Modded Camera Help Needed (better description)

[johnb]

So i had my Cannon 450d modded and the IR Filter removed, I took a test shot which was a guided 300 Sec shot of M42, Camera set to RAW and ISO800

I stacked the single shot in DSS and it detected plenty of stars but seemed very red \ orange in colour and I noticed it took so much longer to register and stack than prior to modding, I also noticed the image you get at the bottom looked very different see below

Anyway took the image into PhotoShop and I attach the saved image with no adjustment the hist is below with the unedited image

Am i doing the right thing with the taking, stacking and processing

Regards

John B

[mikeknowle]

Gosh it is does look red doesn't it? And the whole image is quite saturated.

If there wasn't so much cloud this week/month/year, I'd take a similar photo with my camera and compare the settings/output for you...

And I'm just buying a new version of photoshop so I'll have to learn all about that also!

Mike

[Psychobilly]

DID you use any IR filtering at all?

Unless your doing IR pass then you really need to use and IR Cut with a filter removed camera - you can see the Saturated data at the extreme right of the histogram (thats just the start of the IR hump) thats contributing to your problems...

I use either a CLS-CCD Clip-in or Hutech IDAS (2" or in body) with my modded cameras both of which are effective LP filters with UV and IR Cut...

Billy....

[johnb]

DID you use any IR filtering at all?

Unless your doing IR pass then you really need to use and IR Cut with a filter removed camera -

Billy....

Err thank not sure what you mean by Unless your doing IR Pass ?, im not using any filtering at all but will have read and see what I need thanks.

John B

[Psychobilly]

Hi John,

IR pass is when you use a filter that cuts out the visible light do the camera only captures the IR light....

IR Cut cuts of all light beyond the red end of the visible spectrum and UV cut cuts of all visible light below the violet end...

SO a UV/IR Cut will only allow visible light to be captured...

Billy...

[johnb]

Hi John,

SO a UV/IR Cut will only allow visible light to be captured...

Billy...

Thanks think im understanding, so by using a UV/IR with my modded camera will realy allow a better capture of DSO's espcially those rich in Hydrogen like M42 and by the same taken now with the modded camera Galays and clusters are going to be somehwat more realistic (hope I have got it right)

John B

[Psychobilly]

Basically..

Yes...

[johnb]

Thanks I understand, what a great way to finish the week - Appreciated.

Regards

John B

[acme]

John,

my 1000d with the same mod looks as red as yours, I thought mine was due to the CLS CCD clip filter I use. I need a Photoshop expert to come along and tell me how to process it.

Single 300 sec exposure no PS just cropped .

Acme

[Psychobilly]

Which version of the CLS are you using - for a filter removed camera you should really be using the CLS-CCD variant as this has UV/IR cut in addition to its LP filtering...

Billy...

[johnb]

Im planning to get one of these ?

UV & IR Filters - Baader UV/IR Cut Filter

John B

[Merlin66]

I posted this image by Jack Martin over on the spectroscopy thread, but worth repeating here.

The top image is a spectrum of Vega taken with a 350D with the standard filter in place

You can see on the bottom image taken with a 300D (filter removed) that the camera records both down in the UV and well up into the NIR - you're effectively recording ALL the visible spectrum!!

If you add a Baader UV-IR cut filter then the wavelengths below 400nm and above 700nm will be blocked...

[acme]

Hi,

I am using one of these..Astronomik CLS CCD Filter EOS Clip fit

Acme

[johnb]

If you add a Baader UV-IR cut filter then the wavelengths below 400nm and above 700nm will be blocked...

I thought from what was explained in this thread that it was desirble to do that ?

Starting to get confused again

[dlp]

What is the point of using a CLS-CCD filter on a modded camera on a reflector? It cuts the IR spectrum, which is what the camera was modded to allow? The OP's pic is well saturated because it's 300s - it needs a lot more subs of shorter exposures to be added to the stack. There was also no real point of putting a single shot into DSS - it would have surely been better handled in PS?

David

David

[Merlin66]

No, don't get confused.....

The reason for the filter removal in the first place is to increase the CCD chip efficiency to record the Ha light. Look at the images of Vega spectrum... you can see that the modded spectrum is brighter and definately records more Ha. The efficiency is increased by around 100% (from 20% up to 40-45%).

With lenses or refractors they have real problems focusing the green/ blue and red parts of the spectrum at the same time -that's why people pay rediculous money for APO refractors. This is not a problem with reflecting scopes which bring all the different wavelengths to the same focus.

To prevent further embarressment for refractor owners they ADD a filter which cuts out the far red and NIR thus giving them the benefits of the improved Ha without the hassles of an out of focus IR background.

The NIR also has lots of detail to add to both planetary and DSO objects...IF the camera is properly focused for NIR.

Hope this helps...your camera is doing exactly what the mod was intended to do...enjoy it!

[johnb]

So I think your saying that I should add the UV\IR Filter Im unsure how I ensure im properly focused for NIR ?

As for using DSS I simply wanted to ensure that DSS could register stars on my very saturated image and indeed it can.

John B

[Merlin66]

John,

If you're using it on your 250mm Newtonian reflector then focus is not the issue. But for aeshetics and to keep in line with "expectations" you may want to take some subs with and without the UV-IR blocker that way you can mix and match the data in the final image.

[Psychobilly]

If you can try and use 2" filters and adaptors to reduce vignetting...

Billy

[Guest]

Which version of the CLS are you using - for a filter removed camera you should really be using the CLS-CCD variant as this has UV/IR cut in addition to its LP filtering...

Billy...

Not on a 1000d as the filter removal leaves a second filter in place that cuts IR very effectively, camera before the 1000d did not have this second filter and so needed a replacement IR cut filter like the Astonomik CCD version mentioned. I have the same mod and just use the Astronomik clip LP filter not the CCD version.

Stewart