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Old 04-04-2008, 02:17 PM
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Modded Camera Question

Hi Guys,

I have a question if i may about modified cameras.

If I were to modify a Canon DSLR, and it was only going to used for deep sky imaging, and not normal photography, would it just be necessary to remove the already existing filter that is now in the camera, and not put anything in its place, and that would be it, or have I missed something here.

Thanks for you anticipated response.

Leon
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Old 04-04-2008, 02:59 PM
gbeal
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Some of the more clever dickies will likely chime in, but I believe you will need the IR/UV filter as well Leon. Eric will know.
Gary
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Old 04-04-2008, 03:55 PM
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Hi Leon
My take on this is if you replace the uv/ir cutoff filter with clear glass or no filter at all then the camera will be sensitive to near and far infrared as well as uv. This would imply then that your dso pics would show all kinds of responses to these wavelengths.
From my understanding the astronomical value of these filters is up to about 700 to 800 nm as this will allow Ha through but not IR due to heat etc.
Hutech classify their filters as astronomy and Infra red.
Infra red is useful for heat source detection.
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Old 04-04-2008, 07:32 PM
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Quote:
Originally Posted by leon View Post
Hi Guys,

I have a question if i may about modified cameras.

If I were to modify a Canon DSLR, and it was only going to used for deep sky imaging, and not normal photography, would it just be necessary to remove the already existing filter that is now in the camera, and not put anything in its place, and that would be it, or have I missed something here.

Thanks for you anticipated response.

Leon
howdy leon,

you certainly can just remove the existing filter but don't forget, IR light will need to be blocked. If IR light doesnt get blocked, your focus will not be accurate. IR light will interfere with your focus. If UV light doesn't get blocked, you might get those purplish halo's with bright stars from your refractor

Alternatively, you can leave the DSLR without a replacement filter and just use a UV/IR 2" filter in your imaging chain.
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Old 04-04-2008, 07:43 PM
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If IR light doesnt get blocked, your focus will not be accurate. IR light will interfere with your focus.
Hi Eric and Leon
Question for Eric wrt focus and IR. Does the focus problem only occur when using dslr lenses or are you suggesting that the camera body at prime or eyepiece projection will also have focus problems?
What have you concluded now that you have done the tv remote test and what corrective actions will you take?
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Old 04-04-2008, 07:49 PM
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Hi Steve. If IR is not blocked, you'll notice on bright stars it wil be harder to get accurate focus because your camera is letting in IR spectrum. talking about camera body at prime. This is the case also with my DSI when i removed the IR blocking filter, the image will be more red than without and stars will become larger.

corrective action i have taken with my camera is to get myself a UV/IR filter (for astro use) and for terrestial use, getting myself the IDAS daylight front filter The IDAS daylight front filter is very very close to the original canon filter.

Last edited by EzyStyles; 04-04-2008 at 08:00 PM.
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Old 04-04-2008, 07:59 PM
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Hi Eric
Good to know that the filter issues are now resolved and corrective actions planned.
Looking forward to your next batch of stunning astropix.
Hope Fred has also resolved his filter issues.
Glad to know that my idea wrt tv remote had some value in helping with these issues.
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Old 04-04-2008, 08:03 PM
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no worries steve cheers. now is there some sort of transparent material lying around that i can use to block IR?
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Old 04-04-2008, 09:05 PM
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Thanks guys, I think you have answered my concerns, as I see it my best bet is to have the existing filter removed and UV/IR filter put in its place,

Thank You all for your responses.

Leon
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Old 04-04-2008, 11:04 PM
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Just to add a little and clarify an other.
When mirrors are used, there is no error. All points focus the same.
So if you have a newtonian, then leave it as is, without the glass.

You can also use an external filter to remove any issues, thus saving a little to get it fitted with a IR glass filter.
This is what i do with my 20D

Theo.
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Old 04-04-2008, 11:14 PM
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I would be very interested in seeing a picture taken with a modded camera that has no filter. ie open to whatever wavelengths arrive.
The Hutech filter as i said cuts off very sharply at 700nm and has no leakage above 700nm.
Already 75 sec of eta carinae shows lots of red so i suspect that any more ir would wash every thing out.
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Old 05-04-2008, 12:05 AM
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I have been wondering about this myself. I can get somebody in Adelaide to remove the filter in my Canon 400D, but it starts to get expensive to have them replace it with a Baader. The alternative is to use the Astronomik UV-IR Block L EOS-Clip in filter @ $149. Also, if I use a 2 inch version of the IR/UV, I haven't got room for my CLS filter. Does anyone use the clip in filters from Astronomik?
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Old 05-04-2008, 06:55 AM
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Originally Posted by skwinty View Post
Already 75 sec of eta carinae shows lots of red so i suspect that any more ir would wash every thing out.
Hi,

Not sure what you mean here, Eta is a big mass of hydrogen and is supposed to be very red.

Paul
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Old 05-04-2008, 07:39 AM
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Graig, the only Camera that dosen't support the clip on filter arrangement is the Canon 5D, I have had a look at this option as well, otherwise it would have solved a few problems.

Leon
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Old 05-04-2008, 11:13 AM
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Quote:
Originally Posted by skwinty View Post
I would be very interested in seeing a picture taken with a modded camera that has no filter. ie open to whatever wavelengths arrive.
The Hutech filter as i said cuts off very sharply at 700nm and has no leakage above 700nm.
Already 75 sec of eta carinae shows lots of red so i suspect that any more ir would wash every thing out.

Hi skwinty here is an pic with an modded Pentax *istD.
Single exposure no darks and flats.
Second pic same one but processed in CS2.
90Sec exposure.
Attached Thumbnails
Click for full-size image (_IGP9499_filtered.jpg)
194.1 KB23 views
Click for full-size image (M42_filtered11.jpg)
115.0 KB34 views
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Old 05-04-2008, 06:17 PM
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Originally Posted by skwinty View Post
I would be very interested in seeing a picture taken with a modded camera that has no filter. ie open to whatever wavelengths arrive.
Mine is modded 300D and it has no filter, just Edmund glass.
You can see pictures in this album Five of them taken with this camera, the rest were taken with umodded 400D.

I'd love to take them with a IR/UV filter just to see the difference. However since I want to upgrade to either modded 40D or 450D with UV/IR there is no point for me now to invest money to a separate IR/UV filter.

cheers,

Michael
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Old 06-04-2008, 07:33 AM
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Hi,

Not sure what you mean here, Eta is a big mass of hydrogen and is supposed to be very red.

Paul
Hi Paul
My 40DH filter cuts off at 700nm. This shows the Ha perfectly.
If I remove the filter and everything above 700nm is passed then I suspect the image would become even more red due to the extended IR wavelength.
check Mill's pic of M42 unprocessed.
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