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About London_David

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  1. As a rule of thumb most lenses are sharpest 2 stops down. It varies from lens to lens. A great place to explore about classical photographic lenses is Ken Rockwell’s website. His article on sharpness is very good on this: http://www.kenrockwell.com/tech/lens-sharpness.htm More than anything, photographers pay high premiums to have lenses that give them more options in more situations. It’s more difficult to make a zoom lens that performs well at f5.6-f22 from 75mm-300mm than a fixed aperture prime f4.9 300mm. Hence why — for similar performance — zoom lenses are more expensive than primes, and fixed aperture refractors can be cheaper than adjustable aperture lenses. That’s not to say classical lenses won’t perform for astro, they can and do. If the tool works, then great! The technology is only there to provide options and the ease of use. On the diffraction spikes, personally I would avoid using step down rings as a solution. Step down rings are designed for changing the thread size on the outer thread of a lens so you can screw in filters or accessories of different thread sizes, they cant change the aperture, only the size of the light entrance opening of the lens. Using rings to vignette the image may reduce the spikes but the aperture is set with the blades at the diaphragm inside the lens. If the intention is to optimise the optics and performance, blurring the light path is not a optimal solution. It may blur out the faintest stars for example. That may be fine for the intended final image, maybe a wide field nebula shot rich in colour — but for me I’m often trying to see deep faint objects not make things pretty so that’s not a solution. It just introduces noise in the whole image to soften the spikes in the highlights. There are lots of great options at different costs but classical photo lenses are not necessarily better or cheaper. They can be, but it depends the intended use, and how it works with the camera being used.
  2. As I understand it (and someone may have mentioned this in this thread)... but the two things to be aware of with a regular photographic lens are diffraction spikes and the optimized f stop for the lens. Since refracting telescopes are a fixed aperture, stars have no diffraction spikes: the aperture is perfectly round (whereas on a Newtonian you get the distinctive cross). If you have a classical photographic lens with a changeable aperture, there are moving blades to change the size of the hole and you get a spike for each blade. With some designs you could have 15 spikes coming from your stars. Maybe you like the look of tiny shiny spikes on stars, or maybe not, but it is something to be aware of and historical some have regarded them as "imaging errors". For me, I quite like them sometimes (and now you can even get filters on photoshop to add diffraction spikes to perfectly round crisp stars...). Regular camera lenses are also optimized for shooting below wide open. So an f3.2 rated lens could have best imaging performance several f-stops lower. Buying a great classical photo lens means you will be paying for features, qualities and mechanics you may not need in astro photography (changeable f-stop from mechanical shutter blades being one). Hence why it is possible for a well designed and made refractor to be cheaper than a traditional DSLR camera lens for the same performance. It doesn't make either type of tool necessarily better or worse: they're just different shapes of hammer.
  3. Maybe I’ll give the Takahashi a miss... I’m interested in eea and a occasional undescerning visual use, rather than glossy imaging. So I spoke to FLO about the performance differences between the Z61, the Z71, or something even fancier (Borg 72FL) and they said there probably wouldn’t be a noticeable in terms of performance unless I’m doing long exposure DSLR imaging — but... They pointed out that the Z71 flattener is also a reducer which would help the speed taking the f/5.9 to f4.7 or so. So they suggested the Z71 over the Z61 to me. But... It may be superficial but I like the look of the rack and pinion focuser with temperature gauge on the Z61 and the Gran Tourismo 71. Plus I’ve read on forums that some of the WO Crayford are not so reliable. They do seem to have r+p on all the new scopes. Has anyone used the GT71 compared to the Z71? Or had good / bad experiences with mechanical quality of the Crayford focus? Or is the problem in this price / size range (60-70mm @ £400-1200) there are no clear answers only very small differences.
  4. New portable kit

    I've been tempted to get the GTi too. I have a few questions -- Since it's an AltAz rather than EQ mount -- what kind of exposure length on subs are you getting with the tracking before you get star trails or other problems on you ed80? I've not had an AltAz mount before but I'm really interested for a small travel solution, and I'd be looking at using it with a 60-70mm refractor so... I presume I'd get about the same, or longer. How are you controlling the mount -- over the WiFi? Are you using the Sky-watcher app for goto only, or have you tried with Sky Safari? I've read that you can use Sky Safari but it can sometimes be problematic. How is the Freedom Find feature -- I love the idea of this, but does it work well? I currently use an EQ3-2 controlling it with ASCOM drivers through my PC. I take a usb out of the PC and into the Hand Controller port on the control box. Do you know if the GTi can do something similar since you can use the SynScan handset with it?
  5. The WO Z61 got me interested in picking one up on impluse too - it's cute and small and portable! But I've only ever had Newtonians or SCT's with refractors I'm also not sure where the cost goes in a refractor either. But now I've gone down a deep hole of wanting to buy a small refractor... To throw another one into the mix... the Takahashi FS60CB TSK06210 is £629 for the OTA. It has great reviews and everyone seems to hold Takahashi scopes in very high regard. But is it that much better? I have no idea what I'd see through it that would be different from the Z61 (other than a quick look at Astronomy Tools for the view). Plus... if I buy something small I'll be using it for visual and with an ASI290 or APS-C size. Does the 2x price jump justify that? The TS65 sounds very interesting too... but I can't see them anywhere. Or are you better spending even more (reaching 3x on the WO Z61 price now) on a WO 70 at f4.9 rather than the f5.9 of the Takahashi? Reviews seem to give the Takahashi greater performance than you would expect from a 60 because of the optics but... I think the 3x price jump is too much. I just want something fun and small. I don't know -- I keep ratcheting up the price upsetting myself on scopes I don't really know about! What do people think about the Takahashi, anyone used it?
  6. I'm originally from Stirling... and now dealing with London light pollution! You will definitely achieve a huge jump compared to eyepiece viewing. Personally, I'd highly recommend the ZWO cameras -- I've had great experiences with them using SharpCap which is great software and works very well with the ZWO cameras. The ASI290 mono is very sensitive with low read noise which is great and I get surprisingly good results even in Zone 2 London on a 6" looking at DSOs (mostly I'm interested in galaxies but it's good on nebula and globular clusters too). The high sensitivity of the ASI290 allows me to stack short exposures (0.5-10 seconds) and get good results. I'd say the simplified, quick and dirty answer is that if you want colour the ASI224 is currently the most sensitive, low noise colour camera (barring the Sony A7sII) but there are some new ZWO camera's just about to be released that will either surpass or give you the same sensitivity with a larger sensor. Of course, your decision will not be purely on performance of the camera. It depends on what you want to look at, checking out astronomy tools with your cameras is a very good idea. Don't buy on spec's alone... Essentially your colour/mono choice comes down to mono with more detail and sensitivity or colour with less detail and colour noise, but... well in colour! I went mono because I wanted the performance, and to use a colour wheel for narrowband, but I am now looking to buy a colour camera too. One is not enough! Since I'm interested in galaxies, with the ASI290 you can get exposures under 2 seconds and SharpCap will stack them to give you a good view. I'd recommend checking out AstroJedi's posts over on Cloudy Nights he gets good views of galaxies from a 8" SCT under Southern Californian light pollution. He uses a variety of cameras and you can see what kind of exposure times he's looking at. Seeing image posts here and on Cloudy Nights was how I decided what to buy. As an overview -- in terms of general reputation the ZWO and QHY cameras have similar quality. Rising Tech use the same components but are cheaper, and not quite so polished (lacking features, drivers etc -- depending how much you like to fiddle with computers your milage may vary). Atik is good quality and has user friendly software (there are some good videos on YouTube you can check out to see the software in operation) but is on the expensive end. Mallincam to me seem unimpressive and expensive for what you get but they have very dedicated followers (and haters) so any discussion seems to start big arguments! Altair Hypercam I have little knowledge of. However, I have a feeling they using the same sensor etc. as ZWO, QHY and Rising Tech. I can't remember, but I have a gut feeling that I stopped looking at their camera because it was older and ZWO/QHY had newer features. Personally, after doing this research a while ago ZWO was the winner for me. They come across as astronomers make cameras and have a very friendly accessible forum where you can talk to the founder of the company Sam. Plus SharpCap is great software written by a guy called Robin, who again will answer email personally (I recommend paying the £10 for SharpCap to support his second job!). I've only ever heard good things about QHY and Atik but they seemed a bit less immediately friendly. That was just my impression. Budget/risk would determine things for me... if I were you I would start with a ASI290 mono if you're interested in detail or, if you want colour, the ASI224/whatever the new equivalent is from ZWO. At under £300 uncooled that's not a crazy amount to spend to get started and see if you like spending time at the computer rather than the eyepeice. There's no getting around the fact that if you go this route you will be spending quite a bit of time fiddling with the computer getting things working and playing with histogram sliders to explore the images on screen. I'm very happy doing that, but again, you have to like working with computers as well as working with the mechanical stuff. The bigger sensors I'm a bit less knowledgable about, however there are some new ones on the way too, but even the ASI1600 is over £1000 if I remember right, plus you'll want to start getting cooling, which makes things even more expensive again. Though with your scope a bigger sensor would indeed let you see a wider field. You could also get a focal reducer which would make your scope very fast and give you a wider view. For me galaxies are often small objects so a small sensor can work for me, but it is a good idea to look at your camera/scope combination and what you want to look at. A small sensor camera is not going to be any good if you're looking to get the whole of Andromeda in one shot. The new colour ASIxxx camera that is the replacement for the ASI224 is currently in beta testing and should be out in the next month or two. That would definitely be a better fit for your scope because it has a bigger sensor than the ASI224. There is a thread about this with the beta testers on Cloudy Nights too. 10" f4.7 is actually good though. So you should get something quite fun working. Under f5 and you are in good shape for assisted viewing and 10" will give you good resolution. The main issue will be tracking with the dob. I have a EQ mount, but as I understand it AltAZ mounts are fine for this kind of use up to about 15 second exposures. Certainly I find that I can skip polar aligning accurately if I am keeping my exposures under that and at f5 or under and a sensitive, low noise camera you should be good.
  7. Imaging Equipment and Light Pollution

    I've found that bad weather and seeing have been a bigger issue for me in terms of the actual experience. Light pollution is obviously a seriousl limit to what you can see but you don't really think about it when you are at the scope. There's still plenty to see and explore. How limited you are only really hits you when you switch out to a visual eyepiece or look through your finder and see nothing. Also, when hunting for dso's, sometimes it can be be hard to find a target because there is nothing to see except through the camera -- and even then only after stacking. But in some ways part of the fun is trying to get good results in a difficult location.
  8. Imaging Equipment and Light Pollution

    Sounds like you are in a similar situation to me, I can't see anything much -- except if you use a camera. Which got me into EEA. I'm in zone 2 central London and can get satisfactory views with short sub stacking (usually under 10 seconds) on an ASI290 mono to see galaxies clusters and nebula. Its not going to compete with Hubble any time soon, so if you have realistic expectations you should have fun. The 224 and the 290 are the best ZWO cameras for smaller dso objects at the moment and they work well with sharpcap live stacking. You need sensitive, low noise cameras and a fast scope. Those cameras fit the bill. 290 is best for mono 224 for colour. They both work for dso viewing. If you're only looking at short subs for EEA you can even go with the uncooled versions to save money. Check out the EEA forums for more info and post questions there too. Also on cloudy nights -- some people are on both forums. Particularly look for HiloDon, AstroJedi's and Martin Meredith's posts. They have a lot of good information and examples of what to do and buy. AstroJedi is particularly technical and very much praises the ASI290 and asi224. You can find examples on his YouTube channel of the results and how fast images come in, he lives in San Diego with bad light pollution too. He managed to image the relativistic jet in Virgo A which is pretty good going. I think a 224 and an evo 8 would be a great combo -- but for EEA you will want to speed up the scope -- rule of thumb is f/5 or under. That allows you to have shorter subs. You can get a hyperstar for the Evo that will make it a stunning f/2. It's not cheap but makes it pretty impressive. I currently use a skywatcher 150pds at f/5. Alas, I didn't have space for an 8" in my flat. You should also check out what your fov is going to be with each camera / scope combo using the astronomy tools website. The best thing is to read around the EEA / video astronomy forums, see what people use and ask some more questions!
  9. Advice on mono camera

    If you have a look in the EEA forums here and on cloudy nights you can find some great examples of DSO imagery using the mono ASI290 which is relatively inexpensive, ultra low noise and very sensitive. As someone mentioned above you can shoot lots of short subs and get some amazing results. With CMOS you don't need to rely on longer subs so much -- if your interested check this post out: It's a slightly different thing to typical CCD photography but definitely something to consider. I have one and really like it. It's a good option particularly on a budget. Check these out: https://www.cloudynights.com/topic/567930-m87-relativistic-jet-and-other-galaxies-using-short-exposures/ https://www.flickr.com/photos/abbeyroadobservatory/sets/72157668589828735/with/26830497230/ Also, the Atik infinity and ASI1600 are worth checking out in your price range but I have no personal experience with them. There are some great videos on YouTube reviewing them, and images in astrobin.
  10. EAA on an iOS Platform - Is this a future Possibility?

    Paul -- full details on my setup here: https://stargazerslounge.com/topic/287811-equipment-suggestions-for-live-viewing/?do=findComment&comment=3207127 No pictures I'm afraid, I've meant to post some but haven't got round to it, since I've not had many good nights for it. The stick has been fiddly to get running, mainly because I couldn't get a game pad that worked reliably. I'm now using the official Microsoft One controller with the dongle, which gives the thing very good range. If your Windows literate it should be a problem to set up, just a bit of trial and error for your exact setup. With Apple, I don't think it's any artificial barriers to be honest. Apple does that in some cases and it is annoying, but in this case I think it's more likely to be a simple lack of demand. We have quite specific niche demands, iOS devices are also designed to fit a specific design aim of being wireless and portable. Cameras and mount control mainly need wires. That's makes the issue Apple then and more Celestron, ZWO, QHC or Starlight Xpress. They would need to build wifi connectivity in. Celestron has built the Evolution with wifi so you can run it from your phone or iPad native though SS5. Or the Sony Alpha cameras can send a live view to their iOS app. Actually, I've just thought, you could set up an A7s with a Celestron Evo Mount and do EEA using live view on the A7s streamed to the iOS Sony app and control the mount using SS5 and the Evo. That could be a pretty cool setup! No live stacking, but simple and fully iOS...
  11. EAA on an iOS Platform - Is this a future Possibility?

    It may not be what your looking for but my EEA setup is entirely wirelessly operated through my iPad: I use iOS Sky Safari 5 for goto control and an ZWO ASI 290 camera into SharpCap for EEA acquisition. I have a wireless game pad for manual mount control. However -- and this is where it may not suit you -- for me to be able to run everything through my iPad, I use a tiny compute stick attatched to the mount that I Remote Desktop over wifi ito. I have a few wires around the mount but everything is easy to keep neat . SS5 is native on iOS is fantastic for goto control. Windows 10 is designed to work with touch and the SharpCap controls for the most part are fine with touch too (best with an Apple Pencil if you have one). SharpCap 3.0 is just out and is really good. I got the idea from AstroJedi on CloudyNights and robrj here. AstroJedi started a long thread on cloudy nights about this kind of set up called "I think Im in EEA Heaven." I am basically doing what he's doing. Worth checking out the threads for inspiration.
  12. Equipment suggestions for live viewing

    Finally a clear night! Unfortunately, we’re also into astronomical twilight time in London so it never actually gets that dark now. I was also too late in setting up to attempt my highly optimistic goal of imaging the relativistic jet in Virgo A from a bad location: a bathroom window in zone 2 London that gives about an 18 degree view over some houses, street lights and the rest of London. You work with what you’ve got. This post should give a sense of what's achievable without any experience (at least only the experience described in this thread) in a terrible location with this rig. Also, everything here is without darks or flats or any calibration images. These all direct screenshots off the iPad Pro RDP into the Compute Stick. The exception is the M5 image that I mention and the inverted the NGC 5248 image, which I cropped and inverted in Photoshop when processing these down to web uplaodable images. First I set up and got in a quick look at Jupiter just to make sure everything was working, I also use Jupiter for polar alignment and achieving focus with the Bahtnov mask. The other evening when it was too cloudy for DSOs, I attached the ASI290 to the Hyperion eyepiece and got a great full screen video of Jupiter. Now when I see it without the Hyperion I think it looks tiny! I went over to Virgo A, but unfortunately I realised that the mount had gone too far round and the scope was now pointing into the wall, not out the window, so the relativistic jet will have to wait. In fact, really the only Virgo galaxy I could get aim at was NGC 5248 (Caldwell 45) an 10.97 apparent magnitude galaxy between 40-75 million light years away in the Virgo Supercluster, most estimates put it at 50 something million. Unfortunately you can’t see a lot of detail in the structure. It’s a little clearer on the inverse. This was the first galaxy I’ve imaged so I’m hopeful that with better conditions I can see crisper structural detail. That I can see anything that’s maybe 75 million light years away out my bathroom window I was pretty pleased with. There's definitely some odd noise in there. Note the multiple right angled jumps. I'm not sure what those are -- it looks to me like some kind of mechanical tracking error. Also, there is definitely a top left to bottom right patter to the image, which suggests that I wasn't totally aligned correctly or something. I did knock the mount at one point and had to re-align. So that might have something to do with it. Since everything was up and going, I bounced around and caught a glimpse of the Box Nebula NGC 6309. No picture though — it was a small overexposed square blotch and was not that exciting. I didn’t spend much time on it since I figured it would be very tricky to get any detail. Eventually, some globular clusters came into view. First up was M5: On the ASI290 you barely even need to stack to get some pretty cool images. I played around with exposure settings, to see if I could get good images stacked from very short exposures (half a second or less) and picking the best ones. I stacked these in post, rather than live viewing because I’m still not quite sure about all the features on SharpCap. Post-stacking helped, but not worth the hassle really, I’m just thrilled to be able to find and see this stuff. Post process stacked: Then M10. I tried here on the ultra short exposure run, with the gain too high really. Only a stack of two in this image — the image did improve on further stacking better but I didn’t take a screenshot. and M12, here I was playing around with the FWHM filter to see if I could get some lucky clear shots through the atmosphere with the 1/2 second stacking: Something I learned last night (I'm sure this is not news to most people...) from reading the info on Sky Safari is that all globular clusters actually orbit in the galactic halo -- above the plane of our galaxy and not inside it. There is a diagram here: https://www.britannica.com/topic/globular-cluster So that’s the first proper run through I’ve had with everything working as it should on a clear night. No galaxies here to compare with other posts in this forum, but looking forward to exploring more with this now it’s all working properly.
  13. Game pad eqmod callabration

    I've had some gamepad issues myself mostly I've found that they're Windows problems rather than EQMod. Check with windows os game controllers monitor that your Xbox controller is actually feeding through button presses etc, then make sure eqmod is seeing them using the eqmod gamepad monitor. Then make sure the gamepad support enable checkbox is ticked. Some gamepad dpads signal eqmod as the joystick. It looks to me from that the gamepad isn't feeding to eqmod. I may be wrong. Try not worrying about the joystick and assigning a button. Does it assign? If not it's not feeding the info through. If it does try clicking the start calibration for the joystick. That is when the program figures out what signals the joystick sends. Also -- sometimes they're flaky for no apparent reason, so I often try a restart of the software, and then the machine if that doesn't help. Personally on a 360 controller I prefer the D-pad for mount control so I turn off the joystick and I don't have to worry about the calibration. I just adding the POV buttons to the slew movement (the N S E W bit in the left column of your screen grab).
  14. I have a Hyperion and attach an ASI290 to it using the Baader Varilock extension tube. This is different from the fine tuning tubes. I've been really pleased with the images I get from it. I don't know exactly about a DSLR since the backfocus will be different. I have the extension tube set to 45mm. You'll need to calculate the distance from the eyepiece you need to get focus and figure it out from there. It should work, since you're doing much the same as me, just with a different camera. I suspect you may get fringing depending on your sensor size and eyepiece size.
  15. There are quite a few great apps, my two favourites are Sky Safari 5 and Exoplanet. Exoplanet isn't a planetarium but it does let you explore the universe which is cool. There are a couple of posts on Cloudy Nights that have a run down on a few of these: https://www.cloudynights.com/articles/cat/user-reviews/phonetablet-apps-and-the-practical-astronomer-r2925 https://www.cloudynights.com/topic/567148-best-stargazing-phone-apps-for-iphone/ I really like using Sky Safari 5 on iPad to explore around. With a dob I would think it would be a perfect companion for a push to setup. I did attempt to mount my iPhone on the telescope with a laser pointer attatchememt in place of a red dot finder but I found it more hassle than it was worth because you can't really use the touchscreen very well without wrecking alignment. The novelty wore off quickly and I bought a Telrad. I'm a heavy light pollution area (Zone 2 London) so I mainly do eea and I can only find stuff like galaxies or globular clusters with a motorised goto. SS5 controlling the mount with my iPad is a great wireless replacement for the handset, but not the motorised goto system itself. Most things I want to see are are just too small and dim to find without assistance. One great thing on SS5 are the reticule hud options. You can overlay the exact field of view you will see through your scope, so you will know I exactly the patterns to look for at the right relative size for your magnification. You can also easily adjust the star magnitude shown, to account for seeing or the power of your scope. It is really excellent for navigating around and makes it fun and easy to explore. I often make a plan to see a few key things using the observation list and it will highlight them on screen. Then it encourages you to make detours to interesting hard to see stuff because it shows you the things on screen. It will kill your night vision unless you switch the red light function, but I don't since I like colour and I'm imaging anyway. Even with night vision I'd never see anything other than Jupiter because of light pollution. I don't use the (expensive) official hardware to connect, instead I use the free WiFiScope app which runs on the pc I use for imaging. It's super simple, fire it up, press Listen on the app, and Connect on the iPad. You're good to go, with full wireless goto mount control from the iPad (and celestron audio commentary too). If you like using your tablet or phone to navigate, I think you'd get a lot out of Sky Safari 5 - it's a great tool. It's the best app for me by a long way in terms of depth and ease of use. You may find you prefer others, some look nicer, some have different options, but overall SS5 I think wins for most people. Red Shift, Night Sky, Sky guide, Luminos, GoSkyWatch are the other planetarium apps I'd check out. Also, ScopeNights and Exoplanet.