Skywatcher 250mm Quattro f4 CF have arrived

[Deneb]

No Worries Im only having some fun

Nadeem.

[shaunster]

One major advantage of the MN190 is that it does not produce diffraction spikes.

[FLO]

Unless you like diffraction spikes

I guess owners of Mak-Newts can stretch wire across the aperture or add them later in photoshop.

[Deneb]

& you dont need a coma corrector

[FLO]

& you dont need a coma corrector

Yes, the sealed tube and not needing a coma corrector would be the Skywatcher 190MN telescope's main advantages. And the 5.3 Mak-Newt optic is more easily collimated than the Quattro's faster f4.

[Tim]

come, come now tim, are you saying these are better then the MN190....?

Dont put words in my mouth

I used one of the first versions of the MN190. Single speed focuser. The secondary was set ever so slightly rotated on its stalk, and the focuser axis was tilted. I learnt a lot about setting the thing up one way or the other! The MN190 is the scope I have most enjoyed using.......so far!! Ask me again in 12 months

I realise it is probably pure luck, but the way my particular Quattro is set up, it is apparent that somebody in the factory has spent the necessary time getting it right. If the pics I have taken show it, I can demonstrate that by the set of the focuser.

With any luck I should be able to use my Hotech SCA with it as well, just ordered an adaptor for the front of my MPCC from Bern, there should just about be room for it.

[Tim]

Dont look now but the sky just cleared here. Shame it is so windy.

I have just run off a couple of star pics, inside/outside focus.

One thing that did strike me right away was the amount of extra stars in PHD visible, and the amount of Ha nebulosity showing through even on 1 sec exposures from the bubble nebula. BIG difference there from the f5.3 MN190.

I'll try and take a few pics, but the guiding graph looks like the trail of a kangaroo with a wasps nest on each foot. Havent known it this windy for a long time

[Tim]

First light just in. Looks good, stars good to the corners, sharp and contrasty. I'll let the pics do the talking, but i'm a happy bunny

[Revs]

Come on TJ, get yer pics out!

[Tim]

Oh right, yeah.

Was short and sweet last night, patchy cloud going over most of the time, but as it was NB filters I just went with it. Got 2 hours in total, split 40mins Ha, 30 mins O3, and 50 mins S2. It was pretty windy, and the guiding graph was rough at first. Precious little data for NB images too, but that is one of the reasons I wanted an F4 scope, to get more in less time.

I have had the day at home today (not by choice, but sick!) to give all of the scopes here a good going over optics wise, including the Quattro. Some interesting results.

Here's the first light, and i'll follow up with a couple of star images eventually. Not too bad, there are some issues to sort that came to light when I put my glasses on, but the stars in the image are "as is", didn't touch them shape wise etc. Make your own minds up for now.

Cheers

Tim

[mikinio]

i will be chuffed if i ever get a pic half as good as that

[Beyond_Vision]

Looking good to the corners Tim and a good a mount of signal for a short time.

Regards

Kevin

[Tim]

That's one thing that really stood out Kev, the amount of nebulosity that shows up even in 1 sec exposures for frame & focus. The extra aperture and lower f ratio really shows over the f5.3 I am used to. In fact I have some MN190 pics of the same region, same framing, and they were 1200 sec shots as opposed to these 600 sec ones, there's about the same amount of data in them. Which hopefully translates into spending half as long on an image.

[Black Knight]

Which hopefully translates into spending half as long on an image.

.... or getting twice the amount of data for the same length of time

[MikeWilson]

Lovely, Tim.

Hope the scope gives you years of pleasure

All the best,

Mike

[Deneb]

mmmm, i don't think anyone can argue with that tim, but that is what i would expect anyway with a system @ F4, more data capture with less time.

Now Tim, yours being carbon fibre how did the focusing appear through the durations of use, as in did you have to tweak it now & again (apart from maybe in between the filter changes) ?

[Revs]

Hi TJ, looking pretty good so far. A little elongation in the top right. What size sensor are you using and is that image uncropped? Also, what are the little black dots in the image?

Hope you're feeling better soon. There's a lot going round at the mo.

[Tim]

@ Nadeem. Focus shift!! The big one for me, as you know I enjoy taking looooooong subs, sometimes up to 2 hours each.

Obviously it is early doors, but once the focus was set for this image, I didn't touch it, even between filter changes. My bahtinov only arrived yesterday so I focused by numbers, but the focus was pretty tight, and remained so at the end of the 2 hours. The real test will be on a night where the temp varies by a good few degrees.

@ Revs, yes, the stars towards the upper quarter are badly stretched. For some reason I removed the nosepiece from the front of the coma corrector and just used the MPCC fitting in the focuser, which I think accounts for that, it is an error typical of a tilted focal plane.

The shot is full frame, no cropping.

I am wondering if I could get away without the MPCC with the little H9 chip, can anybody remember how to work out the coma free field ? If so I could use my Hotech SCA which would make it all more secure.

The little black dots will be artifacts from the darks or something, and there are some larger ones as a result of no flats.

[Revs]

I wouldn't say it's bad, but it's there. Overall the stars are rather nice. I'd be surprised if you could get away without the MPCC even with the smallest of chips, but it's worth a try.

I'd love to see a image taken with a larger chip if you can

[Tim]

When I do the review of the RCC1 and the MPCC side by side, I will use my 400D. That should be big enough

If we ever get another clear night What's with all the clouds?

[Revs]

Tell me about it. I've had the imaging rig for a couple of months now an have only used it twice

[Tim]

I have more or less completed a review of the 10" Quattro CF now, and will be posting it up in the next couple of days. It will include photos and all the tech specs and measurements that you are likely to need.

Interestingly, when comparing the result from MN190 and Quattro on the same patch of sky and the same camera, I am leaning towards the Quattro. At the least it should perform as well as the MN190, but it will do it in half the time!

[Tim]

I will be posting a review soon of the Baader RCC1 coma corrector which can be used with the Quattro telescopes.

In the meantime though here is a picture showing the corner crop of an image taken with Baader MPCC on a 400D. Extreme corner is bottom left.

[zimzimma]

These look like great scopes.

Its kind of got me thinking. I currently have a 200pds and quite happy with it until i decided to clean the primary mirror and im sure ive slighlty scratched it during the process. Anyhow the 200pds is I guess ok at both viewing and imaging, my question would be (as im aware this scope is targeted at the astrophotographers) for general viewing is this comparable to the 200pds and/or what are the differences in the viewing experience? Im automatically assuming it would be better (shorter LE) for astrophotography due to it being an f4.

Thanks guys.

Rich T

[Macavity]

I currently have a 200pds ... Anyhow the 200pds is I guess ok at both viewing and imaging, my question would be ... for general viewing is this comparable to the 200pds and/or what are the differences in the viewing experience? Im automatically assuming it would be better (shorter LE) for astrophotography due to it being an f4.

As you surmise (using arcane terminology), F4 "exposure times" (varying as f-number squared) would be [theoretically!] only 4^2 / 5^2 = 0.64x those required by an F5 scope.

[iMO] the main difference is the adaptation of these F4 scopes for DSLR and larger Format (chip-size), via a bigger secondary mirror, placed closer to the primary mirror. This allows greater back-focus (guaranteeing focus for DSLRs) and full, un-vignetted illumination for larger sensors. VISUALLY however, the (typically 70mm width) secondary mirror cast a 50% bigger "shadow" at the centre of the view and negates any advantage of shorter focal length in achieving wider True Fields - The F4 if limited to eyepieces > 20mm(?) for comfortable viewing. You may need extension tubes to bring eyepieces to focus - A coma-corrector too, probably. Collimation requirements vary as the "cube"(?) of F-number. An F4 is (theoretically) "twice as difficult" to collimate...

NOT all bad news, though. For my VIDEO astronomy, the real time image of an F4 is decidedly brighter. My (TS/GSO) OTA is light and short, so fits my 6' wide observatory easily. Visually, the image is not THAT bad either - A lot brighter (colour free!) when compared to my Startravel F5 Achromat. <G> The newer Skywatcher QUATTRO is cute-looking(!) - Especially in Carbon Fibre, which may have (thermal / rigidity) advantages etc. But overall, unless one wants to *really* get into DSLR IMAGING etc., one might question the advantage of F4 over F5, given the VISUAL limitations, and a certain "increased trickiness" in general use?