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Full spectrum camera vs h-a filter on scope


vertigo262
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It is completely different.

Doing a full spectrum mod, or just the IR filter removal, will, as you say, allow more H-Alpha in your pictures. However, it also allows through all the other wavelengths as well.

Adding a H-Alpha filter will only allow that specific wavelength of light through. 

If you took a picture with a modded camera (no filter) you will still get a colour image, just with more 'red'

If you take the same picture with a H-Alpha filter, everything is red (656nm wavelength). Blue and green light is blocked.

Hope that helps

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is converting a camera to full spectrum the same as using an h-a filter or is it different?

i know by removing the ir filter you are letting more ha in, but if you dd a h-a filter afterwards, are you doing the same thing?

A full spectrum camera will record all the wavelengths from 350nm to 700nm and beyond. An Ha filter will only allow a very narrow band of light passing through to the sensor corresponding to its band pass with 652nm ( Ha waveband ) being in the centre. The two have nothing to do with each other.

A.G

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ok, makes sense.

this is where the question is going. so lets say you takd some pics on a moded camera, then you did some seperate h-a pictures with a filter.then you merged both images doing a h-argb.

would this be pointless, because the modded camera is already getting that wavelength. or would the narrowband data be beneficial to better quality

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ok, makes sense.

this is where the question is going. so lets say you takd some pics on a moded camera, then you did some seperate h-a pictures with a filter.then you merged both images doing a h-argb.

would this be pointless, because the modded camera is already getting that wavelength. or would the narrowband data be beneficial to better quality

Using a CFA sensor ( colour sensor ) to record NB filtered data is not exactly the most efficient way of using the filter nor the sensor. It is doable and it results in an enhancement of the ha regions but the process is complicated and you would probably need extra software to align, rescale and register the subs to each other. Remember that with a CFA sensor and an Ha filter the 2 G and one B photo sites will not record the Ha data and only the R channel will be recording, the other 3 will be busy contributing noise to the already scarce data. There is a way of doing this but as I said it is quite complicated. This is where a Mono sensor wins hands down in resolution, sensitivity and " simplicity " of processing.

A.G

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Can a modded camera (full filter removal) be used for daytime shots? I read somewhere it's just a matter of setting a different white balance.

You can put a filter back in, or as you suggest balance the colours afterwards.

It all depends on how you get it modded though. If you remove the filter, then you will have problems with the Auto-focus (I believe). If you want that to still work correctly, you need to replace the filter with a clear piece of glass.

I guess it depends on how much you spend on the camera. I bought a second hand 1100d for £100 and decided to risk modding it myself. If you have a more expensive camera, it would be worth getting it done properly!

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i did a test experiement the other night. although it was windy, and my first try. so the picture was crappy.

i put a ha filter on, and got a blury cfa, ha shot. i then went in photoshop, removed the R channel out of the ha shot, and replaced it in the rgb's R channel. since the gb was in focus and the r was blury. i could not tell if there was a benfit. also, not sure if i was doing it right.

i am going to retry it when weather clears up. but this is an are where i have not researched as to why peope take the 3 channels manually vs cfa camera. although a lot more work. am hoping to do h-agb. although saw some othee peoples omages in h-a had tonsnof data i dont see in my rgb even with my full spectrum 7d

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Looks to me like you are out of focus. You have to change the focus when you put a new filter in (and that isnt easy with Ha filters because they block so much light).

This is my first attempt at a Ha run. Taken with a Modded 1100d. I am still quite new to this, but still, tis a fun game!

post-39747-0-79323300-1423726046_thumb.j

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I removed the IR filter myself. It isn't a simple task, and boy is it scary, but if you take your time and follow the guides that are on the internets, it can work really well.

I am doing a Ha/Oiii/Sii run. However, due to the weather, I have only manager to get the Ha done so far! 

The forecast says cloudy. Forever.

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Did you remove the CFA and turn it into a black and white?

right now I am using a full spectrum modded 7D, but then I saw some pictures where people are merging 1 Ha with a RGB. So I wanted to try this because it seemed like they had a much better range and details. 

But I am putting the Ha filter on a rgb camera which I don't think is correct. So debating on getting an old cheap aps-c and making it mono, provided it really cheap. I don't know if I want to tackle doing full LRGB due to the amount of time, and trying to fight the weather. If I had a perminantly set up mount, it wouldn't be as bad. 

But then I see how much better the LRGB look. So it's pretty confusing. So merging a HA with an RGB seems somewhere in the middle and I've seen some good photo's that way.

But then I think I need a color camera, and a mono camera. 

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Can a modded camera (full filter removal) be used for daytime shots? I read somewhere it's just a matter of setting a different white balance.

No it can not as it stands. A full filter removal not only takes the hot filter out but also makes the camera record IR as well as the visible spectrum. IR and other wavelengths do not come to focus at the same point using glass lenses so the solution is to use a very high quality UV/IR block , somewhat expensive if your favourite lens has a 72 mm front element,   filter in front of the lens and then using a custom white balance. I believe a camera meant for AP should only be used for AP and it need not need to be a high end one either, a modded  1100d is still more than adequate for hobby purposes. As we used to say in the old film camera days it is not the camera but the person behind it that makes the picture, perhaps the water is more muddy in the digital age.

A.G

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Did you remove the CFA and turn it into a black and white?

right now I am using a full spectrum modded 7D, but then I saw some pictures where people are merging 1 Ha with a RGB. So I wanted to try this because it seemed like they had a much better range and details. 

But I am putting the Ha filter on a rgb camera which I don't think is correct. So debating on getting an old cheap aps-c and making it mono, provided it really cheap. I don't know if I want to tackle doing full LRGB due to the amount of time, and trying to fight the weather. If I had a perminantly set up mount, it wouldn't be as bad. 

But then I see how much better the LRGB look. So it's pretty confusing. So merging a HA with an RGB seems somewhere in the middle and I've seen some good photo's that way.

But then I think I need a color camera, and a mono camera. 

You can do Mono Ha using a CFA sensor. The point that I made was that this method is not efficient as you are only using one out of four pixels to record the Ha with the other three pumping noise into your signal. The process of getting the R photo site to record the Ha signal is simple enough but the correct process of getting that signal turned into a mono Ha is anything but, not terribly difficult but not easy and time consuming. If you are really interested I will write the steps if there is any interest. The procedure of removing the CFA is one of the most difficult modifications that one can undertake and really should not be attempted unless you have a limitless supply of sensors as most will fail. The chances of success is really slim and even then there is no guarantee that the sensor surface is uniform enough to warrant imaging, either due to abrasion or chemical reaction. I have converted a 350d to Mono and I would not like to repeat the experience. It works but the sensor needs to come out and polished smooth by some means. If one is really keen on doing Mono NB or LRGB imaging it is best to save up and buy a dedicated CCD camera from the used market or from a dealer. The normal procedure to do an Ha -OSC combine is normally to obtain the Ha with a CCD and the OSC data with a DSLR. The OSC data is then scaled back and registered to the Ha ( as the Ha will have higher detail level ) and then the Ha is added to R channel of the OSC with perhaps a small percentage as Lum, The ratios are quite important as otherwise the dominant Ha will give you unnatural colour balance and funny looking stars.

Here is a link to a proper Ha capture of IC 1396 using a Modded 1100d and an Astronomik 12nm Ha clip filter.http://www.astrobin.com/119716/

A.G

Edited by lensman57
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What is the relationship between full spectrum, and mono. 

For example, lets say you remove the CFA on an slr, would you also need to remove the IR filter and convert as well? or does mono work differently where your only concern is removing the CFA layer?

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What is the relationship between full spectrum, and mono. 

For example, lets say you remove the CFA on an slr, would you also need to remove the IR filter and convert as well? or does mono work differently where your only concern is removing the CFA layer?

You will have no choice but first to remove all the filters before you even get to the sensor itself. It is the removal of that  last piece of glass that causes as much problem as anything else as past canon 350d the glass seems to have been glued in a way that unless shattered then they won't be removed. This causes the glass bits not only damage the sensor but cut the extremely fine gold wiring that connects the sensor to the rest of the board. A mono mod not only removes the CFA but it also removes the micro lensing that ensures decent sensitivity of the sensor as it concentrates the light on the photo site. These layers are in order of only .001mm thick but very tough so imagine trying to remove such a tough thin layer without touching the sensor itself.

I would still say that a Mono mod should not be attempted. there are a few people that have managed it but if you followed the build log you'd also notice how many times they failed and the camera was thrown in the bin. I have also seen microscopic photographs of some of these sensors with some micro photo sites and micro circuits along the edges of the sensors that if touched render the sensor dead. Best stick to OSC. I am afraid that at the moment there is no cheap short cut to mono imaging. BTW the dedicated mono CCDs do have the micro lensing on top of the sites so they are more sensitive than a mono DSLR by at least 50%. There is a Leica M- Mono on offer for about £6000.00 if anyone is interested.

A.G

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What is the relationship between full spectrum, and mono. 

For example, lets say you remove the CFA on an slr, would you also need to remove the IR filter and convert as well? or does mono work differently where your only concern is removing the CFA layer?

We are talking about 3 different modifications here.

1. IR filter removal:- This removes 1 of the filters in front of the sensor. It is a small IR cut filter which under normal 'daytime' use stops a lot of the red spectrum getting through to the camera. However, in Astrophotography, we WANT the red spectrum to get through (H-Alpha resides in this range), so you take this single filter out. You leave the UV cut filter (second filter in front of the sensor) and CFA (or Bayer Matrix) alone. You can do this yourself, but it isn't easy. You can pay for someone to do it for you (in the UK, cheapastrophotography is a site that is commonly used, and has lots of information about it). I personally would not try this on a camera that costs a lot, or one that you use for normal pictures. When this is removed, some people fit a clear piece of glass so the camera can still be used for daytime things, with some processing after taking the picture.

2. Full spectrum mod:- As above, but you also remove the UV cut filter. This isn't usually done for Astrophotography as UV causes star bloat, and is generally something that we don't need in the pictures.

3. Mono mod/Debayering:- This is where you not only remove the filters listed above (possibly leave the UV one in), but you also scrape off the bayer matrix that is directly on top of the camera sensor. As mentioned above, 9 times out of 10, you will destroy your camera. You should only try this if you have limitless DSLR's lying about (perhaps one that is broken in other ways?) or it your ex's camera and you don't really care what happens to it.

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A full filter removal not only takes the hot filter out but also makes the camera record IR as well as the visible spectrum. IR and other wavelengths do not come to focus at the same point using glass lenses so the solution is to use a very high quality UV/IR block

A.G

2. Full spectrum mod:- As above, but you also remove the UV cut filter. This isn't usually done for Astrophotography as UV causes star bloat, and is generally something that we don't need in the pictures.

 

A Newtonian scope (or other all mirror system) can cope with full spectrum imaging as they are a true apochromatic system (something frequently forgotten by refractor fans.......)

I often image 'full spectrum' with my Newtonian scopes. Other than star cores, the UV component probably doesn't add that much to the mix- but at least it's in focus.

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Is there any advantage to having the UV in there though? I am imaging with a Newtonian, but left that filter in just in case I want to switch over to a refractor or sell the camera at some point. 

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" A Newtonian scope (or other all mirror system) can cope with full spectrum imaging as they are a true apochromatic system (something frequently forgotten by refractor fans.......) "

Hi ,

You are correct in your statement but my answer was to the query whether a full spectrum mod camera could be used for normal daytime photography in which case the answer is no without the use of proper UV/IR block filters as the use of a normal lens is necessary unless the OP wishes to haul a Newt around his neck.

A.G
 

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2. Full spectrum mod:- As above, but you also remove the UV cut filter. This isn't usually done for Astrophotography as UV causes star bloat, and is generally something that we don't need in the pictures.

this one confuses me. So you shouldn't use full spectrum? I am using a refractor as well

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this one confuses me. So you shouldn't use full spectrum? I am using a refractor as well

Hi

Imaging with a full-spectrum modded dslr really needs a UV/IR cut filter - especially with a refractor which will give a blurry result because it can't focus all the wavelengths to the same point. A reflector is better at this but you probably still don't want the UV and IR coming through in normal use (except maybe for planetary imaging, for which I have zero experience!). On the other hand, having a full-spectrum camera does allow you to experiment with IR imaging - with appropriate IR-pass filters. There probably isn't any real reason to have a full-spectrum mod unless you plan on IR imaging. I distinguish between IR (not visible to the naked eye) and far red such as H-alpha and SII.

Louise

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ok, sorry about this but i am getting confused. i am using a refractor for nebulas.

but you say you want a full spectrum with an uv/ir cut filter, but then you say it will be blurry. dont i want all the ir to get the gasses. also, in my image of the horsehead. my stars look too big. is this because my full spectrum conversion?

so what i am asking is, what exactly do i want with my setup. right now i have a full spectrum converted 7d with i thought the ir removed

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