CCD vs Film? Lots of time vs no patience? Alright, this is your place to discuss all the astrophotography what's and what's not. You can discuss about techniques, accessories, cameras, whatever....just make sure you also post some nice photos here too!
Took a couple of images of M42 with Sky-Watchers 100mm ED and FS60C over the last few days.
I found that although the Sky-Watchers telescope is rated at F9, it is still quite good in capturing faint nebulae. The colour correction was better than FS60C and much easier to focus. Price wise, the sky-watchers is a tad more expensive, but with 40mm more aperture.
I'm very please with the result. I was also informed by my dealer that the 120mm ED Sky-Watchers is now available. 20mm more aperture, better F ratio (F7.5) but twice more expensive as the 100mm ED.
So, I guess I have to stuck with the 100mm ED.
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Nice images, Perseid! What mount did you use?
Indeed the F/9 is not a real problem for imaging: my 102 mm refractor is F/8, with a very useful 820 mm FL.
Go well!
Jeremy
Hi CK,
Nice images. Can you confirm that Skwatcher's ED optics colour correction is better than the Tak FS60's fluorite glass? Amazing! That means they have come a long way...
rich
The Boldly Go Where No Meade Has Gone Before Captain, RSS Enterprise NCC1701R United Federation of the Planets
Hi CK,
Nice images. Can you confirm that Skwatcher's ED optics colour correction is better than the Tak FS60's fluorite glass? Amazing! That means they have come a long way...
rich
Not surprising, really. FS60c is f/5.9, ED100 is f/9. Can't have both portability and great color correction at the same time, unless you want to pay big $$$ (even AP Traveler can not match the performance of TMB 100/800)
Hi C.K., very nice images! So sharp and colourful.
I didn't know that such images can be produced with only 10 stacks of 2 mins exposures at ISO800 with a f/9 instrument.
I have a Canon DSLR (350D) and will try to take M42 thru my Tamron 70-300mm LD zoom (f4-5.6) at 300mm.
I also have a Shortube 80mm f/5 achromat (400mm fl), but will use an aperture mask to stop it down to about 60mm at f/6.7 for better colour correction, or even 45mm at f9. Hmmm...
Well, right now I only have a simple CG-3 type motorised equatorial mount. Not sure if that's sufficient. Will give it a try after seeing your images!
What software did you use to stack the images? Is there any special technique?
First of all, thank you all for the nice words of encouragement.
Let me try my best to reply to your questions.
Jeremy,
I have used the GM8 mount for these images. It is not a very good mount for astrophotography, but with guiding it is OK. The PE for my mount is quite bad, and even with guiding, some images still have trails.
I was quite skeptical about using F9 for imaging at first. But after comparing some test samples using the takahashi and the ED, I decided to give it a try.
Rich,
Arief is right. The longer focal length seems to help in colour correction. However, I think the usage of the ED element helps a lot more. I have use F6 and F8 scopes before, and I think F8 produce just a slight improvement in reducing the CA.
I don't compare the colour correction visual of both takahashi and the sky-watchers, but from the photos, I think I like the latter better. The images of bright stars from the SW are less bluish, and bloated. For the FS60C, focusing is much harder. However, the FS60C is about a stop faster, meaning half the exposure time.
Starfinder,
With digital photography, quite a lot of things can be made possible. Few short exposures can be stack to produce the effect of longer exposure. You can take a look at the original image to get the picture.
Your Canon 350D is a very good camera and should be used to take astrophotography. You can start with using your lens and place it on your EQ mount. Use shorter focal length first. 300mm can be a little bit trickly.
Your idea of using 80mm with reduced aperture is a very good one. Maybe I'll give it a try soon.
First I used PS to substract the noise using the dark frame for each frame. Then, I used Registax to stack them. Go back to the PS to make a composite of the shorter exposure over the over exposed core of M42. Then level adjustment and curve manipulation.
AGMI,
Colour difference is quite obvious when taking M42 using different media. I have use film before and it turned out reddish. When I change to digital, this is the colour I get mostly. Of course, you can change the colour easily using software.
Regards,
CK
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Hi,
Why the two stars at the top left corner taken by the Sky-Watcher 100ED got three sharp edge like "thing" in the star?? I didn't see them in the image taken by FS-60C. Wonder what cause them??
Anyway, IMHO, it is very difficult to compare the performance of two so different scope... Sky-Watcher 100ED (100mm F9) and Takahashi FS-60C (60mm F5.9)... both are built for different purpose. The Sky-Watcher 100ED have the advantage of bigger aperture, so stars will be brighter and smaller compare to the Takahashi FS-60C, but it lack the wide field capability of the FS-60C.
IMHO, if you want to have a fair comparsion, you need to compare with similar aperture and f-ratio... may be with the Takahashi FS-102 (102mm F8).
I have used the GM8 mount for these images. It is not a very good mount for astrophotography, but with guiding it is OK.
Hmm... I thought GM8 is one of the best mount for Astrophotography??
Anyway, very nice image.
Have a nice day.
Yang Weixing "The universe is composed mainly of hydrogen and ignorance."
"The universe is composed mainly of hydrogen and ignorance."