Meade 200mm ACF v Vixen VC200L

[mick pinner]

looking for opinions from the optical gurus or people with experience of either of these scopes. any thoughts on which one should be a better option for astrophotography and why. thanks.

[jjjnettie]

My next scope will be the Vixen.

[Hagar]

WOW, difficult question. I have a Vixen VC200L and can only speak of my experience.
The scope is a very well made and optically stable instrument made mainly for imaging. It has a built in field correction lens which produces almost perfectly flat fields. It doesn't have a front mounted corrector plate to frost over although I have had a couple of frost ups on the secondary mirror but this was easily fixed with a dew shield. The scope does suffer from large difraction spikes from the overly thick spider but good collimation helps this small problem. The focuser is not the greatest focuser and at the moment there is no alternative available although I believe one is being made at the moment. The mirror is fixed so no mirror flop problems.
Overall this is a great little imaging instrument which performs very well with medium sized CCD's or DSLR's for imaging and it also has a dedicated reducer which drops the FL from 1800mm to 1260mm at F6.4 with the same flat field.

I would still consider this an excelent imaging scope but would also be looking at the 10" GSO or 8" GSO RC's as an alternative particularly after the results Paul Haese has had with his. Then again he has replaced his focuser and it doesn't have a dedicated FFlattener as yet and appears to require some form of field corrector. I think Paul uses a Tak TSAor TOA field flattener to correct the field rotation.

Again a hard question and really a matter for personal choice. Check out some images from them all and see what you would be happy with.
This scope has served me very well.

[mick pinner]

thanks Doug, l don't know why people have an issue with the corrector plates dewing up, l put a dew shield on my LX200 and never dewed up once and l do like the idea of a closed optical system, less contamination of the primary.
probably the one draw back for me is the diffraction spikes although l could learn to live with them.
both can be brought back to around f/6.3 with focal reducers so this evens out which makes the decision harder because both scopes have good and bad points although l am leaning slightly to the Meade.
as for the GSO R/C's l just don't see the advantage given the after sales modifications needed to fix obvious problems that should have been rectified before release.

[Gama]

The Optics on the ACF are pretty good.
I have the RCX-14, and images are as flat as the CDK i have, and as sharp too.
You really need to see the optics in real life to appreciate the image quality.
The vixen also has great optics as well, so really come down to your preferences.

Theo

[mick pinner]

thanks Theo. appreciate the comments.

[Terry B]

I've owned my VC200L for many years. I haven't looked throught an ACF so can't comment on it.
I now use my scope only with a camera attached. Having never used anything else I didn't understand all the hassles others have with coma and needing field flatteners etc.
The VC200L has round stars to the edge of a 35mm film frame.
When I did try imaging through an APO refractor I then realised how good the VC200l is. The refractor has better contrast but needs a field flattener. This is a major hassle.
I like the diffraction spikes and they are a great focus aid.
Visually the diffration spikes arn't noticeable. Contrast on planets isn't great but I have only compared it to a 14" celestron that does show planets better. My 127mm refractor is no better on planets visually than the VC200l.
Good luck deciding.

[Tandum]

I initially got my vixen to solve weight problems with an heq5 mount, it only weighs 6kgs. I don't have a problem with the focuser, mine has a 10:1 knob fitted and I found that the 2 tiny grub screws on top of it are there to adjust for any issues with tension and slop.

[marki]

I have a 10" LX200R/ACF. Nice flat fields, nice sharp optics, mirror lock and plenty of aftermarket gear available eg focusers, reducers etc. Same as you Mick, I have never needed any more then a dew shield to hold the dew at bay so I am not sure what all the fuss is about although the air is pretty dry over here. Only problem is its weight, its a heavy tube for its size. I guess it really depends on your mount. As has been mentioned here I would also be looking at the GSO RC's as they are a nice scope (yes I have looked through TrevorW scope) for about the same price as the Meades. Vixen I have no idea, never even seen on in real life.

Doug, I am pretty sure Moonlite make focusers for the vixen tubes and there must be others e.g. Feather touch?????

Mark

[Alchemy]

had the vixen ..... sold it.

fine if you are weight limited. blocky stars due to large spidervanes.

as for the meade offerings stuart (rat ) gets excellent results with his 10 inch.

on a personal note i wouldnt buy either.

[gbeal]

I'm sort of with Clive here. I have had the Vixen, a couple in fact, and never had the Meade. The newer ACF are getting very good reviews however.
The one thing that I would not enjoy with the Meade is the excessively long (for me) focal length, and the only real way to tame this is the reducer, which is as bad as a corrector on the refractor argument.
The VC200L at 1800 is about as long as I need, but like others found the blocky stars, and spider vanes not for me.
The focuser on the Vixens left me cold as well, and no, right now there isn't really an after-market alternative, although there is the odd murmur of one soon. The problem (I know I pulled it all apart to see if I could do it) is the front section of the focuser draw-tube has the correction lens system built in, and this would need to be done with whatever replaces it.
In the end I settled on a Maksutov, so I still have the potential for dew, and it is heavy, but for visual as well as imaging I am liking it. Each to their own, all are good.
In respect of the thrust of the original post, Mick I reckon you could be happy with either or any, and really it is fun to try differing scopes, settling on one that suits after trying a few. The one thing that is apparent from your sig is the longer focal lengths, for galaxies etc, and the two scopes you mention will do that admirably, each with their own benefits and disadvantages.
Gary

[marki]

Yeah you are right Gary, the Moonlite focuser option is for the VMC260L. I wonder if Ron would do a custom flange for the 200 ???

Mark

[gbeal]

Mark,
I am sure Ron would he is that sort of guy, and IIRC Starlight were thinking of looking at a fix as well. I looked at it with the Vixen in one hand, and the Feather Touch in the other and decided that without a lathe I was stumped. Not rocket science, but difficult without the tools and knowledge. The RoboFocus is another alternative.
Gary

[Paul Haese]

ACF gets my vote, purely on the basis of the lack of blocky shaped stars. I have looked through one and they are very nice. Get around the dew problem and you should be happy.

The problems with the RC have been fixed and the new 10" will not have them. However, that is not the question being asked.

Everything depends on what focal length you want to operate at. Long focal lengths are good for galaxies. Medium you can do most nebula and a lot of galaxies. The ACF can be converted to do both with a ACF reducer. The standard one is not made for the ACF from what I have read and understand.

Best of luck with your selection.

[mick pinner]

thanks for the input guys, Paul, l cannot seem to find reference to a specific ACF reducer.

[Gama]

Many use the AP reducer, but you mainly want a reducer with no flattner.
I use the Lumicon Giant reducer on my RCX, it does over correct a little, but start are still pretty good, and reduces my scope to f5.5 .

Theo

[marki]

As Theo said the AP works well. Paul I don't know where you got your info from but the standard SCT reducers work with the R/ACF scopes as well. I have used them a few times without too much fuss.

Mark

[Tandum]

Off Topic.. Paul, have they got them to balance without hanging weight off the front?

[coldspace]

I have been using the optec 3.3, 5 and F7 reducers on my 12 inch LX200ACF. They are great reducers and although pricey work a lot better than the cheaper ones I have tried.

Regards Matt.

[Paul Haese]

The info I got from CN during conversations with Jerry Wise and it seems one you check with the techs the standard corrector is not designed for the ACF. Certainly many other RC reducers would work, everything depends on the metal back distance really. It has to be right to over correct the stars which are typically flat near the edge of the field without correction.

Robin, I did not have this problem at all. I used a longer dove tail bar and that solved any balance issue. Every telescope has balance issue, imagine putting an SBIG with eight hole filter week on an FSQ? You need to counterweight this at the front too. So just a longer bar is the answer to the problem..

[mick pinner]

so there is nothing definitive answer on which reducer works best?

[coldspace]

From all my research, I found that the Optec F5, and F7 reducers would be one of the best for the ACF corrected optics. I and a couple of friends that use them on our 200R( ACF) scopes have been more than happy with the performance.

Regards Matt.

[mick pinner]

thanks Matt, l'll look into them. any suggestions for a supplier?

[coldspace]

The F7 and F5 Optec is really good for Apo's and corrected optics of the ACF scope. They are pricey but when you hold the 2inch reducer in your hands the quality is there and the performance is excellent both visualy and for imaging. The F3.3 was not really designed for the ACF but we have been using it with the ACF on the recommendation of some cloudy night members and it works just as well. We have done FOV measurements with all 3 reducers and find that they are spot on with the reductions. Way better than the cheaper reducers.

Ron, at Sirus optics in Brisbane is a supplier along with the Optecs different attachments for the scope and camera that you need. You can also order from Opt corp but I got mine from Sirus as the price was only about 20 bucks more and no wait time.

Regards Matt.

[rat156]

The only problem with the f/5 and even the f/6.3 reducers is that if you get a large chip CCD, such as the ST-10 that I use the guide chip is outside the illuminated circle for my scope, so the guide stars were dimmer and had weird shapes.

I use the AP 0.75 telecompressor system with mine, as there is no field flattening the distance between reducer and CCD chip only affects the reduction ratio. I have noticed with my new setup, and corresponding lengthening of the back focal distance that the reduction is more than the 0.75. This brings other problems in that the field of the RCX is curved towards the outside, normally not a problem, but when you're using pretty much all of the available field, any abberations become more pronounced.

The ACF scopes being f/10 will probably not show this, mine didn't until I lengthened the distance between the reducer and the CCD.

Cheers
Stuart

[rat156]

I should add that I have the Optec f/5 reducer, with the matching adapter for an ST series camera and CFW which I could be talked into selling...

Cheers
Stuart

[mick pinner]

and how much would one have to offer for the reducer itself.

[mick pinner]

well l think the ACF has won over the Vixen, now before the final decision has anyone got any alternatives they would like to offer up, remembering that for portability 8" maximum.

[rat156]

I'll stick it in the classifieds when I work out how much it's worth.

Cheers
Stuart

[rat156]

Are you going OTA only? I would seriously consider the GSO RC scopes for astrophotography, particularly the 10" version. I don't think that portability would be a problem, availability is another question.

Cheers
Stuart

[Paul Haese]

The ACF would be good, GSO too. Just some items needed for each scope.

[mick pinner]

yes Stuart OTA only, will be on a G11. l'm a bit sceptical on the GSO's given the issues with the 8" although l take Paul's thoughts on board that certain things will be rectified on the 10".

[marki]

Well on the basis of points made in this discussion I have just ordered an optec 0.7 reducer. Picked that one as the F3.3 and F5.0 are both made to fit on the SCT versions not the ACF plus I already have F3.3 and F6.3 reducers to fit SCT's in any case. Just curious to see if it makes much of a difference. I also ordered an adapter to fit the starlight express SXV H9 T thread and hope like hell it fits the QHY8 :D. If not I will have to spin one up on the lathe.

Mark

[gbeal]

Mark.
the threads are likely to be similar or the same, T thread, but the distance, chip to reducer will likely (Sods Law) be different, and this is what will give you less then ideal images. Optec will be quite specific on the distance, IIRC it is on their website.
Gary

[mick pinner]

where from Mark?

[coldspace]

Mark, you willbe happy with the F7 reducer and your Starlight express camera. You have to have the right distance with the Optec and your chip to get the ideal reduction, but if you have ordered the adapter this should be good.
PeterM on this site has been getting great results using a Starlight express/ Optec F7/ 12 inch LX200R for his succesfull supernova searches. I love the F7 on my 12 200R as it gives me good speed and still good image scale with out any distortion to my images.Shoot Optec a e-mail about your QHY8 if it does not fit and they will help you out.

Regards Matt.

[mick pinner]

the Meade ACF is the choice, ordered from Bintel today and a new shipment is arriving this week.
l am also fitting a new W.O linear design 8:1 crayford focuser.

[coldspace]

Nice scope, you will be happy. A friend of mine fitted a feather touch focuser to his 14 inch 200R and it works great.

Regards Matt

[marki]

The back focus on the QHY8 is 21mm. Using the info on the optec page the adaptor I ordered will be 3mm too long :P. Have lathe will fix if needed. I am sure I can pinch 2 mm from some where to get within the 1 mm tolerence stated. If not I will make another one the correct length (or buy an SVX H9:D).

Mick I looked on the sirrus web site but could find no reference to the part in question so I ordered from OPT in the US. Should be here in the next week. Cost $275 for reducer, $48 for the adaptor and $50 freight (all US $ it's $471 AU total).

Mark

[coldspace]

Yep, you won't find the Optec parts on Sirus optics site as Ron has not got them there, but if you shoot him an e-mail or phone he will be able to help you out with what you need or price. He usually stocks a bit of Optec gear at his shop.

Regards Matt.

[mick pinner]

l rang today and he's all out. next arrival is about 4 weeks so if anyone has one for sale let me know.

[coldspace]

Mick, order 1 from OPT, you will get it in a week or so, great service ad they usually always have stock. Shoot them an e-mail regarding any questions and you should have an answer by morning.

Regards Matt

[mick pinner]

thanks Matt.

[marki]

Mick I ordered mine on monday night and UPS tracking states it has already landed in Hong Kong. They say it will be delivered to my doorstep by friday and previous experience with ordering from OPT backs this up. Not bad, order it on monday and get it by friday. Wish some of the OZ crew could match this.

Mark

[Lester]

Celestron has just anounced the Edge HD flat field telescopes that are supposed to be better than the Meade type. JUst got it on email this morning.

[JohnH]

A bit late spotting this thread but just in case it is useful for others - the VC200L at F9 with a DSLR gives a nice flat sharp field yes indeed. But an image scale in the order of 0.75"/pixel (Canon 20D) I fonf to be not a very practical for imaging (I did not own a G11 though!) thus the FR was pretty much mandatory. The FR cost image sharpness/flatness and in my experiance leaves you with images less crisp than I have seen from either a well corrected newt or the ACF. Sitting on a G11 though the fl might not be an issue (seeing will prob mean you are still way oversampled though..)

The FR has to be the Vixen unit ($) due to the built in corrector in the draw tube and with the FR inline you now cannot use the flip mirror or an OAG (well not the Vixen one anyway). So yes blocky stars, loss of contrast (not due only to the spider but also to the large central obstruction) a R&P focusser and odd Vixen threads limit which accessories you can use. VISAC system means only Vixen can recoat the mirror if it is ever required and collimation is more complex due to the corrector in the draw tube.

On the plus side - no mirror flop, open tube, very light for its size, industrial strength spider keeps collimation once set.

Unlike another poster I find my 127mm APO to be a much superior imaging scope....each to his own in the end I guess.

[marki]

Well my optec reducer turned up today and it looks like a nice bit of gear. Shame I will have to stick it in the lathe and shave 3mm off the tube to get the distance right for the QHY8 (is it worth it?). Another problem is that I can see no way to use both the reducer and OAG at the same time. I cannot see a way around this which is a shame as it is possible with the meade reducers.

Mark