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Purchasing first OTA


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Hello ladies and gents, happy easter! 

I'm feeling like it is soon the time to make a start on building an astrophotography kit. I think I'm going to go the DSLR route to start with, as it seems more simple to actually aquire the images this way than, say, ZWO, ATIK and the like - attach the camera, find the object, frame the object then set ISO and exposure time etc. I believe this will be a more forgiving way to get my feet in. I think the DSLR route will allow me to fairly easily use my 127 Mak as well for solar system objects when I fancy. 

I'm after your guidance guys to steer me in the right direction. My garden is hopelessly light polluted, street lights everywhere, trees, houses etc blocking the sky, so it'd need to be a more portable setup. Here are my thoughts:

Firstly the OTA. I'd be leaning toward a Skywatcher 72ED, 80ED as a scope with a huge following, reputation and value for money. As I understand it, I'll need a T-adaptor appropriate to the camera, and a camera rotator piece to frame the object at minimum. Depending on the desired target, is it going to be useful to have the appropriate field flattener/focal reducer? Is it going to be useful to have extension tubes to reach focus? 

Then the mount. Having owned one several years ago, I'd like to go with an HEQ5. I understand this is more than capable of carrying the weight of the finished OTA, tracks nicely and is solid (and somewhat future proof). I believe this mount is good for around 2 minute exposures without guiding(?) which, again, helps keep things more simple to start with whilst learning the ropes. 

After these I'd get a stronger power supply, dew prevention and other sundry items as required. Once all together, I'll make my virgin AP outing! In the mean time I've been doing a lot of reading into stacking, lights darks flats, tutorials on post processing and the like, and the more I research, the more comfortable I become with the thought of the task. 

Thank you for reading - what are your thoughts on my desired approach? 

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Hi,

Is your DSLR modded?

The HEQ5 mount is heavy and not very portable. Have you considered Star Adventurer type mount?

If you plan to work from your heavily light polluted back garden then your astro kit will become very expensive to produce decent results!

You may be better using DSLR plus prime lenses (14mm to 100mm) to capture constellations with nebula and galaxy content on a portable mount like the Star Adventurer? You can get great Milky Way shots too!!

Gerr.

 

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Your approach to starting AP seems sound to me, i think the choice of mount is a wise one. Better to go with a big mount and a small scope than the other way around, and one day you can upgrade the scope for something bigger and still have a good mount with that setup.

I would be wary of 2min subs unguided with the HEQ5 though, from what i am reading online i see the HEQ5 can have a 30'' peak to peak error over 480 seconds, meaning that 1'' trailing happens in 16 seconds. In reality the periodic error is not smooth and there are parts where shorter than 16s will have 1'' trailing too. In short, expect to either have trailed subs, or reject most of your 2min subs unguided. 30s subs are probably mostly solid and this is what i would start with. If you are imaging from light pollution then the 30s will be plenty long enough, if from darker skies then it will be less than ideal.

Guiding solves that issue, but i think its wise to start without guiding, if for just a little while. There is far too much to learn as it is with astrophotography so taking this in steps is a good idea IMO.

As for the flattener, yes you will want to have one. If you dont get one you will have significant field curvature and everything except the center of the image will appear trailed and out of focus. With the flattener you have to keep in mind what kind of backfocus is needed (depends on the flattener) and may need to buy extensions and adapters to reach the required backfocus with a DSLR. Remember though that a DSLR+T-ring will already eat around 55mm of backfocus. That is a good thing for the most part, since many correctors are designed for 55mm so if you get a flatterer like that there is no need to get extra spacers.

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I'm going to disagree quite strongly with your opening assumptions about DSLRs. You will be using a DSLR in an environment, and for tasks, for which it was not designed. This does not make life easier, it makes it more difficult.

Astro cameras, by contrast, are operating exactly as intended. They are unfamiliar and lack the external controls we are used to in regular cameras but all these controls are available in the control software. They do require a PC in the field, yes, but the PC serves other purposes on an imaging run as well and is something you might very much appreciate. If using a PC in the field is out of the question then stick with a DSLR.

Dragging an imaging rig into the field is heroic and I admire those who do it. It's hard enough with a fixed observatory.  However, working in your garden would become a perfectly reasonable option if you went for a monochrome camera and narrowband filters. The objects which are worth shooting at short focal lengths are mostly emission nebulae and these give great signal in Ha and OIII even from light pollution.  Dusty nebulae are also nice at short focal length but require a lot of exposure time, guiding and experience, so I would leave them till later.

In a nutshell, mono and narrowband would let you work from home.

Note also the point made above about the need to modify DSLRs for decent sensitivity to Ha.

A majority of members here will agree that it is logical to start with a DSLR. I have never taken this view and don't take it now. I've been introducing people to astrophotography for many years and think it is best to begin with kit designed for the job.

Olly

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14 hours ago, OK Apricot said:

Hello ladies and gents, happy easter! 

And a Happy Easter to you too! 

Biggest question of all is what's your budget - and with previous experience of astronomy - what are your aspirations? 

The 'don't buy twice' argument applies if you have the budget to support it, and the 'start off simple' applies if you don't. 

Many start off with a dslr because of budget, and if this applies to you it is a very reasonable place to start. 

PS - I can't see you 'needing' a rotator as you can usually do this manually.

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Re DSLR or dedicated astro camera (OSC or mono),  what Olly says about astro cameras being designed for purpose unlike the DSLR is true.  However I would advocate starting off with a DSLR but only if you already own one.  In terms of technicality and difficulty of operating/learning curve I think they are exactly the same as using an astro camera.  In fact if you team an astro camera with the like of the ZWO ASiAir or similar then you are getting very close to point and shoot.  If you already own a DSLR then that at least would allow you to invest in say a more capable mount. At least with a DSLR you have a camera that can be used outside of astro photography.  If money is no concern then sure go for the astro camera from the outset. 

Jim 

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I agree with Olly that you may find a dedicated astrocamera with a method of control (such as an ASIAIR) easier to use (and better) than a DSLR. But as Jim says, if you already own a DSLR then it may make sense to start with that.

I also agree with Olly about imaging from home being a lot easier than travelling. You'll get loads more imaging time, which can make up for your light-polluted skies. (Trees and houses blocking your sky would still be an issue though!) An OSC camera plus dual-band filter is relatively simple and can be effective from a city. There's some content on my website that you may find useful (I image from my city centre back garden), and you may find this article interesting.

I think you're on the right track with a wide-field refractor, they're robust and good fun.

-Lee

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6 hours ago, ollypenrice said:

I'm going to disagree quite strongly with your opening assumptions about DSLRs. You will be using a DSLR in an environment, and for tasks, for which it was not designed. This does not make life easier, it makes it more difficult.

Astro cameras, by contrast, are operating exactly as intended. They are unfamiliar and lack the external controls we are used to in regular cameras but all these controls are available in the control software. They do require a PC in the field, yes, but the PC serves other purposes on an imaging run as well and is something you might very much appreciate. If using a PC in the field is out of the question then stick with a DSLR.

Dragging an imaging rig into the field is heroic and I admire those who do it. It's hard enough with a fixed observatory.  However, working in your garden would become a perfectly reasonable option if you went for a monochrome camera and narrowband filters. The objects which are worth shooting at short focal lengths are mostly emission nebulae and these give great signal in Ha and OIII even from light pollution.  Dusty nebulae are also nice at short focal length but require a lot of exposure time, guiding and experience, so I would leave them till later.

In a nutshell, mono and narrowband would let you work from home.

Note also the point made above about the need to modify DSLRs for decent sensitivity to Ha.

A majority of members here will agree that it is logical to start with a DSLR. I have never taken this view and don't take it now. I've been introducing people to astrophotography for many years and think it is best to begin with kit designed for the job.

Olly

Yeh, I kind of agree with that. But it is a big investment. I got my 6d from ebay for £250. A second hand asi533 is, what.. £700. And it's a one trick pony. From a beginners POV it is a difficult sell.

Looking back, I don't regret buying the 6d. I later bought an asi533, asi1600, and rooms full of other stuff, but I still like using the 6d - that big lovely FF OSC sensor 🙂

But I think the logical thing would have been to jump straight to a used asi533.. and know that I could sell it for the same I bought it for, same as the 6d.. and hence wasn't really costing me more really. It's easier to use with L-extreme filters, etc and easier to control, possibly to temp control, etc etc.

And I've certainly never bought into the 'buy a small motorbike before you buy what you actually want' philosophy.. if you know you want a 900cc fireblade, get one. This idea that you have to somehow 'apprentice' through the DSLR world is nonsense for sure. But if it's done for budgetary reasons I suppose it's still valid ?

One thing for sure, if 2600MCs were 300 quid I'm sure we wouldn't be discussing DSLRs.

stu

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@Gerr I don't own one yet, but notice a few astro modified jobbies popping up used from time to time - my intention would be to buy one of those. I used to take the HEQ5 out in the field for visual those years back and had no real trouble, not enough to put me off buying one. I don't plan on the back garden as its severely light polluted and there's so much obstruction I can only see less than 10% of the sky!

@ONIKKINEN my thoughts exactly re the mount. The fact it will need guiding gives me another area of AP to learn, though all in good time and once I've got the hang of taking exposures, stacking and processing - I'm only going to want to improve and guiding will do that. I read about the OVL generally being a more affordable option for the 72ED for example which helps budget wise.

@ollypenrice Using my laptop in the field isn't out of the question, but it seems like more to "set up" and learn before even getting to take a picture with an astro cam. As above, the garden is pretty much not an option mainly due to the obstruction. I may be putting myself off the astro cam route though - is it as simple as install the software (which software?), mount camera, plate solve, shoot? In the interests of being future proof an astro cam would obviously be more appropriate? 

@adyj1 Budget wise would be up to £600 max for the OTA, around the £400 mark for a camera. The HEQ5 is pretty much a given so not to worry about that one. My aspirations are to produce my own pictures of nebulae, galaxies and the like. The wide field of a small refractor will be more forgiving to start with on nebulae, maybe eventually going up to an 8" SCT for galaxies, solar system etc. I guess my budget is more the "start off simple" side of the fence for now. Think I'll leave the field rotator alone then! 

@saac As I mentioned above, how point and shoot can I get for 400 with an astro camera? Initially this quality is most appealing of the DSLR?

 

Thanks for all the input guys, it's much appreciated. Right, I'm off to do a "30th birthday present" thread now 😅

 

 

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25 minutes ago, OK Apricot said:

£400 mark for a camera

An astro camera with a sensor the size of a dslr starts at around £1500. Call it £2000 if you don't use AliExpress.

HTH

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8 minutes ago, alacant said:

An astro camera with a sensor the size of a dslr starts at around £1500. Call it £2000 if you don't use AliExpress.

HTH

Whew... DSLR it is in that case! 

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13 minutes ago, alacant said:

An astro camera with a sensor the size of a dslr starts at around £1500. Call it £2000 if you don't use AliExpress.

HTH

Nonsense; there are outstandingly good used CCD cameras on the market for much less than half that, including ones with APS-c sized chips. (Anything with the Kodak 8300 chip, for instance. Atik, QSI, whatever.) And is it all that important to have an APS-c sized chip anyway? I'll link to a couple of images using the small Atik 460 CCD chip. I doubt that I'd get more than £600 for this camera but, since I'm not selling it, I don't really mind!

https://www.astrobin.com/400050/

https://www.astrobin.com/6f5tfl/

Those were taken with just over a meter focal length so, of course, a shorter FL would give a wider field.

As for ease, most people find the hardest part of astrophotography to be the processing. The better your data, the easier the processing. I don't think anyone is going to argue with that, but you never know!

😁lly

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All I can add is that I could have saved a lot of money and frustration if I had gone straight for a good mount, a dedicated cooled camera and an ASIAirpro and guide camera. 

You'll need around 3k. Thank me later ;)

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5 hours ago, OK Apricot said:

@saac As I mentioned above, how point and shoot can I get for 400 with an astro camera? Initially this quality is most appealing of the DSLR?

 

Quite a few of the ZWO cameras come in under the £400 mark - even more choice if you go second hand route!  Match this with much of the freely available software, EQMOD, and the supplied ZWO AS Studio and you have rudimentary point and shoot.   Match it with an ASiAir and you have a really capable (fire and forget) rig that does polar alignment, plate solving, auto focus, image plans including auto exposure on flats, guiding, meridian flip etc without using a laptop!!  But like I said a DSLR will be useful outside of astrophotography and you will still have it if and when you switch to an astro camera.  Loads of choice whichever route you decide to go down, good luck :) 

https://www.firstlightoptics.com/zwo-cameras.html

 

Jim 

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1 minute ago, alacant said:

Mmm. You must have been lucky. Used and old even more so!

Where do you get this idea from? All my cameras are old. Not only are they old, but they have run up literally thousands of hours in commercial use. In that time (with about seven cameras) I've had one Peltier cooler fail. That's it. I bought the Atik 460 second hand and it never occurs to me to doubt that it's going to work when I go outside at night.

Olly

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23 minutes ago, ollypenrice said:

As for ease, most people find the hardest part of astrophotography to be the processing. The better your data, the easier the processing. I don't think anyone is going to argue with that, but you never know!

😁lly

Spot on , totally agree.  The hardest part I find is certainly processing, it is a skill set all of its own.  I find skill fade is a seriously limiting factor; 12 month intervals with only a few nights active work dose not help with retention. 

Jim 

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6 minutes ago, alacant said:

Congratulations. Your experience is better than ours.

And perhaps more extensive? I host seven robotic setups as well as my own and camera failures so far stand at zero, if I'm not mistaken. We have a lot more trouble with mounts, though Skywatcher and Avalon are very good and Mesu are pretty well perfect.

Olly

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7 minutes ago, ollypenrice said:

failures so far stand at zero

Mmm. One used camera with which you've had no failures...

By all means recommend otherwise. We however, do not recommend used.

Cheers

 

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Anyway, I'd like to focus this a bit more on the OTA. With £600, is there anything that would be particularly suitable for a beginner? This doesn't have to include a flattener/reducer as I can get those later on when the collection is coming together. Actually read a few mixed feelings about the 72ED recently. 

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