Jump to content

Narrowband

Anyone regret buying a 'Large' Refractor??


Recommended Posts

I am thinking about placing an order for a Slywatcher Esprit 120ED, but keep holding back on pushing the buy button because I am just a little nervous about how much extra work it is going to be.  I will be using the scope for imagining, primarily for getting more close in shots of galaxies / star clusters and maybe for allowing myself to image Jupiter / Saturn (with a 4x barlow attached) and get more than just a small dot :)

This scope weighs in at ~10kg, so once I have got my ADM dovetail, camera etc on it, let say that takes it up to ~15kg (33 pounds), so that is approximately half the capacity of the CEM60 so hopefully the mount should be able to cope with this Ok; although I am slightly nervous about this statement? 

Does anyone know how much more difficult it is going to be setting up and using this scope, compared to an 80mm refractor which is F6 (the 120ED is F7)? 

Will guiding be much harder (currently use the OAG on the Atik One 6.0)? 

Will balancing be hard / more critical?

Are my expectation about the extra detail I am going to see in smaller things be OTT, because I will be forced into doing shorter exposures, on a scope which has a bigger F ratio? 

Basically, has anyone else done what I am planning on doing it and ended up regretting it, or did they love the new scope and everything new it brings to the table :-)

Attached is a quick FOV of the two scopes:-

astronomy_tools_fov3_zps2txdn7nb.png

Any advice / warnings gratefully received,

Cheers,

Dave :)

Link to comment
Share on other sites

  • Replies 40
  • Created
  • Last Reply

Shouldn't think it would trouble the CEM 60, you probably need to get involved in the tricky math stuff of arc secs / pixel resolution.

If you really want to get up close and personal you need an SCT.

I've found I needed four scopes and four cameras to frame different targets nicely, oh and a couple of Solar scopes  :grin:

Dave

Link to comment
Share on other sites

If you an competently set up a system with an 80mm then you are way capable of setting up a 120mm. I do not image but have 152mm, 127mm, 120mm &st120,

The real difference is balance, the jump to 127mm is quite large but the 152 mm is a big un. Your mount should cope, is there anyone nearby who might assist with trying a 120mm???

Link to comment
Share on other sites

Shouldn't think it would trouble the CEM 60, you probably need to get involved in the tricky math stuff of arc secs / pixel resolution.

If you really want to get up close and personal you need an SCT.

I've found I needed four scopes and four cameras to frame different targets nicely, oh and a couple of Solar scopes  :grin:

Dave

I have an SCT, which is good for Planets, but I thought that the high F number (F10), would make it no use for DSO? 

Link to comment
Share on other sites

I have an SCT, which is good for Planets, but I thought that the high F number (F10), would make it no use for DSO? 

I would tend to agree. Perhaps a 6" or 8" RC would be better than an SCT? Altair Astro do a nice one, currently on my wish list.

Regards

John

Link to comment
Share on other sites

SCT's are a great all rounder!! I had to sell my 10"Lx200 and still yen for it now. Even though it was goto, just put a wide angle 30mm and swing on the forks and voila!.

Your 8se is a capable scope, whilst larger  nebulae will not fit in frame I think you will find it a capable dso hunter.

Link to comment
Share on other sites

SCT's are a great all rounder!! I had to sell my 10"Lx200 and still yen for it now. Even though it was goto, just put a wide angle 30mm and swing on the forks and voila!.

Your 8se is a capable scope, whilst larger  nebulae will not fit in frame I think you will find it a capable dso hunter.

For DSO visual, definately, but not for DSO imaging.

Link to comment
Share on other sites

I dabbled with DSO imaging a while back using mainly ED80, ED120 and C11.

By far the most awkward was the C11, especially as I had no obsy so had to set it up from scratch each night for use with an off axis guider. It was disheartening on the nights it soon clouded over. It can be done, but you probably need to have a better idea of what you are doing than me :D

The 120 I found closer to the ED80 for low hassle, though the 80 got more use partly because it was more wind resistant.

You do have to be a little more careful with balance than with an ED80.

I have given up DSO imaging (life had other ideas and I truly am no night owl - what a daft choice of hobby for me considering...). But I love the ED120 even more now as it's my favourite scope for solar imaging. So glad I bought it over the Mak Newt 190 (thanks to Steve at FLO for nudging us towards the frac) as the Mak Newt isn't compatible with my solar filters.

Link to comment
Share on other sites

Ok, I am pleasantly surprised by all of the replies so far, I was half expecting people to be saying that they were a pain, but maybe what I was calling a Large Refractor, is not actually all that large  :p.  Please keep comments coming and I will make my descision tomorrow; got a gig to go to tonight, so better get on the road to Portsmouth :)

NB.  One more question, but I vaguely remember going to a photography course a while back where I am sure the guy said that 5 minutes exposure with an F6 scope was equivalent to X minutes with an F7 scope and XX minutes with a FXX scope.  Does anyone know how you determine equivalent exposure times for different F numbered scopes?

Link to comment
Share on other sites

When I purchased mine, I was torn between the 85 and the 106. My conclusion was that had I gone with the smaller scope i'd inevitably wondered what if. By going with larger scope, I've never once looked back.... although this could be a result of extremely limited use thanks to the weather, but I'm confident I made the right choice.

Sent from my iPhone using Tapatalk

Link to comment
Share on other sites

@strutsinaction,

Pete Shah had my Lx200 before I bought it. He might disagree...

Hi Damian

I was referring specifically to the 8SE. I've no idea what the LX200 is capable of but I do have an 8SE and know that DSO imaging is not its forte  :smiley: Great for planetary imaging and DSO visual though in my experience!

Regards

John

Link to comment
Share on other sites

NB.  I vaguely remember going to a photography course a while back where I am sure the guy said that 5 minutes exposure with an F6 scope was equivalent to X minutes with an F7 scope and XX minutes with a FXX scope.  Does anyone know how you determine equivalent exposure times for different F numbered scopes?

300 seconds (5 minutes) with an f6 scope is equivalent to [300 x (7 x 7) / (6 x 6)] with an f7 scope or in this case 408 seconds (6.8 minutes). You can do similar sums for other values of focal length over aperture (the f number).
Link to comment
Share on other sites

I've not seen an Esprit 120 but I'm not sure an ED120 is actually a particularly large refractor after owning a 6" F/12:

Unless that photo was taken in a doll's house, that is one big scope :D.  Wife would kill me if I tried to bring that anywhere near the house  :rolleyes:

Link to comment
Share on other sites

300 seconds (5 minutes) with an f6 scope is equivalent to [300 x (7 x 7) / (6 x 6)] with an f7 scope or in this case 408 seconds (6.8 minutes). You can do similar sums for other values of focal length over aperture (the f number).

Thanks alot for that; so that single F unit does make a significant difference.....

Link to comment
Share on other sites

I love my two refractors and warmly recommend both. The Tak FSQ-106 is a very nice allrounder and the TEC-140 is exceptional. I do like the warm refractor touch in imaging (never do visual) over the cold reflector.

/per

Link to comment
Share on other sites

As a non-imager; what does a 120mm F7 frac at 840mm FL 'manage' that a 8SE with an F6.3 reducer/corrector at 1260mm can't in terms of getting closer to small DSOs?

In my head (a messy place, I'll admit) the SCT working at F6.3 is both faster and working at a greater image scale, plus potentially more stable owing to the more compact length. I'm assuming optics/mirrors aren't deficient in either respect, both are well collimated and sensor coverage isn't an issue

Is this purely a central obstruction issue and if so, what is the issue generated - Contrast? Can't that be sorted in Photoshop?

Russell

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.