113 replies to this topic

[cfosterstars]

Previously I mostly used a modified full-spectrum Canon 6D. I now have an ASI1600MM-C with the EFW7 and 36mm ZWO filters. Here are some of my images with this setup. These are literally the first LRGB and NB image I have ever taken. 

 

 

I love my ASI1600 and really see the advantage of a mono camera in spite of the image processing learning curve. 

 

I have really wanted to do this post and find out what do you get for more expensive filters and I ask to please show examples to demonstrate why they are better. I honestly don't know what people are seeing that would justify spending 3X the price. I really would like a clear answer.

I have a PHD in physics with specialty in infrared and pulsed laser optics. I also worked at the advance photo source and know a fair amount about x-ray optics. I have build entire optics labs. I have looked at the specs for the various filter manufacturers. I have seen no claim on their web site for differences that would justify improved imaging.

 

The narrowness of the bandpass for the NB filter is about the only thing that i can see as a big driver for the cost and that makes sense. It is much more difficult and expensive to narrow the bandpass requiring significantly more multilayer interference coating layers. However, at least from my experience in an orange zone, unless you are in seriously heavy light pollution or imaging at the full moon, its not going to buy you that much. The flatness of the filters from an interference point of view might be a big deal, but I dont specs stating that as a difference nor is there really much difference in peak transmission. There might be some significant engineering for high off axis transmission characteristics for very high F ratios, but again there are no claims for technology advantages. For LRGB, matching to be a parafocal set is an advantage but if you have doing autofocus with SGP, then that doesn't matter either. IF there is som thing with respect to color balance matching, I could understand that, but we all digitally process our images, so why is that so important. We do so much washing of the data for sharpness and other characteristics how does the filter quality differences play a role.

Anyway, Is there a reason for spending more on one filter over another? - I cant really come up with an answer. I did however, go with larger filters since I do have a full frame camera and have fought vignetting issues to death so I spent more for the 36mm. Maybe I wasted my money, but it was mine to blow.

I think that I get good imaging with the ZWO filters and they are not what is limiting my image quality. Will that situation change - I COULD ONLY HOPE SO. If my filter quality was what was my limiting factor for my final images - that would be awesome. That would mean that the huge number of issue other than filters that I currently KNOW are causing me problems would all be fixed!! I would love to just throw money at this and get better results. For me at this point, I would always go for a better mount if I have money to burn on this - that always seems to pay off. Or buy darker skies and fewer clouds. 

 

So now, if you have some technical defensible reason and hopefully can demonstrate with data, please reduce my ignorance. If you just think that your image look better when you forked out for Astrodons - that is a perfectly reasonable answer. In the end, it all comes down to how much we enjoy the pictures that we create. 

 

Please comment.

 

thanks,

 

 

[pfile]

i know another guy who has a phd in a related field and he always wondered what the big deal with astrodon filters was as well - for the biology (imaging) stuff he was doing they would use scientific filters from some optics manufacturer and felt they were vastly superior and cheaper. but i suppose those companies don't make filters for the wavelengths of light that we're interested in.

 

just an anecdote but it lines up with your thinking.

 

just about the only thing that i can think of that separates astrodons from lower priced filters is the AR properties of the astrodon filters. compared to baader filters the AD's are way ahead - the baaders suffer really bad reflections whereas i don't think i've ever seen a reflection on my ADs.

 

rob

[cfosterstars]

i know another guy who has a phd in a related field and he always wondered what the big deal with astrodon filters was as well - for the biology (imaging) stuff he was doing they would use scientific filters from some optics manufacturer and felt they were vastly superior and cheaper. but i suppose those companies don't make filters for the wavelengths of light that we're interested in.

 

just an anecdote but it lines up with your thinking.

 

just about the only thing that i can think of that separates astrodons from lower priced filters is the AR properties of the astrodon filters. compared to baader filters the AD's are way ahead - the baaders suffer really bad reflections whereas i don't think i've ever seen a reflection on my ADs.

 

rob

Rob, very interesting point. This will be something I will be looking at in the winter as I go back to Orion. If I see a lot of reflections or flairs from Alnitak that will say something. I wonder if there are any specs on the websites for AD or Baader that discuss this. However, unless you own both sets of filters, I dont know of a way to do a really apples to apples test. If the AR property of my ZWOs is poor, I should see a lot of interference effect when I image around very bright stars like Alnitak. With my DSLR and a focal reducer I would get really bad halo and even multiple reflection flairs in my images. That will be a good test. Right now I have clouds for the next two weeks. That why I am so board that I can pose these head scratchers.

Edited by cfosterstars, 09 November 2017 - 09:07 PM.

[buckeyestargazer]

There are so many factors that come in to play when evaluating the quality of filters.  The same filter on two different systems can show different characteristics.  What I mean is, with less expensive filters you may not get star halos with slower systems but that same filter on a fast system will have horrible star halos.  Speaking from experience, Astrodons are the only filters I have never had star halos with.  Every other brand I've tried had varying degrees of star halos ranging from obnoxiously bright and distracting to subtle.  It's up to you to  decide if that is worth paying the premium.  For me it was.

[cfosterstars]

There are so many factors that come in to play when evaluating the quality of filters.  The same filter on two different systems can show different characteristics.  What I mean is, with less expensive filters you may not get star halos with slower systems but that same filter on a fast system will have horrible star halos.  Speaking from experience, Astrodons are the only filters I have never had star halos with.  Every other brand I've tried had varying degrees of star halos ranging from obnoxiously bright and distracting to subtle.  It's up to you to  decide if that is worth paying the premium.  For me it was.

Do you have any example images you could post to show the difference? I know that I dont keep anything that I dont like, but if you still have images with the old filters that you could compare to the ADs, could you share?

[buckeyestargazer]

Do you have any example images you could post to show the difference? I know that I dont keep anything that I dont like, but if you still have images with the old filters that you could compare to the ADs, could you share?

 

 

 

Here's one example.  Optolong SII 6.5nm on the left, Astrodon 5nm SII on the right.  The Astrodon image was taken right after the Optolong image in the same equipment (I had both filters in the same filter wheel).

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[Jeff2011]

I can’t give any concrete examples as I bought Astrodons from the start.  I had seen too many guys do the filter upgrade.  I figure that I would save money by not having to upgrade.  Similar philosophy I took when upgrading my beginner mount to an AP.  I have been very happy with both purchases.

[Alex McConahay]

>>>>>for the biology (imaging) stuff he was doing they would use scientific filters from some optics manufacturer

 

It may be that stars (bright, high contrast points of light) present problems that the biological subjects do not present. 

 

Alex

[pfile]

could be, but i think the point he was making is that the bandwidth and optical quality of the filters they used were similar to ADs, yet the ADs are ridiculously expensive in comparison.

 

rob

[ZL4PLM]

as I said in a similar thread where this was raised ... I have spent hours looking at images / reports and discussions. Some it was less than subjective, some emotive and some that had some sound explanation behind it.

 

What I can say is that I have seen astrodon's with mediocre images and ZWO's with stunning images. And vice versa, and inbetween a mix of baaders and astronomiks all showing the same.

 

I've seen astrodons with halos and ZWO's with none and I think that the whole thing is a mix of factors that makes them deliver or not. 

 

I am not sure about the upgrade path.. we are taking alittle more than just a small step .. 500 to 1500 USD is a huge leap and a few steps in between for other brands.

 

What I can also say is that the results are not night and day, not 100% better or 200% better for 200% cost increase etc 

 

its small things...

 

And fore sure its gonna be a brave man that says I paid 1500 bucks for filters and the results show little for it.

 

If you have loads of disposable income fine .. but 500 to 1500 is a lot of cash for many.

 

Personal choice but I wouldn't say the ZWO's deliver poor images .. they all have differences to the eye - its what you personally see as a MUST have and your wallet size I reckon!

[yrb]

I had problems with reflections and halos with astronomics narrowband filters, even when a bright star was off sensor I would get big nasty rings that were very difficult to deal with. I then switched to astrodons and those problems have been greatly diminished/more or less gone, processing is much easier. Maybe this is not universal, but for me it WAS night and day. Buckeyestargazers image is a good example of what I was experiencing, many times the reflections were much much worse and I ended up tossing enormous amounts of data because I couldn't fix the problems in post-processing. It has been a significant improvement in data quality for me, it makes the whole process much more fun when you have good data from the get go and has saved a significant amount of time as well.

[dan_hm]

Those are excellent images.  I've only used Astrodon, and I bought them because I wanted to have as much flexibility as I could given both the heavy LP where I live and the infrequency of clear nights.  It's rare that I get more than one or two clear nights during a new moon, which means the bulk of my imaging has to be done when the moon is out.  Not having used filters from other brands I can't say if my Astrodon Ha filter actually does better with moonlight than a different Ha filter would, but that's why I bought it.  Also, imaging from an orange zone makes things significantly easier.  You can easily get by with wider-bandpass filters when LP isn't totally overwhelming. 

Edited by dan_hm, 10 November 2017 - 01:48 AM.

[freestar8n]

I think it's clear that in the past some filters had problems with reflections - but at least some of them fixed those problems years ago with updates to their filters.

 

So in terms of differences among filters you can buy right now - I'm not sure how much it matters.

 

Astrodon offers a wide selection that includes 3nm.  He also has Sloan and continuum filters.

 

For OAG work - it's very helpful to have everything accurately parfocal - and mixing other filter providers can cause problems.

 

With regard to 3nm, the reduction of sky background noise goes as the square root of background - so going from 5nm to 3nm is only a 29% reduction in background noise.

 

So - for me it amounts to deciding what types of filters you want to work with and what you want to do.  If a modern provider has what you need then I would look at recent results indicating if there is a halo problem.

 

I wanted sloan and 3nm and continuum - so I am down an Astrodon path.  But I'm aware of the trade offs - and cost is certainly one of them.

 

Frank

[TareqPhoto]

Reading these kind of topics putting me as a beginner into confusion, should I buy the best or not, and if it is the best then the best in what? Is it just only people keep saying it is the best because it is expensive and they try hard to justify that?

 

Sometimes we don't know what we need, is it the expense of items or the quality or what exactly? And is it always true or a fact that an expensive item means it is always high quality? If so then who need cheap items when the quality is with expensive ones?!!!

 

I bought only one Astrodon filter so far in 1.25" size, but I wanted 36mm just in case, and for that I planned I don't want to go with high quality too for 36mm, so I ordered 36mm non Astrodon to save something, I won't care much about the quality difference, and sounds there is always an issue even with high quality items, no need to have Astrodon in both sizes anyway.

[terry59]

I use Baader narrowband filters because the cost of Astrodon narrowband filters is more than I am willing to pay for the increased contrast. I am happy with my choice. It has allowed me to spend on equipment to be completely computer controlled...which is far more important to me for getting quality images

 

Image done with this scope and Baader NB filters

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Edited by terry59, 10 November 2017 - 07:07 AM.

[gunny01]

Something else to weigh in the decision: https://www.cloudyni...odon-filters/. 

 

 Don really needs to improve the final product before shipping out.  The filters are good, but having to clean the grim and oil off of them is ridiculous for this kind of money.  Not just me, but others are also seeing similar problems.

[Kepler1349]

This is particularly relevant for me at the moment. Since I just had an long discussion with my fellow remote telescope operators. Right now it uses Baader filters (RGB + 7-8nm NB). However, I really wanted to do Sloan, and with the OAG it's better to be parafocal. So I also ordered the LRGB and 3nm NB set as well (and Sloan R'G'I') , we'll see if it makes a difference under good sky conditions!

Edited by joelkuiper, 10 November 2017 - 07:49 AM.

[Alex McConahay]

What is being said about these filters can be said about many different pieces of our kits. 

 

Fact is, you are asking several questions here:

 

1. What is money worth to you? For some people the premium they pay for the Astrodons is rather significant. For others, it is not. 

2. Where is the breakpoint where spending more does not get enough more? There is a diminishing return on any investment. If you spend twenty per cent more with any given piece of cheap equipment, you will probably get thirty or forty percent gain in performance. But if you spend that same 20 percent  on an expensive piece of equipment (and 20 per cent of $10,000 is a lot more than 20 per cent of $1000) the gain may be only two or three percent. 

3. How much is a few percentage gain worth to you? If you are out jogging on a Sunday morning, beating your best time by a second is no big deal. If you are running a race in the Olympics, a few hundredths of a second may matter a whole lot. 

 

If you are getting the performance you want with the filters you have (or any other other piece of equipment) then you have no reason to change. 

​Alex

[maxmir]

I have tried many of the brands.
AD is almost always better. Most of the other filters show halos.
I have set of latest Astronomiks LRGB that are very good even at F3.6.
Some mfrs are doing better.

If the NB band pass is important to you go with the ADs.

Just because it is labelled 6nm on the box does not mean that is what you get.
Don checks every filter.

Don gets plenty custom orders from large observatories that you don't hear about.

The word is out in professional world too that he sell the best product.

Buy quality and only cry once.

[TareqPhoto]

What about those who used less expensive filters and yield so amazing great images which speaks? So it is always about the final image, if it is great with cheap filters it is great, then what we can say about those bad images or say not that decent enough images done with for example Astrodon filters?

[cfosterstars]

What is being said about these filters can be said about many different pieces of our kits. 

 

Fact is, you are asking several questions here:

 

1. What is money worth to you? For some people the premium they pay for the Astrodons is rather significant. For others, it is not. 

2. Where is the breakpoint where spending more does not get enough more? There is a diminishing return on any investment. If you spend twenty per cent more with any given piece of cheap equipment, you will probably get thirty or forty percent gain in performance. But if you spend that same 20 percent  on an expensive piece of equipment (and 20 per cent of $10,000 is a lot more than 20 per cent of $1000) the gain may be only two or three percent. 

3. How much is a few percentage gain worth to you? If you are out jogging on a Sunday morning, beating your best time by a second is no big deal. If you are running a race in the Olympics, a few hundredths of a second may matter a whole lot. 

 

If you are getting the performance you want with the filters you have (or any other other piece of equipment) then you have no reason to change. 

​Alex

The purpose of the thread is to quantify what makes ADs better than other filters. I was asking for technical specs or performance examples which show why they are better and what different aspect of the filter and how they mesh with other factors would justify a 3X higher prices. We are not talking about 10-20%. Even if you have lots of money, triple the cost is still something you should but may not look at. I have ZWO filters and have looked at ADs. I was hoping for a technically validated reason that ADs are better than the filters that I have. So far, I see three potential reasons:

 

1) bright halo's due to internal reflections - easy to check and verify. Why they are better could be due to differences in the AR coatings. I have noticed and found with my ZWOs is that the filters are not reversible. They have to go in the beam path in with the correct face towards the camera or you get lots of reflections.  You can clearly see this in flat frames and you dont even need to see halos in the stars. HOWEVER, the images above were WITH the Ha and SII filters in the wrong direction and I did not see that ugly and issue. I will check with even brighter stars to see if this is still a problem for me. In looking at the AD website, the AR is held as an advantage. They also specifically state that they darken the filters edges for reflections also. 

 

2) Filters are parafocal - the ZWOs with my ASI1600 are not perfectly parafocal but are close. The LRGB filters are very close, but not the NB filters.  I can clearly see that this is a serious advantage if you are using OAG if they truely are parafocal, but not if you are using a guidescope or a ONAG. This would be a good technical reason for the cost delta if it applies to your setup or you see yourself going in this direction.

 

3) Narrower bandpass - this does technically lead to higher contrast potential and better performance in heavy light pollution. I am in an orange zone and may not see a huge difference. If you are in dark skies, it may not show that much difference, but for very faint targets, it may be a differentiator. 

 

4) Quality control - this seem to be an area of active discussion and goes both directions. This may or may not be an issue from AD but from distributors causing problems. I will not comment. My ZWO filters were clean and well packaged when I got them so my single data point is hardly statistically significant.

Edited by cfosterstars, 10 November 2017 - 10:37 AM.

[Jeff2011]

I think it all boils down to your equipment and conditions as to what filters you can use and be happy with.   Here are my responses to your 4 you listed.

 

 

1.  I have not had any halo's due to internal reflections with my astrodons.   I have had one weird reflection with the green and blue filters when I put Gamma Cas in a corner of my image and the reflection was opposite but that was easy to process out as it was very faint.

 

2.  I use OAG so parafocal is important and I have had no issues with guiding using these filters.

 

3. I don't like to use silly colors for light pollution but if I must I am in a white zone. My SQM is around 17 to 17.3 when I measured it.  Narrower bandpass is another reason for me  buying the astrodons given my severe light pollution and they do well in it.

 

4. My astrodons arrived in a clean and undamaged state from OPT. This was several years ago.

[psandelle]

Have you tried emailing Don? He's always willing to discuss, and he's a very knowledgeable guy who truly cares about his products. He probably has the specific particulars of what he puts into his filters to separate them from other filters. I've never found him to be particularly biased, either. He's been very open about suggesting cheaper 5mm narrowobands over 3mm narrowbands for specific purposes. He's a good guy. I think starting there would probably give you the best info, then you can take that data and ask again here (and elsewhere) to verify about what other brands do. For all we know, Don might quietly put a tiny speck of Unobtainium in his filters for some reason or other.

 

Paul

Edited by psandelle, 10 November 2017 - 12:02 PM.

[Alex McConahay]

Cfosterstars,

 

Nobody is saying other filters don't work, or do not work well. If they do what you want, then they are fine. 

 

Several people have testified (one with photographic examples) that the Astrodons avoid problems that they sometimes see with others. 

 

It is like so many other things in life...most of the time it does not matter. 

 

But sometimes it does. And for those times, it is nice to not worry about things. Some people pay a big premium for that luxury. But for them, it is not a luxury, just how it should be done (in their mind). 

 

Alex

[natwin]

Since exploring the possibility of switching to a mono camera with a filter wheel, I have had similar questions as the OP. There is a lot of anecdotal "evidence" out there justifying one brand of equipment over another. In my search, I came across a posting comparing Astrodon, Baader, and Astronomik LRGB filters. I downloaded the examples to compare them side by side on my monitor. This was a while back, and unfortunately I don't remember the site and can't credit the poster. I assume since they were posted for public consumption, that it will be OK to repost them here. If not, I'll take them down. The original post had separate LRGB frames for the three brands. I aligned and stacked them to create the full color images which are shown below. The original captions didn't align, so you see multiple captions in each image. I'll let people draw their own conclusions.