Cosmic Geoff

I wouldn't worry about pinholes and scratches on the full-aperture filter. With a 127mm scope, a pinhole 0.127mm in diameter would let through one millionth of the unfiltered light.

I did however have an accident with my home-made solar filter, where the pistoning effect of putting it on and taking it off displaced the inadequately secured film so that some unfiltered light got around the edge of the film.  It made a nasty glare, but fortunately I realised something was wrong before my eyesight suffered any damage. 

To repeat what others have said, the Herschel wedge does require a supplementary filter. 

The Herschel wedge system, unlike the full-aperture filter, has the potential for overheating parts of the telescope, as noted.

The projection method is probably safest of all for one's eyesight, but has the potential for overheating parts of the telescope, especially eyepieces with plastic parts, e.g. the basic eyepieces supplied with many Skywatcher and Celestron kits. Bits melt.  I also have an eyepiece cap with a hole melted in it.

I have an 'older' Canon camera - a 300D, which I acquired from another astronomer to see how I got on with a DSLR.  I found that (with a zoom lens purchased separately) it still works well as a daytime camera BUT at night I could not see any of the controls, the screen on the back is fixed, tiny and does not give a 'live view', the support software to facilitate downloading images only works under Windows XP.  And it is not supported by the astronomy program APT.

It was possible to get the images out using a card-to USB adapter, or, oddly, using Mint Linux.

I have not seriously tried using the 300D for astro imaging. It seems like too much bother.  Before buying any older camera, I advise you checking carefully to see you don't run into the same problems that I did.

Alas, astronomy is not a cheap hobby.  Both the scopes you cite look like models to be avoided at all costs.

If your budget is severely restricted, I suggest you look at the type of scope known as a 'Dobsonian' or 'table-top Dobsonian' which should give you a fairly decent scope on a very basic chip-board mount.  Most of your dollars will hence go into the optics, and if you decide you don't like the mount, you have the option of saving up for a better mount and putting the tube on it.

Some budget Newtonian or Dobsonian-mounted scopes now have fixed collimation of the primary mirror, which takes that issue out of your hands.

On 06/07/2022 at 23:10, chrisv said:

The small sensor ASI 120MM is very narrow, even for a 600mm focal length,

I tried an ASI120MC against a ASI224MC as a trouble-shooting excercise recently, and concluded (among other things) that while the ASI120MC worked well enough as a planetary camera (its intended role) it is too noisy to be very useful for long exposure deep space imaging.  Yes, the field with these planetary cameras is small, but it might conceal optical aberrations in some scopes that would be more obvious with a larger sensor chip.

Since you have a Celestron scope, I suggest you read the above and take a good look at the diagonal that came with your scope, before throwing your money about.  If you can find an extension tube, you can test the scope straight-thru without a diagonal.

My Celestron C8 came with an excellently performing prism diagonal. (#93653-A)

That particular telescope is intended for wide fields and does not do well at high magnification.  With low power/wide field the manual equatorial mount is less useful and an alt-azimuth mount would be easier to use.

Some beginners find the equatorial mounts a pain to set up, and they are not particularly useful unless motorised or in full GoTo form (highly desirable for imaging).

I could not navigate the Norwegian website but (if available) you might look at a longer focal length version of the 102mm, or a table-top Dobsonian of 130mm or 150mm aperture.  Or a ground-standing 150mm Dobsonian.

Some of your wants are contradictory.  "Extensive lunar study" does not seem compatible with having to continually nudge an manual alt-azimuth mount.

"Lunar/planetary digital photography" requires at least a driven mount (meaning equatorial), or alternatively an alt-azimuth or equatorial GoTo. You could try managing without, but you will probably find that it is no fun.

I have a C8 SE, and with the stock 25mm Plossl eyepiece supplied the FOV is about half a degree, allowing the whole Moon to be visible.

The FOV also depends on the eyepiece design - some offer more FOV for a given focal length than others.

If you view with glasses this can also cut the field visible (I always remove my glasses to look theough an eyepiece).

Some more results from these planets, imaged with CPC800, ASI224MC, ADC, captured with Sharpcap 4. Mostly processed from 5000 frames of video.

The visible region images of Mars were just an orange blur, but the IR images, shown here in original size and x2, show some detail despite the small angular size (7.5").

I need to find a Mars ephemeris and map to check what the Mars images appear to show.

The Jupiter and Saturn images show less detail than I have captured at previous apparitions.  The seeing did not look great. Saturn shown in visible & IR.

I suggest you take a hard look at what you want to achieve.  Refractors are the traditional scope design, but there are other scope designs that get the job done and are much more cost-effective in the larger sizes.  Dobsonian mounted reflectors give you the most aperture for your buck, but the simple mount restricts what you can do with them.

You express an interest in imaging - well there are different styles of imaging: planetary, deep space, and EVAA - the latter combines the features of visual observing and imaging.   There is widefield imaging - capturing the Milky Way and huge nebulae - and narrowfield imaging - planets and planetary nebulae and small distant galaxies. One set of kit will not do them all. And the kit is often expensive.  And high demands are made of the mount.

You only need a large scope nowadays if you want high resolution e.g. for planets, etc.  For anything else, if you are not wedded to looking through eyepieces, a small refractor, a sensitive camera and some exposure time can do the job.

I have the EQ-5 mount which uses the same software.  You will probably find that you don't get the uniform all-sky GoTO performance which an alt-azimuth GoTo mount usually delivers.  Use two alignment stars in the East and look for objects in the East - should give good results.  Use two alignment stars in the East and look for objects in the West - be prepared for major inaccuracy.

Why a refractor? A SCT with f6.3 focal reducer could give you a much larger aperture and focal length with a €3500 budget.

3 hours ago, JayMS said:

To perform GoTo function this mount need a computerized application like Synscan of Sky-watcher, while it can be SkyX, AsiAir, APT etc. where APT has more functions like Photography, Plate Solving etc. Thanks.

Quite.  You need to find out which piece of software is causing the problem.  I looked through the APT online help and there is a lot about cameras and no mention of e.g. a two-star GoTo align.  So if your GoTo is going wrong, you should be checking that your GoTo app is performing properly, and if it is, then you need to look at APT or the integration of APT with the GoTo app.

I had a go at imaging Comet C/2017 K2 PANSTARRS on the night of 5 July.  EVAA mode with 102mm f5 achro, ASI224MC, EQ5 Synscan. Post-processed with GIMP. Poor sky conditions.

I had considerable trouble trying to obtain a verified image of NGC6776. Taking the image wasn't the problem, but confirming the object was.  Virtualcolony.com and several other online sources quote it as being the same object as NGC 6884 (in Cygnus) while my Synscan and Cartes du Ciel indicate that it's a separate object in Lyra. 

The FITS stack is now working properly, and I think I have figured out the answer to this. If you set 'Debayer Preview' to ON, all is well, similarly if you set it to RGGB (with an ASI224MC).  But if you set the 'Debayer Preview' to an incorrect setting like GRBG, it looks wrong on the preview and this wrong colour balance persists in the saved stacked FITS image.

Somwehere on this forum I recently saw a link to a company that supplies replacement corrector lenses for these SCTs.

If you do as you suggest the assembly will suffer from the aberrations the corrector plate is supposed to correct.

Having looked up the specs, I see what you mean. Despite the eye-watering price, the mount does not come with a smart handset of the kind provided by Celestron or Sky-watcher. So I'll modify my question to: can the GoTo functions be performed successfully via your tablet or laptop if you don't involve APT etc (which are not needed to make a Celestron or Sky-watcher mount work)?

BTW, to successfully restart from PARK with a Sky-watcher mount, one has to perform the following: mechanical polar align, star align, select PARK, & Park to Home Position in utilities (mount moves to home position, announces parameters saved, requests power off.) On power on, it requests: Start from PARK yes/no?   I expect that your mount will have to do the same (though not with the same software or technical terms.)

I installed APT on a laptop but have not done more than set it up as I found that Sharpcap 4 performed all the functions I really wanted.

A lot of people are confused by the Sky-watcher alignment system, which assumes a Home position pointing at the NCP and will slew to the general direction of sundry objects (algnment stars) before a star alignment is performed, using only the home position and the time/date.

I found that virtualcolony.com/sac/ has useful lists of planetary nebulae down to very faint ones.  I printed off lists for Aquila and Cygnus down to mag. 15, lists that contain a number of planetaries not in the "!00 Brightest" list.  On June 25 2022 I had a go at some with NGC catalog numbers (easier to enter into Synscan). 

Gear: 102mm f5 achro, ASI224MC, EQ5 Synscan, captured with Sharpcap.  I targeted IC4846, NGC6766, NGC6772, NGC6778, NGC6785, NGC6807, NGC6833, NGC6881, NGC6894 and NGC7026 and identified almost all of them.  I had a problem with the colour of the stacked images. 

I was puzzled by NGC6766 which seems to be the same position, brightness and size as NGC6884 which I recorded last year - an easy blue object.

Three sample images are shown below.

Some people may not enjoy using just one eye, but the only way to know if you will get on with this or not is to obtain (or borrow) a starter telescope and try it.  For beginners on a budget, neither electronically assisted astronomy (which requires a substantial outlay) nor binoviewers (which have a significant cost, and not all telescopes work with them) are an option.

Binoviewers potentially give an enhanced view, but are more difficult to use than a single eyepiece. Making the two images merge can be tricky.

Binoculars are a reasonable option for a beginner but restricted to low magnification.

JayMS - can you confirm that the mount works properly when operated according to the user manual without the computer connection and with the handset?  If it doesn't there is no point in trying to use APT etc.

I am not sure what you mean by sync.  You might find it useful to explain that in more detail.

6 hours ago, JayMS said:

Is it O.K. to adjust it manually instead of using hand controller in order to make the star centered? It's not easy for me to navigate on RA and DEC using hand controller.

Moving the mount manually rather than via the GoTo handset is usually a no-no.  It should be easy enough to centre the star with the hand controller if you can see it on screen - just press the direction buttons till you hit the ones that move it in the right direction. That may sound dumb but it's just how it is. (With an alt-azimuth mount one can predict what the buttons are going to do.)

Again, I am not familiar with your mount, but most GoTo mounts work in a similar manner, and some may use essentially the same software as more popular brands.

24 minutes ago, Calculad said:

Most reviewers (astrophotographers) advise that this system is not up to astrophotography. As you can see I think my requirements are

Depends what kind of astrophotography you have in mind.  Some people use Schmidt-cassegrains for imaging small galaxies and the like. Also great for planets. (Smaller aperture refractors are considered more user-friendly than a big SCT for astrophotography.)

Some might think that an 11" SCT is under-mounted on an AVX. I suggest seeking further advice.

Keeping a stellar image inside a 2' (two minutes of arc?) for 10 seconds does not seem an exacting requirement for a GoTo mount. I think my GoTo mounts perform much better than that.

15 hours ago, Mackem said:

But as I think I will be  doing imaging as well as EEVA I was thinking along the lines of an equatorial mounting system .

I have  had this in my FLO basket  for two days Sky-Watcher EQ6-R PRO 😳 

Haven't clicked through yet and so tempted.

If I do I will have to sort a scope to go with the celestron mount to give to my grandson's.

I suggest you hold fire on all that for a while.  The EQ6 is a popular imaging mount but by all accounts a C9.25 is not the ideal scope for a beginner in deep space astrophotography.  Something like the 80mm refractors often recommended would be far easier to use. You don't need a large aperture - I have imaged mag. 14 objects with a 102mm refractor, even got Pluto with an alt-azimuth GoTo mount.

I suggest you see how long an exposure you can run with your existing setup without getting star trails - you may be pleasantly surprised. 🙂

I am not familiar with your mount, but I do not  see any indication above that you performed a goto alignment at any time. Typically this entails entering the date and time and geographical position, and fine-aiming the telescope at one, two, or three bright alignment stars.  A mechanical polar alignment is only part of the process.  This full process has to be mastered before using software like ATP and Stellarium.

I got up early on 2nd July to have a go at imaging Jupiter, Mars and Saturn in visible and infrared.  I forgot to use the ADC and the images of Jupiter and Saturn were a little disappointing. CPC800, ASI224MC, captured with Sharpcap 4. At least got to practice my methods.

The Mars images however exceeded my low expectations, and show some surface detail. Two are visible light, two IR.