-band filters are better suited for use with Mono cameras - yet not much people use them that way.

I am a newbie imager, so I'm not going make any claims to quality.  But being an inveterate tinkerer, recently put a synthetic dual/tri band filter (basically a stacked Astronomik CLSCCD & UHC filter - if you look at the spectra on the Astronomik website you can see the interaction) in front of an old ASI178MM-cool.  I liked what emerged - but as I say would make no claims to absolute quality (a proper imager would have done far better) nor on how the same target would have been w a OSC+tri-band!  But I do think @vlaiv is right - until I eventually get individual filters (maybe sometime in the next 24 months!) I'm going to try mono+triband a bit more.

[vlaiv]

2 minutes ago, vineyard said:

until I eventually get individual filters (maybe sometime in the next 24 months!) I'm going to try mono+triband a bit more.

Even with individual NB filters - you can still use tri band filter as luminance and shoot all four but with different time ratios - say spend 3h with tri-band and 20 minutes with Ha and OIII (you don't even need SII in that case). Ha and OIII will be only for false color composition while tri-band is luminance.

[ollypenrice]

1 hour ago, vlaiv said:

Interestingly enough - dual and tri-band filters are better suited for use with Mono cameras - yet not much people use them that way.

They are in fact equivalent of Lum filter for NB imaging.

People also don't use mono + filters in most effective way to really show biggest difference between mono + OSC. They shoot LRGB instead of LRG. Later requires somewhat special processing - but not different processing to what should also be done with LRGB and OSC data alike.

 

Tell us more!!! 😁

Olly