Can i use a CCD filter on a normal DSLR?

[jezhughes]

I'm not sure how i can elaborate past what the title asks!

Am i able to use a narrowband / Ha filter on a DSLR? Or is it absolute that it needs to be CCD?

The descriptions on the filters are a bit vague.

Thanks!

[GlassWalker]

Short answer, yes you can, assuming you have a suitable way of making it fit.

[jezhughes]

Short answer, yes you can, assuming you have a suitable way of making it fit.

Thank you! The name of the filter stumped me a bit as it was labelled a 'CCD filter', but at the end of the day a filters a filter and a sensors a sensor, so wanted clarity.

Its a 2" so will fit my rig just fine. I haven't used a narrowband filter before and it looked much much less transparent than my IR cut filters so it stumped me a bit and i was concerned i just spent a lot of money for something incompatible.

Any other feedback welcome!

[GlassWalker]

The whole point of a narrowband filter is it only passes a narrow band! So you get relatively little through.

As for the "CCD" designation, that can vary by manufacturer. I use mostly Astronomik filters for example, and they have CCD and not CCD versions, the difference being the CCD versions have IR cut built in, and tend to cost a little more. The non-CCD version could be used either if your imaging system already has IR cut, or if you're using it for visual.

[Sp@ce_d]

Not sure how well an Ha filter will do on an unmodded dslr as I never bothered to try it. Not too well I suspect. I use a baader 7nm with my modded 1000D and get decent results. However, you'll need to increase exposure time to compensate and that brings with it more issues of noise with an un-cooled sensor.

[GlassWalker]

I don't have a link to hand, but the difference in H-alpha sensitivity of an unmodified DSLR compared to modified is something in the ball park of 2x to 4x. The increase in noise isn't a major issue once you do anything much beyond a short exposure anyway.

[jezhughes]

Thanks all

modding a cam is next on the agenda when i can afford to do so. probably should have done it the other way around but wanted to learn how to get filtered results before.

[todd8137]

You benefit from these filters with a mono camera Ha ect would not be worth it if you cam is unmodded and if it's a color cam then you would b wasting your money am surprised no of Hesse imagers have said this ,already save ya money even a modded dslr is still color it. Lt of money to pay out

[pilkinn]

Narrowband will not really work with a DSLR whether it's modded or not. A DSLR is colour and has a bayer matrix over the chip. These are red, green and blue filters in a 2x2 matrix. Ha and SII wavelengths will effectively get blocked by this matrix. OIII less than the others but without the other 2 there's not much point. As you've said you can't see much through the Ha filter - and neither will your DSLR. CCD cameras have chips that are sensitive to the narrowband wavelengths and providing they aren't colour (and hence don't have the bayer matrix) they can "see" those wavelengths.

[GlassWalker]

Ha or other narrowband on DSLR does work, just not as well as a far more expensive mono CCD. Due to its relatively massive sensor, even throwing away 3/4 of the sensor you have a lot of data to play with. The loss in sensitivity is also a negative for sure, but to upgrade to a comparable dedicated CCD is a major spend, and not everyone wants to throw 4 figure amounts around for this.

[pilkinn]

I'm probably missing sethimg here, but what's the 3/4 you throw away?

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[ollypenrice]

I'm probably missing sethimg here, but what's the 3/4 you throw away?

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A Bayer Matrix for obtaining one shot colour has a pattern of one red, two green and one blue filter repeated over its surface. If you put in, say, an Ha filter as well, Ha is red, so the light passed by the Ha filter can only trigger the red filtered pixels, ie one in four. It will be stopped by the blue and green.

Olly

[Sp@ce_d]

This might help you see what you're likely to get. Here's a (very) roughly processed example of NGC1499 I did as a test last year. Modded Canon 1000D, Baader 7nm Ha.

[pilkinn]

Ok fair enough, you can get Ha recorded on a DSLR - more so if it's modded. I suppose you'll also get SII from the red pixels and OIII from the blue and green pixels. However would you "recommend" a DSLR imager buy narrowband filters - which let's face it aren't cheap?

All my narrowband filters came from disillusioned DSLR owners.

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[Sp@ce_d]

Ok fair enough, you can get Ha recorded on a DSLR - more so if it's modded. I suppose you'll also get SII from the red pixels and OIII from the blue and green pixels. However would you "recommend" a DSLR imager buy narrowband filters - which let's face it aren't cheap?

All my narrowband filters came from disillusioned DSLR owners.

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I think you probably need to have decided to go down the modded DSLR and onto CCD route to justify the cost..you'll need 2" filters too which are more expensive. Like all hobbies it depends on what you are prepared to spend and how deep your pockets are. Imaging is addictive, frustrating and expensive. But when things come together its very rewarding. When I first used the Ha filter on the DSLR it was a bit of a wow moment for me.. so yes if you can afford one it's worth it in my opinion.

[Luke]

I use a Baader 7nm Ha as well, 2 inch, with my modded 450D, and am really happy with it. I used it on some nights last year where I normally wouldn't have bothered to image because the moon was fairly bright (I don't think you can completely ignore the moon if it's close to the target, though I am still learning).

This video inspired me to give it a go:

If you think you might switch to a CCD later on, it might be worth thinking about whether the filter you get now would be compatible with the filter wheel/CCD you might get, I think my Baader might not fit all current wheels but not sure.

I personally would not worry too much that the Ha is only reaching 1/4 of the pixels. 12 megapixels down to 3 megapixels is still a lot of pixels. I believe the height and width effectively get halved each (not quartered, as I initially thought), so that's still a lot of data

I have not tried the Ha filter on an unmodded camera. Personally I'd get the mod done or at least be sure it will be modded at some stage to get the most out of what is quite an expensive filter. I feel it's given my SLR a new lease of life and it's holding off the temptation at the moment to get a CCD (though never say never, a CCD deal at AstroFest almost got me!).

[GlassWalker]

If narrowband for DSLR is worth it depends on an individual's value, planned expenditure, and other considerations. To me, a half reasonable astro-CCD starts at £1.5k or so alone. A DSLR starts around £300 new and you can mod it yourself if necessary. No doubt the CCD is generally better, but most people don't have bottomless pockets and a line has to be drawn somewhere.

I can reluctantly accept the resolution loss due to the colour filter. It's 1/4 area, or 1/2 per axis. Narrowband is pretty much essential for me since skies are rarely clear enough for me to do useful broad spectrum imaging even with LP filter. Anyway, just today I got an EQ6 so that should resolve my tracking issues with longer focal lengths so I hope to give better examples of DSLR imaging in the near future.

And just to finish on a rant if it doesn't drag this thread too far off course, why do colour CCDs of a given spec tend to be cheaper than their mono counterparts? Most frustrating...

[dugpatrick]

In my case I already had an old DSLR, so going with a DSLR was the cheap option. I removed the IR filter myself using online guides. Here's an example of H-alpha with a Canon 350d:

Resolution is hurt by the bayer matrix but it works.

A bigger problem for DSLR users is lack of temperature control. This is mostly a problem in the summer, especially where I live. I have my camera in a cooler which brings down the temperatures 30 degrees F.

Doug

[ollypenrice]

I don't use DSLRs for astronomy but 'is it worth it' is going to be a personal choice. Ha opens up moonlit nights though O111 is quite badly affected. A lot would depend on your F ratio. If you have a fast scope it is going to be a lot more productive.

In any imaging of galaxies and emission nebulae an Ha layer is going to make a big, big difference.

Olly

[jezhughes]

Thanks for everyone's feedback, glad to see it provoked some discussion too!

As with all my equipment, i buy with scaling in mind. I didn't only buy narrowband filters to improve my rig at this very moment, but also to allow me to scale up to a CCD if i choose to. Replacing / upgrading equipment over and over again is a massive money sink in my previous experience with any hobbie! The more you can invest in future adaptable gear the better in my eyes. As people are saying, Ha is going to improve performance through a DSLR, i have a mount that allows me to track efficiently.

Points taken in regards to how the filters apply specifically to CCD imaging, but i think everyone's case is different. I live in a really high LP area, so actually a narrowband filter is great for me, i've got a few different LP filters but they still bleed after certain exposure times.

Anyway, i'll let you all know how i get on in a few weeks or in to the winter i might have modded the camera by then.