Mounts etc

[NickW]

Hi All

Its newbie first post time! So greetings to you all.

I am researching buy my first scope. Hot on my list is the Skywatcher Skymax 127. I notice this is available with various mounts including the EQ3 pro synscan and AZGoto. Can someone tell me why I should choose one over the other? My assumption is that the EQ3 is better on the basis it costs more... but I would like to know why?

Also are there any other manufacturers mounts I should look at given I could by the OTA seperate as I understand it?

and finally one of my main aims is to try and mount my Canon SLR and take pictures so is this scope a reasonable choice.

Many thanks in advance.

Nick

PS: Any good places to find second hand equipment??

[Jim-a]

try http://www.astrobuysell.com/uk/propview.php for second hand equipment

[Bizibilder]

Welcome!

An AZ (altazimuth) mount moves up/down and left/right - so to track an object in the sky you have to move both axis at the same time. An EQ (equatorial) mount has one axis (Polar) aligned with the North Celestial Pole with the other axis (Declination) at 90° to it. To follow an object you set the Declination axis to that of the object and can then track it across the skt by rotating the polar axis only. A properly aligned Equatorial mount is far easier to use for astronomy (although far more confusing to start with!!). The AZ type is normally used for birdwatching etc (although some quite "posh" scopes are supplied with quite sophisticated AZ mounts.

If you are contemplating any form of astrophotography then the mount is the most important part of your set-up. Go for the best you can afford. For serious astrophotography the HEQ5 is generally considered the minimum - an EQ6 is better. If you only want to photograph the Moon and planets you may get away with an EQ5.

I hope I've not put you off! But you will be much better off with a decent mount to start with, as ell as being somewhat future proof.

BTW the Skymax 127 is a favourite and good starter scope.

[Etoille]

You don't mention your budget but if you are buying the OTA seperately, this might be worth a look:

http://www.amazon.co.uk/gp/offer-listing/B007MRO26C/ref=dp_olp_used?ie=UTF8&condition=used

[Mark1970Vintage]

I was in a similar position to you a few months ago. The 127 mak was well in the running but I ended up choosing the 150p. That choice was easy though compared to umming and ahhing over the mount. I finally plumped on an Eq5pro with some basic photography in mind. I have been very impressed with it . Coming to astronomy from photography the tripods and mounts look frighteningly big but you get used to them. The Eq5 tracks like a dream and is a good balance between being robust enough for basic photos and easy/light enough to lug around and set up quickly.

[NickW]

Thanks for all the really helpful tips and pointers!! So take home message is the mount is absolutely vital. Moving forward seeing as Etoille pointed out the Skymax 150 I have now become slightly confused again after more research....

The EQ5 Pro mount states it has a payload of 9kg does that exclude the weights it comes supplied with? Also I note many pairings of the Skymax 150 with the EQ5 Pro... yet the OTA weighs in at 14Kg and the payload capacity of the mount is 9kg according to the specs..... am I missing something???

Nick

[Bizibilder]

The "official" payload of a mount is without the counterweights. For astro imaging there is a rule of thumb that you should not load the mount with scopes/camers/etc above 50% of the stated maximum load. For visual you can go to the full amount.

[Cornelius Varley]

Thanks for all the really helpful tips and pointers!! So take home message is the mount is absolutely vital. Moving forward seeing as Etoille pointed out the Skymax 150 I have now become slightly confused again after more research....

The EQ5 Pro mount states it has a payload of 9kg does that exclude the weights it comes supplied with? Also I note many pairings of the Skymax 150 with the EQ5 Pro... yet the OTA weighs in at 14Kg and the payload capacity of the mount is 9kg according to the specs..... am I missing something???

Nick

The Skymax 150 weighs about 5.6kgs (12.34lbs) definitely a lot less the 14kgs. The payload of a mount doesn't include the counterweights - these are part of the mount and are not included as part of the payload.

Peter

[NickW]

Thanks Roger.

I think the OTA weight I saw must have been wrong.... more research has shown a figure of 5.6Kg elsewhere which explains the EQ5 Pro pairings I have seen.

So just to get this straight in my head... a Skymax 150 = 5.6 Kg + SLR body = 1kg so the counter weight would prob be another 5Kg so approx 12kg in total. The EQ5 Pro payload is 9kg.. and so could go up to 9 + 4.5 = 13.5kg safely

Apologies if I am making a meal of this.. just trying to understand.

Nick

[Cornelius Varley]

You don't include the counterweights as part of the payload, these are part of the mount. The payload should be considered as the telescope, eyepiece, finder, camera etc.

Peter

[JamesF]

I've done a lot of planetary imaging with a 127 Mak on an EQ3-2 and it's been fine. The biggest problem is wobble when adjusting the focuser, which I sorted by fitting a motorised focuser. If your camera weighs in at 1kg however, I think you might be really pretty borderline for the mount at that point. You might get away with it for solar/lunar imaging, but I wouldn't like to say for certain. That said, I'd be quite comfortable removing the diagonal and webcam and putting my 450D on the back of mine, but it is only about 475g.

James

[NickW]

Yeah its heavy (900g) as it has a magnesium body.. Canon 7D

[Etoille]

Just to point out that I wasn't specifically recommending the 150, just thought I'd point it out since you were looking at Maks and I happpened to see that one a few minutes before this thread. If you're doing imaging then you might need to think about the image shift issue that is inherent with a catadioptric design scope (Hint: do a google search for "sct image shift") - JamesF above mentions it as the 'wobble when adjusting the focusser'. This is more of a problem with bigger SCT's but it seems that it can also be a problem on the 150 (not sure about the 127) and could make accurate focussing a tad frustrating. The problem can be fixed by adding a secondary focusser (something like a borg helical focusser or a motorised one as JamesF says) onto or in place of the visual back. I mention this only because it I think it helps to be fully informed possible extra costs that might arise (aside from EP's!) before making a purchasing decision.

Hopefully someone with experience of actual use might be able to indicate how much of a problem this might or might not be in practice.

[JamesF]

I think there are a couple of issues with mirror movement in SCTs (and Maks)

The first is that the mirror can shift as the weight is redistributed as the scope moves around the RA axis. I *think* this is particularly a problem as the mirror becomes larger, but means that over time, and particularly as the scope crosses from east to west or does a meridian flip, the image position can shift.

The second is that the focuser does not act centrally on the mirror, so either pulls or pushes on one side of it as the focus is moved in and out. As the mirror bearing can't be an interference fit on the baffle tube that means there's a slight rocking of the mirror as the focuser changes direction. This also changes the image position. On my 127 Mak at f/40+ it's enough to shift the image right across the short side of the webcam sensor.

James

[Ronnie Mackay]

Hallo Folks another Newbie here also What i know about astronomy you could write on the back of a stamp.

But have always been interested in the night sky So finally took the plunge I am currently building a small observatory.

I am thinking of buying a Celestron 127SLT for my first scope But really want to mount it on a good solid metal pole for stability.

If this is actually possible with this Telescope.

I know i may have to make some adaptor Unless there are ones on the market.

Have any members actually done this if so how did they go about it.

Thanks

Ronnie

[NickW]

Etoille...no worries re recommendation. I had looked at the Skymax 150 after seeing some brilliant photos taken with it but figured I couldn't afford one hence my earlier focus on a 127.... until your post... gulp. Looks in empty wallet wondering where all that money went... I have already recognised that this hobby will be unfortunately a financial black hole!!

Am I understanding it correctly, you may get wobble/image shift because:

1. the focusing mechanism works only on one side of the mirror via a rod and thus it wobbles as it moves up and down the tube. Thus adding another focuser allows adjustments to be made without having to move the mirror?

2. that because you effectively have a weight hanging off the back (the camera) as the scope moves the weight is redistributed on the mirror and so causes the focus to change? This makes me wonder if there is someway of providing more support for the camera rather than relying on the camera connector etc to support its weight.

so much to learn... so little time!

[NickW]

Hi Ronnie

I think you can buy pillar supports but you still need to put a mount on it. I saw some when I have been looking at mounts e.g.

http://telescopesandbinoculars.co.uk/acatalog/Mounts_and_Motor_drives.html near bottom of page.

No idea if they are good etc. as I am a newbie myself.

[JamesF]

Etoille...no worries re recommendation. I had looked at the Skymax 150 after seeing some brilliant photos taken with it but figured I couldn't afford one hence my earlier focus on a 127.... until your post... gulp. Looks in empty wallet wondering where all that money went... I have already recognised that this hobby will be unfortunately a financial black hole!!

Am I understanding it correctly, you may get wobble/image shift because:

1. the focusing mechanism works only on one side of the mirror via a rod and thus it wobbles as it moves up and down the tube. Thus adding another focuser allows adjustments to be made without having to move the mirror?

2. that because you effectively have a weight hanging off the back (the camera) as the scope moves the weight is redistributed on the mirror and so causes the focus to change? This makes me wonder if there is someway of providing more support for the camera rather than relying on the camera connector etc to support its weight.

so much to learn... so little time!

1. That's about right. I've not noticed wobble whilst moving in one direction, but when you change direction that's when it can happen. I'd never noticed it visually, but it's quite obvious with a 3x barlow in the back of my 127 Mak, and even more so at 4x.

2. Not specifically related to the camera. It's more the weight of the mirror itself, I think. The mirror in, for example, a C9.25, or C11 or C14 weighs quite a lot.

James

[NickW]

Well I've gone and done it....

Skymax 150 Pro and EQ5 PRO SynScan purchased... sweaty palms

.... thanks for all the advice and help thus far... I am sure I will be asking lots more questions very soon..