Toltec

Interesting thread as I'm planning on having a go at this myself this year.

I tried the sv41, it is possible that I got a bad sample because the collimation was way out, off focus the pattern looked more like a wankel rotor than a disc and any bright objects has noticeable flaring to one side. Having said that it has a 48mm thread which you can just screw a 2" to 1.25" adaptor to to take normal eyepieces. I spotted this alternative, but not tried it https://www.rothervalleyoptics.co.uk/acuter-voyager-mak-80-telescope.html I have ended up using an old 60mm refractor on a photo tripod with a fluid head for now.

I've been wondering this for a while, I did think it was maybe the physical chip size rather than the sensor area, but even that seemed odd. Not unlike the scaling from a 35mm film format for dlsrs I guess. I have looked at the actual sensor dimensions as even the diagonal is dependent on the shape anyway.

Worth checking the cabling, as per my later post I found the car type plug to 5.5/2.1 plug cable was dropping a significant amount between the battery and mount cable.

I have been trying out a kneeling chair with gas ram height adjustment. It allows me to take up various positions, from sitting on the lower pad and leaning back against the upper pad, good for high angle with a refractor or using binoculars, sitting on the lower pad with elbows resting on the upper pad to look down into a diagonal, to simply sitting on the upper pad at full height. Gives me seat heights between 20 and 57cm. Only used it with a mak and refractor though and I have just acquired a 10 newtonian so I suspect I'll need something else for that.

The boost psu is running off the same battery and it doesn't pull the battery voltage down noticeably. It is just the small 7Ah SW power tank, with a new battery, it will run the mount for four hours and still be above 12v. Im going to have to test the mount handset reading at various input voltages now Edit: The handset does read the input voltage correctly, within 0.1 at least which is within reading error. What I must have done is measure the voltage at the battery first then at the input after putting the boost psu on. Turns out the lead supplied with the power tank drops half a volt or more even without driving. I have another cable which was much better. The cable supplied with the mount is fine, very little drop on that. They do want over 12v though so a 12v psu with a not so good connection lead is not going to do the job.

I started up again late last year and ended up buying a Skymax 127 on an Allview mount. It was used for about £300, it didn't have any eyepieces, but I bought 3 basic ones used for £15 which got me going. The Allview will take a 102mm refractor, but struggled a bit with a 2" 23mm eyepiece attached unless rebalanced. A key reason for going for the mak was the relatively low cost for the aperture and portability, the other big thing was not having to worry about collimation checks. I bought the refractor to get wider fov, but it cost significantly more than the mak and mount did. I'd say keep your eyes out for a used setup that will start you off, see if you have a local astronomy society, mine has monthly observation evenings which are good to go and see some kit and chat with people. Don't stress too much about your first telescope, if you really get into this you will upgrade as you find what types of astronomy interest you most. If you buy used well known kit you can likely sell it again with little loss once you grow out of it. Not that I have yet, though I should having just acquired a third mount and ota within six months.

There is something a bit odd with the SW mounts and supply. If I run my AZ-EQ5 from a battery with a measured 12.4v at the mount input (12.6v at the battery) the handset says 11.8v. When I put a boost switching psu in line set to 13.5v the handset reads 13.4v I'm wondering if they have an internal regulator, typically when you drive one of those below the set output voltage you lose a little voltage across it. I haven't bothered adjusting the output to see if that is the case though.

My understanding is that the mirror in a mak needs to be larger than the aperture so while the mirror is 127mm the effective aperture is less. I have seen 118mm mentioned before. This is why the OO omc140 has a 152mm mirror.

Hi, I grew up in Bridlington, though live in the South East now. I envy you the lovely dark skies you have up there, enjoy your new obsession.

NIce images, the SCT image does look like it has more detail, particularly the rust coloured object in the lower right spiral arm. I don't image, yet, however I have a background in optics and metrology so I appreciate the discussion.

Hi Paul I started up again late last year and bought a used Skymax 127 on an Allview GOTO alt/az mount for £280, I based my decision partly on this being a modest sum to see if I wanted to get back into astronomy and if it was practical in my location. I'm in a Bortle 7 area and I would say the GOTO really helps as you/it can find objects that you would not locate easily if at all visually if your sky isn't great. I then bought some more eypieces, a 102mm F7 refractor, then an AZ-EQ5 mount and some more eyepieces. I'm just in Orpington if you ever feel like coming over to try out my setup and my local society has observation evenings every third Thurday in the month at Otford which are open to non-members. Liked a few of your posts to help with the count to get you to the selling forum, still working on that myself.

The extra luminance subs really helped pull out the detail in the dark sections. Love the star colours.

This is precisely one of the things I love about observartional astronomy, that photon from a distant star that excited the photosensitive molecule in your eye just connected you to that star instantaneously. On time travel, something which has been covered in various books and films is that the moment of conception is so tightly bound to the moment and circumstances that the tinest change by a time traveller would result in a number of people never being born.

Finally got to try it out on a clear night, unfortunately the collimation was poor, flaring lines upwards from stars in focus. Sirius in focus had diffraction rings shifted mainly to the upper third and out of focus looked more like the rotor of a Wankel engine than a set of concentric rings. Already processed the return with Amazon. It was a warehouse deal so maybe that was why rather than just being a change of mind. Worked really well on a camera tripod with a fluid head so I'll definitely be looking for something to replace it. One of the other chaps at the local society has a 70mm Celestron which isn't much longer and gave very good views.

I consider it in the other direction as well. If you think of the surface of the camera sensor as projecting a collimated point of light or beam from any given pixel that passes through the centre of the objective lens then the shorter the focal length the greater the angle subtended from one edge of the sensor to the other. The diameter of the lens makes no difference because the beam is always passing through the centre.

Just waiting for a clear sky to try it out, curious to see if it will vignette with my 40mm Vixen NPL. If not it should have enough fov to take in the Pleiades. Sold it to my wife as a cheap compact holiday scope rather than taking the AZ-EQ5 and 102 refractor.

Turned up this evening, a 2" to 1.25" adaptor from a diagonal screws straight on to take my Baader zoom.

Saw you posts on the little scopes thread and did a quick search, found one on Amazon for £68 and thought why not. Should turn up on Wedneday. I already have a Svbony helical focuser on a 127 mak so I can try that out too.

I have been trying to split Sirius with my Skymax 127 recently with no luck as well. Rigel is quite possible, if you haven't tried that? Have you taken a look at ngc 2169? It looks great through my mak. I've only just got back into astronomy and I'm like a kid in a sweet shop at the moment. I enjoyed reading your report.

Yes, AZEQ5 with the pedestal tripod and one extension, I have a couple more extensions and might try it with one more, but for the moment just the one gives a good saddle height for observing right up to high altitudes with a seat six inches off the ground.

Looks like I have the same pair as you ScouseSpaceCadet, I tend to have a 23mm Axiom LX in the Altair and a 8-24mm Baader zoom in the Skymax.

This is what I eneded up making last Sunday, I can move the balance point by trimming both the position and weight on the balance arm. Note the flats on the thread of the weight holder, this allows the100g discs to be added and removed without having to completely unscrew it. I am using an az-eq5gt in dual mount and while that makes it possible to release the clutch without losing alignment I intend to work out the position and weight needed to balance various combinations of eyepieces. The extra vixen rail is handy for holding the tube while mounting up as well. What do you think?

I don't do AP, yet, or at least the last time I did we were still using film. What I used to do is build test systems for imager development, mainly IR, but the testing included the human visual interfaces so characterising what a human would see with the system in terms of thermal and spacial resolution. One project involved designing a test rig to scan a spot of light less than half the size* of a ccd pixel across a sensor to characterise individual sensors for selection for a satellite package. No, they are not fundamantally square, that is an artifact of the system, if the pixels were circular or hexagonal the output could still look square on a screen if that is how the processing chooses to represent it. Unless the light reaching the sensor is a small fraction of the size of the pixel there is going to be some light reaching surrounding pixels and that can be used to display circles on an output that has more pixels than the light reached on the sensor if disccs is what they are assumed to be. What you cannot do is extract more detail than you have information for, if you have two stars overlapping and imaged on to the sensor on a single pixel you might get an oval blob on the display or the processing might just turn it into a disc, you are not going to get overlapping discs. What Vlaiv is trying to explain is if the smallest artifact you want to see is the disc of a star then sampling at 1.6 times the resolution or star size will get you that. You can oversample, but then you start to trade off noise and exposure time because each pixel is receiving less photons. I was trying to think of an analogy, lets say you are trying to measure rainfall, if you have a 10cm diameter funnel going into a 1cm diameter measuring tube you will get a measurable reading over a wide range of fall rates. If you instead have and array of a 100 1cm tubes some of the droplets will fall between the tubes or hit the lip with some going into the tube and some running down the outside. At lower rates of fall you will be getting different amounts in each small tube and measuring it accurately can become difficult. * The spot of light was at less than 10% illumination at a diameter equivalent to half of the pixel size.

That takes me back, exactly what I did in the early 80's, buy not grind that is, almost everything else was home made. There are still mirror sets available if you check ebay.