Cosmic Geoff

I have never bothered my head about "back focus".  I use a CPC800 + Celestron prism diagonal + ZWO manual 5-filter wheel + ADC + ASI462MC for planetary imaging. 

The diagonal is for convenience, and for preventing the image train colliding with the bottom of the forks.  It also gives the right spacing when I use a f6.3 reducer for deep space shots.

A 3x Barlow on a scope with a 2000mm focal length is probably overdoing it.

"I have the same legs and spreader/tray., in white.."

Alan, that looks like a Skywatcher tripod to me, not a Celestron SE tripod.   That might be a good tip about the washers though, and the spreader is identical asides from the colour. My used Skywatcher EQ-5 tripod has legs that are too loose after some idiot dismantled it completely for shipping.

As Peter says, turn the tripod upside down to check that the legs all splay to an equal angle and there is no manufacturing defect.  The spreader should touch all three legs.

FYI, with the legs retracted, the three tripod feet should form an equilateral triangle about 61 to 62 cm.  on each side.   If yours differs, you should be able to figure out where the problem lies.

(In practice I don't touch the spreader unless I am transporting the setup to a remote site.  With the telescopic legs retracted the tripod (and scope) can be carried through a domestic doorway so there is no need to dismantle anything.)

We have seen problems with faulty Sky-watcher tripods, but not with Celestron SE tripods AFAIK. 

Don't use an eyepiece. Remove the eyepiece and connect the camera directly.  (will require an adaptor.)  Do not add a Barlow until you have tried it without.

 A dedicated planetary camera will probably give better results.

I have tried two setups for EAA, both using equipment to hand:

102mm f5 Startravel achromat, ASI224MC, EQ-5 Synscan.

CPC800 f6.3 reducer, ASI224MC 

EAA is not the same as visual. You don't need a large aperture. If you want to go fainter, lengthen the exposure.   I have found that the 102mm will show me as much or more from an urban location as a 203mm will visually at a dark skies site.

If you want a larger image scale, e.g for imaging planetary nebulae, you need a bigger scope.  However, if the focal ratio remains the same, you will not record fainter objects with the same exposure.  I found that my CPC800 f6.3 setup requires a longer exposure to image planetary nebulae to the same image brightness compared with the f5 Startravel.

40 minutes ago, random said:

I have a Celestron NexStar 8SE and have found that using the supplied 25mm eyepiece gives substantially better quality than Celestron X-Cel LX 5mm and 9mm eyepieces. I appreciate that lower magnification is likely to give a clearer view but the X-Cel give very unclear views. Is this to be expected?

You are not comparing like with like.  I have all the above-mentioned items, and find that the supplied 25mm Plossl is an adequate eyepiece.  The X-Cel LX are mid-priced eyepieces which perform quite well, but the C8 at f10 is not going to challenge any of these eyepieces.  The 5mm will give a magnification of x400  which will be too much magnification for a clear view  under average seeing conditions.

What setup do you have in mind and what do you intend to image? I have a flip mirror but I only ever used it for imaging relatively faint things.  I have since found that an alternative is to use Precise GoTo.  With a little luck, this gets the image on the camera chip, especially if you are using a focal reducer.  Or try plate-solving.

My cameras screwed onto my flip mirror via a T2 adapter that came with the flip mirror assy.

I have used a similar setup, and I was able to flip between the ASI224MC (in focus) and 25mm eyepiece (roughly in focus) with the camera screwed directly to the mirror box via the T-thread adaptor.

TBH I have never bothered my head about "back focus". 

Unless the camera is a) in focus and b) accurately aimed at Jupiter, i.e dead center* in the eyepiece, you won't pick up a thing.   The camera field is much smaller than the eyepiece field even if you select the full chip as the ROI.

I suggest dispensing with the flip mirror as you should not need it for locating in-your-face bright objects like Jupiter.

* or maybe offset by a small amount depending on the mirror setup.

1 hour ago, mr saddo said:

Hi, I've just bought on if these zwo 120..had a go on jupiter last night, cold! Clear,  I could not get image on screen  using sharp cap,  it was just a round light properly the front correcter plate on the  mak 127  tried inward outward focus, I focused on a 10mm e.p then put the camera in to the diagonal, does the diagnal need to be off, with the camera up the back of scope, or in a barlow in the diagnal, spent 2 hours nothing, gave up, very annoyed. Scope skywatchher 127mak. 

Been there, had that experience. Read my earlier post.  You will not get anything unless the camera is almost in focus.

If you want a quick and comprehensive answer, I suggest you read the other threads here generated in answer to similar queries. 

As for 

11 minutes ago, timfoster said:

Ability to connect a phone (either remotely or as the screen)

you will need to define what you mean. There is nothing in a £150 telescope outfit that will connect to a phone, unless you mean using the phone as a camera to take snaps through the eyepiece.

2 hours ago, reddish75 said:

Here it is, finder scope wasn't included, any suggestions on what to replace with?

You may get various suggestions about the finder.  A straight-thru optical finder will prove a pain in the neck (literally).  A 9x50 right angle or corrected-image right angle finder (RACI)  plus a red-dot finder is a good combination. You could add another bracket, or get an adapter to mount both on the same bracket.

Forget the Celestron wedge. Your 8SE outfit is primarily intended as a (portable) visual scope.  It can also be used for planetary imaging with its alt-az mount, but it is better to use a dedicated planetary imaging astro camera.  With patience, it is possible to get good results. The mount is really not suitable for long exposure deep space imaging.

It is possible to re-mount the optical tube on an equatorial mount (at considerable expense) and use it for deep-space imaging of smaller objects, but this is not really an exercise for beginners.

The consensus among people who have actually tried imaging with a wedge is that it is a bad idea, and it is better to use an equatorial mount, which gives a superior performance and is easier to polar align.

You have not specified what size of scope you are using, or the camera, or the size of the captured video, or the programs used to stack and sharpen.  If you are asking for feedback, it helps to give as much detail as possible.

I have not double-checked by comparing your image with one of my recent shots, but have you corrected for the L-R swap introduced by a star diagonal? (You can easily correct this by ticking a box in Registax.)

Overall, your image is not bad and shows a lot of surface detail.

As for the fringing, there is an effect that occurs when trying to process Mars images. it is common enough to have acquired the name of "rind", and is an artificial brightening of the fully illuminated limb of the planet.   It seems to occur with over-sharpening.

I have found that with the similar EQ5 Synscan that inaccurate GoTo is all too common.  If you want a more accurate GoTo, you need to select alignment stars on the same side of the sky as the object you want to observe, and with one of them not too far from it.  Or use platesolving.  I routinely find that platesolving corrects the aim by 0.3, 0.5 or 0.7 degrees.  

15 minutes ago, Nitecoda said:

Thank you @Cosmic Geoff. I looked at the Moon, Mars (albeit close to the horizon), and Jupiter through a 102/500 Skywatcher StarTravel with various eyepieces at the latest gathering of my local club. I've also looked through a friends 76mm Takahashi. There was a lot less false colour through the Tak and it made the Skywatcher look almost fake and out of focus to me. I know I can't compare the equipment at the price points, and I'm not proposing a Tak. I'm trying to find that happy medium.

Ideally it won't be an expensive premium scope - I didn't think that was what I was aiming at with a £900 Frac. I'm happy to consider lower quality glass if it's not going to result in a lack of excitement when we use it for live viewing only.

Thanks 

I have a 102mm Skywatcher Startravel, and agree that the performance is not great.  But this is a f5 achromat, and if you think its performance is typical of what you would see with a f10 achromat, you are entirely missing the point.  A chart has been posted more than once on this forum showing the colour correction performance of achromatic telescopes according to focal ratio and aperture.   Large apertures with short focal ratio are dire, while small apertures and long focal ratio are very acceptable.   

I own a vintage 70mm achromat refractor with a very long focal ratio and the colour correction is entirely adequate, and the overall performance is superb.  On the other hand, it is rather long and heavy.  🙂

You clearly appreciate the quality of premium priced kit. But will your family appreciate the difference when looking through they eyepiece? I doubt it.

If you want a 4" refractor for visual use, there is no need to spend that much money.  For centuries, amateurs were entirely happy with achromatic refractors of long focal ratio. A present-day example is here: Sky-Watcher Evostar 102 (EQ3-2) | First Light Optics

Recently the various ED scopes have appeared, which offer a potentially better colour correction in a shorter tube, at a substantially higher price.

The combination of a short focal ratio and good colour correction is particularly relevant to deep-space astrophotography.  Not so much for visual use.

If you want to spend your money on an expensive premium scope, that's up to you, but if you are willing to spend £2000 there are plenty other options with bigger aperture and features like GoTo.

Good effort with a 70mm refractor.

If one likes an 8" Dobsonian, that's fine.  But if you decide it's not for you, the options (at the same aperture) are to go for an equatorial mount, with the pluses of potential use for imaging, having GoTo, and the minuses of increased cost, weight and complication.

Or go for an 8" SCT, with a much lighter OTA and the potential for having a lightweight GoTo mount in a portable visual setup, or an equatorial mount with potential for imaging.  Or on a heavy duty fork mount if that takes your fancy. 

Here is one of my best results on Mars, taken at 22.40 UT on 8 Nov.  8" SCT, ASI224MC, IR-cut filter, ADC, Sharpcap 5000 frame video.  Processed with Autostakkert, Registax, Photoshop Elements.   Diameter=15.9", so almost at maximum dia for this opposition.

No replies yet?

One would expect collimation to be more critical than with a f6 Newtonian.  But does it go out of collimation? Is there even a collimation adjustment?  Are the cheap eyepieces good enough to give the best performance?  A f4 Newtonian would normally demand some rather expensive eyepieces.

As you can see from my signature, I have some equipment similar to yours.  I would suggest that you get a tri-pier (a semi-portable pier with three feet) and park it in a suitable part of your garden, put the EQ-5 Synscan mount head on it, polar align it, and leave it permanently in position.  Sky-Watcher Pillar Mount | First Light Optics

You will need a waterproof cover.

Then after a session you can 'park' the mount, power off, remove the scope and cover the mount.  At next session, attach the scope, power up, un-park, and you are ready to go - no polar aligning or GoTo aligning needed.

I use the mount mainly for EEVA (q.v.) style imaging, and plate-solve to confirm the targets.

6 hours ago, Seoras said:

Hi, here’s a couple of photos of my finder. The top down photo shows the direction of the wobble and in the side view I’ve pointed to the joint that seems to be loose.

I have a C8 SE with the same style of finder.   Sorry I can't offer any further advice. I assume you have tightened the two long bolts that pass through the 2 inch long clamp under the finder body?   My finder is fairly rigid for what it is. 

Is there any way you can get someone familiar with these finders to take a look at it?

If you want to replace the whole thing, I recommend the Baader SkySurfer III finder.  I have had three of the basic red dot finders like the one in your photo and they all started acting up after a while and refusing to light up the red dot.

This is a common request. I suggest you read the replies here made to similar queries, and come back if you need an answer to a more specific question.  £100-£250 seems too low for a tracking mount.  Either simplify your requirements or be prepared to spend a lot more money.

A dew shield is an essential accessory for a SCT, not an optional extra.  A dew heater may be additionally needed in severe cases.  (I don't use dew heaters myself).  I have recently learned that Celestron supply a heater ring that replaces the corrector plate retaining ring and gives a neater solution than using a heater band.

51 minutes ago, imakebeer said:

Don't these cameras have a much smaller sensor? I.e. they only have the the area we actually need for capture. But doesn't that mean you lose that wider of field of view making it hard to actually acquire your target in the first place prior to capturing? (Unless you have a guide cam, which I don't)

Yes, they do have small sensors, and the FOV is small.  Acquiring the target is a skill you just have to master.  One way of doing it is to center the planet in an eyepiece (it does not have to be in focus) and then swapping in the camera.  Another way is to use a good quality optical finder to get the planet on the sensor.  The capture software should be set to acquire all the pixels when finding the planet - you can reduce the ROI (region of interest) to e.g. 320x240 pixels once the planet is centered.