Video Imaging with a "fast" Refractor?

[Macavity]

Imaging with a FAST refractor? (A subject to which I have alluded elsewhere)

Maybe it requires specific *video* experience to get a response? [teasing]

But I have a recent "bank error" windfall, and was considering getting a FAST

F<=500mm ED "APO" refractor. My budget is more £300-400 than £600-700.

I already have an ST102 f/5 achromat which I am considering upgrading...

A decent focusser, "Carbon Fibre" to cover the random holes in the OTA.

I remain confused whether "budget" EDs are much better than Achromats?

Are there Video Astronomers with a typical £350: 60, 70, 80mm (semi-APO)

F6 ED refractor (w/optional reducer / flattener)? Does it WORK for you?

A virtue is these can mount one of these "piggyback" on a main scope...

P.S. Mostly thinking of imaging Open Clusters... These tend to be *just* a tad

too large for the a 200mm / F4 Newt field. Hey, I'm working on "mosaics". 

P.P.S. Maybe I'd be better investing in FAST 300mm Ebay (D)SLR lenses?

A lengthy <wibble> But BRIEF (Heck, any!) responses are very welcome!

[shirva]

The ideal choice would be the ed80 if you get the scope only it may drop into your price range..this scope Is well worth the money. .I bought the st102 prior to the ed80..I thought to myself wont be that much if a difference. .eat your words davy..this scope is a steal and under priced ps don't tell skywatcher.the clarity is brilliant no coma or VERY little..this scope is ideal for a/p and video .

[Macavity]

Thanks, Davy. The Skywatchers seem to be a "safe pair of hands" generally. The ED80s seem "a bit slow"

(at f/7.5?) for Video - But maybe not! I might just stretch to an Equinox 80 for the slightly faster f=500mm?

Other manufacturers remain a bit of an unknown... Reviews vary! Some attractive offerings - the WO ZS71,

the various "Altair Astros" scopes... My ideal focal length (less than 500mm). But not everyone rates 'em.

A bit disappointed that budget (£350) ED APOs only rated "7/10" in independent reviews - Compared to Achromats at 5/10 and triplet (genuine) APOs rated 10/10. Just surprised that doublet APOs aren't THAT much better than Achromats? Or indeed, maybe they are, once your get to over (say) £400! Still pondering...  

[Martin Meredith]

Interesting thoughts. We don't see many images taken by premium refactors on this forum (I guess for obvious reasons: if you spend that much on a large flat corrected unobstructed FOV why waste it on a small sensor ;-). If money were no object I'd be really interested to see how something like the 5-element WO Apo 71mm f/4.9 you mention performs in electronically-assisted mode. Its a bit early to pick one up second hand… Coupled with a lightweight mount it would make a great grab-and-go too.

I enjoy using my 80mm f/6 achromat but realistically the star bloat is a bit of a pain compared to a nice fast reflector.  I'm finding the 8" f/4 Newt a real pleasure to use for this style of observing. Fast, plenty of aperture, and negligible coma on small sensors. Perhaps for wider work 6" f/4 is the way to go?

Martin

[DoctorD]

Hi

I have an INED70 which, visually is much better than my old ST80, with little or no noticeable chromatic distortion. At F6 it's not that fast, but works well with both my SDC435 and Lodestar.

I use an SCT F6.3 reducer with an SCT to 2" nose piece and a 20mm spacer - about F4.5 and can just get focus.

Great 10:1 Crawford focuser and a shiny carbon fiber tube.

Also makes a great grab and go visual scope.

HTH

Paul

[Dragon Man]

Thanks, Davy. The Skywatchers seem to be a "safe pair of hands" generally. The ED80s seem "a bit slow"

(at f/7.5?) for Video - But maybe not! I might just stretch to an Equinox 80 for the slightly faster f=500mm?

Other manufacturers remain a bit of an unknown... Reviews vary! Some attractive offerings - the WO ZS71,

the various "Altair Astros" scopes... My ideal focal length (less than 500mm). But not everyone rates 'em.

A bit disappointed that budget (£350) ED APOs only rated "7/10" in independent reviews - Compared to Achromats at 5/10 and triplet (genuine) APOs rated 10/10. Just surprised that doublet APOs aren't THAT much better than Achromats? Or indeed, maybe they are, once your get to over (say) £400! Still pondering...  

The ED80 at f/7.5 is only slightly slow at native focal length.

Add a focal reducer and you'll be pleasantly surprised.

If you can get your hands on the 500mm Equinox ED80 at a good price, go for it.

Check my Live Screen Grabbed images using an ED80 and a home made 0.58x and other Focal Reducers. Go to 'IMAGES FROM ED80' here:  http://ballaratman.wix.com/mallincam#

ED80 is great for Video. Makes an Achromat look like a toy.

Yes, the Skywatcher brand of ED80's are highly recommended. They are made by Synta and released under different names but all are the exact same scope: Synta, Skywatcher, Orion, Saxon, Skywatcher Pro, Skywatcher Black Diamond.

They are all made in the same production line, then painted different colours, brand names added, and some have the 10:1 focuser, some don't. But all the same scope.

[shirva]

Mmm Williams telescopes are definitely beautiful scopes. . Second hand they still hold there money. .ken dragonman has probably used the ed80 more than most on this forum taking video and wether its a bit slow compared to a fast newts you cant argue with his captures both with a sammy 4000 and mallincam 1/2" sensors..homemade focal reducer...so a budget ed80 homemade focal reducer add a great camera = great images what more could you ask for...ok one more thing ken or dons dark skies

[shirva]

Lol ken you beat me to the post

[shirva]

Hi chris..forget the 7/10 review it's probably been rated for visual or ap...if I rated it it would be an 8.5 out of ten for video..

[Dragon Man]

We don't see many images taken by premium refactors on this forum (I guess for obvious reasons: if you spend that much on a large flat corrected unobstructed FOV why waste it on a small sensor ;-). 

Martin

The obvious reason isn't as you think.

There are plenty of Video Astronomy Screen Grabs shown in other places.

Quite a few people with small Video sensors are 'wasting' high end Apo scopes.

Try some of the other Forums and Yahoo groups and you'll find them. 

[Dragon Man]

Hi chris..forget the 7/10 review it's probably been rated for visual or ap...if I rated it it would be an 8.5 out of ten for video..

Totally agree Davy.

I would rate the ED80:

Visual: 5/10

Astrophotography: 9/10

Video: 8/10 or 9/10 

[Macavity]

I'd like to think that (generally) ED APOs were "somewhat more superior" to achromats. 

- Nothwithstanding the merit of the latter. I have long known my ST102 has a few other

limitations re. general optical quality. I sense APOs are "back in the running" now...

Thanks ALL for the above comments. As ever, the issues of aperture, quality, f-number

are not completely obvious - Better indicated by practical examples - So thanks Ken.

I sense, my Watec, plus small APO, will have sufficient "oomph" for open clusters etc.

TBH, I won't be able to "rest easy in my bed" until I've had some personal experience of

a small APO. As they say "You're only young once" ... (Not true in my case, but Hey)! 

[Martin Meredith]

The obvious reason isn't as you think.

There are plenty of Video Astronomy Screen Grabs shown in other places.

Quite a few people with small Video sensors are 'wasting' high end Apo scopes.

Try some of the other Forums and Yahoo groups and you'll find them. 

I do follow a few other fora but I don't see many high end Apo shots. I'd love to see them so as to see how they handle star bloat. Can you be more specific? I just checked the last 4 months on CN and didn't see a single such shot, but maybe our definitions of high end differ.

Martin

[shirva]

Hi martin.

to me the high end would be the ed80, I dont wish to be confrontational I say this because to me the essence of video astronomy is to get the best possible images with whatever scope you have..a small cheap refractor with a video camera on it becomes a very good scope. .the video camera enhances scopes. .so to me the ed80 is as good as you would need to buy to do video very well..so can the image from a £1200 scope justify the price, ok if it's what you want to buy no problems but most guy's cant afford to do a/p so this is ideal for them, other is outreach make it affordable to all.

[Martin Meredith]

Hi martin.

to me the high end would be the ed80, I dont wish to be confrontational I say this because to me the essence of video astronomy is to get the best possible images with whatever scope you have..a small cheap refractor with a video camera on it becomes a very good scope. .the video camera enhances scopes. .so to me the ed80 is as good as you would need to buy to do video very well..so can the image from a £1200 scope justify the price, ok if it's what you want to buy no problems but most guy's cant afford to do a/p so this is ideal for them, other is outreach make it affordable to all.

Hi Shirva

Sure, high end will differ from one person to another and I'm with you on this 100% on making things as affordable as possible. I was just interested to see what a really high-end apo (e.g. a Tak) could deliver to see if there is much benefit for a small sensor. If you're paying a lot for a well-corrected flat field at the edges then it might be that there isn't much noticeable gain. I'm not in the market for one myself   . There's plenty of APers who have that kind of kit but insist on using the Lodestar as a mere guider   .

Martin

[HiloDon]

Hi Chris,

I'm a little late in this thread because of the time zones, but here's my thoughts. You might want to first determine what field of view you want and then get that length at native format. Recently I have been playing around with larger FOV scopes even trying finder scopes with my Lodestar X2. They work surprising well, but do start showing a bit of field curvature at the edges. These finders are under F4 and speed will do that to you. Using focal reducers will likely do the same thing along with other abberations. In my opinion it's always best to use scopes in their native format. I searched my image captures and found the same object taken with my Barska 80 triplet APO and my Orion 80mm ST achromat. The Barska is F7 and the Orion is F5. Attached are the comparison captures. I personally find the Orion ST a little better and it's native FOV is larger at 400mm. The Barska capture used some focal reduction and was at F5.6.

Hope this helps.

Don

[shirva]

Not a problem martin..I cross the divide on astronomy issues. .for one I like and love astrophotography and video astronomy. .ye gods they all cringe. .how dare he they cried out..

Why not ,,my life my hobby and I do it to destress and relax..ha ha destress aye right..

So where do I stand ..8" newt l love doing ap on nice aperture..ed80 totally brilliant for ap on a superior mount than mine..visual brilliant very clear image no coma or very little. .st102 now I was happy as a pig in mud with it ok it's torture coma wise compared to an ed80..thing is if I hadnt it already I would want it defo..it was a toss up between it and a williams ..the posts I read on the ed80 swayed it and im glad I listened it's that good for its price.thing with ap is they spend fortunes compared to us and will be a slow process converting them im afraid..

[shirva]

Nice images don

this is what it's all about..look at the differences of both in one I like the detail in the neb but too many stars in next it's the other way..two great shots ..so now it comes down to preferences. .will be the same on different priced scopes..what makes you happy. .no we look at video without capturing how much difference would you notice on a near live view..form cheap to expensive scopes.

[HiloDon]

Thanks, Davy. I found two other comparisons. I agree with Davy, it comes down to preferences. For NRTV, they both do a good job.

Don

[shirva]

Dons images say a thousand words perfectly

[DoctorD]

HI

Here's M42 captured with my INED70 and F6.3 reducer:

1. Showing nebulosity:

2. Showing more of the core:

3. With my 102MAK and F3.3

Slightly wider FOV with the INED70 and F6.3 reducer

CS

Paul

[Macavity]

That they are often surprisingly similar (Not being funny, as they say!).

The "quality" scope(s) look smoother, but achromat surprisingly good?

I once did a daylight side by side visual test on a MAK127 vs an ST102.

Setup to give the same magnification (24mm & 8mm e.p. respectively):

The ST102 looked much more "dynamic" (contrasty?) the MAK "dull"... 

However, when it came to actually reading the name on the Irish ferry,

there was only one winner... The MAK127 had much better definition.

But what is the verdict above? Or might be more a "preference" thing? 

[Macavity]

Many Thanks for ALL your thoughts guys! Much appreciated.

At the moment, I feel unable to decide. lol. For many reasons,

my preference is for a doublet ED of f=420mm scope at F/6...

(It'd be of about the "same level" as my 8"/F4 & MAK150?)

FWIW, within my limited budget (upto £400), it'd be a toss up (lol)

between a Williams Optics ZS71 and Altair Astro Starwave 70ED.

I sense better scopes are slightly more expensive (£500-800) 

There are still things that I want to buy FIRST with my "windfall".

The "mundanities" of Video Astronomy still consume budgets? 

[DoctorD]

HI Chris

The Starwave 70ED looks remarkably like my INED70 (although the INED70 has a carbon fibre tube).

Looks like the prices have gone up - I got mine two years ago, €299 for the OTA but I also bought the 2"diagonal and a 24-8m Baader zoom lens at the same time which fit into the carrying case nicely.

The package at £399 looks good value, the RDF is very similar to mine and works well with the scope.

A small windfall for me too - I sold my motorbike that had been sitting in the garage for 10 years!

Clear Skies

Paul

[Macavity]

The Starwave 70ED looks remarkably like my INED70 (although the INED70 has a carbon fibre tube).

Looks like the prices have gone up - I got mine two years ago, €299 for the OTA but I also bought the 2"diagonal and a 24-8m Baader zoom lens at the same time which fit into the carrying case nicely. The package at £399 looks good value, the RDF is very similar to mine and works well with the scope.

A small windfall for me too - I sold my motorbike that had been sitting in the garage for 10 years!

Belated thanks Paul,

Good to clear a bit of space, tho' I suppose you never know when you might suddenly need a motorbike.

I do think a generic 70mm f/420mm ED doublet would suite my purpose. But maybe (cash juggling) later. lol

Decided to continue rebuilding by (much abused) ST102. Maybe if I stop it down AND focal reduce it...

I suspect my "fairly cr*ppy", much over-processed, image of M31 was the ST102 + 0.5x reducer.

We VIDEO Astronomers are such adventurists...