Regarding switching from Optolong to Chroma for broadband filters

Hi Youngwoo.

A few years back I moved over from Baader RGB filters to Chroma and was delighted with the results. I used to get very small 'flares' on stars using the Baader filters but this is no more with Chroma.

With regard to the filter thickness, this will require a small adjustment to back focus and you will likely need to add a small spacer between the extenders you use. These are usually very cheap and you can buy packs that have varying thicknesses. As a general rule you should take the thickness of the filter glass and divide this by 3. So in your case you would need a spacer of 1mm in thickness.

Here is a link to an example spacer set https://www.firstlightoptics.com/adapters/astro-essentials-t-m42-adjustment-spacer-ring-set.html They come in M42 and M48 depending on what diameter extender you need to put them on in your image train.

Hope this helps.

John

What scope are you using?  Backspace error will be system dependent on whether it is significant or not.

I have used Chromas for years, as well as astrodon but about a year ago changed all of my filters over to Astronomik and have been very happy with the change.  I was having some reflection issues with both Chroma and Astrodon on my epsilon and thats what made me look at Astronomik.  They are significantly less expensive than Chroma and IMO offer a ton of value and for whatever reason the AR coating seemed a bit better.

They are 1mm thick, but considering the price you might be able to upgrade all your filters to Astronomik and have a universal thickness filter as well as an upgrade.

If you do look at doing this, I'm talking specifically about the Deep Sky RGB and the MaxFR for narrowband.  The NB are 6nm, so if you NEED a narrower bandpass than that it might not interest you.  It really depends on your light pollution….

The Chromas are excellent quality so either way you won't go wrong.

Bruce Donzanti:

Youngwoo Yoon:
I've recently come into a bit of disposable income.
So, I'm contemplating switching my LRGB filters from Optolong to Chroma, but I'm unsure if it's worth the investment. 🤔
Additionally, I'm currently using Antlia narrowband filters, which have a thickness of 2mm.
I'm concerned that using LRGB filters at 3mm might cause issues with the back focus.

I haven't been involved in this hobby for very long, so I'm not entirely confident about this aspect, which is why I'm seeking advice.
Thank you for taking an interest.

Well- I would simply get Antlia LRGB which are just fine and work well with their NB filters.    I have both Antlia and Chroma filters, but on different scopes.  The price hike in Chroma filters is ridiculous (I bought mine years ago) and simply not worth the investment in my opinion.

Yes that price rise was a shock and certainly reduced the value proposition.

I've never used Antlia filters but I've heard a lot of positive feedback on them. Both of my CDK Systems use Chroma filters, and I use Astronomik for my Epsilon. I had halo issues years back with 5nm Astrodon filters, but haven't had that occur with the Chroma or Astronomik filters.