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DSLR used for astrophotography???

Posted: Thu Jan 09, 2020 12:50 am
by lsintampa
I may want to venture into astrophotography, but I've read too much that I'm very confused.

Initially I was under the impression that you could use a good Digital SLR with native camera lenses or connected to your telescope for astrophotography. Given that you need good exposures and stacking software, seems rather straight forward, albeit complex.

Then I've read (recently) that all DSLR camera require some sort of sensor filtering modifications to work well for AP.

Then there are mono and or color CCD cameras specifically for AP.

Then some sort tracking mount is also necessary.

I'm a "proof" of concept type of person. Meaning if I can get decent results with existing gear and or minimum investment, I have no issue investing in better equipment.

I currently have a old Nikon DSLR (D50), no tracking device, no dedicated CCD. My telescope is the Celestron 102eq refractor. GSO 2" Barlow, three good eyepieces, moon filter, t-mount for the camera.

I've had very good luck with moon shots, but have not attempted any other types of photos.

All that said, I'm not only confused but wondering what next steps might be to my proof of concept theory????

Seeking some guidance here.

:think:

Re: DSLR used for astrophotography???

Posted: Thu Jan 09, 2020 1:16 am
by metastable
I did this one with a nikon d800 and 14-24mm nikon lens with photo tripod & 10sec, 2000iso, 2.8f shot in raw, then processed in lightroom with these settings:

Temp: 4637k
Tint: +2
Exposure: -0.97
Contrast: +87
Highlights: -100
Shadows: +100
Whites:+73
Blacks: +100
Clarity: +22
Dehaze: -1
Vibrance: -61
Saturation: -40

(make sure you manually focus by zooming into a star in the live preview while adjusting the focus ring)

Image

Re: DSLR used for astrophotography???

Posted: Thu Jan 09, 2020 1:21 am
by UlteriorModem
The IR filter mod is not 'required' at all. I will just leave it at that.

Re: DSLR used for astrophotography???

Posted: Thu Jan 09, 2020 1:54 am
by Thefatkitty
Well, with what you currently have... I like what metastable did; that might be the way to go.

I have essentially the same scope as yours; mine is a Celestron 102SLT. Two years ago almost to the day, I mounted it on my CG4, did a rough polar alignment, and put my Canon T3 (1100D) in the focuser. I manually guided it on Orion for 15 seconds; bit of star streaking but you get the idea. Problem with an achro is the green stars. Also my pics shows lots of LP and dust bunnies, but that's another matter.
Orion_15secs_102SLT_CG4.png
DSCF6905.JPG

Some people on here use DSLR's and quality (APO, ED) scopes with great results; the proof is in the pics. But you'll need some do-ray-me for that :lol:

I'm with UlteriorModem on his comment as well :D

All the best,

Re: DSLR used for astrophotography???

Posted: Thu Jan 09, 2020 2:06 am
by KathyNS
You can take perfectly respectable photos without the filter mod. You don't need that. Use your existing camera.

Without a tracking mount, you will be limited in your exposure time. The limit is 400 divided by the focal length. So, with a 50mm lens, you could go up to 400 / 50 = 8 seconds. With a 400mm lens, you could only to up to 1 second. If your telescope is 1000mm focal length, your maximum exposure time would be 0.4 seconds.

You should be able to do some really nice nightscape photography with a wide-angle lens.

The first piece of equipment you should look at is a good tracking mount. Something like the Celestron AVX is a good place to start, and will allow for future expansion of your interest. If budget limits you, you could start with a star tracker. It would have less room for future upgrades, but will get you started with your camera and lenses.

Re: DSLR used for astrophotography???

Posted: Thu Jan 09, 2020 2:12 am
by JayTee
First off, go read all the stickies on these forums that pertain to AP. Look in the Software forum and the AP forum.

Secondly, there are three very distinct types of AP - 1) Lunar/Planetary, 2)Long exposure deep-sky object AP, and 3) Ultra wide-field Nightscape AP. All these disciplines use scopes/lenses of very different optical characteristics.

#1 Requires long focal length and (if you can afford it) large aperture (bottom line: expensive OTA).
#2 Requires much shorter focal lengths and just about any aperture (bottom line: expensive mount). Keeping in mind that the lighter the payload the less expensive it is to move it accurately across the sky!
#3 The needs for this discipline is much less severe - a camera with its lens and a tripod.

So which is it, Lunar/Planetary or Long Exposure or Nightscape?

Knowing this information completely changes how we give suggestions.

Cheers,
JT

PS, I used the word "expensive" more than once!

Re: DSLR used for astrophotography???

Posted: Thu Jan 09, 2020 3:10 am
by lsintampa
JayTee wrote: Thu Jan 09, 2020 2:12 am First off, go read all the stickies on these forums that pertain to AP. Look in the Software forum and the AP forum.

Secondly, there are three very distinct types of AP - 1) Lunar/Planetary, 2)Long exposure deep-sky object AP, and 3) Ultra wide-field Nightscape AP. All these disciplines use scopes/lenses of very different optical characteristics.

#1 Requires long focal length and (if you can afford it) large aperture (bottom line: expensive OTA).
#2 Requires much shorter focal lengths and just about any aperture (bottom line: expensive mount). Keeping in mind that the lighter the payload the less expensive it is to move it accurately across the sky!
#3 The needs for this discipline is much less severe - a camera with its lens and a tripod.

So which is it, Lunar/Planetary or Long Exposure or Nightscape?

Knowing this information completely changes how we give suggestions.

Cheers,
JT

PS, I used the word "expensive" more than once!

I'd say NOT AP type 1, but 2 &. 3 would play into my thinking.

Re: DSLR used for astrophotography???

Posted: Thu Jan 09, 2020 5:43 am
by JayTee
Thank you for your reply.

I'm hoping you will start with #3 because that is by far the easiest and least expensive way to start. Let us know how you'd like to proceed.

Cheers,
JT

Re: DSLR used for astrophotography???

Posted: Thu Jan 09, 2020 8:20 am
by OzEclipse
Hi isintampa,
You don't have to have the modification made and yes you can take AP with DSLR camera and camera lenses. The modifications change the filter in front of the sensor to allow more red light to reach the sensor. Many modern DSLR's are being released with decent red sensitivity.

The picture posted by Metastable is taken with a D800, a very capable 2012 model camera. Your D50 is a 2005 model and relatively noisy compared to a modern sensor. So you can do work. I suspect you will find it very noisy so you'll need to take many identical pictures and stack and average to reduce the noise inherent in your camera.

Good luck.

Joe

Re: DSLR used for astrophotography???

Posted: Fri Jan 10, 2020 2:09 am
by lsintampa
IDK, I took my camera out tonight, set my wide angle zoom to about 20mm, set ISO to 1600, took several pictures of just the sky - it was about 8:30PM - FLorida - so it was dark. Not as dark as it will get, but it was dark. Mounted on my eq-4 mount.

Photos came out like it was daylight - the sky was blue, the trees were green / brown and no stars at all.

In my disappointment, I just deleted all the photos - they were awful.

I took the shots using a 10 second shutter delay, with the shutter at 25 - 30 seconds, f stop wide open (I think), ISO at 1600.

Not off to a good start.

Re: DSLR used for astrophotography???

Posted: Fri Jan 10, 2020 2:51 am
by UlteriorModem
Hrm, did you process the frames? It sounds like the Bayer Matrix was wrong.

Re: DSLR used for astrophotography???

Posted: Fri Jan 10, 2020 3:05 am
by lsintampa
I shot in raw format. It saves two files, raw and jpeg.

I did not process the frames. A - I don't know what that means and B - therefore I did not do that.

What does processing mean exactly?

Re: DSLR used for astrophotography???

Posted: Fri Jan 10, 2020 3:24 am
by Sky Tinker
Your camera has a rather large CCD-sensor for gathering light, and a small pixel-density for reduced noise within the images...

https://www.digicamdb.com/specs/nikon_d50/

You're good to go there, but the Celestron CG-4 and the Omni XLT 102 OTA are not ideal for imaging with a DSLR, at prime-focus, not by a long shot. You can take afocal shots through an eyepiece(limited to the brighter objects), and perhaps even attach a webcam-type camera, but only if you motorise the RA-axis of the mount.

This book contains a wealth of information on the subject...

Re: DSLR used for astrophotography???

Posted: Fri Jan 10, 2020 3:55 am
by Juno16
Isintampa was shooting with a zoom camera lens at about 20mm wide open.

If you can see stars naked eye, you definitely should see stars in a raw (Nikon “nef”) file at iso 1600 for a 25 second exposure. Any way to retrieve a file so that you can attach it?

Thanks,
Jim

Re: DSLR used for astrophotography???

Posted: Fri Jan 10, 2020 4:41 am
by JayTee
Many things were involved in making the background of your images so bright. Light pollution, the Moon, atmospheric junk like moisture and dust. Can you please go back out and shoot some more images only this time share a couple of them with us so that we can evaluate them. Thank you.

Cheers,
JT

Re: DSLR used for astrophotography???

Posted: Fri Jan 10, 2020 6:23 am
by OzEclipse
If you expose for long enough even on the darkest night, any photo will end up looking like daylight.

So....what JayTee said. Show us some results. We're not psychic! :D

Cheers

Joe

Re: DSLR used for astrophotography???

Posted: Fri Jan 10, 2020 8:35 am
by yobbo89
lsintampa wrote: Fri Jan 10, 2020 2:09 am IDK, I took my camera out tonight, set my wide angle zoom to about 20mm, set ISO to 1600, took several pictures of just the sky - it was about 8:30PM - FLorida - so it was dark. Not as dark as it will get, but it was dark. Mounted on my eq-4 mount.

Photos came out like it was daylight - the sky was blue, the trees were green / brown and no stars at all.

In my disappointment, I just deleted all the photos - they were awful.

I took the shots using a 10 second shutter delay, with the shutter at 25 - 30 seconds, f stop wide open (I think), ISO at 1600.

Not off to a good start.
don't do that, the data is more than likely there and hidden,processing will lower the values for certain pixels (sky glow/light pollution) and shift up the values where the data is ie stars ,nebula ectt. having a washed out background is also an indication on how bad your sky is or exposure setting, but if there's plenty of signal from a target in their then it isn't a total loss, it will come out in processing.

sky glow is just a part of astrophotography that is unavoidable, the trick is,is to get less of it as possible so you can bring out the fainter stuff. exposure setting and time is a cause of saturation of background sky glow,filter reduce it, and moving to a darker site.and the last-processing will remove a lot of it.

Re: DSLR used for astrophotography???

Posted: Fri Jan 10, 2020 3:16 pm
by lsintampa
OK, thanks all on the feedback on my first attempt... as soon as I deleted the files, I thought that I should not have done that.

1) I'll see if I may be able to recover any of those files - if so, I'll post them.
2) I'll try another round, and post those photos as well.

It may be a bit - as the weather isn't all that good - but I will get around to it.

So when I took the photos, there was a near full moon, I tried to shoot so it was behind me. I'm in a zone 7 for light pollution, and there was a street lamp about 100' from me (blocked mostly by oak trees).

In any event, this is something I want to get a grip on so I'll be back!

Re: DSLR used for astrophotography???

Posted: Fri Jan 10, 2020 3:38 pm
by lsintampa
I was able to recover the NEF files - I only took three shots - these two - the best of the lot. Not what I was expecting at all.

Not sure how I can post them here. The file uploader will not allow .nef file types.

Re: DSLR used for astrophotography???

Posted: Fri Jan 10, 2020 3:45 pm
by lsintampa
took one of the NEF files - opened in photo editor - saved as jpg