Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

renskav

On the mak-refractor fence. Help with selecting first "real" scope.

Recommended Posts

I'm sure this question has been done to death, but my head is reeling from information overload after three weeks of research and i need to vent :)

Some background

2 years ago my girlfriend got me a photographic tripod for my birthday. I used this with my Eos1100D DSLR to shoot the dark night sky at my summer house, and was simply blown away by the pictures that came out. Star streaks aside, the milky way was entrancing. I spent almost a week learning all about the constellations, and did some "manual plate solving" to figure out what i had shot. When i realized that one of those blobs was actually the andromeda galaxy, my mind was blown.

For my birthday last year i wanted something bigger, so i wished for and got a small Celestron C70-mak cass spottning scope advertised as 25-70x. I promptly plopped it on the balcony for some nighttime terrestrial viewing, and was sorely dissapointed with the views at anything more than 30x. Blurry and out of focus when light levels were poor. I tried using the C70 on my tripod ball head but the small FoV meant finding and keeping planets or objects in view was a pain.

I splurged some money on a small motorized azalt mount (synscan merlin) to screw onto my tripod for tracking of objects, as it would carry either my DSLR with my 270mm Tamron lens and 2x extender, or my C70. I also bought some USB cabling which meant i could control both the mount and the DSLR from my computer and have the equipment outside, which means i don't have to freeze while gazing (Sweden is cold). Being able to shoot jupiters moons was my next big wow.

Being sorely dissapointed with the C70, i really want to upgrade my scope, and have been researching different scopes for the last three weeks, but i feel i have reached a dead end as i keep flipping back and forth between alternatives.

What i want

  • Optical tube assembly only as i want to use what i already have (quality photographic tripod, and merlin mount)
  • To do both visual and "astrophotography" - I know that you will probably call me on this as this seems to be the #1 beginner mistake - but i really feel that shooting and saving some of the experience is a big chunk of the fun for me. I know the Azalt mount will give me field rotation, at this stage i think i can live with stacking semi short exposures as i do it for my own enjoyment and not beating those people with 24" dobs ;)
  • I want to have the ability to have the scope set up outside and sit at my computer and enjoy the view - but of course the ability to use it for visual as well.
  • Portable - means should be carried by my merlin-mount on my photographic tripod - not more than ~4 kgs total OTA weight including camera body.
  • Want to be able to do both DSO and planetary work (with a slight inclination towards DSO) - i'm a newbie here really looking for my next "wow" moment.
  • Wide field of view seems nice, the C70 has taught me the annoyance of a small FoV.
  • Stowable - not to big OTA as i pack everything up when i use it to not annoy my significant other half.
  • My normal sky is in a pretty light polluted city, but i can get nice dark skies at my summer house.
  • Pricewise i am not super sensitive, but also don't want to spend alot on something which will go into a drawer. I am willing to go to approximately the $1000 range at this point.

What i am currently choosing between.

- A refractor in the 3.x" inch range, currently the WO Megrez 88 seems enticing.

- A 5" mak cass, the Skywatcher Skymax 127 is what i'm currently considering.

A refractor seems enticing because of the FoV, the Mak-cass seems enticing because of the increased aperture (but will i be able to live with not fitting the pleiades into my view?)

TL;DR: 5" Mak-cass or 3" refractor?

Please, help me not regret my choice! :)

Share this post


Link to post
Share on other sites

You really are not talking semi short you are talking about 20-30 sec max. if its really imaging you want I would suggest using your camera on an ioptron skytracker and a pair of binoculars for viewing

http://www.teleskop-express.de/shop/product_info.php/info/p5940_iOptron-SkyTracker-V2---ultraportable-star-tracker-for-astrophotography.html

Ypu can't use a mak because the focal length is too long and its too slow so if you are set on the scope the wo88 will be best its not really optimal though on a merlin.

Have you read this book? its a bit of an imagers bible it tells you what you need for good photo's and more importantly why

http://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html

personally I would get the book before I buy any equipment

  • Like 1

Share this post


Link to post
Share on other sites

Get both - they are complementary and both excellent at what they are designed for!

Chris

Share this post


Link to post
Share on other sites

Get both - they are complementary and both excellent at what they are designed for!

Chris

Actually it is a fair point about imaging planetary I got side tracked by the dso imaging. You should be able to  do planetary imaging with the merlin and the skymax a dslr gives a very small image however

Share this post


Link to post
Share on other sites

Limiting the weight to 4Kg with everything is a challange.

A reflector would have a higher body weight.

A short F ratio refractor would suit nicely but it would not be so good for planetary and lunar for getting high magnification. It would be good for widefield and DSO.

Have a look at the Skywatcher rnage of refractors and reflectors. Another good quality rnage is from Borg and Telescope Service.

Share this post


Link to post
Share on other sites

Thanks for the reading tip. I will definetly get the book before i spend on anything else.

I have done some research into EQ-mounts (the advanced VX seems best for my needs), and the importance of the mount for quality AP, and i know i might probably want one at one point -

Just now however the fuss with polar alignment, and the big hit to portability is not worth it for me. My main observing site is my balcony facing due south, with has no clear view of the northern sky (no stella polaris!), and i will be forced to do meridian flips continoously.

I would love to get both OTA's and i might at some point, but which would you buy first? ;)

Could you clarify what you mean by small image?

Share this post


Link to post
Share on other sites

I can only answer from a very unscientific view! I had a maksutov (skywatcher) it was utterly stunning. Unfortunately with limited time and no funds for a goid goto tripod I simply couldnt use it. The field was so narrow it could be difficult finding the moon on a push pull tripod. I sold it and have a 6 inch refractor instead. That's not too easy and I m hoping to buy a goto motor to power it. Really if I had the money I d buy the mak( although Celestrons are nt quite the same as Skywatchers) but only with a slightly over the top tripod. Otherwise you may end up with a superb piece of equipment you cant use!

Share this post


Link to post
Share on other sites

I have trouble with technical definitions so I was looking for a better way to say it by providing a link. ignore what I said about dslr's it seems things have moved on since I last used a camera on a scope.  you use the dslr in movie mode and then capture the live stream  on a laptop or something like that. In the old days you used to use a webcam

Share this post


Link to post
Share on other sites

There is a limit to how far you can magnify an object based upon the apeture as well as the quality of the objective lens or the main mirror.

A rule of thumb is 2x the objective , so an 80mm refractor would be hard pushed over 160x magnification. For planetary work folk on here are often working at near 2x that.

If you are directly attaching the camera to the OTA then you do not have that luxury. The OTA becomes a super telephoto lens and magnification can depend on the size of the imaging chip in the camera.

Make Every Photon Count is an excellent book and explains the pitfalls and pratfalls realy nicely.

You can still get a reasonable polar alignment by using an inclinometer to set the altitude and a compass to find true north. OK not so accurate but sufficient for 20-30 sec exposures which can be stacked. I have to use this method when I lived in Aus' as the South Celestial Pole star is over a degree off the SCP and on the edge of being naked eye. 

The iPhone app, ScopeTools is very useful, and there are a couple of inclinometer apps online. I use the iPhone app, but I also found a 2 decimal place inclinometer at a DIY store.

Share this post


Link to post
Share on other sites

Imaging aside I like wide field astronomy which is why I have an 80mm scope, it doesn't give as good a view on planets but its much better at sweeping through the milky way and at wider dso's. Its just a question of which you prefer. in truth a 127 mak isnt brilliant on planets its just much better than the williams. if you want very good on planets you need more apparture although  that could be said for dso huntting as well. The mak will see further but it also needs longer cool down to work properly. the choice is simple which do you prefer milky way or planets? milky way go williams planets go mak

Share this post


Link to post
Share on other sites

@Baggywrinkle -  I can achieve 20-30s exposures with my current merlin mount without having to polar align (i do two or three star align with Pointing Error Correction as i keep observing) which is why i'm not yet sold on the EQ mount as my next investment. Thank you for the tips on the app though - i will keep that in mind. I will also consider the Skywatcher and Borg refractor product lines.

@rowan - Yes, i use the live view feature of my Eos1100d in combination with Backyard EOS software - it can even do some real time stacking of the live view frames. I think your last comment summarizes the problem well "milky way or planets" - i'm trying to do two things (at least) at the same time.

I'm trying to get a feel for "how bad would the mak be for DSO" vs "how bad would the refractor be at everything else than widefield" and "which will give me my next wow moment"?

It seems it is leaning towards the refractor both for viewing pleasure and fast optics - i also suspect there might be more long term exitement to find in wide field DSO viewing and imaging (there are only 3 viewable planets after all) - although i would feel bad if it would disqualify me from planetary viewing altogether. Is there some webpage or image that can give me a feel for what i can expect at 160x mag planetwise?
 

Share this post


Link to post
Share on other sites

you will see saturns rings although not cassini,  jupiter's cloud belts and four moons the moon will be good even in a small refractor and white light solar should be fine on a refractor. The mak see's further and it is better on planets but not by so much, its really at bigger appartures that cassegrains shine

Share this post


Link to post
Share on other sites

One other item you might consider is a catadioptic camera lens.

Focusing them is not easy but I like my Samyang 800mm, has a 100mm objective. I am taking it with me to Sweden next month. It works at F8 so not excatly fast.

I have to go to the UK in Feb and my company has asked me to do a one week trip in South Sweden teaching some metrology and measurement techniques. So I am packing a camera, tripod my Nano Tracker and the Samyang lens. Just hope there are some clear skies.

Share this post


Link to post
Share on other sites

The Samyang 800mm+DSLR+Nano tracker is a really interesting portable set up i had not heard about previously, thank you so much for the tip!

The Samyang 800mm seems to be getting mixed reviews, then again it's very cheap compared to other things i'm considering, so it might be a logical next step. I just wished there was one with a motorized focuser that didn't cost the equivalent of a downpayment on a house. What's your experience with the Samyang for AP?

The nano tracker looks very interesting and perhaps a lot less of a hassle compared to the AstroTrack or the Polarie.

The weather in Sweden in February is treacherous. If you're unlucky the week will be completely overcast and rain mixed with snow. If you're lucky open skies and lots of degrees freezing - bring thermal underwear (2 layers is not overdoing it), cap, warm socks+shoes and extra batteries for your camera and tracker if you expect to spend any extended time outdoors :) I find gloves with a few fingers cut off are almost madatory if you're operating cameras or equipment outdoors in the winter here.

Again, thank you for once again for making me confused as to what kit to buy ;)

Share this post


Link to post
Share on other sites

I have a c70 and it is sorely let down by the supplied zoom eyepiece, using a standard eyepiece greatly improves the image even using the free 25mm one that came with my other scope is miles better. It needs time to cool down before use.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.