Cosmic Geoff

Of the suggested items, a AZ-EQ5 + 10" Newt costs around £1814, an AZ-EQ6 + 10" Newt costs £2284, and a Celestron Evo 8 costs around £1970. 

A CPC800 is ~ £2025.

An Evo 925 is around £2449, a CPC925 £3249

A CPC1100 is £3995.

Note that used SCTs seem not to hold their prices well, so can often be had for far less than the new price (as I can personally confirm 🙂) ie arounf 50%.  So many C8's have been made that if you want to buy a used one you can always find one.

As is widely quoted, for other astro gear it's more like 66%.

The new CC scopes look good, but seem to be available as OTA only - attractively priced (in 8" size) but look like they would need a substantial mount.

3 minutes ago, PeterC65 said:

I keep meaning to use my existing mount manually but it always seems like such a faff so I haven't tried it yet.

I wouldn't - it is clearly designed to slew under power only.

With a manual Dobsonian I was thinking I could add a setting circle and an inclinometer

I tried using manual setting circles and inclimometer with a 8" Newt and EQ5 manual mount, and soon decided it was a waste of time and I wanted a used C8 SE (which cost me £650).

1 minute ago, PeterC65 said:

I should have mentioned that I only do visual astronomy which is why all of the mount options are AZ.

 

I have looked at the Celestron NexStar 8SE. The OTA seems to be a basic version. The C8 XLT may be better but is more expensive. Some reports say that the 8SE included mount is operating at its limit with this OTA and it is a very similar mount to the SynScan AZ GOTO that I have already, just a little taller to accommodate wider scopes, so it doesn't gain me anything for my other scopes. Having said all this, I do like to sit while observing which is why an 8" Cassegrain is so appealing.

 

 

All the C8 OTA's are essentially the same - the only differences are the various colours and that some have a grab handle - it depends on what mount it is bundled with. (There is also the Edge HD, but that is intended for imaging as well as visual). As for the SE mount, it is on the limit, but good enough for visual use in a sheltered location, and on the plus side is portable enough for you to pick up the whole setup and carry it through a domestic doorway. The SE 6/8 mount is a little more substantial than the SE 4/5 mount, or your Synscan AZ GoTo, but I suggest you reserve it for the C8 only as you don't want to be detatching and re-attaching the fat and handle-less C8 OTA unless it's really unavoidable. It's alto the wrong shape for long OTAs. 

The Celestron Schmidt-Cassegrains have been in production for at least 40 years. Some people have re-mounted the really old ones and found they work as well as ever after a bit of maintenance.

As I mentioned, you have a choice of bundled mounts for the C8 OTA (and Celestron also do their Schmidt-Cassegrains in larger sizes).

If you have no interest in imaging, either a Schmidt-Cassegrain or a Classic Cassegrain, or a GoTo Dob should suit you.

You could have a 10" Dob Newt, but from what I've read the Goto Dobs are suited to visual only (check the imaging threads).

A Newtonian on an AZ-EQ mount would work, but the mount would be a bit pricey.

I have an 8" Celestron Schmidt-Cassegrain and am quite pleased with it.  You can buy the Celestron C8 with a choice of bundled mounts, both Alt-AZ goto and equatorial GoTo. Or put it on any other mount you like (it's not a heavy OTA).  Used, they are quite reasonably priced - half the price of new last time I checked.  The SE mount is portable but a but flimsy, the Evolution is said to be better and the CPC800 package is great for visual and some kinds of imaging and solid as a rock, but a bit heavy.

CC has good reports if you want a visual or planetary imaging scope, but never seen one.  Apparently heavier than the Schmidt-Cassegrain of same aperture..

What do you want to do and what's your budget?

Unless your object is to buy a good spotting scope with occasional astro use, I would recommend avoiding the 'One scope does all' solution and buy 1 spotting scope and 1 astro scope with your budget.

BTW, if you buy a Startravel 102mm widefield achro telescope for around £200, it comes with a terrestial 45 deg erecting prism and 2 eyepieces, so as well as its (widefield) astro uses, it could be used as a spotting scope (though not the best-ever spotting scope regardless of expense).  Also needs a mount.

For a satisfactory view of Saturn or Jupiter (rather than seen the rings and belts, sort of) a fairly high magnification is required.  Some spotting scopes will zoom, but zoom telescopes and eyepieces have some undesirable issues.

You don't explain how you are taking the image. If you are using a planetary camera, the capture software should have a histogram tool or suchlike to tell you if the image is correctly exposed.  If you have live view, adjust the exposure till you can see the cloud belts.

1 hour ago, Mandy D said:

@Carbon Brush You've nailed it: I'm a complete beginner with the EQ mounts, but do have mechanical experience! Sorry for the confusion.

The lead took me by surprise, too. I've felt for concealed holes for screws under the tape, but nothing. I think I'll end up drilling the screw out. I may need to get someone to heat the weights to get them off if the penetrating oil does not work, but I'll try twisting them off in a vice first.

I'm definitely planning on having easily adjustable counterweights. I've machined the small one up and bored for 3/4" to match the shaft. I have yet to drill and tap it for a grub screw.

Photo of first attempt at machining a counterweight. What size screw do you think? I'm tempted to go with M8.

The thumbscrew for an EQ-5 5Kg weight has a thread of 8mm diameter, but only the outer 20mm is threaded.  The end of the screw is plain and thinner (and the inner part of the hole appears smaller).  If you copy this, it should be easier to make, and you are less likely to break off your tap in the hole if you are only threading the first 20mm or so.

If you think the lead is holding the weights in place, then applying sufficient heat from a gas burner etc will melt it and free the weights.

In commercial mounts, the weights have a clearance hole and are held in place by a side screw with hand knob, backed up by a safety cap on the end of the rod.  If you can get these weights off, you could replace them with commercial weights - at a cost. Otherwise you will have to drill & tap a long side hole.  Or fix a common circlip on the shaft below the weights.

1 hour ago, nubs292 said:

Hello,

for anybody who has experience with the ES iEXOS 100 PMC 8 mount, how precise can you get the polar alignment without the azimuth adjuster and polar scope, just looking through the hole in the mount? I want to use this mount with 300 mm optics, but I don't really know if it is absolutely necessary spend extra 100$ on the azimuth adjuser or the polar scope.

Thanks!

I assume this is not much different from polar aligning the EQ5 mount which also has a central hole.  Rather than crouching to peer through the hole, it is actually easier to mount a scope in the 'home' position and use its finder, followed by a look through the main scope (at low power) to confirm you have the mount set in the right direction.  You should then be able to look throuh the axis (probably after moving the scope to horizontal) to confirm you can see Polaris.  In an urban environment, the extra light grasp of a polarscope makes it easier to see Polaris and fine-tune the alignment.

If you have got this far, this ia more than good enough for visual use, but if you are taking images with a long focal length and long exposures it may be necessary to tweak the alignment further. In which case I think you will need the polarscope and polar adjuster, which will certainly make the process less trying.   Note that there are electronic methods of gaining an accurate polar alignment for imaging purposes (which assume you have mechanical adjusters that work smoothly).

I assume 300mm is the focal length??

9 hours ago, Mandy D said:

Given that the RA drive is missing, am I wasting my time on this?

Depends on how much you want it to work and how much time and money you are prepared to invest. To bring it up to the standard of a manual equatorial mount, it will need a RA drive & slow motions designed and fabricated, part of the DEC drive to be designed and fabricated,  the weights cut down to size and paintwork done.  If you have to hire someone to do the work, the costs could be significant.

If it's a Project to restore a loved mount, carry on.

If you just want a mount for your 8" Newtonian, order a new one and get it by next week.

Looking at the photos, it appears that any RA drive is entirely missing, while the gear (?) on the other axis is for a declination drive.  It looks like a significant amount of work would be needed to provide hand slow-motions or motorized drives.

Judging by the number of counterweights, assuming they are all solid steel, the scope originally fitted must have been unusually heavy. My 8" Newtonian required two 5Kg counterweights IIRC.

I have tried unguided imaging with a C8, and ASI224 MC camera. At f10 most images were so soft and small-scale as to be almost unusable.  Results at f6.3 were much better. I think the seeing affects the softness of the images achieved.

The choice depends on how much you value the GoTo function. In turn this depends to a degree on whether you live in an urban area (where the GoTo scores) or im a location with dark skies.

Of course you can see more objects with an 8" ... if you can find them.  But even a 130mm will show you plenty.

If you want to do astro-imaging, you should aim for a small scope on an equatorial GoTo mount.  An 8" Newtonian on a (massive) equatorial GoTo mount is not ideal for a beginner in astrophotography. 

If you get the 130 SLT you can dabble with astrophotography and EEVA (q.v.) - at least enough to let you see the potential.  I tried EEVA with a 4" reftactor on a SLT mount and was astonished at the results - the results onscreen surpassed what was visible visually with a 8" scope at a darker site.

46 minutes ago, david_taurus83 said:

Why would it be scrap? Surely they are mass produced to the same tolerances so a new corrector should work the same as the old?

Apparently with older SCTs the primary, secondary and corrector plate were figured as a set, rendering replacement of one component impractical. Hence the advice to mark the orientation of a corrector plate before removing it.

With later SCTs and improved production methods, it is said that the orientation does not matter and parts may be replaceable.  One of the links above is to a 3rd party maker of replacement corrector plates, which one assumes work with recent SCTs.

Unlucky owners will have to compare the cost of repair with the value of a used SCT.

If the corrector plate is cracked, the scope may be effectively scrap, unless its optical performance is unaffected.

The issue is not unique to your mount. Slide the counterweight up the rod toward the mount.  If that's not sufficient, buy a smaller weight, or see if the mount simply ignores the imbalance.

I bought a smaller weight for my EQ-5 - I think the weight was intended for an EQ3-2.

I would rate a GoTo mount as essential.  As noted above, all the serious imaging mounts have GoTo, and though you could use an electrically driven mount with ST4, you will be spending half the night trying to locate your objects instead of getting them within seconds with a "Platesolve & Resync". The GoTo mounts are also said to have more effective motors.

I tried imaging some galaxies on the 4th May and on examining my image of M60 I found a bright star between it and NGC4647 that wasn't on internet images.

A quick search established this was the supernova.   Taken around 22:44 BST with 102mm achro, EQ5 Synscan, ASI224MC, 1304x976px, stacked 10 frames of 29.6 secs, sky transparency poor, crescent moon.

I would suggest that swapping the visual back or diagonal is not a priority. Your money would be better spent on replacing the kit 9 or 10mm eyepiece with something decent ( budget around £50, or more if you like).

As for finders, bear in mind that that you should only need to use the finder once a night if you are using the GoTo. I put a straight-thru 30mm finder on my Mak.

The Nexstar version of your outfit (from Celestron) does not offer up objects (e.g. planets) that are below the horizon. With the Synscan, it should display the altitude and azimuth, allowing you to see where the object is and choose whether to GoTo or abort. My Synscan handset has one or two buttons that do not respond unless pressed firmly.

2 hours ago, Stu1smartcookie said:

Thanks Geoff ... i suspected that was the case but i had a converstaion with a supplier who said that the thread on the centre bolt was different . As you have the AZ4 and an EQ5 could you possibly check for me . ( at this point i am assuming the bolt on the eq3 and eq5 are the same ) 

I already checked ages ago and they were totally interchangeable. Could not see any differences asides from the paintwork.

I don't know, but the AZ4-2 steel tripod is identical to the EQ-5 tripod.

2 hours ago, spikkyboy said:

I have a HEQ5PRO mount and really struggle with alignment.

My experience of alignment with the similar EQ-5 Synscan is that it can perform well if you do a two-star align with two stars both on the same side of the meridian (e.g. East), and then GoTo objects in the East.  Go anywhere else (e.g West) and the GoTo is so inaccurate as to be useless.

I have a Starsense and find it convenient but not particularly accurate.  The alt-azimuth Nexstar GoTo however performs well with a two-star align anywhere in the sky.

I'm sure it is technically possible, but whether the astro equipment manufacturers have the funds to develop one and the astronomy community have the cash to buy it in significant numbers is another matter.  An alt-azimuth mount with a Starsense-like plate-solving self align, coupled with a field rotator, ought to do the job.  The mass-produced Chinese mounts have never been re-designed from scratch - for instance why does a USB port (if provided) need a serial driver? There are some nice mounts from specialist companies, some of which may actually do what you ask, but at prices that make one exclaim 'HOW MUCH?!'

There is a reducer for the C8 - known as the Celestron f6.3 reducer.  ( so called because it converts the f10 C8 to a f6.3) They are not cheap - mine cost £100 used, and they go for more than that on ebay. New around £150.

If you tell us what camera you are using, we can give you an idea of the FOV (or you can find out yourself with an online app).

54 minutes ago, Splreece said:

I'm hoping to do moon/planet imaging via the telescope (so closer and more detailed than dslr and zoom could do) but that sounds quite a range, maybe I need to be specific with which planets due to distance etc (assuming focal length and fstop and tripod make a difference.   If I were to say the moon and possibly Saturn viewing, would that give a hint as the which focal length and tripod mount I needed

 

 

If that's your aim, your DSLR might suffice for imaging the moon, but for the planets you really want a dedicated astro camera e.g. a ASI224MC that can take a video to be processed later by 'lucky imaging'.   For a telescope for planetary imaging, I would recommend a medium aperture SCT, eg a Celestron C8 or C9.25 (though you could use a Newtonian).  For a mount, an alt-azimuth GoTo mount will be entirely adequate (but if you envision deep space long exposure imaging you may prefer to use an equatorial GoTo)

Note that some combinations of camera and telescope will not get the whole Moon in field.

I've already spent more than your £2000 budget for you. 🙂  You will need to decide on your main interest and priorities.

As others have hinted, you can't cover everything with one set of kit.  So far as imaging goes, I have one outfit for widefield & longer exposures & EEVA (q.v.) - (on equatorial GoTo), and another for planetary imaging and shorter exposures of small objects (alt-az GoTo).