What else do I need?

[jet486]

Hello, before I pay out over $2500 for the Orion 12" SkyQuest XX12G at Bintel is there any other pieces of kit that I need other then the standard pieces that comes with the dob? Cheers

[astro_nutt]

Unless you have already collected the following items.
Plasiphere, Star Atlas, Collimation tools, observing chair and card table.
I would then consider a quality 2"-1 1/4" Barlow, a suitable cover for the scope and mount, a bulls-eye level, and a red dot finder.
Cheers!

[astronut]

And a dew controller with heaters. Otherwise your first observing session could end as quick as it starts.

It's not just an option, it's a necessity, winter or summer.:)

[Allan_L]

As already suggested, plus
Assuming it is truss dob, then a light shroud may be useful.
Also, an external battery pack may be of benefit. (I use a 18amp/hour deep cycle battery)
(especially with using the suggested dew controller).

[barx1963]

I believe the scope comes with a red dot finder, which is all you need if using GoTo. These don't come with a shroud, but I believe Bintel sell a shroud for it. Not essential unless you have significant stray light sources where you observe.
An atlas is a good idea, but if using GoTo, some good observing guides may be more useful. The Deep Sky Observing guides are a good option.
Dew heating equipment is next obvious ones. I use a Kendrick Digifire7 and it has given years of service without any issues. For the heaters I use the Kendrick ones, again no issues apart from the Velcro tabs on the eyepiece heaters comes away after a while, easy to fix with a needle and thread though!
Collimation tools, try a Cheshire first before using a laser. I use both but have found the Howie Glatter stuff to be noticeably better than the inexpensive lasers.
Table and chair pretty much essential if wanting to work through charts and guides or keep notes of observations. An observing chair is nice, but not essential.
I am not a big fan of barlows, prefer good quality stand alone eyepieces. The scope only comes with a 32mm ep and 12.5 illuminated plossl, so a good mid power ep should be considered. Eyepieces can be expensive so I am hesitant to advise without an idea of your budget. Having said that the 15mm GSO/Bintel Superview is a nice inexpensive performer for only $50 so worth giving a go while you make up your mind.

Cheers

Malcolm

[jet486]

Thanks Malcolm for your suggestions but where do I get the items you mention?

[ausastronomer]

Hi Malcolm,

I can only assume from the above comment you do not have a Servocat, or some other drive system on your scope. Would that be a correct assumption?

Cheers
John B

[ausastronomer]

Wait till Malcolm answers the question before you race out and order a Digifire 7 or 10 dew controller. There "can" be problems with the Kendrick Digifire controllers :lol:

The scope you are planning to buy has goto and tracking which will likely cause problems with one of the Kendrick Digifire units. I had a Digifire 7 on my 18" Obsession and threw it to the dunghouse after 18 months of frustration.

Cheers
John B

[barx1963]

No, it is purely a push to with Argo Navis. Was not aware of any issues operating it with a Servo cat, I am assuming some sort of electrical interference occurs?

Malcolm

[barx1963]

All the items I have mentioned are available from Bintel. Regarding the issue with the Digifire controller, as I said mine has operated flawlessly for years, but if there are issue with using it with a motorised scope it may be worth investigating further.

Malcolm

[ausastronomer]

No, it's a lot simpler than this but far more damaging to your nights observing. It puts an end to it.

The Kendrick Digifire units have a built in "low voltage cut-out". You cannot disable the low voltage cut-out, or over ride it, or at least you couldn't on the older units. I am not sure if they have changed this, but I doubt it. I believe the low voltage cut-out kicks in at about 11.5 volts. I have no idea why they have this, but I can only assume it is to prevent people flattening their car batteries to a level which prevents them from starting their cars and getting home. It is also worth noting for scopes that have the Dew Heater controller mounted on the upper cage assembly using "powered truss poles", there will also be a slight voltage drop from the bottom end of the scope to the upper cage assembly. This might be in the order of .2 to .4 volts depending on how its all wired up. Notwithstanding your battery is still running at 11.8 volts your dew heater controller will only be receiving about 11.5 volts and the low voltage cut-out will kick in at this level.

At the beginning of an observing session all is fine for the first couple of hours. However, with scopes which have several dew heater straps, motorised go to and tracking drives and a few other electrical gadgets in use the power drain can be heavy. While Servocat tracking doesn't use much power, Servocat GOTO's certainly do. After a couple of hours the battery voltage drops to a level where the low voltage cut-out in the Digifire unit begins to work its magic. The first thing you notice is when you do a GOTO and the power drain is heavy the LEDS on the Digifire begin to flash. This means power is getting critically low. The next thing that happens after another 30 minutes or so is that the Digifire unit switches off every time you do a GOTO. After the battery recovers a little from the GOTO the Digifire unit might start up again. After another 30 minutes or so the Digifire unit will just shut down completely and not restart for the remainder of the evening because as far as it is concerned the battery is critically low. The bigger the scope the worse it gets, as a big scope chews up more power being moved around when you do GOTO's. The voltage drop of the battery does not cause problems with any of the other devices powered by the battery. They will just pull more current to work as the battery voltage drops, but they will continue to work perfectly all night. This includes, the Argo Navis unit, the Servocat, the Dew Heater Straps and the fans. This of course can depend on the size of the battery you are using and its condition, but it is a very annoying thing when it happens and IMO you are better off looking at one of the other dew heater controllers if your scope has motorised GOTO and tracking. I speak from experience. I got dewed out several times after my Digifire 7 spat the dummy. I ended up selling it to a guy whose scope had no tracking and I bought a Thousand Oaks controller.

The Thousand Oaks controller also has a low voltage warning and cut-out system which gives a flashing light at 11.5 volts and cuts out completely at 11.2 volts, but you can disable the cut-out when using a scope dedicated battery. There is a switch which enables you to disable the cut-out. The Thousand Oaks unit is about 70% of the price of the Kendrick Digifire 7 and works perfectly.

http://www.optcorp.com/th-ddhc-dew-heater-controller.html

In addition, in all circumstances but more so in cold weather the dial knobs on the Thousand Oaks unit are much easier to adjust individually than the press panel on the Digifire units. The Thousand Oaks system like the Digifire 7 has 4 outputs individually controlled. The Digifire 7 has 2 additional non controlled outputs, but on a Newtonian with a separate secondary heater, you don't need those. I use 4 outputs on my 18" and 14" scopes (objective and eyepiece on the finder, Telrad and the eyepiece). I only use 3 of the outputs on my 10" as I only have an optical finder, not a finder + Telrad. Peter Read at SDM Telescopes used to fit the Digifire 7 units as standard on all the scopes he built. In light of the issues explained above, he now fits the Thousand Oaks controllers as standard on all scopes.

Cheers,
John B

[barx1963]

Thanks for the detailed explanation John.
I have never had an issue with the Digifire 7 actually cutting out as I always carry spare batteries and simply replace it when the low voltage light cuts in. Of course I am not running Go To so my power usage is lower.
Kendrick have an interesting discussion of the reasons why they implemented this feature on the their website ( see http://www.kendrickastro.com/lvc.html ) which makes the reasons clear. Whether this is valid, I am not qualified to argue having just about zero knowledge of electronics.

Obviously whether this feature is seen by the OP as a positive or negative point in their circumstances would have to be left to them.

Malcolm

[jet486]

Sorry fella's being a beginner please excuse my ignorance but what is a servo cat, Digifire 7, and Thousand Oaks. It is mention the problem about the loss of power with GoTo's so how does one ensure to have enough power to enjoy a 3-5 hrs observing?

[barx1963]

Jet
My apologies, sometimes beginners threads divert a little way from your original query. To clarify, in my reply to your post, I mentioned getting dew control. Eyepieces etc can dew up very quickly which can bring an end to a nights observing. This is solved by attaching a heated strap to the eyepiece that warms it slightly which is enough to prevent dew forming. To do this we usually have a dew controller that allow you to run several heaters and control their temperature independently of each other. I use a Digifire 7 by Kendrick (see http://www.bintel.com.au/Accessories/Dew-Control/Controllers/Kendrick-DigiFire-7-Digital-Controller/40/productview.aspx) which works fine for me. John has mentioned that he has had some issues with these and has recommended a Thousand Oaks version ( see http://www.optcorp.com/th-ddhc-dew-heater-controller.html ). The main issue is with the Servo Cat which is the controller for the motors on the Go To setup on his scope, which draws so much power the battery powering both systems runs out and voltage drops below the level set in the Digifire, causing it to cease working and resulting in dew on eyepieces etc.
This could be an issue for you as your scope is a Go To (although it doesn't use Servo Cat). I am not qualified to give advice as the issue are electrical.
A stop gap if you do not want to fork out money for dew contol is to remove dew during the night with a hair dryer, not as convenient as you have to regularly stop to do it, but cheaper!

Cheers

Malcolm

[ausastronomer]

Hi Malcolm,

Someone mentioned to me a few years ago that the low voltage cut out was to preserve battery life, which I take on board. On the Dew Buster website they say it is to ensure people don't flatten there car battery. Both reasons are plausible. The low voltage cut out on the Kendrick is stated as 11.6 in the commentary on their website (11.5 was a good guess). On both the Dew Buster and Thousand Oaks controllers the low voltage cut out is set at 11.2 volts. The problem with the Kendrick Digifire 7 in my case (and anyone mounting the dew controller on the UCA with powered poles) is that I had a voltage drop of .3 volts from the battery to the top end of the scope. Consequently, the Digifire 7 was shutting down when my battery was still at an actual level of 11.9 volts, which is too high. I have disabled the low voltage cut out on the Thousand Oaks controller with the built in switch. This means I never have a problem with the unit shutting down and keeping the dew at bay. Notwithstanding this and what Kendrick says and all the battery experts might say, I still get over 3 years of life out of my 12V 24AH SLA battery. I have replaced 2 in my jump starter pack over the past 8 years. The replacement batteries are well under $50 posted from EBAY. That to me is the best option to ensure dew free observing nights and I don't need to lug more than one battery with me when I travel.

Cheers,
John B

[dannat]

if it were me id just get the collimation eyepiece or cheshire -its essential your mirror is lined up with your focuser -the other stuff id leave for now

if you get to some kind of viewing night see what other access people have & whether you like them or not