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mftoet

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mftoet last won the day on April 4 2014

mftoet had the most liked content!

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About mftoet

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    http://www.mauricetoet.nl

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    Zoetermeer, Netherlands
  1. Thank you! @HunterHarling: yes, that’s the exceptional image of Marcel I referred to in the opening post.
  2. Thank you for all your nice comments. It’s a joy to work with fast optics (although collimation comes very critical).
  3. This is my second and last image from my stay at @ollypenrice's 'Les Granges' last week. I didn't spent as much capturing time on it as I did on the Cocoon Nebula (which was actually the only subject on my agenda for that week), but fast optics help a lot to get a good S/N-ratio in a mere 4 hours of acquisition time. I could have added another 7 hours if I hadn't break down my equipment on the evening of the last night. The skies of course cleared when the equipment was packed in the car (NEVER trust the weather forecast...). This is the Seahorse Nebula (B150) east of the Fireworks Galaxy (NGC 6946) and open cluster NGC 6939. On the far left a red wisp of the Flying Bat Nebula (Sh2-129) can be seen. I hope to continue photographing splendid object in the Cepheus area next year. Acquisitions details can be found on my website. After a night of deep sky astrophotography and some visual observing, a very old crescent moon came to say good morning. I've always loved the ashen light of a young or old moon. A 1 second exposure with the Epsilon-180ED was all it took to capture it.
  4. During my current stay with friends at Olly's 'Les Granges' in Southern France (where the skies are much darker than at home in the Netherlands) my friends and I had a clear spell from August 23 to 26 and - inspired by the images of Fabian Neyer and Marcel Drechsler - I decided to go deep on the Cocoon Nebula. Captured with a Takahashi ε-180ED and Nikon D810a. Total integration time is 21 hours and 10 minutes of which 8 hours and 10 minutes through a 3.5 nm Hα filter (during the period the moon was above the horizon). The Hα layer gives an incredible debt to this field of view. The Hα signal was blend in by mixing it 50% (layer in 'lighten' mode) with the red channel in Photoshop.
  5. In fact, currently I am at Olly's 'Les Granges' (since yesterday). There are several reasons why I've gone back to DSLR from CCD. To be more accurate: I've gone back to a digital camera with a CFA sensor. I've been pursuing astrophotography for about 20 years. My route went from a 35mm SLR (Olympus OM-1) > 645 medium format camera (Mamiya 645) > QHY8 OSC CCD-camera > SBIG ST-8300 mono CCD-camera > Atik 11000 mono CCD-camera > Canon 5D Mark II DSLR > Nikon D810a DSLR. Here's why I prefer using a DSLR (in random order): 1) a DSLR is more versatile than a dedicated CCD or CMOS astro-camera (mono or colour). Important to note is that in all those years of astrophotography I also like to pursue landscape and macro photography and since recent years also time-lapse and nightscape photography. I can (and do) use my current DSLR for daylight photography all the time, including taking family pictures and such (like I did in my early years with a 35mm SLR). Or how about photographing a lunar eclipse? Not very convenient when you (only) have a mono camera. So I spend about € 2500 on a 'secondhand' (demo-model) D810a, giving me the pleasure of doing all sort of kind of photography. 2) My time under dark, clear skies is very limited. Maybe about 10 to 20 nights a year if the weather cooperates. I want to spend that time as productive as possible, so my equipment needs to be as reliable as possible. Do we think computers are reliable? I don't think so. Do I need to mention Windows updates and driver issues? I guess not. I dare say Olly would totally agree with me on this. In fact, he calls himself a stone-aged astrophotographer keeping things the least automated as possible (manual filters wheels, manual meridian flips, manual focuser). Being a mobile astrophotographer my experience is that matters can go worse when you need to setup and break down your equipment every session. Therefore I don't use a computer/laptop in the field, but operate my DSLR with the standalone Lacerta MGEN. Focusing is done on a bright star by inspecting the spikes of a Bahtinov mask on the LCD screen of the DSLR. When you have an observatory (in your back garden or on a remote site), you don't have to worry (as much) about connectors and such getting damaged. You can tidily permanently bundle the cables. You continually optimise your setup and therefore it becomes reliable. If I would have an observatory, I would totally opt for a mono camera for deep sky work but still would like to have a DSLR besides for travels and other kind of photography. 3) As clarified above, I started astrophotography with a 35mm SLR. Back then guiding was doing done by eye keeping a star on the cross hairs of a guiding eyepiece making slight corrections with the handbox. Declare me nuts, but I liked that way of astrophotography in the style of E.E. Barnard. It gave the satisfaction that is was you that provided that crisp image without guiding errors and aeroplane trails (you would shield the aperture during the exposure when an aeroplane was about to enter the field of view). The current way I pursue astrophotography best approaches the way I did it in the early days. By using a DSLR I see and experience more of the beautiful starry sky than I did during the period I was using a laptop to operate the camera. 4) Dew issues. Probably bad luck, but I have owned two CCD camera where dew would form on the window in front of the sensor during the course of an imaging session. Current DSLRs perform very well, so cooling is not necessary. The D810a (and other high-end DSLRs) doesn't need dark frames (low dark current, no amp glow). However it is important or at least preferable to dither between subs. 5) Power consumption. A cooled CCD and a laptop drain a relatively large amount of current. I can operate my setup in the field without having to worry my battery will run flat. I don't need a large battery in the first place.
  6. The following was just posted by John Kroon on Astrobin: I see several pictures from the HLA and they're beautiful, but I have a question. Why do people just snag data from the archive and process it? Isn't it a bit too far removed from the craft? You know, like setting up your gear, calibrating everything, framing the shot, taking exposures and all that, and then processing the data the next day. Isn't that what this is all about? Grabbing data off of the HLA seems like it wouldn't feel like astrophotography anymore. I've never tried. I don't mean to be rude, but I'm just curious about how people decided to do HLA processing only. And how fulfilling it may or may not be. For example, if I were to ever log-on to a remote site and click the mouse a few times and have data in the morning, even that would sort of feel like a let down. And here comes the part that sums it up for me: There's no substitute for being out under a clear dark sky in the thicket of it all! To let your eyes dark adapt as you scan the heavens while your rig loops through exposures to to be immersed in that calm chilly night air with nothing other than yourself and the Universe…where all worries and stress of your job and finances and relationships melt away and it's just peaceful calm beauty. You sort of let yourself go and become part of the night. Another shadow drifting under the cool glowing light from the early fall Milky Way. For me the field work is way more important than the processing part. Maybe that’s because I can only spend a few days a year (a total amount of maybe 3 weeks at most) at a dark sky location (such as Olly’s). Due to excessive light pollution (assimilation lights to cultivate flowers and vegetables) the sky at home is terrible. I cannot enjoy the splendour of the night sky at home and neither in a 100 km radius. (I feel sorry for the children growing up in large cities. They might never witness the splendour of the Milky Way, but that’s another discussion.) Traveling to a dark site packed with all my gear after thorough preparation of what to image and how to compose the field of view must be like a scuba diver traveling to coral reef instead of diving in a local, muddy pond or going to a deep sea aquarium to admire coral and sea live from behind glass. Another reason is that I started astrophotography using (slide) film. No processing back then. Your image was either sharp (well focused and guided), nicely framed, exposed long enough and free of airplane and bright satellite trails or the opposite. For me an important part of processing is in the first place to see if everything in the field went well and what improvements or adjustments might have to be made to deal with errors or to get even better results the next time. I dare say most of us enjoy continuously optimising their gear (also by acquiring new and better equipment / accessories) and simply being busy with it under the stars. Proper data (acquired under a 21+ magn. sky) are easier to process than data acquired under (heavy) light polluted skies. Your nebulae are there instead of having to separate them from noise that almost has the same intensity (signal) as the nebula you’re after. Normally I don’t spend more than 2 hours on post-processing an image (including gradient removal; cleaning the background) captured at a dark site.
  7. The Lacerta MGEN can guide in RA only. I’ve been using one for about 7 years now and I’m very content with it. In fact, I love it! It also controls the camera (Canon and Nikon DSLRs, not sure about other brands) as a remote shutter and it supports dithering which is essential for reducing noise patterns when using a DSLR. Stay away from the Synguider and LVI smartguider. I don’t have first hand experience with these standalone autoguider, but I’ve heard a lot of people struggling in order to get theme to work. There’s a new interesting player on the market developed by a Dutch team of astrophotographers: the StarAid. Check staraid.ai for info. It is quite an expensive unit though and it doesn’t support camera control and dithering yet. If you plan to use the StarAdventurer for wide field imaging only (lenses with a focal length of 85 mm max) you probably don’t have to (auto)guide. Just take extra time for proper polar alignment.
  8. Thank you! Don't forget the Epsilon-180ED produces very tiny star images. In the image below I've combined the spot diagrams of the Epsilon-180ED with the FSQ-106 (fluorite version) and scaled them to the equal resolution. Here's a single frame (300s) straight from the camera without any processing (That is: JPEG preview / gamma stretch in the camera). Focusing was done on the LCD screen of the camera (using a magnifying glass) and a Bahtinov mask in front of the aperture. Post-processing took less than 10 minutes.
  9. Separated 725,000 light years from each other: the Little King and the Leo 1 Dwarf Galaxy. Captured from Grandpré (Northern France). Total integration time of 1 hour and 40 minutes. 5 minutes subs @ ISO 400. Takahashi Epsilon-180ED and Nikon D810a.
  10. Thank you for all the nice remarks.
  11. I've just replaced the images with slightly warmer versions.
  12. Thanks, Olly. I totally agree on this subject. Maybe I’ve missed an exit. Might need to start from scratch. It’s a nice drive though.
  13. Rogelio Bernal Andreo pointed this one out: patches of dust near the Black Eye Galaxy (M64). I found this one quite difficult to process and I'm still not sure if I'm happy with the colours... There's a large difference in brightness between M64 and the lane of dust. Usually I try to keep away from local brightness adjustments, but this time I had to process M64 separately, because otherwise it would be completely overexposed. Captured last weekend from Grandpré (Ardennes, Northern France). Total integration time of 5 hours and 40 minutes. 5 minutes subs @ ISO 400. Takahashi Epsilon-180ED and Nikon D810a.
  14. I saw my name mentioned here... Ok, here's my point of view on the subject. If you solely want to pursue deep sky astrophotography and you want to do that from your back garden or - even better - an observatory shed, go the mono astro CMOS/CCD camera route as @ollypenrice pointed out. However, many benefits of the DSLR are often overlooked: - More versatile than a dedicated CMOS/CCD camera: deep sky, nightscapes, time-lapses, star trails, solar and lunar photography, eclipses, polar light, daylight photography... - Can be used/operated stand-alone. Low power consumption. Especially beneficial for mobile astrophotographers (like me, the 'extra-ordinary' astrophotographer ?) - Modern DSLRs have low dark current; no need for cooling. - No fuss with (third party) adapters to get the sensor at the correct distance from field correctors (flatteners/reducers); just use a (wide) T-mount. I have experience with several cooled CCDs (QHY8, ST-8300, Atik 11000). Due to returning issues with Windows glitches (USB and driver errors) and sensor fogging, I switch to 100% DSLR photography around 2013. The ongoing Coca Cola - Pepsi discussion. Stick with Nikon. The cameras of these leading brands are equally matched. Today Nikon may even be ahead of Canon, but next week... who knows? The so-called 'star eating' issue is obsolete with current Nikon models. The D810a is a limited model specially designed for astrophotography. It is indeed more sensitive to H-alpha/near IR (the hot mirror filter cuts the light just past the H-alpha line). It also has some additional on-camera options, like longer built-in exposure times. You can find extended reviews by Alan Dyer and Jerry Lodriguss on the web. The D810a can be used for daytime photography. No obvious red shift. I guess only professional photographer might notice it and consider it as a concern. Even the preset white balance settings work like a charm. In principal any IR modded DSLR can still be used for daylight photography, as long as it's not a full spectrum mod (removal of the hot mirror). You do, however, have to make a custom white balance. I've switched from a Baader IR modified Canon 5D MKII to a Nikon D810a. The latter performs better (less (read) noise in the 'shadows'). Of course the Nikon D810a has newer sensor technology. I still consider the 5D MKII as a very good DSLRs for (deep sky) astrophotography. Important notice: DSLRs work best for deep sky photography when you dither between exposures. Dither a least 10, preferably 15 pixels on the main sensor. You have to calculate/make a wild guess/experiment what this means for your the dither settings of your guide cam. I dare say dithering without using dark frames works better than no dithering using (mismatched) darks. In principal, a good masterdark need at least as many darks as lights (sub-exposure), otherwise, you'll be injecting noise. You can, of course, always make of bad pixel map out of several darks for cleaning hot and cold pixels.
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