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modding my 1000D....clarification needed....

stan26

By stan26
in Discussions - Cameras

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stan26

stan26

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Hi Guy's,

I know this subject has been done to death over the net across various forums etc, but I just want some final clarification on the filter removal affects with my newly acquired canon 1000D.

I will be using the modded camera ONLY with refractor's and my canon lenses. My intention is to remove only the necessary ir/uv cut colour balance filter to allow more red response etc etc, My big concern is that because I'm using refracting optics I will get star bloat and slightly out of focus images. I have read in many threads that if i only remove the blue'ish filter closest to the sensor chip I won't have these problems because the front filter (dust shake thingy) actually cuts enough IR to prevent this bloat/oof from happening.....? Can anyone 100% confirm that this is the case..?

If the above is correct and people are getting good results using a modded 1000d with no replacement filters and no clip filters just pure colour balance filter removal etc, then I guess I just need to follow Gary honis;'s instructions on self modding the 450/1000d....?

Thanks guys, I though i had it all clear in my mind, but now im ready to rip apart a £200 dslr i'm having a bit of an ocd moment!

Regards

Stan.

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Bizibilder

Bizibilder

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I had the filter removed from my 1000D (by Astronomiser) and have no problems when using the camera with my ED 120APO (or ED80APO). You will get slight colour fringing with an achromat whether the camera is modded or not. You can get filters that help but cannot say how good they are as I have never used one.

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stan26

stan26

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Thanks guys, I thought that was the case, I just wanted to make sure I was leaving some sort of IR cut in there.

And I can now proudly announce I have a modded DSLR ready for the autumn/winter season! :cool:

It wasn't really that hard to do either. Took me about 2hrs (inc a slight hiccup on re-assembly :rolleyes: ), Taken a few pics around the house with it, obviously everything now has a nice red/pink hue, and also the AF still seems to function pretty well but that doesn't concern me anyway, its now a dedicated astro cam. Can't wait to test it out!

Stan.

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stan26

stan26

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Guys, here is the first test image with my modded 1000d.

For comparison the first image is from my stock 500D. Both pics are taken in the cygnus region with roughly the same framing. Both are 30sec subs at ISO 800. Both cameras set to auto white balance, both images taken through my 200 2.8 lens with skywatcher LP filter installed.

Initial thoughts on the results: An obvious jump up in red response from the 1000D, slight nebula showing just low and right off center frame. Star colour is not quite as good as stock 500D, but focus, star shape/sharpness seems to be ok. Overall i'm happy with the out come.

I will do some in depth testing/imaging and post the results once the moon goes away.

500D stock camera.

7925051294_de57bfa8bd_b.jpg

500D VS Modded 1000D test by James stannard, on Flickr

Modded 1000D

7925045098_29d2df8cd7_b.jpg

500D VS Modded 1000D test by James stannard, on Flickr

Stan.

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Gina

Gina

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You can correct the colour balance in the processing quite easily. I use PhotoShop but I think you'll find most if not all image processing software has this facility. I don't bother to correct white balance in the camera.

A point when using normal photographic lenses for AP - these lenses are not fully apochromatic, unlike telescopes such as the ED series and other APOs (or Newts which don't use glass and are totally clear of chromatic aberration). This means that you get some CA with photo lenses which shows up as either red or blue/green fringes around stars. This is due to the focus being slightly different for red light.

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stan26

stan26

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You can correct the colour balance in the processing quite easily. I use PhotoShop but I think you'll find most if not all image processing software has this facility. I don't bother to correct white balance in the camera.

A point when using normal photographic lenses for AP - these lenses are not fully apochromatic, unlike telescopes such as the ED series and other APOs (or Newts which don't use glass and are totally clear of chromatic aberration). This means that you get some CA with photo lenses which shows up as either red or blue/green fringes around stars. This is due to the focus being slightly different for red light.

Hi Gina, Yes as you say I will probably sort WB in post processing, but I will experiment with the custome WB function to see what results I get.

I appreciate your point about camera lenses and CA, but I bet my Canon 200L stopped down to f4 would give any sub £1500 APO a run for its money, not just regarding CA, but also field flatness etc. The only real problem with a high quality camera lens such as this one is that when stopped down to give preferable results the lenses aperture blades (8 in my case) cause the star light to diffract, but this is simply rectified with a front apeture mask. I do however agree that the cheaper lens will cause CA, quite bad in some cases, but anyway thats a whole different discussion. :laugh:

Stan.

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Gina

Gina

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Hi Gina, Yes as you say I will probably sort WB in post processing, but I will experiment with the custome WB function to see what results I get.

I appreciate your point about camera lenses and CA, but I bet my Canon 200L stopped down to f4 would give any sub £1500 APO a run for its money, not just regarding CA, but also field flatness etc. The only real problem with a high quality camera lens such as this one is that when stopped down to give preferable results the lenses aperture blades (8 in my case) cause the star light to diffract, but this is simply rectified with a front apeture mask. I do however agree that the cheaper lens will cause CA, quite bad in some cases, but anyway thats a whole different discussion. :laugh:

Stan.

Ah yes, I gather the 200L is a very good lens :) Also, I think maybe longer lenses are better for CA.
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stan26

stan26

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Guys, can anyone point me in direction to a site/link where I can see exactly how broad a spectrum my modded camera is now capable of.?

Also how effective would it be using a 30 or 12nm HA filter even though it still has the front filter (dust shake) still in place which has an ir/uv cut....?

Stan

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Merlin66

Merlin66

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The front filter only cuts at 400nm and 700nm. The Ha is well within the transmission curve.

Using narrowband filters will cause a loss of resolution and some detail (only the one red pixel, out of the group of four is being used - Bayer Matrix)

IMHO narrowband filters are for mono CCD use, not DSLR.

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stormlv

stormlv

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I can confirm 100% that the front "dust" filter acts as an effective UV-IR blocker.

I don't know exactly about what camera's you're referring about but for the newer cameres the front filter actually is made of two filters:

1) Anti-alising filter

2) Hot mirror (UV-IR blocker)

One only needs to replace the hotmirror and leave the AA filter alone

(http://www.rocklandastronomy.com/NEAIC/talks/Hap_Griffin.pdf)

The front filter only cuts at 400nm and 700nm. The Ha is well within the transmission curve.

Couldn't be farther from the truth... The hotmirror filter starts cutting around 550nm and gradually descends to around 20% transmittance @ Ha (check link above)

Replacing the original hotmirror with an AstrodonInside filter increases this transmittance to around 95% or more (almost 5x increase) - not at all neglijable...

Using narrowband filters will cause a loss of resolution and some detail (only the one red pixel, out of the group of four is being used - Bayer Matrix)

If you'd compare a DSLR or a OSC camera with a mono, then I'd agree a 10MP OSC will have a lower "color resolution" than a 10MP mono camera.

But I don't really understand why you'd "lose resolution and detail" if you're using NB filters...

If your object is just emitting Ha - let's say - either way only the red pixels will light up. Having a NB filter or not, won't matter.

By using a NB filter you're going to severely limit the impact that sky glow will have on your photos...

Like here (Canon 40D with Ha 5nm filter) ->

7829091616_ac91089ea6_h.jpg

Emission nebulae are mostly bright in Ha, OIII and S2 - all the rest is sky glow which limits the exposure time and your ability to see nebula details.

By using NB filters you're not losing any resolution - you do gain contrast however and a much higher SNR...

IMHO narrowband filters are for mono CCD use, not DSLR.

I do agree that narrowband filters are more suited for CCD, but if you're into nebula work from a light polluted area - they can be a great addition. Either way, you can "recycle" then when going to a CCD...

If you

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Gina

Gina

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Regardless of the above I can confirm that with the 1100D removing the colour correction filter (looks blue coloured and is nearest to the sensor) and putting back the IR/UV clear filter, increases the response to Ha by about five times. I have now done the filter mod on several 1100Ds and all give the same result.

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stormlv

stormlv

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I think if OIII were added to the Ha and combined as Ha, Ha+OIII, OIII the result would be superb.

Is the Ha taken with the same camera as the colout image? Botth DSLR?

Yup, both were taking with the same camera : Canon 40D

First one (ha) was taken using a refractor (500mm , F/5)

Second one was taken using a newton (750mm, F/5). I couldn't use the same scope since the SX filter wheel introduced too much backfocus and wouldn't work on the newton...

Here are the images that I took with the Canon 40D and NB filters (http://www.flickr.com/search/?w=9967669@N08&q=canon%2040d)

Here's a Ha + O3 image of lagoon nebula for fun:

7743394122_70bb1cd4b7_h.jpg

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Gina

Gina

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Goodness me - that's beautiful :) It'll be quite a long time before I can afford a mono astro CCD camera but it looks like I should get plenty of use out of my DSLRs :) Thank you for posting that :)

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stormlv

stormlv

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Goodness me - that's beautiful :) It'll be quite a long time before I can afford a mono astro CCD camera but it looks like I should get plenty of use out of my DSLRs :) Thank you for posting that :)

Thank you!

I have been doing astrophotography with a DSLR for three years now (http://www.flickr.com/photos/stormlv/collections/72157629085557466/ - Some of them with the Canon 40D, and the rest with the unmodded Sony Donkey, A77 or A700)

Just now I managed to switch to a CCD (which because of the damn weather, I can't get my first light out of it)

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