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Imaging Rho Ophiuchi Region.... how to?

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#1 Seanem44

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Posted 25 March 2014 - 02:21 PM

I'm doing some (way) forward thinking, as I want to make sure I don't botch the one attempt I may have at imaging this region when I head to the AHSP at Spruce Knob this summer.

Questions for those who have imaged it....

What did you use? What do you recommend?

Will my AT65 at 420MM be too much? Has anyone attempted with an AT65EDQ or similar OTA?

I have a D800 with a 200mm lens. It is un-modded though so I will miss out on a lot of nebulosity. Or will I?

Should I buy a nifty fifty for my modded 1100D and image with that? Will (an effective) 75mm not be close enough? Or will 75mm of that region look amazing?

Just trying to do some early planning in case I have to buy a new lens for the canon.

Thanks guys.

#2 calypsob

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Posted 25 March 2014 - 05:45 PM

That target is at the top of my list right now. A 50mm is best, you can composite in the detail with longer focal lengths as well.

#3 fishonkevin

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Posted 25 March 2014 - 06:04 PM

Have you tried doing a search on Astrobin? By checking there I'm sure you'll get a feel for how your AT65 will frame it or the Nifty 50.

#4 Seanem44

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Posted 25 March 2014 - 06:53 PM

I have not. Really not to familiar with astrobin I am ashamed to say, other than seeing it linked to images on this site

#5 fishonkevin

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Posted 25 March 2014 - 10:11 PM

Sean, I am not either. But I have been doing searches for FOV with different camera lenses on objects.

BTW, here is a FOV for the Rho Ophiuchi Area that I did in my Starry Night Pro using your AT65( green ), my Canon 200mm (orange ), and Sigma 50mm ( green again) using my Canon 450D. Personally, for your projest I would use the 200mm. Get a Canon adapter so you can use it on your Canon.

Attached Files



#6 jgibson1@emich

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Posted 25 March 2014 - 10:36 PM

I find my 200mm lens frames the region quite nicely with an APS-C sensor. If you want a less tight fit a 180mm would work well. A full Frame DSLR would be ideal with the 200mm lens.

Here is a shot I took last year from the Chiricahua Mountains southeast of Tucson. It isn't nearly the number of hours as I want and plan to grow the integration to 10-12 hrs this summer if the monsoon season isn't too terrible. This image is cropped minimally and is a good representation of the FOV with a 200mm lens on a 350D.

Posted Image

Clear Skies,
Jason

#7 srosenfraz

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Posted 26 March 2014 - 01:04 AM

Sean - here's my 200mm image of the region and here's my 50mm image of the Rho Ophuichi region. You really can't go wrong at any focal length.

It'll respond a little better to a modded camera, as there is some Ha in the area. Not a huge amount, but enough to add some nice color. If I were in your shoes, I'd probably start by buying a Nikon to Canon adapter so that you can use the 200mm Nikon lens with your modded 1100D. If its in the budget, a 50mm lens makes for great images of more than just Rho, and summertime is a great time of year to capture some beautiful widefields.

Good luck with it!

#8 Samir Kharusi

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Posted 26 March 2014 - 01:33 AM

Frankly, you can use whatever focal length you wish. There is always a good composition available. BUT! When you are in the field you need to have a plan for exactly where you wish to place Antares in your frame, and how you wish the frame orientated. There is a plethora of small targets in that region, but nothing is visible in the viewfinder other than Antares :confused: So homework definitely required. Also, a modded camera shows up much more nebulosity, with less integration time, than an unmodded. Hence I would also urge getting an adapter for your Nikon 200mm lens to be usable on the modded Canon.

14mm lens on unmodded full 35mm format Canon 1Ds, single 5 minute exposure at f4:
Posted Image

100mm lens on unmodded Canon 1Ds, 19x2.5min at f2.8. This camera passes essentially nil Ha, hence no red stuff anywhere:
Posted Image

200mm lens on a modded Canon 20D, 59x1min at f2.8:
Posted Image

NB that I missed most of the red stuff extending beyond the bottom of the frame. Prior homework required to know exactly where you want Antares placed, or exact RA Dec to point at. The longer the focal length, the greater the precision required.

#9 Seanem44

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Posted 26 March 2014 - 05:34 AM

Wow! Thanks guys for all the replies and suggestions! Looks like 100-200mm is the sweetspot. 420mm would take too much away.

#10 Seanem44

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Posted 26 March 2014 - 06:03 AM

After research, it looks like the Nikon to Canon adapter is the way to go. The Vello brand is slightly more at $30, but has very good reviews on BHphoto. I had no idea these were so cheap now, and it seems they do the trick retaining sharpness.

This will allow me to use my Lenses now. So I can shoot with my Sigma 70-200mm or my Nikon nift fifty which is an effective 75mm on the APS-C sensor.

Awesome! Looks like I will be set.

Thanks for all the inspiring images!

#11 Seanem44

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Posted 26 March 2014 - 06:07 AM

Sean - here's my 200mm image of the region and here's my 50mm image of the Rho Ophuichi region. You really can't go wrong at any focal length.

It'll respond a little better to a modded camera, as there is some Ha in the area. Not a huge amount, but enough to add some nice color. If I were in your shoes, I'd probably start by buying a Nikon to Canon adapter so that you can use the 200mm Nikon lens with your modded 1100D. If its in the budget, a 50mm lens makes for great images of more than just Rho, and summertime is a great time of year to capture some beautiful widefields.

Good luck with it!


your 50mm is beautiful, but it looks like a lot more work went into that one, with the blending. Was the non blended image not as sharp or lacking to your eyes?

I wish I had more than 4 nights at a DSS (if weather cooperates). Its really making me think hard and plan ahead of time what I want to image and when.

#12 srosenfraz

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Posted 26 March 2014 - 03:16 PM

Thank you for the nice compliment, Sean. The 50mm image would have looked fine without blending in the 200mm images. Blending in the 200mm images allowed for improved details in those three areas, but they didn't look that bad without it. Also, when I blended in the 200mm images, the opacities were typically 50% or lower. So, when you look at the image in those areas, there's still a lot of the native 50mm data showing.

#13 Jon Rista

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Posted 26 March 2014 - 09:36 PM

Thanks for asking this, Sean. I've been seeing Scorpius rise in the early mornings lately after long nights of imaging. It's probably one of the more recognizable regions in the summer sky, and I too have been looking forward to imaging it. It's good to know that 200mm seems to frame the whole region nicely on FF. I might use 180mm on APS-C.

#14 fishonkevin

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Posted 26 March 2014 - 11:15 PM

Sean,
One thing to remember when using your Nikon leses with your Canon camera. I know for certain that you will lose the autofocus and auto-aperature functions of the lens. You would know if you can manually focus the lens or not, I assume they can be set to either af or manual. Can Nikon lenses have their aperature set manually? My Canon's can not. You may have to use step-down rings to adjust the aperature.

#15 Hilmi

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Posted 27 March 2014 - 03:05 AM

I found that with an APS sized sensor, my Canon 100mm f2 lens gives very pleasant framing. I set the camera on f2 and crank up the ISO, then I take a quick shot for composition. If I am happy with the results, I close down the aperture and adjust ISO to what I plan to image at.

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#16 Hilmi

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Posted 27 March 2014 - 03:07 AM

On more point, with a 100mm lens you have room to crop out the slightly deformed stars from the edges as well as stacking artefacts from imperfect tracking.

#17 Seanem44

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Posted 27 March 2014 - 04:20 AM

Sean,
One thing to remember when using your Nikon leses with your Canon camera. I know for certain that you will lose the autofocus and auto-aperature functions of the lens. You would know if you can manually focus the lens or not, I assume they can be set to either af or manual. Can Nikon lenses have their aperature set manually? My Canon's can not. You may have to use step-down rings to adjust the aperature.


My nifty fifty has an aperture ring. My sigma 70-200 does not.

#18 boandpokey

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Posted 28 March 2014 - 06:35 AM

I LOVE the 14mm shot but thats a pricey lens. anyone use the Rokinon Canon Compatible??






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