ScopeTech 80mm Fraunhofer Telescopes

[John]

Does it deal with the moment arm issue John ?

 

[johninderby]

It does seem to greatly reduce it. TS claims that it allows perfect balance of the scope and reduces loading on the motors. Just feels a lot more stable with vibration greatly reduced. With the alt clutch released the scope can be moved up or down and just stays in place unless you try to point it at the zenith where you would need to rebalance the scope. 

Haven’t used it enough yet but does seem to do the job. TS also recommends it for mounts such as the Skytee. 

Will have to try it on the AZ100. 😁😁😁

Edited May 23, 2020 by johninderby

[johninderby]

Hmmmmmmmm 😁

[Steve Clay]

1 hour ago, johninderby said:

I’ve been testing the TS Alt-Az counterbalance system and it’s surprising how much it improves the stability of a small mount with a longer scope on it as well as allowing you to mount a heavier scope. 

 

John how is the red clamp attached to the azgti. I'm looking for a better solution on my solar quest. Cheers Steve

[johninderby]

30 minutes ago, Steve Clay said:

John how is the red clamp attached to the azgti. I'm looking for a better solution on my solar quest. Cheers Steve

It’s a William Optics saddle bolted onto a Geoptik short dovetail. The whole thing just fits into the mount saddle. Don’t like those stock saddles with a holding screw. Don’t mind the screw gouging the Geoptik dovetail but not the scope dovetail. 🙂

https://www.amazon.co.uk/Geoptik-30-A058-Vixen-Sledge-Orange-Black/dp/B0153EZFHU/ref=sr_1_6?dchild=1&keywords=geoptik+clamp&qid=1590255595&sr=8-6

Edited May 23, 2020 by johninderby

[Steve Clay]

47 minutes ago, johninderby said:

It’s a William Optics saddle bolted onto a Geoptik short dovetail. The whole thing just fits into the mount saddle. Don’t like those stock saddles with a holding screw. Don’t mind the screw gouging the Geoptik dovetail but not the scope dovetail. 🙂

https://www.amazon.co.uk/Geoptik-30-A058-Vixen-Sledge-Orange-Black/dp/B0153EZFHU/ref=sr_1_6?dchild=1&keywords=geoptik+clamp&qid=1590255595&sr=8-6

Brilliant. Just the solution I'm looking for, for same reasons. 

Thanks

Steve

Orderd 👍

Edited May 23, 2020 by Steve Clay

[Stu]

41 minutes ago, Steve Clay said:

Brilliant. Just the solution I'm looking for, for same reasons. 

Thanks

Steve

Orderd 👍

I think the ADM replacement saddle is much more effective seems better to replace the whole saddle to me.

https://www.firstlightoptics.com/adm-replacement-saddles/adm-dual-dovetail-adaptor-for-az-gti.html

[johninderby]

The ADM saddle is too short and fitting a wider saddle gives more room for adjusting the balance of the scope.

And why is the ADM saddle a dual fit? Don’t see much need for a Losmandy plate on an AZ-GTi. 🤔

Edited May 23, 2020 by johninderby

[Stu]

10 minutes ago, johninderby said:

The ADM saddle is too short and fitting a wider saddle gives more room for adjusting the balance of the scope.

And why is the ADM saddle a dual fit? Don’t see much need for a Losmandy plate on an AZ-GTi. 🤔

Personal choice I guess. The weakest link is the rather poor quality standard saddle on the mount which you are still using so the length of the WO saddle doesn’t actually add any security to the system.

Nothing about the ADM limits the range of movement for balance though, and given the weight limit of the mount it is perfectly adequate to cope with anything you would put on there. It also keeps the weight closer to the mount which is a good thing. Agreed there is no need for losmandy fitting but it makes no odds, very solid.

One thing to note, I assume this fits the SolarQuest but it may not. Worth checking if interested.

[johninderby]

Same setup I used on the SolarQuest.

The stock saddle is fine if not used too much. It doesn’t stand up to constant loosening and tightening but not a problem if the WO saddle is left permanently in place.

Also the ADM wouldn’t be very good with the Omegon Mak I usually use with the mount as the OTA needs positioning too far forward to still fit in the ADM saddle properly.

Edited May 23, 2020 by johninderby

[Shaun_Astro]

Well, back on track...

There's a nice clip of the moon using the STL-80 Maxi on youtube here: (a surprising amount of blue?)

 

[Stu]

4 minutes ago, Shaun_Astro said:

Well, back on track...

There's a nice clip of the moon using the STL-80 Maxi on youtube here: (a surprising amount of blue?)

 

Good.....!

It would be good to know what the views are like visually. Cameras are much more sensitive than eyes, so tend to show up this CA far more than you would see at the eyepiece. I’ve seen similar when taking phone images through achro scopes I have.

[John]

If the objective is made to a good quality (which I'm sure it is) the CA levels in the F/12.5 would be very low and the F/15 should be visually colour free I would think.

[johninderby]

I think the F15 will be a great visual scope with only an insignificant trace of CA and not really noticeable.

Wonder how it would compare to my F15 127 Mak? 🤔

[Shaun_Astro]

 

1 hour ago, Stu said:

Good.....!

It would be good to know what the views are like visually. Cameras are much more sensitive than eyes, so tend to show up this CA far more than you would see at the eyepiece. I’ve seen similar when taking phone images through achro scopes I have.

 

That's true. It is a very crisp view of the Vallis Schoteri and Aristarchus, I recall this is one of the features I looked at using my Meade Polaris 70/900 a few weeks ago with a yellow filter at 180x and to be frank this blows it clean out of the water (as one would expect).

But then a 150pl for £185 (42% of the price) could perhaps give as good or better views?

Edited May 24, 2020 by Shaun_Astro

[johninderby]

Found a couple more photos.

[John]

I'm sure they will perform to the limits of an 80mm aperture unobstructed scope.

 

 

[John]

There seem to be some rumours circulating on another forum that plastic is used quite a bit in these refractors. I know that was the case with the Bresser ones but I would have thought that the ScopeTech ones would use mostly metal / alloy construction. Is that the case ?

Thanks.

[johninderby]

Just looking at the pic of the objective and those three spacers do look a bit big. 🤔

[Shaun_Astro]

25 minutes ago, John said:

There seem to be some rumours circulating on another forum that plastic is used quite a bit in these refractors. I know that was the case with the Bresser ones but I would have thought that the ScopeTech ones would use mostly metal / alloy construction. Is that the case ?

Thanks.

Do you have a link? The entire focuser looks plastic to me.

[johninderby]

Found this on a French forum.

The 80-1200 with its RC 2.8 is barely below a Telemator RC2.4 in corrected chromatic range, but ... it will diffuse less in blue-violet (F2 glass) and brings 60% more light .

Only the bulk and a good modern planetary eyepiece of 5mm diffusing little available would make me choose an 80-1000.

But be aware that these poor 200mm more, bringing to f / 15, easily brings the last jump in magnification x200. It is accessible with the old simple eyepieces: 6 mm orthoscopic or asymmetric plössl whose ergonomics is, by experience, without difficulty.

Unfortunately, with a 1 "1/4 eyepiece holder, this limits access to the deep field, expressing the reduction in luminosity brought by the diameter. A 32mm plössl for example brings an apparent field of 50 ° but only 2.13mm of pupil The 80/1000, with a 40mm allows to reach the 3mm threshold but the apparent field is still limited to 40 ° with the eyepiece but 1.6 ° on the sky, effective for large galactic objects like M31, the double cluster of Perseus ... f / 12 seems to me the upper limit in this format so that the instrument expresses the diameter of the objective. °°

Historically, to give access to the deep field and make eyepieces of longer focal length useful for f / 15 instruments, Zeiss fitted an eyepiece holder with 38mm of free opening (same as T2 format) instead of the 28mm 1 "1/4 format and provided a Kellner or a Huyghens for the wide field, which allows a pleasant 45mm at 48/50 ° and the 3mm pupil.

In the end, for this instrument, everything is in the quality of production to tickle these limits. The optical formula being a Fraunhöfer, it offers a certain tolerance to the barrel / tube / focuser misalignment due to the advanced correction of the coma. A non-collimating but good quality cell with few de-adjustable parts is probably sufficient, Vixen manufactures it for the 102M. And without hesitation, it passes in front of an apo 80f6 in planetary.

Edited May 24, 2020 by johninderby

[Chris]

2 hours ago, John said:

There seem to be some rumours circulating on another forum that plastic is used quite a bit in these refractors. I know that was the case with the Bresser ones but I would have thought that the ScopeTech ones would use mostly metal / alloy construction. Is that the case ?

Thanks.

I really hope not Upon setting eye's on the Scopetech f15 I kind of wanted it like I did the StellaMira 80mm f/10 when I first saw that. For £430 it needs to be made to last with good fit and finish, else why would you not get the plastic but optically very good Bresser's 90/1200 at a fraction of the price? I can't abide too much plastic on a scope, I'm hoping the speculation is wrong. 

[Greymouser]

This may be a silly question/point, but here we go: Just how good does the quality of the lens affect the image quality at F15? I ask because not so long ago I was tempted to get to get this Celestron 60mm scope and mount, from PC world of all places, for the mount so I could use the counterbalance bar on my AZGTi. I didn't as I found a second hand mount for even less, ( lying forgotten in one of my sheds! ) but I did wonder how usable the scope would be, seeing as it was F15 and made by Celestron, so a reasonable make. Evidently Celestron still make the scope, at least it can be found on their website, but may only be purchasable from the USA. How easy is it to discover the quality of the lens before buying? I must assume a lot of trust is needed.

The scope I got with the mount, from a second hand shop, was awful and I cannot remember its make, but it was unusable. It only cost me £25 though, so no biggie, considering the counterbalance bar could prove very useful. .

£439 seems a lot for a non ED scope, so what makes it special? I have seen no reviews as of yet, but assume the quality must be above the standard.

[johninderby]

Many nowadays who have become used to the bottom of the range cheap achromats and equate an achro with being a low end scope don’t realise that they used to make great achros with optics that were as well made and figured as an APO. 

Some of these long achros can out perform a modern short focal length APO on planetary viewing. 

[Dave1]

If you click on this link https://stargazerslounge.com/topic/341473-takahashi-starbase-80/?do=findComment&comment=3832402 you can see all the tests that have been done by Wellenform, which is who APM Markus Ludes in Germany use to test there telescopes. And Wolfi at Wellenform really knows his optics. This test was done on behalf of the French astronomers. It has a Foucault test, Diffraction test, Wellenform report technical conclusion, Strehl ratio achieved in specific light rays F, E, D, C. Going off of the tests the French had done by Wellenform, these are not cheap entry level optics, they are high quality optics made in the best time honoured Japanese tradition. 

David