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Archive 2015 · 100-400II for Astrophotography

jforkner
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p.1 #1 · p.1 #1 · 100-400II for Astrophotography

I recently acquired the new 100-400 II lens for my Canon 6D DSLR, and wanted to see how it worked as an alternative to my motor-driven 600mm refractor telescope. So I bought a dovetail bar, mounted the lens to it, and slid it into the mount in place of the telescope—you can see a pic of the configuration below. I transferred my green laser pointer to help with aiming via a hot shoe adapter, and voila!

Last night I took the first photos using the setup and captured the Orion Nebula, Horsehead Nebula, and Pleiades Cluster. I took a series of shots that need to be stacked & processed; and as you might expect, the images are somewhat wide-field. While waiting to stack the series, I processed a couple of single-frames in PS CS6. I’m pleased with the quality of these, and am anxious to see if the stacked ones look any better. FWIW, the Orion/Horsehead image was taken at 400mm, ISO 1600, f/5.6 with a 120 sec. exposure; Pleiades was taken at 400mm, ISO 3200, f/5.6 with a 120 sec. exposure.

This isn’t an endorsement of the telephoto over the telescope, but it’s nice to have another tool in the arsenal. Curiously, the lens cost about twice what the telescope did.

Jack

http://jackforknerphotography.com/Temp/_1143024.jpg

http://jackforknerphotography.com/Temp/_MG_4006-II.jpg

http://jackforknerphotography.com/Temp/_MG_4020.jpg

Jan 15, 2015 at 02:43 PM

JoelWilcox
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p.1 #2 · p.1 #2 · 100-400II for Astrophotography

Good lord. I've never tried astrophotography, but this sure is interesting -- and motivating. Thanks for posting.

Jan 15, 2015 at 03:15 PM

kabraxcis
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p.1 #3 · p.1 #3 · 100-400II for Astrophotography

I wish I lived in a less light-polluted area.

Jan 15, 2015 at 03:21 PM

dgdg
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p.1 #4 · p.1 #4 · 100-400II for Astrophotography

Very cool.
When the milky way core rises should be another fun opportunity.
The coma is well controlled, I only see a little on the big peripheral stars.

David

Jan 15, 2015 at 03:30 PM

matanuska
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p.1 #5 · p.1 #5 · 100-400II for Astrophotography

Looks good! Though, not surprisingly for a photo lens I am seeing a bit of coma on the outer edges.

BTW, what is the clear aperture of this lens? I would think that this would be very comparable to my TV-76.

Jan 15, 2015 at 03:57 PM

Tom_W
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p.1 #6 · p.1 #6 · 100-400II for Astrophotography

120 seconds - tracking mount, I presume?

I'm not much of an astrophotographer so I have to ask.

Jan 15, 2015 at 04:10 PM

Tom_W
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p.1 #7 · p.1 #7 · 100-400II for Astrophotography

Really nice captures and setup, BTW!

Jan 15, 2015 at 04:10 PM

RobDickinson
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p.1 #8 · p.1 #8 · 100-400II for Astrophotography

Tom_W wrote:
120 seconds - tracking mount, I presume?

I'm not much of an astrophotographer so I have to ask.

Yep thus the telescope mount. Tracking tends to be accurate for a 'short' period of time for this kind of stuff then you stack multiple shots for better resolution/lower noise.

Great test, wonder how it compares to the 400/5.6L

Jan 15, 2015 at 04:13 PM

jforkner
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p.1 #9 · p.1 #9 · 100-400II for Astrophotography

matanuska wrote:
BTW, what is the clear aperture of this lens? I would think that this would be very comparable to my TV-76.

Aperture is 77mm.

Jack

Jan 15, 2015 at 05:46 PM

jforkner
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p.1 #10 · p.1 #10 · 100-400II for Astrophotography

Tom_W wrote:
120 seconds - tracking mount, I presume?

Yes it's a tracking mount---motor drive; not star-guided.

Jack

Jan 15, 2015 at 05:47 PM

jforkner
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p.1 #11 · p.1 #11 · 100-400II for Astrophotography

kabraxcis wrote:
I wish I lived in a less light-polluted area.

Can't help ya there, Bud. Fortunately I do, my driveway is my planetarium.

Jack

Jan 15, 2015 at 05:49 PM

Tom_W
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p.1 #12 · p.1 #12 · 100-400II for Astrophotography

jforkner wrote:
Yes it's a tracking mount---motor drive; not star-guided.

Jack

Wow - just learned something again. I knew of motor drive, but hadn't heard of star-guided tracking. I'll bet that's extremely precise.

Jan 15, 2015 at 06:15 PM

jforkner
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p.1 #13 · p.1 #13 · 100-400II for Astrophotography

Tom_W wrote:
Wow - just learned something again. I knew of motor drive, but hadn't heard of star-guided tracking. I'll bet that's extremely precise.

Not so much, but the mount has to support it---mine doesn't. Here's a link to some examples.

Jack

Jan 15, 2015 at 06:36 PM

dwweiche
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p.1 #14 · p.1 #14 · 100-400II for Astrophotography

If those are the single shots, then I'm looking forward to the stacked shots as well. Thanks for posting.

I'd also like to hear the story and setup behind your avatar, assuming that is also a shot of yours.

Jan 15, 2015 at 11:13 PM

EB-1
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p.1 #15 · p.1 #15 · 100-400II for Astrophotography

That looks quite good for a zoom wide open.

EBH

Jan 15, 2015 at 11:26 PM

bnoeggs
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p.1 #16 · p.1 #16 · 100-400II for Astrophotography

WOW!!! Cooool !!
That's it...I'm out of words. Cant wait to see more shots form the venture.

Jan 15, 2015 at 11:31 PM

cameron12x
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p.1 #17 · p.1 #17 · 100-400II for Astrophotography

Very nice images... thanks for sharing!

By the way, comet Lovejoy will be in that same vicinity of the sky for the next several days (see image below).

Comet Lovejoy

You ought to try to image it. Maybe with a shorter focal length, but faster glass to get the full tail.

You'll probably need to stack images to get the best results. You should be able to do at least as well as the image below.

Comet Lovejoy January Positioning

Comet Lovejoy as seen below the Pleiades star cluster.

Jan 15, 2015 at 11:33 PM

jforkner
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p.1 #18 · p.1 #18 · 100-400II for Astrophotography

dwweiche wrote:
I'd also like to hear the story and setup behind your avatar, assuming that is also a shot of yours.

My avatar is the solar eclipse of May 20, 2012. The image was taken with my Olympus E-620 & 40-150mm lens off Hwy. 88 between Stockton, CA and Lake Tahoe about 6:30pm PDT. Specs are: 268mm (equiv.), f/14, ISO 100, 1/4000 sec.

Jack

Jan 16, 2015 at 08:05 AM

jforkner
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p.1 #19 · p.1 #19 · 100-400II for Astrophotography

cameron12x wrote:
You ought to try to image it. Maybe with a shorter focal length, but faster glass to get the full tail.

You'll probably need to stack images to get the best results. You should be able to do at least as well as the image below.

I did capture Lovejoy, but not with the new lens. I used the 6D on my telescope. But you're right, I should try with the new lens. Meanwhile, here's the image I got---again, it's a single frame. I've had a great deal of trouble processing the comet with my stacking software, DSS.

Jack

http://jackforknerphotography.com/Temp/Lovejoy-StarTools-No%20NR.jpg

Jan 16, 2015 at 08:15 AM

cameron12x
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p.1 #20 · p.1 #20 · 100-400II for Astrophotography

That's still a very nice image... thanks again for sharing.

I'm going to try to image the comet with my 6D and a couple of lenses, but the weather in central Ohio hasn't been good enough recently.

As for processing Lovejoy, I'd approach it this way. The coma of the comet is very bright, so you probably only need one good exposure for it (underexpose it, relative to the tail). I'd then capture multiple images, exposing for the very dim tail (Lovejoy's tail is very faint) and do some post processing.

I'd first crop all of the tail images, removing the section where the coma begins. Then I'd use DSS (or any other stacking software) to additively build up signal and improve the S/N ratio of the tail section. I'd then layer and paste the resulting stacked image into the image where you originally exposed for the coma.

Make sense? I think that could work well. Good luck!

Jan 16, 2015 at 08:28 AM

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