150 PDS or 200PDS ?

[sshenke]

Hello, this is my first post here and thank you all in advance for your advice.

I recently decided to upgrade from using skywatcher skyliner 200P Dobsonian which I have had for some years to buying a proper mount for DSO observation and photography. I was really taken in by the reviews for the skywatcher HEQ5 mount and thought that I could use the 200P OTA on the mount, but was corrected by the helpful folks at FLO that it won't stand a chance in even the gentlest of breeze for photography, but can still do visuals. So, now I am thinking of buying the mount as well as either of skywatcher 150P-DS OTA https://www.firstlightoptics.com/reflectors/skywatcher-explorer-150p-ds-ota.html)  or skywatcher 200P-DS OTA, which is lighter and has a shorter tube (https://www.firstlightoptics.com/reflectors/skywatcher-explorer-200p-ds-ota.html).

I was told that the 150 P-DS OTA will be better for DSO photography as it will give a wider field of view than the 200 P-DS. Is this correct?

Thanks again for you help.

_SSh

 

[Whistlin Bob]

I use a 200p and a 130pds on an HEQ5 and would agree with the advice given. I can get away with the 200p only in still conditions. The 130pds is much smaller and more usable, which is a boon for people new to imaging. I doubt there's much in it between a 130 and 150, but have a look at the fov calculator in the resources on this site- there are quite a few popular targets that cannot be captured without mosaics on a 150. 

For my money I'd go with the 130. Check out this thread:

 

[R26 oldtimer]

If you're keeping the dob, then it would be better to go for an ed80 frac. It's more plug n play than newts when it comes to A.P., and it will compliment your dob nicely as grab n go. If not keeping the skyliner, then a 150/750 newt, will be a good compromise, manageable for A.P. and decent aperture for visual.

[wimvb]

I've used the 150pds a lot, and it's a fine scope. Quality wise I would say that it's the same as a 130pds, but with a somewhat longer focal length. As @Whistlin Bob suggests, use a fov calculator to get a feeling for the difference. It's the targets that you intend to image that should decide which scope suits you best. A longer fl will put more demands on guiding than a shorter, and a longer scope with a larger mirror will always be more sensitive to wind than a smaller one.

[sshenke]

Whistlin Bob and R26, thank you both. Thats been great advice. Feeling a lot better now as I have been scratching my head for a long time with making a decision on this.

R26, is this the frac you mentioned? https://www.firstlightoptics.com/pro-series/skywatcher-evostar-80ed-ds-pro-ota.html?

I would definitely like to keep the Dob, as it has served me well over the years.

Thanks again for your prompt response.

[sshenke]

Thanks wimvb.  That's really great. btw, your images are fantastic!

[Uranium235]

80ED or 130pds? Hmm, ive had both.

130pds: Bang for buck, faster (f5), cheap, but may require user improvements or mods.

80ED: Ease of use, slower (f6.35 with 0.85x), nearly double the price with reducer, requires very little in the way of tweaks (usually the focuser tension).

[ollypenrice]

Getting into AP will expose the difference between theory and practice. It's an activity in which an enormous number of things can go wrong. A refractor will present fewer opportunities for things to go wrong but will not be as fast as a reflector of similar focal length and larger aperture - provided that the reflector has been sorted out.

But one thing is certain: aperture in itself is a very small player in deep sky imaging. This is very different from deep sky observing where it clearly matters a lot.

Olly

[Adam J]

15 minutes ago, Uranium235 said:

80ED or 130pds? Hmm, ive had both.

130pds: Bang for buck, faster (f5), cheap, but may require user improvements or mods.

80ED: Ease of use, slower (f6.35 with 0.85x), nearly double the price with reducer, requires very little in the way of tweaks (usually the focuser tension).

I see that you say you "HAD" both, which did you end up keeping?

I know the answer mind you lol.

[Knight of Clear Skies]

Have you given any thought to what camera you want to use? It's probably best to think of the scope and camera together as a system, pixel scale (arcseconds/pixel), field of view and focal ratio are what will determine the final image. Also, what kinds of targets do you want to go after? I tend to think of the 200 PDS and 150 PDS as galaxy imagers, whereas many nebulae benefit from a larger field of view and shorter focal length. FInally, are you intending to use a guidescope?

My personal recommendation for anyone looking to get started at AP is the Samyang 135mm f2 lens due to ease of use and speed of data collection, but it depends on what interests you.

[sshenke]

1 hour ago, Knight of Clear Skies said:

Have you given any thought to what camera you want to use? It's probably best to think of the scope and camera together as a system, pixel scale (arcseconds/pixel), field of view and focal ratio are what will determine the final image. Also, what kinds of targets do you want to go after? I tend to think of the 200 PDS and 150 PDS as galaxy imagers, whereas many nebulae benefit from a larger field of view and shorter focal length. FInally, are you intending to use a guidescope?

My personal recommendation for anyone looking to get started at AP is the Samyang 135mm f2 lens due to ease of use and speed of data collection, but it depends on what interests you.

I have a sony A200 DSLR camera with zoom lens kit, which is what I am planning to use. I hope it will work? Will look into buying a dedicated lens such as the Samyang that you had mentioned when the budget allows. In terms of what I wanted to image- I just want to try and picture the popular deep sky objects, the likes of what I see in this forum ( far too ambitious, I know!!). Also, I didnt know anything about guidescopes until you asked me. Is it an absolute must or is it something that I could buy later after getting the hang of it initially?

Thanks for your advice.

[happy-kat]

Why not buy the book Making Every Proton Count before spending any money it hopefully will help provide more background knowledge to your choices.

[spillage]

I have the ed80, 130pds and 150pds. I like the fact that the ed80 just works out the box but like the fiddling of the 130pds to get the most out of it. The 150 has not been used in a while but was meant to be my galaxy scope. For some reason the 80 seem easier to sort out the FF spacing than the 130 but I am sure this is user error. Collimation can be a pain and one day I will master it but for now am happy to keep trying. If cost is an issue then the 130 wins, if your mechanically minded and like mucking around with kit the 130 wins. If you can afford it and do not want to be having to make adjustments to your scope then the 80 wins for me. This is course is just my opinion.

[wimvb]

2 hours ago, sshenke said:

Also, I didnt know anything about guidescopes until you asked me. Is it an absolute must or is it something that I could buy later after getting the hang of it initially?

Guiding is a must, but you can get decent images without it, initially. Just expect to lose a fair number of exposures. Follow @happy-kat's advice and get the book. It's available from our sponsor, FLO.

As you already own a dob, I assume that collimation isn't going to be a problem. With a refractor you need a field flattener, but with a reflector and a dslr you will need a coma corrector.

This hobby is a money pit, because once you have the necessary hardware in place and start to collect data, you'll see the need for software to help you turn that data into presentable images.

[Knight of Clear Skies]

9 hours ago, sshenke said:

I have a sony A200 DSLR camera with zoom lens kit, which is what I am planning to use. I hope it will work? Will look into buying a dedicated lens such as the Samyang that you had mentioned when the budget allows. In terms of what I wanted to image- I just want to try and picture the popular deep sky objects, the likes of what I see in this forum ( far too ambitious, I know!!). Also, I didnt know anything about guidescopes until you asked me. Is it an absolute must or is it something that I could buy later after getting the hang of it initially?

Thanks for your advice.

Glad I could help.

The camera isn't ideal I'm afraid as I believe it doesn't have liveview, which will make focussing tricky. I also notice that it only goes up to ISO 3200 which can be an indication that the sensor may produce a fair bit of noise, and I don't know whether it would be practical to mod it for greater sensitivity to hydrogen alpha. Good budget DSLRs are available on the second hand market (my Canon 1100D is only slightly newer than yours).

The smaller the image scale (so the greater the focal length) the more important guiding becomes. I try to avoid it as I have limited time to debug my setup, by either working at very short focal lengths, fast focal ratios, by choosing bright targets or by using my 1600MM Cool astrocam (unusually, it works well with short exposures as it produces very little read noise).

I'd recommend taking a step back, do some more reading and think about what you want to do. It's natural to think of AP in terms of the scope first but there is a bit more to it than that. AP is a learning curve, it's not especially difficult to get some decent results but diving in with a complicated setup could be a recipe for frustration. Just to throw this out there, this is a real budget image taken with a cheap modded DSLR, Ha filter, 70s vintage 50mm lens and basic tracking mount, with an hour of data. Although I now have a scope and dedicated astrocam I still tend to reach for my DSLR first as I know I can quickly get some fair results, even if conditions aren't great.

[sshenke]

Thanks everyone for your advice. Just amazed and humbled by the amount of knowledge and experience in this forum. I will certainly start with the book and will likely buy the SW130 PDS . Obviously a lot further to do with getting a decent imaging device, coma corrector and guidescope.  Thanks

[jimjam11]

18 hours ago, Knight of Clear Skies said:

Have you given any thought to what camera you want to use? It's probably best to think of the scope and camera together as a system, pixel scale (arcseconds/pixel), field of view and focal ratio are what will determine the final image. Also, what kinds of targets do you want to go after? I tend to think of the 200 PDS and 150 PDS as galaxy imagers, whereas many nebulae benefit from a larger field of view and shorter focal length. FInally, are you intending to use a guidescope?

My personal recommendation for anyone looking to get started at AP is the Samyang 135mm f2 lens due to ease of use and speed of data collection, but it depends on what interests you.

I think this is really important. With a modern camera and small pixels an ed72 with reducer will get you to 2" per pixel @f4.9. That gets you the benefits of a refractor with the speed (mostly) of a reflector. The ed72 is also tiny and cheap...

Your Sony camera has large pixels which would reduce image scale substantially. However, if any any stage you buy another camera it is likely to fall <4 microns which would get you into 2"  per pixel territory...

[Erling G-P]

Regarding cameras, I used to have a Sony Alpha 100.  Nice camera (I always loved my analogue Minolta SLRs, and the Alpha 100 is for all intents and purposes a Minolta in Sony guise).  However, it was very noisy - anything above ISO 100 would produce visible noise in plain ordinary photos (never used it for astro).  The Alpha 200 is supposedly better, but probably not by leaps and bounds, so most likely not ideal for low light photos.

Incidently, I'm fumbling my way into this hobby with a 200PDS on a HEQ5Pro mount.  Have so far only been imaging in very wind still conditions, as I didn't think it would work otherwise.  A couple of days ago, I set up in fairly still conditions, only to have a minor gale blow up after having started the camera.  Decided to let it run as an experiment - seemed a good opportunity to find out if I could actually image in windy conditions (believe the forecast said gusts around 8-10 m/s).  As expected though, practically all the images were ruined.  Having a huge dew shield on the 200PDS, making it even more of a sail no doubt didn't help either.  Whether a 130PDS could have handled it, I  can't say, as I haven't tried it yet (I consider getting one, for the wider view required by some subjects, and for being able to image under more windy conditions than with the 200PDS - the OTA itself is quite modest in price, so tempting to get one, since I already have a mount to put it on)

[sshenke]

3 hours ago, jimjam11 said:

Your Sony camera has large pixels which would reduce image scale substantially. However, if any any stage you buy another camera it is likely to fall <4 microns which would get you into 2"  per pixel territory...

Thanks jimjam11, what sort of camera would you suggest? 

[jimjam11]

I have no experience of it personally but I believe the d5300 is considered very good. Canon equivalents are likely to be similar.

If you can (and are willing to) spend more get a dedicated camera such as the atik 460 or asi1600.

[sshenke]

42 minutes ago, jimjam11 said:

I have no experience of it personally but I believe the d5300 is considered very good. Canon equivalents are likely to be similar.

If you can (and are willing to) spend more get a dedicated camera such as the atik 460 or asi1600.

Thanks, thats great