Cosmic Geoff

I have done EVAA with a CPC800 (8" SCT fork mounted, alt-azimuth GoTo), Celestron f6.3 focal reducer, ASI224MC camera, Celestron standard diagonal, Celestron dew shield.  Software: Sharpcap 4 on Windows 10 on Dell Vostro.  That's it: I don't think I need any other bits & bobs.  It works quite well on small targets like planetary nebulae.

Good luck and clear skies!

I have the setup to do platesolve & resync but this technique works better with a wider FOV.

Note that if you are using a fork mounted scope like the C9.25 Evo you will need to use a diagonal, both to get the correct spacing for the focal reducer and to prevent the large camera hitting the base of the mount.

Assuming you intend to put it on an equatorial mount, read up on 'cone error'.

I had a further look into this and am more confused than ever.  I was wrong about that setting in Sharpcap 4 :

Debayering FITS with PIPP Not Working in Version 4 - SharpCap Forums

It looks like I was not using 32-bit files so this is not relevant.

I was also wrong about the camera not being relevant - I tried some shots with my ASI120MC camera of the same targets as with the ASI224MC. With the ASI120MC the .png single shot and the .fits stack come out having the same colour rendering (and the bright stars don't have green haloes).

With the ASI224MC the results are as above.

I also noted that when processing a FITS file in PIPP, it does not matter what debayering options are selected, the result is exactly the same. Maybe the stacked FITS file is already debayered?

Also noted that when processing a .png file from either camera, it is possible to recreate the 'green halo' effect by selecting a 'wrong' debayering option.

Still baffled.

14 minutes ago, LaurenceT said:

Does it make a functional difference if the GoTo kit is an addon or if the mount was sold as a GoTo originally?

I upgraded mine and I do not think there is any difference at all. Doing the upgrade is simply a matter of unbolting the unwanted parts and bolting on the kit parts.

While doing some EVAA imaging of faint planetary nebulae I became aware of a problem with live stacked images stored as FITS files.  Kit: 102mm f5 achro, ASI224MC camera, EQ5 Synscan mount, Sharpcap4. 

I noticed that the colours in some of the de-bayered FITS images, converted to TIFF in the de-bayering using PIPP, looked off.  I nearly always take a companion single shot saved as a .png image. I will try to give examples below.  You will note that the de-bayered .png image has credible colours for various stars and for the nebula in the centre, which looks blue-green.  The live-stacked FITS image, hovever, debayered and converted to .tiff in PIPP, exported as a jpg in GIMP, has green stars! -which is plainly wrong.  They also look green in the PIPP preview, BTW. This is the most extreme example I have found so far - mostly the FITS colours just look less saturated or a bit off.

(Note that I am not concerned about those blue or green fringed stars as such - they appear because I have not invested in an ED or APO scope.)

So what's wrong? Clearly not the camera. After some digging, I found that Sharpcap 4, unlike the previous version, has settings in the Image tab where one can set the indication of the Bayer matrix to be correct for PIPP (etc) or Astap (etc) and unlike the previous version it defaults to the latter. 

OK, fine, so I just have to change that setting to PIPP (etc), reprocess the previous images (since I installed Sharpcap4) and the problem is solved? Actually, no...☹️.  I tried loading the NGC7026 FITS into ASTAP and found I could have either green stars (which it seemed to default to) or a perfectly monochrome image. Nothing else. That leaves two other programs (mentioned in the Sharpcap settings.  Pixinsight is a paid-for program, and My Windows 10 wanted nothing to do with opening Siril.

At which point I gave up.  Any ideas?

Stack_16bits_10frames_100s.tif

18 minutes ago, Jonathan_Shields said:

Thank you Geoff. Its interesting that an achro refractor can get good results in EAA.

If you search in the EAA Reports you should find some images I made with the 102mm achro.

I use for EAA both a 102mm achro refractor on an EQ-5 Synscan with an ASI224MC camera, and also a CPC800 with a f6.3 focal reducer and the ASI224MC camera.  If I had to pick just one I'd use the 102mm setup.  The  CPC800 setup (which gives much the same FOV you'd get with an 8" Newtonian) is more suited to small objects like planetary nebulae.  

I basically used kit I already had on hand (except for buying the focal reducer. )  Your choice is whether to aim for a widefield or narrowfield setup, and how much you want to spend on a camera. The ASI224MC is a planetary camera but works just fine for deep space except that the chip is small, hence narrow FOV.  I also strongly recommend that you aim for a full GoTo, which will let you easily find faint targets and use platesolve & resync to confirm you are aiming at the right place.  An equatorial mount is not necessary for the short exposures you are likely to be using, but the choice of alt-az GoTo mounts is limited, and the equatorial gives you the option of trying long exposures.

It could be anything. Is there no label on the tube that gives a clue?

You don't need to know the make in order to clean it.  The question is, what parts do you think need cleaning? With any telescope of this sort, shining a torch on the mirrors will highlight any dust and make them look horrible.

If you do remove either of the mirrors you will need to understand about collimation in order to get it working after you reassemble. I suggest you reaearch that before you touch anything.

9 hours ago, Rusted said:

An image of an astronomical object is a historical and "scientific" record of that moment or moments. This is not a trivial matter IMHO.

Would you post a picture of a hijacked bus or a famous person upside down? Presumably not. It would trivialise the moment.

Anyone wanting a "scientific" record of sunspots could look on the daily SOHO site.

As anyone who spends any time looking at astro images will know, the orientation of the images varies a lot.  Traditionally, many are shown inverted because classic refractors show the object that way.  I have also seen deep-space images that were mirror-reversed.

The make-a-finder-into-a-guidescope works best with a specific model of finder and an astro camera with the standard thread, plus an adapter ring that costs 30 to 40 Euros. Or with finder/guidescopes (sold as such) which accept 1.25" eyepieces. Otherwise you may have to to make adaptors up from stock material.

Onstep is a DIY GoTo syetem. Search this forum for 'Onstep' and you should find various threads.

You should decide though whether your hobby is astrophotography or building stuff. 🙄

The Evo 8 at f10 will be tolerant of eyepieces.  If you want a wider field of view, a 32mm Plossl ( or a shorter focal length eyepiece with wider FOV and higher price) will prove useful.

The highest power eyepiece  I regularly use in my C8 is 8mm.

If you have the budget, try using a dedicated planetary camera (+ Barlow lens) + 'lucky imaging' software. 

I can't remember if I tried imaging Saturn with my 127mm Maksutov, but I have tried it on Jupiter and got various shots showing the cloud belts and Great Red Spot quite clearly. 

Maybe it's my eyesight, but I can see a lot more on the processed images than I could visually.

The proper EQ5 kits (including handset controller) are sometimes available used, and not expensive.  I assume budget is an issue here.

There are actually several variants of motorizing available to you:

RA only

RA + Dec

RA + Dec (enhanced) to facilitate guiding for imaging.

D.I.Y. GoTo (various).  Cheaper than the real thing but involves a lot of skilled work.

Skywatcher EQ5 Synscan GoTo upgrade kit. Recommended for imaging and easy to fit. Makes your mount equal to the commercial Synscan mount.  Synscan is capable of impressive aiming accuracy but needs some skill and effort to get the best out of it.

I observed this last night with my C8 and a magnification of about x250 as an easy double-double (7.9" and 11.9")  Splitting the 1.1" AB would have been a tough call under these conditions.

I could also just see the split of Nu Scorpii CD in the multiple Nu Scorpii system - another visual double-double (actually septuple)

Two elusive planetary nebulae in Sagittarius: I tried to image these with my CPC800, but it was a total fail.  I tried again last night with my 102mm achro, ASI224MC camera, EQ5 Synscan + platesolve and resync.   For some reason the NGC6537 field refused to platesolve but the target was in field anyway.   The starfield around NGC6567 is exceptionally rich.  I had to look at online images today to pick out the planetary nebulae.  Both were low down in a hazy sky.

See this post:

I think you may be in danger of trying to run before you can walk.  It also appears that you want one scope and mount to cover all bases. From your equipment list it seems you are mainly interested in imaging.   There is no such thing as a telescope that can do it all. That's why I have four, and four GoTo mounts.

The Star Adventurer seems mainly suited to wide angle imaging with a telephoto lens or small scope.  The 6" SCT (mainly suitable for visual use) does not seem a good match for it.

I suggest that rather than buying an expensive cooled camera you start with a cheaper uncooled one or a DSLR (you may have one of the latter already) and instead of the ASAIR use an existing laptop.

Once you have had a go you will be better placed to judge what you really need to buy.

If you intend to image with a 6" SCT you need a serious mount like a  HEQ5.

Check your local laws before going anywhere near a green laser pointed at the sky.

The mount looks rather like the SLT mount. I don't know how helpful this information is.

I have three Nexstar alt-az mounts of varying ages and models, and several handsets (Nexstar*, Nexstar+ and Starsense).  I have swapped the handsets around for various reasons and found that all the combinations worked, so the mounts are clearly not fussed about what version of handset is connected.  My SLT mount works with both the Nexstar* and Nexstar+ handsets.

If possible, ascertain what firmware is actually loaded in the handset and mount. Then you can figure out with the aid of nexstarsite.com whether they are actually compatible.   Do not try to upgrade the firmware unless you are really sure what you are doing.

I have found that the SLT mount firmware is prone to getting corrupted (giving an error 16 or 17 = no response) which can be fixed by reloading the firmware.

What kind of imaging do you want to do? I have two imaging setups, one with a 102mm achromat and the other with a 8" SCT + focal reducer.

They address different field widths.  If you want to capture wide (ish) fields, you want a short focal length and a small scope.  If you want to capture detail on small planetary nebulae and diatant galaxies, you'll want a longer focal length and a bigger scope.

The 102mm achromat is set up to plate-solve and re-sync, but that does not work so well with the SCT and its narrower field of view.

You don't mention a camera - many people use a DSLR.  You may already have one. Note that using an older model of DSLR can be a severe pain for various reasons. Dedicated astro cameras are easier to use but those with chip sizes comparable with a DSLR are expensive.

No, but I have a flip mirror I bought used IIRC, which has no evident branding other than 'TS'.  It worked well, and has various bits which unscrew to make attachments more versatile, and the eyepiece focus can be adjusted.

However I have switched away from using it, partly because the combination of this and a focal reducer and camera was too long for my SCT mount and made it impossible to image anything at medium or high altitude.  The equally effective alternative is to use Precise GoTo and if necessary a right-angle finder to get the supplementary guide star centered.

I also had a worrying accident when I unscrewed the camera from the flip mirror in the dark and found I had unscrewed part of the camera and nearly lost the optical window.

It is notable that views tend to differ depending on which side of the Atlantic the respondent is on.

Personally I feel no need or desire to use a laser pointer. My scopes are aimed by GoTo, which means that if I am using a red dot pointer at all I am not aiming at alignment stars with extreme altitude, and I also have a right angled finder. 

Starsense also avoids the desire to use a laser pointer.

Not trying to point the finger at anyone, but are some respondents (legally) using laser pointers that would be illegal under UK regulations?

This is the early single-arm GoTo model? Some pictures and part numbers might jog someone's memory.

If the LCD on later models is the same, that raises hope that it can be sourced from somewhere as an electronic part.

Is there any serial port that could be used to computer control the mount, thus bypassing the display or handset?

The nuclear option is to de-mount the OTA and put it on a new mount.

You could replace the altitude T-bolt with any bolt of suitable length with the correct thread.

As for the loose leg bolts, any hardware shop or car accessory store should be able to sell you a suitable spanner or adjustable wrench.

20 hours ago, _evenstar said:

(maybe an easier AZ mount for <£40

You won't get an easier mount for <£40 unless you are very lucky and find one in a charity shop.   There are mounts that would suit you better but they would cost you more like £200 new.

You could try obtaining a suitable external regulated +12v power supply with centre positive and plug it in and see what happens.  Few people continue to use these mounts with internal batteries.

One possibility is that the handset has developed a bad connection where it plugs in so you can't see it light up.