Odd query

TelePaul · 03-12-2007 4:23pm #1

Haha I said query

Ahem. Anyways, I was wondering has anybody pursued lunar photography or fitted a camera to a telescope with an adapter mount? Considering going down the route of telescopes but it could be pretty expensive for this particular niche. Your thoughts?

Fajitas! · 03-12-2007 4:30pm

I'm not too up on it, but as far as I know, you're going to have to get your sensor's IR filter removed...

Then again, 20D's are pretty cheap these days, just buy one second hand.

Exposures are still quite long, so you're going to have to get a tripod head that can follow the earths rotation too, if I remember correctly...

TelePaul · 03-12-2007 4:59pm

Fajitas! wrote: »

I'm not too up on it, but as far as I know, you're going to have to get your sensor's IR filter removed...

Then again, 20D's are pretty cheap these days, just buy one second hand.

Exposures are still quite long, so you're going to have to get a tripod head that can follow the earths rotation too, if I remember correctly...

Ouch, the guy in the shop didn't mention that, thanks alot Fajitas. Do you know why exactly I'd have to get that done?

trishw78 · 03-12-2007 5:06pm

cause the earth is rotating, ok smart ass answer

the stars will leave a light trail on very very long exposures

TelePaul · 03-12-2007 5:07pm

trishw78 wrote: »

cause the earth is rotating, ok smart ass answer

the stars will leave a light trail on very very long exposures

I meant why I'd have to have the sensor removed, not about bulb exposures with a tripod. Is your answer still valid?

dr strangelove · 03-12-2007 5:08pm

Yeah, i tried it a couple of times - I've got a fairly bottom-end scope - one of these - and an Olympus E300, and these are the results:

http://www.flickr.com/photos/reverend_smarm/2060954860
http://www.flickr.com/photos/reverend_smarm/2060172849
http://www.flickr.com/photos/reverend_smarm/2060172749
http://www.flickr.com/photos/reverend_smarm/2060172601

Exposure was 1/200 or 1/60 sec depending on iso.

They're not particularly brilliant, they're not as sharp as i'd like, but i'm not sure what the problem is - either the camera or the telescope, i'm not really proficient enough in either field to figure it out.

trishw78 · 03-12-2007 5:11pm

@ Telepaul no sorry.That is an interesting question though about the IR sensor

nilhg · 03-12-2007 5:14pm

trishw78 wrote: »

cause the earth is rotating, ok smart ass answer

the stars will leave a light trail on very very long exposures

Even on quite short exposures, if you are using any sort of telephoto lens or telescope.

Some reading here.

TelePaul · 03-12-2007 5:28pm

dr strangelove wrote: »

Yeah, i tried it a couple of times - I've got a fairly bottom-end scope - one of these - and an Olympus E300, and these are the results:

http://www.flickr.com/photos/reverend_smarm/2060954860
http://www.flickr.com/photos/reverend_smarm/2060172849
http://www.flickr.com/photos/reverend_smarm/2060172749
http://www.flickr.com/photos/reverend_smarm/2060172601

Exposure was 1/200 or 1/60 sec depending on iso.

They're not particularly brilliant, they're not as sharp as i'd like, but i'm not sure what the problem is - either the camera or the telescope, i'm not really proficient enough in either field to figure it out.

Thanks man. What I heard was when it comes to telescopes, lens construction is less important than the amount of light it lets in. The mor elight, the sharper the image. Do you know anything about the infra red sensor?

dr strangelove · 03-12-2007 5:36pm

Dunno about the infra red sensor - the camera is stock (as far as i know - it was bought second hand).

the telescope comes with a lens cover in two parts - one part like a standard lens cover about 3" dia, the other like a donut about 5" o/d with a 3" hole in it, into which the other part fits (does that make sense?) so you effectivley have two levels of light allowed in. it's pretty basic, and when i have the time and the clear skies i'll monkey around with the set-up a bit more.

isadub · 03-12-2007 5:45pm

You might some info on astronomy.ie, and their Artane shop.

TelePaul · 03-12-2007 5:51pm

Thanks for your help everyone, I like the idea of astro photography but I think it'll require quite a bit of research and even more funds. I'm supposed to be picking a christmas present for myself but I might just have to go with another guitar. Will let you know how I get on.

Fajitas! · 03-12-2007 6:00pm

IR filter is due to the earths athmosphere or something like that? I'm very very tired.

nilhg · 03-12-2007 6:24pm

Explanation re IR filter removal from the site I linked to above

"Normally the CMOS and CCD chips used in DSLR cameras are sensitive to red light. Most DSLRs however, are designed with a built-in, low-pass, long-wavelength cutoff filter in front of the sensor. The low-pass characteristics of the filter are designed to prevent moire. The long-wavelength filtration is designed to improve color reproduction and make it more like our human visual perception.

The problem is that the long-wavelength filtration also filters out most of the light at 656.5nm, the wavelength of hydrogen-alpha. This is the red light of emission nebulae. Filtering out most of this light is a problem for astrophotography if you want to take pictures of these red nebulae, which are some of the largest and most beautiful objects in the night sky.

Canon was the only manufacturer to make a DSLR camera body specifically for astrophotography with improved hydrogen-alpha sensitivity, the EOS 20Da. Canon however, has discontinued production of this camera as of the spring of 2006.

It is possible to modify other DSLR cameras for astrophotography of emission nebulae by removing the low-pass, long-wavelength filter. This, of course, invalidates the warranty and runs the risk of ruining the camera if not done correctly. However astrophotographers have successfully removed the filters in both Nikon and Canon cameras and produced excellent images of objects with emission wavelengths.

Additionally, third-party vendors such as Hutech offer modified cameras with these filters removed and various replacement filter options. These modified cameras come with their own warranty from Hutech."

TelePaul · 03-12-2007 6:26pm

nilhg wrote: »

Explanation re IR filter removal from the site I linked to above

"Normally the CMOS and CCD chips used in DSLR cameras are sensitive to red light. Most DSLRs however, are designed with a built-in, low-pass, long-wavelength cutoff filter in front of the sensor. The low-pass characteristics of the filter are designed to prevent moire. The long-wavelength filtration is designed to improve color reproduction and make it more like our human visual perception.

The problem is that the long-wavelength filtration also filters out most of the light at 656.5nm, the wavelength of hydrogen-alpha. This is the red light of emission nebulae. Filtering out most of this light is a problem for astrophotography if you want to take pictures of these red nebulae, which are some of the largest and most beautiful objects in the night sky.

Canon was the only manufacturer to make a DSLR camera body specifically for astrophotography with improved hydrogen-alpha sensitivity, the EOS 20Da. Canon however, has discontinued production of this camera as of the spring of 2006.

It is possible to modify other DSLR cameras for astrophotography of emission nebulae by removing the low-pass, long-wavelength filter. This, of course, invalidates the warranty and runs the risk of ruining the camera if not done correctly. However astrophotographers have successfully removed the filters in both Nikon and Canon cameras and produced excellent images of objects with emission wavelengths.

Additionally, third-party vendors such as Hutech offer modified cameras with these filters removed and various replacement filter options. These modified cameras come with their own warranty from Hutech."

I really appreciate that, thanks so much!

Fajitas! · 03-12-2007 6:38pm

Aha! I knew I was right. I just didn't know why!

Actually, I believe there's a 20D made specifically for astrophotography - the 20D B or something. Has mirror lock up as standard, and the IR filter removed, maybe one or 2 other bits and bobs.

TelePaul · 03-12-2007 6:54pm

Fajitas! wrote: »

Aha! I knew I was right. I just didn't know why!

Actually, I believe there's a 20D made specifically for astrophotography - the 20D B or something. Has mirror lock up as standard, and the IR filter removed, maybe one or 2 other bits and bobs.

Just ordered this instead

Actually I meant to post some pics of my guitars and combine both of my interests. I dunno how I could go about making them artistic though.

Fajitas! · 03-12-2007 6:59pm

Money wasted!

nilhg · 03-12-2007 7:05pm

TelePaul wrote: »

Just ordered this instead

You will be warmer with that, than you would be out in the dark with a telescope.

Odd query

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