Light scope for AP, mostly DSO

[CC_Japan]

Hi, this is my first post. I've been reading these forums for quite some time, before deciding to join at last.

Sorry to start of my membership here with the classical newbie question "which scope".

I have been into photography for quite some time, shooting mostly landscape/sunrise/sunsets pictures and at some point started getting interested in astrophotography. I've dabbled around with my Sony Alpha and lenses for some time, but decided that I would like to take the plunge and try my hand in DSO imaging. Nothing too fancy, primarily Andromeda, Pleiades, Trifid, Horsehead nebula.

Now, I hope I've avoided the first pitfall of "bigger, better, more" trap, as I'm not in the market for a big scope. In fact, living in a place that is probably as light-polluted as it gets and not having a car (I usually rent cars, but need to get to the store by train), my setup has to be reasonably mobile. Therefore, I have pretty much decided to go with an Ioptron mount (probably the ZEQ25GT over the SmartEQ Pro, as the latter looked very fragile).

Now, the hard part is the scope: Needless to say, I need something that is 1. light (less than 4kg) and 2. not too long (ideally, it would fit into carry-on luggage). I have looked through some scopes and looked at many more and came up wit the following choices. Since those are just my thoughts based on limited experience, talking to people and a lot of reading, any sort of suggestions or comments from experienced users would be much appreciated.

1. Stellarvue Raptor 90 carbon fiber: Stellarvue products are not available at reasonable prices here in Japan, so I'd have to order it directly at Stellarvue. Since it's currently available at $1495 and their QA is supposedly top-notch, this looks like a nice deal to me.

2. Orion ED80t CF: This would be the shorter, lighter and cheaper alternative to the Stellarvue. Plus, I can order it from a dealer nearby.

3. Explore Scientific ED102 carbon fiber: I could probably get this from a domestic store as well, at roughly the same cost as the Stellarvue. Being a 102, it's already quite long from my perspective, though.

4. Last but not least, Sharpstar AL80 II: This looks like it's (almost) the same as the Orion, even though the Orion is apparently slightly lighter and smaller. Again, I could get this scope from a respected dealer here in Japan.

I have to say, I also looked at the three Japanese makers (Takahashi, Vixen, Borg) but I'm not impressed. The Vixen ED81s is more cheaper than any of the scopes listed above, but also much longer and several people here in Japan have told me to stay away from that scope, because the optics weren't great.

Takahashi is nice and all, but the FS-60 is too wide, the FC-76's cost performance (especially if you include the reducer) is pretty bad compared to the scopes mentioned above, and while the new FC-100d looks decent and light-weight, at 80cm or what it's way too long for my needs.

As for Borg, the 77ED2 looks interesting, but most people seem to use the Borgs for planetary observation, birding and what not, but not for DSO imaging; hence, I'm suspicious.

Again, any thoughts or recommendations would be much appreciated. Thank you.

[Scott]

wow chris, you certainly have a nice choice of scopes there. As you probably know, Japanese optics are concidered to be among the best in the world and the takahashi is one of the best although as you have mentioned, they are not cheap. I would have thought that the borg range of scope would be quite good for ap as they are quite fast although I don't know anyone who's used one. I would be happy to own one though .

As you have mentioned, size is not the main thing with imaging. what you are after is a fast scope on a solid eq mount.

Good luck with your search and I hope you get what you are looking for

[CC_Japan]

Thanks, Scott. I guess, finding a scope with very good optics packed in a small, light body is the main challenge.

That's the thing with Borg. They offer a nice 77ED2 scope plus reducer set (510mm f6.6 -> 330 f4.3), which looks quite tempting. I've been told they are quite good, but there seem to be very few people use them for DSO imaging, even here in Japan.

With the four scopes listed above I have reviews and pictures to judge their performance, there is little in terms of hands-on reports on the Borg.

May be it's just that they don't have the brand power and marketing budget to compete with Takahashi and Vixen or the extremely modular design turns people off. However, it makes you wonder.

[swag72]

Would you consider second hand? I ask as the Pentax 75SDHF is a fantastic scope (I had one for a while) and I'm sure you'll be able to pick them up easier in Japan than the UK.

[CC_Japan]

Would you consider second hand? I ask as the Pentax 75SDHF is a fantastic scope (I had one for a while) and I'm sure you'll be able to pick them up easier in Japan than the UK.

Thanks for the suggestion, Sara. Judging by the specs, it certainly looks like a nice scope. I'd thought about second-hand, but since I don't have enough confidence to judge whether the scope is in solid condition optically and otherwise, I don't want to buy from any Joe Doe. One or two star shops periodically auction off used stuff. Currently, there is no used 75SDHF available. I just checked. But still thanks for the hint.

[Uranium235]

I may suggest that you search again?

There are other alternatives (though maybe available not in Japan), but you need to find one that has a dedicated reducer and flattener - or at least a demonstrated and proven combination of telescope and 3rd party FF/FR. I think you should also look for evidence of good blue and field edge correction (with said FF/FR in place) before deciding. Also consider the camera connection, you need to avoid push-fit adapters and have threaded connections only - which includes how the FF/FR attaches to the focuser tube.

But out of your choices, I'd probably go with the Orion 80T CF (80/480 F6). Ive seen a few nice photos from one of those, plus im pretty sure the TV 0.8x reducer works with it.

Edit: Just found this:

http://stargazerslou...st-impressions/

And this:

http://www.cloudynights.com/ubbthreads/showflat.php/Number/4319731

[CC_Japan]

I may suggest that you search again?

There are other alternatives (though maybe available not in Japan), but you need to find one that has a dedicated reducer and flattener - or at least a demonstrated and proven combination of telescope and 3rd party FF/FR. I think you should also look for evidence of good blue and field edge correction (with said FF/FR in place) before deciding. Also consider the camera connection, you need to avoid push-fit adapters and have threaded connections only - which includes how the FF/FR attaches to the focuser tube.

But out of your choices, I'd probably go with the Orion 80T CF (80/480 F6). Ive seen a few nice photos from one of those, plus im pretty sure the TV 0.8x reducer works with it.

Thanks for the suggestion. Much appreciated. In fact, I'm sort of debating with myself whether the SV-90 is worth the premium over the Orion.

I have actually conducted my search with that mind. There are reducers available for all of those scopes. Stellarvue offers a flattener for the SV90, even though I've read somewhere that the TV 0.8x supposedly also works with it.

Just to get this right, ideally there are little to no adaptors between the scope and the camera, right? So, the focuser-tube connects to the flattener/reducer which connects directly to the camera's T-ring.

[Uranium235]

Just to get this right, ideally there are little to no adaptors between the scope and the camera, right? So, the focuser-tube connects to the flattener/reducer which connects directly to the camera's T-ring.

That would be the ideal situation, as you can then be sure everything is on-axis (which is important for proper field correction). But check the links I added in my previous post, someone seems to have gotten decent correction using the 80T CF and the TV reducer, though it is a push-fit arrangement.

This is the setup that ive been eyeing up, maybe not suitable for your use becuase its quite heavy (for its size) - but its fast and should be flat enough for a 22mm diagonal chip (and probably up to APS-C size at least).

Scope: http://www.altairast...&cat=268&page=1

FF/FR: http://www.teleskop-...102mm-Apos.html

There are other reducers available with more reduction (0.75x) but thats where it starts to get expensive!

[CC_Japan]

Thanks for that.

Sorry, I had missed the links in your previous. The second threat you liked to, I had actually seen before. The Orion looks like a really nice tool.

Last time I checked the Altair scope wasn't readily available in Japan. That TS reducer/flattener looks quite nice, though. I'm using a Sony Alpha A77, so usability with a APSC size camera is certainly a necessity.

[Uranium235]

No problem

But whatever you choose, it needs to be fast(ish). You are using a DSLR, which lets face it - arent the most sensitive of instruments so you need a telescope that gives a bright image. Therefore you may be better off with getting the Orion (+ reducer) and then diverting the remaining funds towards a CCD camera.

A modest APO and a CCD will take you a long way.

But be warned.... the dark side of AP can get very dark (and expensive)

[CC_Japan]

Thanks. The Orion has a lot going for it. It's fast, small and light, a lot of people seem to use it for AP and the knowledgable authorized dealer is within striking distance.

Ah yes, in camera speak it's called "lens lust" . I know it too well. My wife has already complained about my investments into camera lenses .

[E621Keith]

Borg are good DSO imaging scope. In fact I think it more correct to say they are designed as astrographs and later adapted for birding use. 77ED usually show more CA than Chinese ED scopes when used on planet.

You can see a lot of 77ED DSO samples on Borg's International dealer's blog

http://digiborg.wordpress.com/?s=77ed

Since you live in Japan, I would go for a Borg over any other scope on your list. Even more so if you use DSLR, because Borg reducers have DSLR system specific adapters that will give it the correct reducer to chip spacing. A number of Borg astrograph will illuminate 35mm chip, as well as APS-C. As far as I know, none of the Chinese scope will.

Keep an eye out on this site. I've seen Pentax scope coming up a few time last year

http://www.starshop....lebid-2012.html

Kyoei seems to get a few used Borg every now an then

http://www.kyoei-tok...brand/024/001/X

http://www.kyoei-osa...65262/list.html

[Uranium235]

Dare I mention the blue performance of the Borg? Maybe not a problem if using a CCD camera or narrowband imaging, but give it an OSC camera and a bunch of hot blue stars and the results might not be what you expected.

[CC_Japan]

Thanks for the info, Keith. I look at Starshop's website quite regularly.

I found these samples on Borg's Japanese website. They do look quite good.

http://www.tomytec.co.jp/borg/world/photo/borg-1/edf4dg/

[CC_Japan]

That being said, the Borg is a doublet, the scopes on my list are triplets. Supposedly, the latter are better far AP than the former, right?

[Uranium235]

Yes, exceptional (quick) doublets are rare things indeed. Once you get down to about F6 native, it needs to be a triplet - but then a corrector is mandatory due to increased field curvature of the triplet. If anyone can make a doublet faster than F6 with good or perfect blue performance, I'd also expect them to be able to walk on water and feed a thousand with a only a loaf of bread and a fish.

[dmahon]

You mentioned Takahashi, but not the FSQ85 (which would be my choice of short, portable astrograph) if I had the money.

[E621Keith]

That being said, the Borg is a doublet, the scopes on my list are triplets. Supposedly, the latter are better far AP than the former, right?

A well made doublet will always beat a poorly made triplet. Optical configuration doesn't tell you everything about the quality of the instrument. So no, triplet are not 'FAR' better than doublet, in some case they can be worse. (e.g. Pentax 75SDHF is a doublet with integrated flattener. )

The scope you listed are good scopes (not sure about the Sharpstar), but you also need to consider the reducer/field flattener. As for as I know, most of those scopes you listed uses generic field flattener. Borg designed their scope and flattener to worked with each other, so that is a significant advantage over the others. Borg 77ED was redesigned into the 77EDII specifically so it would work better with their range of flattener/reducer.

[CC_Japan]

You mentioned Takahashi, but not the FSQ85 (which would be my choice of short, portable astrograph) if I had the money.

The latter part is the issue. Even if a dealer offered me a good deal on the FSQ85, the scope and the reducer would still cost twice as much as the Orion ED80t CF. I can't spend that much money on just the scope and the reducer.

[CC_Japan]

A well made doublet will always beat a poorly made triplet. Optical configuration doesn't tell you everything about the quality of the instrument. So no, triplet are not 'FAR' better than doublet, in some case they can be worse. (e.g. Pentax 75SDHF is a doublet with integrated flattener. )

The scope you listed are good scopes (not sure about the Sharpstar), but you also need to consider the reducer/field flattener. As for as I know, most of those scopes you listed uses generic field flattener. Borg designed their scope and flattener to worked with each other, so that is a significant advantage over the others. Borg 77ED was redesigned into the 77EDII specifically so it would work better with their range of flattener/reducer.

A legitimate point. The question is whether the BORG 77EDII plus dedicated reducer combo beats the SV90 or the Orion 80 with a decent 0.8 Televue reducer. If performance were similar it comes down to size and price.

Talking about the SV90, has anybody used that scope? The reviews and first-hand impressions I've seen sounded all very good.

[E621Keith]

A Borg with dedicated reducer will certainly beat a SV90+TV0.8x with the wrong spacer. All normal refactors have curved focal plane, so stars at the edges will appears out of focus without a field flattener. Field flattener only flatten the focal plane at a specific distance from the flattener, the focal plane will be curve either side of this specific distance. The flattener to sensor distance is determined by the design of the flattener as well as the scope. The distance is variable depending on the scope used.

Borg and other scopes with dedicated flattener has predetermined flattener flange - focal plane distance. TV0.8x when used with third party scope do not. You will either have to experiment with different spacers to find the correct distance, or find someone else with a similar set up who has done that already. As far as I know, the popular TV TRF-2008 cannot fully flatten the field of a 80mm f6 triplet for a APS-C sized sensor.

If you are interested in the SV90, check with Stellarvue to see if they have a dedicated flattener. They should be able to recommend you a flattener and be able to supply the necessary spacer for that scope.

The latter part is the issue. Even if a dealer offered me a good deal on the FSQ85, the scope and the reducer would still cost twice as much as the Orion ED80t CF. I can't spend that much money on just the scope and the reducer.

If you can afford a FSQ85, get it. It is the best 3" astrograph on the market. The FSQ is a 4-element Petzval, so it has a flat focal plane. It doesn't require a separate flattener like normal doublet or triplet. The FSQ has a native F ratio of F5, so it is faster than any scopes your listed with flattener.

[CC_Japan]

A Borg with dedicated reducer will certainly beat a SV90+TV0.8x with the wrong spacer. All normal refactors have curved focal plane, so stars at the edges will appears out of focus without a field flattener. Field flattener only flatten the focal plane at a specific distance from the flattener, the focal plane will be curve either side of this specific distance. The flattener to sensor distance is determined by the design of the flattener as well as the scope. The distance is variable depending on the scope used.

Borg and other scopes with dedicated flattener has predetermined flattener flange - focal plane distance. TV0.8x when used with third party scope do not. You will either have to experiment with different spacers to find the correct distance, or find someone else with a similar set up who has done that already. As far as I know, the popular TV TRF-2008 cannot fully flatten the field of a 80mm f6 triplet for a APS-C sized sensor.

If you are interested in the SV90, check with Stellarvue to see if they have a dedicated flattener. They should be able to recommend you a flattener and be able to supply the necessary spacer for that scope.

If you can afford a FSQ85, get it. It is the best 3" astrograph on the market. The FSQ is a 4-element Petzval, so it has a flat focal plane. It doesn't require a separate flattener like normal doublet or triplet. The FSQ has a native F ratio of F5, so it is faster than any scopes your listed with flattener.

There is a dedicated flattener for the Stellarvue SV90, just no reducer at this point.

The FSQ-85 would stretch my budget quite significantly, even though I might be able to afford it, if I don't need to spend a lot of extra money on a reducer/flattener. Is this scope really that good, that it doesn't require a flattener at all? That sounds pretty impressive.

[swag72]

The FSQ85 is a fantastic scope, that by design does not require a reducer / flattener. It is a step above all of the scopes you mention. I would dare to say it's one of the best refractors out there

[CC_Japan]

Not having to spend 500 bucks on a flattener/reducer is huge. It might be worth considering, if I can get a decent deal.

[CC_Japan]

After pondering the scope question some more, it has come down to essentially two choices: Bite the bullet and get the FSQ-85 or opt for a lower priced 90/600 APO (TS or Stellarvue). The latter plus flattener/reducer would be around 30% cheaper than the Takahashi.

I'm torn because on one hand I think the Takahashi is a future-proof choice which I probably won't out grow and since it's a domestic product I can easily reach them, if there is an issue. What is more, the Tak not needing a flattener should reduce the margin of error. On the other hand, I wonder whether it isn't pure overkill to get a Tak as a first scope. If I went with the TS or Stellarvue, I'd save some money initially, but I wonder whether I would not start lusting for a Tak at some point.

Any thoughts, opinions would be much appreciated. I really would like to decide one way or another this week, as I feel that I have done enough research and it's time to go ahead with ordering, so I can actually start getting acquainted with the scope and scope-mount setup.