Lightweight imaging mount for a 150mm f/5 reflector

[kitsune]

Are there any lightweight equatorial mounts for a 6" f/5 Newtonian reflector such as the Skywatcher 150PDS that can be used for astrophotography and don't break the bank? I don't need super-long exposure times or goto.

[JamesF]

How much would you say is "not breaking the bank", roughly?

James

[RikM]

This was shot with a 150P and unmodded Canon 1000D on a Skywatcher EQ3-2 with the dual axis motor drives. With a good polar alignment 90 sec exposures were possible but any gust of wind and the sub was ruined.

[kitsune]

@RikM: A very nice picture! You also have an AZ4, imaging aside, how do you rate that mount with a 6" reflector for visual use?

Breaking the bank... Well my budget is not that high at the moment, but I do think I might get into imaging at a later stage. I'm pretty much set on the 150PDS. Just wondering whether there are some lighter alternatives / combinations to a HEQ5 or EQ5.

The Vixen GP2 seems to be lighter than an EQ5 for instance, but sturdier than an EQ3-2.

[RikM]

I like the AZ4 and 150P combo very much. It is nice and stable and a brings the eyepiece to a convenient height for me ( I am 180cm). Some say that it doesn't balance well but that has not been my experience at all. I do tighten the alt clutch quite firmly, but the movement is still very smooth and controllable even at high powers. I wouldn't put any larger Newtonian than the 150P on the AZ4 though.

CG5-GT is a lighter alternative for an imaging mount that would work nicely with a 150P...if you can put up with the noise

[Chris]

Hi Kitsune, I currently have a 150p on a mk1 HEQ5 (non goto mount), I previously had the EQ5 with added motor drives. Based on my experiences with both these mounts I would whole heartedly recommend getting the sturdiest mount you can find when imaging with a newt which acts as a wind sail. Newts also have a longer focal length than a lot of imaging refractors which makes accurate tracking more tricky. Surprisingly I don't find the HEQ5 much more difficult to carry than my old EQ5, I'm fairly skinny and I can carry the HEQ5 complete with the 150p through 3 rooms to the back garden without too much difficulty. Price wise, my HEQ5 mk1 cost 280 pounds second hand and they have built in motors for both axis and a polar scope. As for the lighter duty EQ5 you can pick up these with added drives and polar scope for about 200 pounds, but I honestly believe its worth the extra 80 pounds for the far sturdier mount as it means that you keep most of your sub exposures intsead of about half of them.

hth

Chris

[kitsune]

Hi Kitsune, I currently have a 150p on a mk1 HEQ5 (non goto mount), I previously had the EQ5 with added motor drives. Based on my experiences with both these mounts I would whole heartedly recommend getting the sturdiest mount you can find when imaging with a newt which acts as a wind sail. Newts also have a longer focal length than a lot of imaging refractors which makes accurate tracking more tricky. Surprisingly I don't find the HEQ5 much more difficult to carry than my old EQ5, I'm fairly skinny and I can carry the HEQ5 complete with the 150p through 3 rooms to the back garden without too much difficulty. Price wise, my HEQ5 mk1 cost 280 pounds second hand and they have built in motors for both axis and a polar scope. As for the lighter duty EQ5 you can pick up these with added drives and polar scope for about 200 pounds, but I honestly believe its worth the extra 80 pounds for the far sturdier mount as it means that you keep most of your sub exposures intsead of about half of them.

hth

Chris

Hello Chris. The problem is that I have to carry this mount for more than 3 rooms and I'd often have to walk with it for a couple of miles (I don't drive, so I'd have to rely on my friends for transportation by car). I'm willing to sacrifice imaging capability for that. Around here, the 150PDS with EQ5 is as expensive as the 150PDS with an AZ4. So while my head tells me that I will never be able to lug around 16.5kg (EQ5) plus 5kg (Telescope), my inner gadget monkey tells me that it would be stupid to buy an AZ4 mount when I could take some basic (abysmal?) pictures with an EQ5 mount...

That's how I got across the GP2 which seems to only weigh 14.5kg (9.5kg + 5kg counter weight)... a bit less than the EQ5, still very heavy however.

If I'm correct, the lighter and sturdier the mount / tripod combination, the more expensive it gets?

The more I'm thinking about this, I probably might wanna ditch the 150PDS all together and get an 150P for visual instead. I don't know whether the better focuser alone is worth it for visual use. And later down the road maybe some small refractor and light mount for imaging.

Sigh... choosing a telescope is hard Thinking about all the hours I've already invested, I might have picked something expensive already and be done with it.

[Chris]

I've not had my 150p for that long but already I love it for both visual and imaging, so I don't think the dual speed focuser of the pds is essential when starting out. However, having said this FLO have just started selling the 130pds which would be lighter, slightly less focal length so less demand on tracking and less of a wind sail. You'd probably get away with this on an EQ3 if like you say you need an ultra portable setup, sorry yes I agree the HEQ5 would hospitalise you after 2 miles I reckon:D

[RikM]

I once carried my AZ4 and a Skymax 127 about 1.5 miles to a public meet, wow talk about heavy and I am fit and strong guy. If you have to walk that far then I would seriously consider nice binoculars or a small richfield refractor on a camera tripod or something. ( I use an ST80 on a Manfrotto tripod for exactly this).

If you want the best chance of observing now and imaging later then for the same amount of money you could have a Skyliner 200P Dobsonian, which is much better than the 150P / PDS for observing. Then later, like you say, a small refractor on an EQ mount for imaging. The Dob has nice carry handles and it is lighter than the equivalent EQ mount, but I still wouldn't want to walk a couple of miles with one.

[kitsune]

I once carried my AZ4 and a Skymax 127 about 1.5 miles to a public meet, wow talk about heavy and I am fit and strong guy. If you have to walk that far then I would seriously consider nice binoculars or a small richfield refractor on a camera tripod or something. ( I use an ST80 on a Manfrotto tripod for exactly this).

If you want the best chance of observing now and imaging later then for the same amount of money you could have a Skyliner 200P Dobsonian, which is much better than the 150P / PDS for observing. Then later, like you say, a small refractor on an EQ mount for imaging. The Dob has nice carry handles and it is lighter than the equivalent EQ mount, but I still wouldn't want to walk a couple of miles with one.

Thanks for your input. I think that the AZ4 and 150PDS weigh around 13.5kg combined. Add eyepieces etc. I think I can handle the weight. I do trekking trips with similar or higher loads, and I have some good trekking backpacks which support the back and shoulders.

I really can't see myself getting comfortable with a Dobsonian, to be honest. I don't know why however In three months I will probably curse myself for not getting one.

About the topic: So from all I gather is that unless you have a very small and portable scope, the minimum equatorial mount for "good" results is a HEQ-5 or higher? There are no "lightweight" options that do not also compromise imaging in some way or another?

By the way, this is not relevant from a qualitative point of view, but, boy, the Vixen GP2 looks very nice.

[Chris]

This is a good point Rik, do you definaley want a Newt for your portable setup kitsune? I've got my little WO 66 Apo on a camera tripod at the moment and it gives amazing views for its weight, you could get something like this on a camera tripod to begin with and later down the line stick it on an imaging mount, My little apo weighs something 4kg with the tripod, I often just pick the whole thing up and use it like a binocular which is great fun and the tripod helps dampen hand held image shake:)

[kitsune]

This is a good point Rik, do you definaley want a Newt for your portable setup kitsune? I've got my little WO 66 Apo on a camera tripod at the moment and it gives amazing views for its weight, you could get something like this on a camera tripod to begin with and later down the line stick it on an imaging mount, My little apo weighs something 4kg with the tripod, I often just pick the whole thing up and use it like a binocular which is great fun and the tripod helps dampen hand held image shake:)

The problem is that there are no star parties around me (I've checked), so I don't know exactly whether I'd be disappointed by a small aperture refractor or not. I have consulted many "what can you expect to see in a telescope" articles and the 150p seems to be a good compromise between portability and capabilities.The dobsonians seem to be heavier than a 150p + AZ4 mount.

[Chris]

The problem is that there are no star parties around me (I've checked), so I don't know exactly whether I'd be disappointed by a small aperture refractor or not. I have consulted many "what can you expect to see in a telescope" articles and the 150p seems to be a good compromise between portability and capabilities.The dobsonians seem to be heavier than a 150p + AZ4 mount.

I agree, the 150p is a cracking little scope its light and will show you a lot, and at f/5 it will suck in the photons:) A general rule of thumb is that Newts will give you the most bang for your buck, however, I wouldn't rule out a frac they do have advatages e.g. a 4" inch frac will match a 6" newt for what you can see, plus you have no issues with collimation, so fracs do make good travel scopes. I have both types of scope and I can see the virtues of both:)

[kitsune]

I agree, the 150p is a cracking little scope its light and will show you a lot, and at f/5 it will suck in the photons:) A general rule of thumb is that Newts will give you the most bang for your buck, however, I wouldn't rule out a frac they do have advatages e.g. a 4" inch frac will match a 6" newt for what you can see, plus you have no issues with collimation, so fracs do make good travel scopes. I have both types of scope and I can see the virtues of both:)

Is this true for achromats and deep space objects?

[JamesF]

a 4" inch frac will match a 6" newt for what you can see

I struggle to see how that can be justified, I have to admit. Even with a 25% central obstruction (which is huge), a 6" newt still has more than double the light-gathering area of a 4" unobstructed aperture. If we work in millimetres because it makes the maths clearer, a 150mm (6") scope with a 25% obstruction has about the same light-gathering area as a 140mm clear aperture. There'll be some light loss at the mirrors, certainly, but you'd need to lose more than 15% at each mirror which is a bit extreme to get close to the 100mm figure and that's before allowing for the light loss in the 'frac's optics.

Is there something else I'm missing here?

James

[JamesF]

Need to make myself clearer there. I mean a central obstruction which is 25% of the diameter of the primary.

James

[kitsune]

Need to make myself clearer there. I mean a central obstruction which is 25% of the diameter of the primary.

James

I don't want to further derail this thread. I'll order the following:

Tele Vue 2x Barlow - 1.25" - achromatic-

TS 1,25" ED Eyepiece 8mm - 60° Flat Field - high contrast

TS Newtonian Laser Collimator - 1.25" connection - full metal

Skywatcher Explorer-150PDS / 6" f/5 Newtonian - 2" Dual Speed

Skywatcher AZ4 Steel Mount

Imaging has to wait

[RikM]

Sounds like a great choice for visual observing.

The issue I had with carrying it wasn't really the weight, I am an experienced trekker and have the right equipment for that. It just won't fit in any rucksack I own. The largest being an old 80L Karrimor Jaguar. Since it just a few big solid lumps, getting it balanced is not that easy so I just lugged in a couple of shoulder bags. Mistake.

Edit: just remembered I was also carrying a laptop and projector, so that may be biasing my memory here.

[springbok]

@RikM, that's a great image, was it from the 1000D?

I have been inspired to go down the DLSR route after seeing images that are being obtained.

I part ex'd a 400D for a 1100D to get the live view option, running though Backyard EOS.

The full blown CCD imaging rig can be saved up for in the mean time.

[RikM]

@RikM, that's a great image, was it from the 1000D?

I have been inspired to go down the DLSR route after seeing images that are being obtained.

I part ex'd a 400D for a 1100D to get the live view option, running though Backyard EOS.

The full blown CCD imaging rig can be saved up for in the mean time.

Yes, standard unmodified 1000D. I think something like 45 x 90sec exposures is all. These newer DSLR's actually have pretty good sensitivity to red. Much better than the older models.

[kitsune]

Sounds like a great choice for visual observing.

The issue I had with carrying it wasn't really the weight, I am an experienced trekker and have the right equipment for that. It just won't fit in any rucksack I own. The largest being an old 80L Karrimor Jaguar. Since it just a few big solid lumps, getting it balanced is not that easy so I just lugged in a couple of shoulder bags. Mistake.

Edit: just remembered I was also carrying a laptop and projector, so that may be biasing my memory here.

Thanks for your insight. I figured I could attach the tripod to the outside of the rucksack... I hope that works

[Chris]

I struggle to see how that can be justified, I have to admit. Even with a 25% central obstruction (which is huge), a 6" newt still has more than double the light-gathering area of a 4" unobstructed aperture. If we work in millimetres because it makes the maths clearer, a 150mm (6") scope with a 25% obstruction has about the same light-gathering area as a 140mm clear aperture. There'll be some light loss at the mirrors, certainly, but you'd need to lose more than 15% at each mirror which is a bit extreme to get close to the 100mm figure and that's before allowing for the light loss in the 'frac's optics.

Is there something else I'm missing here?

James

Hi James, the only other thing I can think of is the photon scatter in Newts from folding the light path a couple of times over, I think this is why the background in Newts looks a bit brighter than fracs and therefore contrast is reduced ontop of the reduced contrast from the central obstruction, thus reduced contrast makes it more difficult to resolve objects.

Don't get me wrong though I love all types of optics, they all have strenghs and weaknesses, I think the 150p is a great choice for an all rounder, I'm sure you'll enjoy it kitsune:)