Mandy D

@Captain Scarlet Thank you. Yes, I understand the arrangement of the elements that should be achieved by perfect collimation. It is perfectly logical. Your description of the laser proces confirms this in my mind. I completely agree that the location of the secondary in space does not affect this element of collimation and now I understand the effect it has on the resultant image, thank you. So, for visual use the centring is not as important as for photographic, because for the latter an even illumination is of paramount importance. Of course, due to perspective (the far edge being more distant) the secondary should not actually appear circular, but distorted by that perspective. But, as you note the shape is not terribly important and we could use a rectangular mirror here as long as it, at least, covers the section of the light cone at this interface. I think I have a much clearer understanding of what is going on from a practical point of view, now.

It appears @Mr Spock and myself are both British! I had not thought of using the American spelling for centre (AKA center). Thank you!

@Mr Spock Thank you. I have seen your guide to this before, but I'm always confused by your reference to a concentre. Googling the term along with astronomy brings up nothing helpful and neither RVO nor FLO seem to list such a thing. What is it and how do I get hold of one? I can see the primary mirror clips in the secondary, as expected. The vane lengths have been adjusted to be within 0.5 mm of each other. Cheshire alignment of primary is spot on, as far as I can tell. All of my Newts have focusers with alignment bases, but I have yet to find and mark the postion diametrically opposite on the inside of the tubes.

That's pretty much what I found and in line with my advice, above.

@Mr Spock There are so many different tutorials available online, that seem to take many different approaches to explaining the process, it is hard to determine which one is best. I know that Astrobaby offers a guide that a lot of people rave about, but for me it simply does not come across as clear. There are others that talk about A=B, etc that makes it no clearer for me. Don't even mention videos, as I have never found one on anything that helps in the slightest! I finally found a web page that I could get my head around and think I have my 200P near perfect collimation, but really I am not certain. It snaps into focus just like a good refractor, now and with excellent seeing, my Moon photos are very sharp, even before stacking, so it must be close, right? I have the secondary perfectly centred on the focuser and the Cheshire shows perfect alignment of it's spot with the centre spot on the primary, yet is not concentric with the focuser tube and Cheshire crosshairs. What gives? I'm currently ploughing my way through Suiter: Star Testing Astronomical Telescopes in an attempt to better understand all the elements of collimation. I know that once I understand it properly and have seen a telescope in perfect collimation, it will then seem so simple. You are right, probably an hour with a mentor and I would have the process licked.

I'm confused as to why you have not simply tried this. My experience with an Explore Scientific focal extender on an RC6 is that I run out of focuser travel with it inserted directly into the focuser and have to add more extension pieces between it and the scope. Your diagonal will be performing this function in it's normal position in the optical train, will it not? So,I'm guessing, you might find it is not that simple, but I really don't know. Try it and see.

D'oh!

What things do you want to image? It makes a big difference to the equipment you will need and to the costs involved. Moon is not too hard and you can try at 190 mm, but I would suggest 300 mm and longer would be better. You will need a tripod. Planets, you will not see anything worthwhile at 190 mm. Go to 900 mm and more to image the discs of Venus, Mars, Jupiter and the rings of Saturn. Star fields you can image widefield with short focal lengths, such as your 10 - 20 mm. You can also capture the planets as dots when they are nicely aligned. Galaxies and Nebulae are going to require more significant investment in telescopes and tracking mounts. Although, you can capture the Orion Nebula without tracking, but it won't look like the fantastic images you see on the web.

Two members have vrey generously offered their assistance with this, already. Have you responded to them? See their replies, above.

@tico A 2 inch focuser is a better option than 1.25 inch, as you can reducers to use the smaller eyepieces in a 2 inch. Plus they have a larger drawtube, so less flexing. Yes, a fan is a possibility and many 10 inch Newtonians come with a mounting plate on the mirror cell to fix an 80 mm fan to. If not, it is easy to make something. The fan will cool the telescope quicker, so is a good idea. It's very much your personal preference on whether to use an optical finderscope, laser or red dot. They all work.

@Carbon Brush Long River Company? A search brought up nothing for me. I guess your quotes mean the phrase is perhaps not literal ...

On the fifth Thursday in July when the clouds briefly clear, it being on the Welsh border and all that! Access by 4x4 sounds fun, though!

Yes, it certainly is fascinating. Arm yourself with some free software, now, as it will make a huge difference to the final result. My recommended list for starters is: PIPP: This software basically crops all images to size and centres the target, as well as grading the images form best (100%) to worst. Autostakkert: Stacks a set of images taken in a single session and spits out a sharper, better result than any sub. GIMP: General photo editing and not too hard to learn. All of the above software is free! There are many tutorials on the web for all of the above. Others will have their own preferences and routines. I basically shove a set of images of the target through PIPP to crop and grade. You have to feed some basic info in and tell it what size to crop to, then it does the hard work. Next, I take that set of prepared images and feed them into Autostakkert (AS3!) and it analyses and stacks them. You can select what percentage or quantity of the set to work on. Then, I do my final editing in GIMP. For the Moon, I often convert to B&W first, then I adjust the curves for contrast and brightness and try a bit of sharpening to see if it improves the result or just adds noise. Personally, I would practice acquiring good images, first. Learn to use the tools on your camera, especially the exposure graphs. You don't want any completely dark blacks or blown-out whites, so exposure is important. Use low ISO for best results, as you get less noise in the images.

@gamermole I've taken the liberty of processing your Moon image in GIMP and have attached a copy of the result. Whilst I have not done a perfect job with it, this does show that there is something in the original to bring out in processing. So, you have a basically OK image. The 700D appears to have Muppet mode. You can find out all about it in your manual. There are few real advantages to recent DSLRs, so I would not fret about the 700D being old. It is still just as capable as it was when it was launched. You will definitely be able to take snapshots of brighter nebulae, such as Orion, M42, but they won't be anything like what the gurus achieve.

We all do it! I'm not so young now. My journey into this started with a 250PX and a Nikon D3200 and I've never looked back. Still using both and all the other kit I have bought since.

Drop the Barlow out as it is likely causing you major problems. You would be attempting to image at a focal length of 4.5 metres with it in the Skymax. That is not a good focal length for a complete beginner and you would need a very solid setup for it to work. The Skymax at 1500 mm FL coupled with any modern DSLR (what model is yours?) will give a decent size image of Jupiter at that focal length. I've used a D800 with 4.88 μm pixels and a 200P with FL = 1200 mm and get an acceptable image, OK, it is only tens of pixels across, but clearly identifiable as Jupiter with bands and red spot. Do NOT use the touchscreen shutter release! You will induce camera shake, no matter how careful you think you are being. Muppet mode or a remote release are the only ways to go. Once you have mastered it at this level, then start putting Barlows in, but start with a 1.5x or 2x first. Make the learning curve less steep. I'm glad you appreciated my previous post.

Whilst some solid advice has been given here, no-one has bothered to ask the OP what type of astrophotography they are interested in attempting and have all assumed that this means long-exposure deep-sky. For lunar photography, any modern DSLR is good and can be combined with an inexpensive Dobsonian mounted Newtonian reflector to achieve very good to excellent results. The whole lot, camera included can be had for less than £300 secondhand. £200 gets you a very nice Skywatcher 200P and leaves £100 for a decent DSLR, such as a D3200 which would work well, but the OP already has a very suitable camera. Basic planetary photography can also be attempted with the same setup. Solar imaging with a small further investment in the proper filters. Heck, you can even acquire basic images of some of the brighter deep-sky stuff, such as M42 without tracking mounts and cooled astro cameras. Starfields, which have been mentioned are also within easy reach of the most basic setup. £300 will not get a decent, sturdy tripod and mount in the camera world. I have a £230 carbon fibre tripod and a £220 head. It still wobbles and I would not call it good. To overcome this sort of issue, you would need a wireless remote control system (I use Hahnel) and an understanding of how to use Muppet mode (Mup - mirror up). You also need to use liveview for focusing if this is the way you wish to go. I will concur with the advice to get decent books on the topic ahead of attempting it. My favorite is Astrophotography by Thierry Legault.

I would say you almost certainly have camera shake on the Jupiter image and probably on the Moon, too. Your focus looks off on the Moon and probably on Jupiter, too. A rigid setup is required when imaging at extreme focal lengths. This means a solid tripod or pier. Most camera tripods are inadequate, although it is possible to get good results with them if sufficient care is taken. As you are using a DSLR, there is another problem which is never discussed enough: mirror slap. This is where the mirror is lifted as the first part of the exposure process and is taken care of by the camera when you press the shutter release. The camera wobbles, even on a solid tripod and is much worse on a spindly, wobbly one. Touching the camera to release the shutter is a complete no-no. I always use a remote, wireless shutter release with my DSLRs. I use the Hahnel system and have an intervalometer option for longer exposures. This removes the need to touch the camera, but does not resolve the mirror slap problem that is inherent with all DSLRs. Hence, I use "Muppet" mode, labelled "Mup" on the camera function wheel or in the menu system somewhere. Mup is a contraction of Mirror Up. So, once in Muppet mode the first press of the shutter release or button on the remote lifts the mirror and you get the characteristic heavy clunk. Now, it is vitally important that you wait at least two seconds to allow the vibrations caused by this action to subside before taking the image. Note: no image has been taken yet, the camera has simply lifted the mirror out of the way and obstructed the viewfinder. After two or more seconds press the release again and you will hear a second clunk as the mirror drops back down. This clunk is not a problem as it occurs after the image has been taken and the shutter is once again closed. Now, I called it Muppet mode because it is very easy to leave the camera in this mode and forget about it, so when you come to take a photo under other circumstances you forget you are in this mode and cannot understand why nothing is happening and feel like a right muppet! Regarding focusing, do not try to do this through the viewfinder as it is not accurate enough. Use liveview on the rear screen of the camera and zoom right in. Go through the point of focus from both sides with the focuser so that you know fairly precisely where best focus is, then make the final focuser movement in the direction of travel of the focuser tube that carries the weight of the camera. This reduces the backlash problem. So, if the camera is hanging off the focuser, like on a refractor or mak, you should make the final movement an outward one - away from the telescope. On Newts, it is generally the opposite.

Here is my B&W result of stacking the best two images and no sharpening applied in AS3! Processing in GIMP, as follows: Convert to B&W using mono mixer, dropping out the blue channel. Adjust curves to deepen shadows and balance highlights. Sharpen 0.500. The result is much closer to what I was expecting and looking for. I wanted to pull out some detail of the crater in the second image. I'm going to have to get closer in next time, as I was only at 600 mm with 4.88 μm pixels. Last night was a rush job with poor conditions and sub-optimal equipment.

@geeklee Thank you! I hadn't spotted that. I've just tried again and, yes, it is giving more the result I would expect. In the output folder it normally places two images and I now understand that one is the unsharpened and the other is the one that has been over-processed. I've always used the latter. I still have much to learn about this process. I'll stick to GIMP for sharpening, now. Thanks.

I did a two image stack of the Moon last night. Each of the subs were not exactly sharp, but were what I had, so I decided to stack them. The result, straight out of AS3! without any futher processing looks over-processed to me, especially considering the quality of the originals. Does anyone have any idea what is happening here? Both subs and the unmodified AS3! output image are attached, along with a screenshot showing the AS3! settings I used.

Rother Valley Optics check some of their scopes (including refractors) before shipping and have a very nice optical bench in a clean room with an interferometer. Having said that, my latest telescope from them, the 300PDS, was collimated before they delivered it to me, but on receipt the collimation was significantly out, but that was very likely down to having been transported.

Very nice! The 190 MN looks like a superb piece of kit.

You remove the lens from your DSLR, then the T-adapter attaches to the telescope and the camera attaches to the T-ring just as if the telescope were a big lens. No other lens on the camera is required. You can use Barlows or focal extenders to magnify the image of small objects like Jupiter if you want. It is possible to attach a camera and lens to the telescope, but you really need filter ring adapters and a threaded eyepiece for that. Some users simply hold their mobile phone to the eyepiece and click, but that is certainly not the best way to do things.

@stuy That, also, is droolworthy. I think it's probably beyond my budget, too. But, budget is not what this thread is about.