Newby Questions and RVO scopes

[Kevin17]

Hi,

 

I have a lot of newbie questions for you all...

 

Im looking to buy my first astrophotography rig, and i have come across RVO https://www.rothervalleyoptics.co.uk/ they do their own line of scopes called Horizon, does anyone have any experience of them (i think i linked an image below), there is very little on youtube / google etc about them.

 

Also, if no one can recommend this brand, i would look for a similar refractor doublet, i think maybe a Skywatcher Evostar 100 ED DS Pro or William Optics Gran Turismo GT81 IV Triplet ED as they are similar money if anyone has any experience they can share?

 

My next question is mount, i  was going to go for a skywatcher eqm 35 pro mount as the weight capacity is fine for what i need, but i have seen some rather unflattering reviews about these suffering from bad backlash and poor tracking, and some that say its a good little mount and the problems are easily overcome. Does anyone have another recommendations for similar mount? or is it a case of just spend more on a Skywatcher HEQ5 Pro GOTO Mount With Rowan Belt Mod?

 

Thanks all, i will no doubt fire more question at all who reply 🙂 

 

Thanks

 

Kev

 

 

Edited September 16, 2022 by Kevin17

[Carastro]

I have used Rother valley Optics a number if times and they seem to be good traders.  However l do not know the telescopes you mention. 

 

regarding  the mount it rather depends what you plan to do.  If astrophotography then you need something sturdier like the HEQ5 you mention. 
 

I should also say that the Sponsors of this Forum - Altair Astro do their own excellent brand of telescopes you might want to take a look at. 

 

Carole
 

 

[Kevin17]

Hi,

 

Thank you very much for your reply, i will take a look at Altair.

 

I did get the impression that you're better off as a newbie getting the biggest capacity mount and as high quality as your budget allows so that it works for whatever you end up getting in to in the future, hence why im thinking the modified HEQ 5.

 

thanks again 🙂

[TerryMcK]

One thing I would ask is what do you want to image? Planets or deep sky objects for instance.

Planetary needs a stable platform so the bigger the mount the better.

 

From your initial introductory post the Skywatcher EvoStar 150 is probably too heavy for the HEQ5Pro, once you load it up with essential items, so you might like to consider going for a mount with a larger capacity like the EQ6-R Pro if you are going for a larger scope. Also that scope is really intended for visual work rather than astrophotography due to its single speed focuser, coated glass (not ED) and f8 speed.

 

On mounts what the manufacturer states as maximum capacity is normally for visual. If they state a capacity for AP then take it with a pinch of salt and opt for about 2/3rds to 3/4 of that. I have the HEQ5Pro with Rowan modification and it is an excellent mount, with around 11kg for imaging, but I wouldn't mount anything bigger than a 4" scope on it. I have tuned my mount replacing all the bearings and my WOZS103 fully loaded is around 8kg and is fine.

 

Look for scopes that have FPL53 ED glass in. Although that is not a magic bullet it helps keep all colours focused at the same point.

 

For deep sky objects you might like to consider the William Optics RedCat 71. That is a fast quintuplet refractor and does not need a separate field flattener. The other two WO refractors that you stated in your introduction and the start of this thread, GT81 and  FLT91, do need flatteners/reducers that costs another £239 on top of the purchase of the scope. This is also valid for any telescope intended for AP so factor the cost of a flattener/reducer in. Otherwise you end up with strange egg shaped stars at the edge of the field.

 

Not familiar with the RotherValley offerings so cannot comment on those.

 

The Skywatcher ED80 Pro is a good choice but the Skywatcher Espirit range is better.

 

Finally, as Carole said, the Altair Astro range of refractors are also an excellent choice. Check out the Altair 70 EDQ-R F5 Quad APO Astrograph.

 

Cameras, guide scopes, filters, filter wheels, focus controllers, imaging computers, power supplies, dew prevention and all the cabling come next. Welcome to the hobby of astrophotography but beware it can get expensive 🙂 .

 

  

 

[Nightspore]

A lot of RVO and Altair refractors (plus several other distributors) are basically the same telescopes but with different liveries and some occasional bespoke/custom differences. I believe a great many are manufactured by Kunming United Optics.

[Kevin17]

hi guys,

 

Thank you for taking the time to reply, im defo leaning towards deep sky photography with a DSLR, i was looking at a Canon EOS 850 camera bundle for about the £750 mark, i figured that has a decent enough ISO range on it to get me going.

 

appreciate the heads up on the WO redcat, i hadnt realized that it was a quad. i will take a look at that Altair one too, i notice there is a sizable price difference between the two scopes.

 

Would you say it is paramount to have a guide scope or is it possible to manage Without one if you have a tracking mount?

 

cheers 

[TerryMcK]

Longer exposures benefit from a guide scope.

I personally would not start with a DSLR and would have gone straight for a dedicated cooled astronomy camera had I known when I started. A DSLR camera has an IR cut filter that requires professional removal to enable the sensor to see the good stuff. Also DSLR sensors get really hot with long exposures, introducing noise, and it becomes difficult to compensate with calibration frames as you are not really sure what temperature each light frame was shot at.

A cooled astronomy camera is a game changer and is fully controllable being able to maintain a set temperature all night. I set my cameras to -20C and the value is written into the FITS header of each shot. In general they have a silent electronic shutter rather than a DSLRs clunky mechanical shutter and mirror which can cause minor vibration.

 

The other thing is you can use different filters mounted into a filter wheel and change them instantly.

Although that can also be done with a DSLR you need big expensive ones to ensure the APS-C sensor is not obscured by the edges of the filter and that produces vignetting.

Dedicated cameras normally have their sensors mounted close to the mounting threads at the front of the camera and therefore you can use smaller, less expensive, filters due to the optical geometry.

 

All cameras have their own pros and cons and the above is just my opinion.

[Kevin17]

Hi Terry,

 

This is why i am here probing and asking questions, i would rather spend 25% more now and get it right than have to shelf a mount i didnt get right or the wrong camera and scope.

 

i was looking at the Redcat, its quite a bit more than a WO - GT81, probably for the 4th lens. I can actually get the 81GT + WO field flattener + WO 50m guide and + ZWO ASI guide camera for the same price as the Redcat 71, and i don't think I'll be getting into this enough to need a quad, i was going to start with a good doublet, that's now turned in to a good triplet.

 

What camera model are you using? The ZWO ASI533MC Pro blows my camera budget, would that work?

Edited September 18, 2022 by Kevin17

[TerryMcK]

Yes indeed the ZWO ASI 533 MC Pro will be ok Kevin - the Pro bit means cooled of course. Best to check on the astronomytools website CCD suitability section http://astronomy.tools/calculators/ccd_suitability for scope/ camera/flattener combination. Even though the camera is CMOS based the calculator is still valid.

 

So inputting all the data it comes up with this:

 

"The ideal pixel size for OK Seeing (2-4" FWHM) seeing is: 0.67 - 2" / pixel.

This combination leads to slight under-sampling. This reduces the influence of guiding errors and improves signal to noise at the expense of finest detail. OK for most deep sky imaging purposes."

 

 

Other alternatives using the same 14bit Sony IMX533 9 mega pixel sensor are the Altair Astro Hypercam 533C  https://www.altairastro.com/altair-hypercam-533c-colour-camera-9239-p.asp which is slightly cheaper than the ZWO but equally as good. The 533 sensor does produce square pictures rather than the more traditional 4:3 format.

Both cameras claim zero amp glow which is explained here https://astronomy-imaging-camera.com/tutorials/what-is-amp-glow.html

Amp glow is easily calibrated out with darks though.

 

For my cameras I personally use 2 ZWO ASI 183 MM/MC Pro cameras - one monochrome permanently mounted on my RedCat 51 quad and the other colour permanently mounted upon the WO ZS73 which has a x0.8 reducer fitted. Those cameras are the ideal pixel size for those two scopes.

I also use the ZWO ASI294MM Pro camera with my larger WO ZS103 scope. That one is capable of silly file sizes and resolutions 12bit ADC, 2.3um pixel size, 47 megapixels, 8288*5644 resolution, 14k full well capacity. when running in what is known as unlocked 1x1 binning mode. I normally just stick to its default 2x2 binning mode of 14bit ADC, 4.6um pixel size, 11.7 megapixels, 4144*2822 resolution, 66k full well capacity as is more suited to the scope.

Finally I have the ZWO174mm monochrome camera mounted onto my DayStar solar telescope.

 

Each of my guide scopes is equipped with the ZWO ASI120MM Mini

 

 

I think the combo you are leaning towards is a fine one and will produce excellent images. Ask as many questions as you like as we are all more than happy to help.

[Kevin17]

Thats great advise, thanks. 🙂

 

I have another about filters (adjustable light filter and light pollution filter), where do they physically fit in to the scope, if i want to use it for some in the garden moon / planet watching etc, i have been looking at getting a couple of barlows and some eyepieces, to keep it less expensive (and uniformed) i was looking at some Explore Scientific 1.25 eyepieces (4.7mm 8.8mm 14mm 25mm 30mm with a 2x barlow and 5x barlow).

 

The WO diagonal is 2 inch but comes with a 1.5-inch reducer, do i need to get 2-inch or 1.5-inch filters? im not sure exactly where they fit in, is it on to the diagonal, barlow or eyepiece or do they screw into the end of the scope before you put the diagonal on?

 

Cheers

 

[Nightspore]

I don't know about AP, but for visual I tend to prefer threading filters directly into the eyepiece. Occasionally I thread them into the diagonal if I plan on changing eyepieces regularly with the same filter. The downside to threading into the diagonal in my experience is that the filters seem more prone to dewing.

 

 

[TerryMcK]

When in AP mode the 2” filter which has 48mm threads goes inside the flattener/reducer. It is a bit awkward to fit but essentially you fit it to the female threads at the front of the reducer and then attach the reducer to the scope. A better option is to buy a ZWO filter drawer like this https://www.firstlightoptics.com/zwo-accessories/zwo-2-filter-drawer-m42-m48.html mounted between the camera and back of the flattener. That way you can swap out different filters. In practice I found that my filter drawer leaked light and I had to put a few layers of black tape around it. Not ideal but it works ok.

For light pollution when using colour (OSC) cameras there are many different filters on the market especially designed for AP. I am plagued by LED streetlights and when shooting colour I use an IDAS D2 filter which effectively cuts out the LED spectrum including neighbours domestic lighting. It also has the benefit of cutting out older sodium, tungsten and mercury vapour lamp spectrum. Then red green and blue come through well. I don’t think that is sold anymore but IDAS do have one that supersedes it.

 

Even under relatively dark skies the camera will be able to detect skyglow from distant towns or cities even if your eye can’t so you do need to use some sort of LP filter especially in the UK.

 

Then there are other filters designed for OSC that let through specific spectra such as Ha and OIII blocking everything else. A lot of manufacturers offer these now and examples are the Altair DualBand ULTRA 4nm, the Optolong Dual-Band L-eXtreme and others.

 

There are many fine examples of images produced by the people on this forum using just such filter types.

[Kevin17]

Thank you both for that that has cleared up a few questions, i was going to ask about the filter drawer too - good catch with that answer.

 

I have 2 filters on my list to get me going i will get the mount, scope and cameras and eyepieces and then probably hit pause until i know what other small accessories i kneed vs want, i probably have enough to go on or soon will have,

 

I do think im going to get a couple of USB dew heaters if you can recommend any of those, not sure what size i need yet though.

 

Appreciate it, so thanks again!

 

Although i dont think my wife will find it funny when i click buy next month and it my £4500 shopping basket hits the card 🤑🤫.  

 

[Nightspore]

Double polarisers are good for observing surface cloud detail on Venus. Anything really bright can benefit from a polarising filter though; single or double. 

[Kevin17]

23 hours ago, TerryMcK said:

Yes indeed the ZWO ASI 533 MC Pro will be ok Kevin - the Pro bit means cooled of course. Best to check on the astronomytools website CCD suitability section http://astronomy.tools/calculators/ccd_suitability for scope/ camera/flattener combination. Even though the camera is CMOS based the calculator is still valid.

 

So inputting all the data it comes up with this:

 

"The ideal pixel size for OK Seeing (2-4" FWHM) seeing is: 0.67 - 2" / pixel.

This combination leads to slight under-sampling. This reduces the influence of guiding errors and improves signal to noise at the expense of finest detail. OK for most deep sky imaging purposes."

 

 

Other alternatives using the same 14bit Sony IMX533 9 mega pixel sensor are the Altair Astro Hypercam 533C  https://www.altairastro.com/altair-hypercam-533c-colour-camera-9239-p.asp which is slightly cheaper than the ZWO but equally as good. The 533 sensor does produce square pictures rather than the more traditional 4:3 format.

Both cameras claim zero amp glow which is explained here https://astronomy-imaging-camera.com/tutorials/what-is-amp-glow.html

Amp glow is easily calibrated out with darks though.

 

For my cameras I personally use 2 ZWO ASI 183 MM/MC Pro cameras - one monochrome permanently mounted on my RedCat 51 quad and the other colour permanently mounted upon the WO ZS73 which has a x0.8 reducer fitted. Those cameras are the ideal pixel size for those two scopes.

I also use the ZWO ASI294MM Pro camera with my larger WO ZS103 scope. That one is capable of silly file sizes and resolutions 12bit ADC, 2.3um pixel size, 47 megapixels, 8288*5644 resolution, 14k full well capacity. when running in what is known as unlocked 1x1 binning mode. I normally just stick to its default 2x2 binning mode of 14bit ADC, 4.6um pixel size, 11.7 megapixels, 4144*2822 resolution, 66k full well capacity as is more suited to the scope.

Finally I have the ZWO174mm monochrome camera mounted onto my DayStar solar telescope.

 

Each of my guide scopes is equipped with the ZWO ASI120MM Mini

 

 

I think the combo you are leaning towards is a fine one and will produce excellent images. Ask as many questions as you like as we are all more than happy to help.

Hi,

 

Just re-visiting the cameras, you mentioned that the one that i found at the top end pf my budget is 1" square rather than 4x3, is there any befefit to having a 4x3 camera, i could probably sacrifice something to squeeze to a ZWO ASI294MC Pro Cooled Colour 4/3" if its a big gain.

 

 

[len2376]

I would say you need to lock your card up till you have done more homework. Then double lock it.

As an aside the William Optics RedCat 51 & 71 have a helical focus ring unlike the normal run of astro scopes. 

Also the ASI294MC is older tech and does come with some issues. Some get along, others find them troublesome. See Astrobin and search for your camera / scope options. See what other folk have achieved. Count the hours to get to these images.

 

If you go down the route to astrophotography then you will likely need a number of items that haven't been mentioned. 

One of my setups consists of:

William Optics GT81 IV, Reducer Flat6A III, ZWO ASI 2600MC Pro, ZWO EAF focuser, ZWO Filter Drawer, LP filters.

SW  HEQ5 modded, but latterly a GEM45. Guide scope, Guide camera. 30mm / ASI120MM fine with this bundle.  All controlled via an Intel NUC local to the mount. Using Win Remote Desktop back to my laptop inside the house. Using NINA on the NUC. Add a homebuilt dew controller with dew bands and a power distribution box. Cables. Then a Nevada PSW-30 25-30A Switch-Mode Power Supply.  Add that lot together and I would guess that your budget might be stretched. 

 

There are alternatives (and some cheaper) for all of the items above but ultimately all will be required in some form or other if you are serious about this. Astrophotography requires hours of exposures to capture deep space images, do you actually have these hours available? Maybe consider visual only for a bit, get used to how good your skies and weather are. 

 

Consider some reads:

Making Every Photon Count

Turn Left at Orion

 

Len

[Kevin17]

Cheers for the reply Len, i appreciate the experience.

 

I had looked in-to some of the additional issues and work around kit you mentioned, i was looking at a ZWO ASI Air Plus for connectivity, auto focusing and cable / power management, going back my laptop.

 

Funny you mentioned visual, I was initially going to go visual, but figured if i was ratcheting up a bill, might as well do it once.

 

My initial 'plan' was to get a WO 91FLT rather than the GT81, as it is a good quality mid-ground scope as my main scope, with an imaging mount and a handful of eye pieces, but also a guide scope and guide camera to start getting used to the guiding software etc and to better see what i was pointing at and then stop there for a year till had an idea how to use all my gear and enjoy looking at things before i started to worry about taking pictures. Then buy the 'big camera' and anything else i was needing.

 

I dropped to the GT81 to be able to afford more kit as there is almost £800 difference between the 81 and 91. the red cat 71 sits in the middle but would like something that can be used for observing as well if possible, so figured on the 91 or 81 as a compromise. 

 

Time I have, although not retired, i have evenings and weekends, i live in a fairly ok place as i am rural (lincolnshire), so can get a good bit of sky in my garden or down a country lane half a mile, but if i need / want to travel I have a nice campervan to base myself out of with a big leisure battery🙂

 

My basket so far is changing weekly thanks to all the great advice i have received and a couple of taster nights I've attended, and i have a work colleague who spent about £9500 2 years ago going zero to hero and he has had a lot of advice to give and seemed to manage to get it right the first time by not going cheap and listening to the likes of you guys. he got a Skywatcher Espirit 120 and has it on an almost permeant set up in his garden (retiring soon).

 

I want something with the potential that i can grab and go and mount on a lightweight manual mount when i go camping for general observing too. i know that the WO 91 or 81 + lens and eye pieces will fit in a pelican case no bother to come camping.

 

So far i am looking at:

 

EQ6 Pro Imaging Mount & Tripod

 

WO GT81 or 91FLT Scope depending on budget and other kit purchased.

WO 50mm guide scope

90 deg diagonal

light pollution filter

adjustable moon filter

2x, 3x and 5x barlow

4,8,16,20, &24mm lenses

ZWO ASI 678 MC Guide Camera

Dew Heaters 

 

Then a potential pause for 12-24 months, before then adding (depending on cost and advancements in tech etc).

 

ZWO ASI 294 or 1600 Main camera + filter drawer + filter bundle depending on budget.

ZWO auto focuser

ZWO ASI Air Pro

 

Your thoughts?

Edited September 21, 2022 by Kevin17

[Andy 274]

All I will say is that there is a difference between Williams optics scopes & the Altair ones of the same or similar sizes. The Altair scopes will come with an individual test report - for the money, I’m not aware of another manufacturer that will do that.

 A report is a sign of their quality.

ultimately it’s up to you, but any beginner I’d recommend a decent mount & a small refractor if your insistent on going for a mount & scope combination, the absolute ground zero to get into astrophotography is a camera tracker, DSLR & fixed prime lenses