Author Topic: Help with choosing first mount  (Read 135 times)

longpetdowntown

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Help with choosing first mount
« on: December 30, 2017, 06:03:21 PM »
I intend to try astrophotography, and need to choose a mount. I will use my Canon 60D with a Sigma 400mm f5.6 Apo Macro photography lens. I live in Iceland, so shipping costs are a major consideration in choosing the mount. I have found that the shipping costs on the UK webstore First Light Optics to be reasonable, and they also deduct the UK VAT, so they are usually the cheapest option.
I know that around here the usual recommendation is the HEQ5 as a minimum for imaging, but it is out of my budget. Also, I don't think I will upgrade to a proper telescope in any foreseeable future, so I'm really only aiming at something that can carry the 60D (755 g.), the Sigma 400mm (1445 g.) and in the future the MiniGuideScope (120 g.) and QHY5L-IIM (600 g.). That's a total of 3 kg. Add in the necessary dovetails, adapters and cables and it's maybe around 3.5-4 kg total.
That's well within the manufacturer's specification of 5 kg. for imaging with the EQ3 Pro. I can have that mount with shipping and local VAT for the equivalent of 680 USD. If I were to get the EQ5 Pro it would be 900 USD. That's a lot more, and would really be stretching the budget. The HEQ5 has really expensive shipping (more expensive than the NEQ6) and would be 1400 USD, and as I said is out of my budget. Another option is the Explore Scientific EXOS-2GT from BHphotovideo for 1000 USD with the polar scope. But that scope can't be controlled by a computer, which is a feature I want.
My question is mainly what the disadvantage of the EQ3 Pro is compared to the EQ5 Pro. As I understand the EQ3 Pro has the same stepper motors as the HEQ5, so they should even be better than the EQ5 Pro motors. The EQ3 Pro only comes with aluminum tripod feet, so that's obviously a disadvantage. But what are the other shortcomings of the EQ3 Pro? I believe the EQ5 Pro doesn't have ball bearings on the Dec axis. But doesn't the EQ3 Pro have ball bearings on the RA axis?
Also, given these costs, and also given the fact that I'm going the low-weight, low-budget route for now, is the EQ5 Pro worth it over the EQ3 Pro? Is the EXOS-2GT so much better than the EQ5 Pro even though it can't be controlled by computer it's still worth it?
Note that I'm not opposed to the idea of buying a used mount, but it doesn't seem common that people sell with the option of international shipping.



John Daniels

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Re: Help with choosing first mount
« Reply #1 on: January 04, 2018, 05:24:08 PM »
I would recommend iOptron SkyGuider Pro since you are not thinking of adding a scopelater. Easy to set up and use.

Arne

Lesego Dowdy

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Re: Help with choosing first mount
« Reply #2 on: January 04, 2018, 05:27:05 PM »
The SkyGuider Pro would cost 780 USD, 100 USD more than the EQ3 Pro. Is it a better tracking mount? It seems less "serious" from the pictures, more like a Star Adventurer/Vixen Polarie than a "proper" GEM. I'm more concerned with the level of performance that is possible than with ease of setup.

Chris Smale

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Re: Help with choosing first mount
« Reply #3 on: January 12, 2018, 06:09:43 AM »
Quote
I would recommend iOptron SkyGuider Pro since you are not thinking of adding a scopelater. Easy to set up and use.

Arne

Based on my experience with its older brother, the Skytracker, it likely won't work with 400mm. 200mm seems to be the limit. It doesn't have GOTO, which is a desired feature. The real advantage is portability, but performance suffers.

The EQ3 may or may not work either at 400mm. It's not just the weight, focal length counts, a lot. You should be prepared to drop back to 200mm. People make lovely images at that focal length, Orion is a fine target.

On paper, the EXOS-2-GT would probably be better suited for that focal length. But this thread is pretty discouraging about that mount.

https://www.cloudyni...rmation-thread/

Unfortunately, people buy expensive mounts for astrophotography for good reason. AP is magic because the tiny pixels can patiently gather light for a long time, unlike your eyes. But a small tracking error, and the magic goes away. Your best bet for a satisfying experience on a small budget is to reduce the focal length. 400mm may, or may not, be too much for your budget.

John Pfister

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Re: Help with choosing first mount
« Reply #4 on: January 14, 2018, 07:01:32 AM »
TL; DR - if you are a hacker you can end up spending way less than $680 and have the satisfaction of cobbling something together. But otherwise the EQ3Pro is a solid choice.

The EQ3Pro (also known as CG-4) is basically the cheapest GoTo mount you can buy. It's a Chinese knockoff of the Vixen Polaris, which is rated 16lb (7kg) for visual. I would not trust the 5kg rating for imaging. I think 3-4kg is more reasonable.

I've never opened up an EQ3Pro but I'm pretty sure it does not have ball bearings anywhere. Celestron claimed the CG-4 had ball bearings on the RA but somebody opened one up and.. no ball bearings. The Vixen Polaris doesn't have ball bearings on either the RA or DEC.

If you really want GoTo, that's the way to go. You'll probably never be able to use anything more substantial than your 400mm lens. Even the 400mm lens will need to be guided for anything longer than 30 seconds - 1 minute exposures.

You can also get it from APM -http://www.apm-teles...unt-tripod.html

May be cheaper, I live far away from Germany but shipping via DHL world packet from Germany is cheap.

I'm surprised that FLO will deduct VAT. Isn't Iceland part of the euro zone?

If you are brave and/or handy with tools, you could buy a Vixen Super Polaris, you can get them used for $250 on astromart if you look hard enough. AstroTreff is more costly, the Germans want more money for their used stuff.

Then you could either build a single-axis RA controller using an Arduino and AdaFruit motor shield (I have done this - and someone has built an ASCOM driver for it so it can be guided in RA) or, build an OnStep GoTo controller for full GoTo.

https://github.com/hjd1964/OnStep

Another option is to find a used Zeiss mount (they are relatively cheap in Europe..) and somehow rig a stepper motor RA drive for it.

Ebay Germany is your friend! I hardly know any German but the magic word is "montierung"

https://www.ebay.de/...OP/172947216888

and here's a dirt cheap Vixen Polaris -https://www.ebay.de/...iv/172912247720

and another -https://www.ebay.de/...iv/272837525058

I have owned two Vixen Polarii and they are OK. You can use the Orion EQ1M motor drive (needs a crystal mod to get the right speed) or make an RA drive using an Arduino and AdaFruit motor shield (see above).

Or you could use a Star Adventurer -https://www.ebay.de/...iv/272837525058

I've tested the Star Adventurer with an 80mm refractor that weighed about 8lb and it's fine. Guides to about 2" RMS which is what a CG-5/EQ-5 is capable of.

No GoTo however and no setting circles (which the Vixen Polaris has).

elunmolunch

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Re: Help with choosing first mount
« Reply #5 on: January 20, 2018, 06:42:24 PM »
Iceland does not use the Euro (we have the Icelandic króna, ISK), and we pay full VAT on goods from the European Union. I did a quick calculation on the EQ3 Pro from the APM site (470 Euro without VAT + 65 Euro shipping + 24% Icelandic VAT makes it 663 Euro, or 770 USD), and it's more expensive than on First Light.

Noone has commented on the EQ5 Pro. What are it's advantages over the EQ3 Pro? Are the motors really worse?

Eric Lara

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Re: Help with choosing first mount
« Reply #6 on: January 23, 2018, 11:12:30 AM »
The EQ5 Pro is a Chinese knockoff of the Vixen Great Polaris / GPDX. I believe it has ball bearings in RA.

The EQ5 Pro uses Synta steppers (unlike the Celestron CG5 and Meade LXD55/75 which are also Vixen GP clones but use servo motors). I do not believe that there is any material difference in the stepper motors used in the EQ3Pro, EQ5Pro, HEQ5Pro, EQ6, etc. etc. they all use Chinese 200ppr hybrid steppers with an external gear reduction.

(I know way too much about stepper motors in telescope mounts..)

The main difference the EQ5Pro would offer is the greater payload. I believe the rating is around 10-12kg, so assume half of that for astrophotography, so 5-6kg vs 3-4kg for the EQ3Pro.

Also as an aside.. when doing astrophotography with a longer lens, you will have two enemies:
- non-round stars due to poor mount tracking
- non-round stars due to optical aberrations in your lens

The former is fixed with a better mount and/or tighter guiding. The second requires that you stop down. The Sigma 400/5.6 doesn't have a stellar reputation, so I'd expect you would need to stop it down to f/8 or even lower to get decent stars. (I tested the Canon 70-200/2.8L and it has ugly stars unless stopped down to f/4).

So in your case you actually have two technical challenges that you need to deal with.. of course if you downscale all your images by 50% that will hide both problems!

Joel Russell

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Re: Help with choosing first mount
« Reply #7 on: January 23, 2018, 06:36:22 PM »
I am the most frugal astrophotographer in existence. OK.. I'm just cheap.

My humble opinion is to consider a little larger mount to start with. I have the Orion Skyview Pro which apparently is the same as the CG-5?

I've modded an older model with the Shoestring Astronomy GPUSB Interface as well as replaced some of the bearings in the mount.

Regardless, the mount is easily capable of handling 20lbs of gear. Therefore it will easily handle a camera and 400mm telephoto, as well as allowing you some room to expand later.

Some have already told you that the mount is most important and you should stay below half of the mount's stated capacity