NEW Starfield 102mm f/7 ED Doublet Refractor

[RobertI]

15 minutes ago, Mr Spock said:

Just go for it! It's a real beauty. That focuser is a heavy duty R&P, but the fine focuser is really smooth. The whole thing has exquisite build quality.

I've had some great lunar views with it at x179. Difficult to judge on solar as I've had poor seeing. Had a really good double star session with it though - I didn't want to come inside but the cloud beat me.

I’ve used mine* for solar with BVs and Herschel wedge at about 180x and the views were superb -  the best I’ve had. 

* Not Starfield brand, but same scope. 

Edited December 7, 2021 by RobertI

[mikeDnight]

On 15/11/2021 at 16:29, Franklin said:

I have two shoes, but one finder. Very useful when using an EQ mount which I do. The finder position inverts as you flip over the meridian. So I just switch shoes, only takes a minute to realign.

I keep my finder directly opposite the counterweight arm when on an eq. That keeps the finder in an accessible position without the need for two finder shoes.

[mikeDnight]

On 19/11/2021 at 14:15, Mr Spock said:

I can't contain my giddyness 

That looks fantastic Michael. It makes me want one too.  May be you'll get a pop at comet Leonard, and drool your way through some glorious star fields using your 42mm LVW when the skies clear. 

[Highburymark]

With such excellent focusers (ie, no longer the component where the manufacturer has obviously saved money), these handsome scopes beg the question, exactly how expensive is FPL53 glass these days? Cheap enough for Skywatcher to use it in a glorified finder. It’s great news for astronomers, but not so great for brands hoping to justify a sizeable price hike for fluorite.

[johninderby]

FPL55 is supposedly the replacement for FPL53. Not quite as good but easier to finish apparently. so probably similar to FPL53 in performance.

Edited December 7, 2021 by johninderby

[paulastro]

6 hours ago, Mark at Beaufort said:

That is what I call temptation. The photos really shows the quality of the focuser which added to the FPL53 optics makes it a very desirable scope.

I think you'd love this Mark.  I have another version, and I hate to say it, but its noticeably better than the AstroTech ED non-FPL 53 version we both used to own.

Edited December 7, 2021 by paulastro

[johninderby]

If the optics are anything like the 125 version I have I'm sure  the 102 will impress. 👍🏻

Edited December 7, 2021 by johninderby

[John]

28 minutes ago, Highburymark said:

With such excellent focusers (ie, no longer the component where the manufacturer has obviously saved money), these handsome scopes beg the question, exactly how expensive is FPL53 glass these days? Cheap enough for Skywatcher to use it in a glorified finder. It’s great news for astronomers, but not so great for brands hoping to justify a sizeable price hike for fluorite.

In 2017 Ohara FPL-53 was priced at 18x as much as BK7 crown glass. FPL-51 was 11x as much as BK7. That was from an Ohara price list. Apparently at that time Fluorite cost an eye watering 75x as much as BK7

I don't know if those relative costs have changed now or not.

 

 

[johninderby]

Found this on CN.

Price of ED glass is substantially stable over time. FPL53 costs 18x BK7, FPL51 11x and FPL55 costs 15.5x.

[John]

Just now, johninderby said:

Found this on CN.

Price of ED glass is substantially stable over time. FPL53 costs 18x BK7, FPL51 11x and FPL55 costs 15.5x.

Same source as my info I expect

 

[johninderby]

Would be interesting to compare an FPL53 to an FPL55 scope to see how similarity they perform. 🤔

[Sunshine]

Anyone know what “FPL” stands for?

[John]

The announcement of this Starfield 102mm F/7 was one of the main reasons that I started my recent thread "Why do really expensive scopes sell ......".

Starfield 102mm F/7 = £899  Takahashi FC100-DF inc tube clamp = £2,300ish.

£1,400 is enough to make me think very seriously about that !

 

[John]

10 minutes ago, Sunshine said:

Anyone know what “FPL” stands for?

From the Ohara website:

"In the course of Ohara’s long history, many types of optical glasses have been developed. In this catalog, you will find over 130 glasses which we have selected as our “recommended glass types”. Each optical glass has its own properties which are closely connected with the key chemical element it contains.

With this in mind, we have developed a new glass type designation system and the new names are used in this catalog. On the nd/vd diagram, located on the Optical Catalog webpage, you will see we have divided our glasses into groups. For each glass type, we have selected on or two chemical elements contained which are considered the most important and have used the atomic symbols of these for the first two letters of the glass type designation. The third letter of the glass type designation refers to the refractive index of each glass type within its glass group: H, M, or L for high, middle, or low. Lastly we assign a one or two digit number to each glass type within a given glass family. Thus each glass type is represented by the above-mentioned three letters plus a one or two digit number.

We are also adding the prefix “S-“ to indicate which of the glass types are ECO optical glasses and environmentally “Safe”. These glass types do not contain any lead or arsenic.

For example, the glass type designation for S-BSL7 is composed as follows:

S- stands for environmentally Safe
B represents Boron, one of the key compositional elements
S represents Silicon, one of the key compositional elements
L indicates a Low index within the BS group
7 indicates this is the 7th glass within this glass family

Along with Ohara’s glass type designation, the technical data sheets will show the six-digit code for each glass type. In the six-digit code the first three digits represent the refractive index at the helium line (nd) and the last three digits represent the Abbe number (vd). These six-digit codes are internationally recognized within the optical community.

So we just need to work out what the F and P stand for.

Edited December 8, 2021 by John

[badhex]

Found this on the Ohara site:

For each glass type, we have selected on or two chemical elements contained which are considered the most important and have used the atomic symbols of these for the first two letters of the glass type designation. The third letter of the glass type designation refers to the refractive index of each glass type within its glass group: H, M, or L for high, middle, or low. Lastly we assign a one or two digit number to each glass type within a given glass family. Thus each glass type is represented by the above-mentioned three letters plus a one or two digit number.

We are also adding the prefix “S-“ to indicate which of the glass types are ECO optical glasses and environmentally “Safe”. These glass types do not contain any lead or arsenic.

 

Full page here: https://www.oharacorp.com/o1.html

Edited December 8, 2021 by badhex

[badhex]

Haha whoops, @Johnbeat me to it! 

[Sunshine]

11 minutes ago, John said:

From the Ohara website:

"In the course of Ohara’s long history, many types of optical glasses have been developed. In this catalog, you will find over 130 glasses which we have selected as our “recommended glass types”. Each optical glass has its own properties which are closely connected with the key chemical element it contains.

With this in mind, we have developed a new glass type designation system and the new names are used in this catalog. On the nd/vd diagram, located on the Optical Catalog webpage, you will see we have divided our glasses into groups. For each glass type, we have selected on or two chemical elements contained which are considered the most important and have used the atomic symbols of these for the first two letters of the glass type designation. The third letter of the glass type designation refers to the refractive index of each glass type within its glass group: H, M, or L for high, middle, or low. Lastly we assign a one or two digit number to each glass type within a given glass family. Thus each glass type is represented by the above-mentioned three letters plus a one or two digit number.

We are also adding the prefix “S-“ to indicate which of the glass types are ECO optical glasses and environmentally “Safe”. These glass types do not contain any lead or arsenic.

For example, the glass type designation for S-BSL7 is composed as follows:

S- stands for environmentally Safe
B represents Boron, one of the key compositional elements
S represents Silicon, one of the key compositional elements
L indicates a Low index within the BS group
7 indicates this is the 7th glass within this glass family

Along with Ohara’s glass type designation, the technical data sheets will show the six-digit code for each glass type. In the six-digit code the first three digits represent the refractive index at the helium line (nd) and the last three digits represent the Abbe number (vd). These six-digit codes are internationally recognized within the optical community.

So we just need to work out what the F and P stand for.

Quite technical, actually, it seems the first two letters refer to the chemical elements of the particular glass. This  leaves us with FP, so to what chemical elements do FP refer to? I regret asking this question lol 

I know, phosphate and Plutonium!

Edited December 8, 2021 by Sunshine

[badhex]

Fluorine and Phosphorous which seem like odd elements to go into glass but I am not a glass chemist! 

[mikeDnight]

I wouldn't worry too much about the glass type. It's pretty safe to assume its a fluorite glass of some type, and so will perform to a large extent like a fluorite crystal lens. The more important factor would be the lens figure. When thermally stable, and under steady seeing, does the Starfield 102 show a near identical, perfectly circular stellar diffraction pattern either side of focus at 200X? If it does its perfect.

[paulastro]

4 hours ago, mikeDnight said:

I wouldn't worry too much about the glass type. It's pretty safe to assume its a fluorite glass of some type, and so will perform to a large extent like a fluorite crystal lens. The more important factor would be the lens figure. When thermally stable, and under steady seeing, does the Starfield 102 show a near identical, perfectly circular stellar diffraction pattern either side of focus at 200X? If it does its perfect.

Well, by the sound of it then Mike, you'll be selling your DZ 😊.

[Mr Spock]

7 hours ago, John said:

Starfield 102mm F/7 = £899  Takahashi FC100-DF inc tube clamp = £2,300ish.

I've had a look through a Tak and can say it is slightly better - slightly. When you add in a decent focuser it's nearly three times the price. Only the owner can decide if it's value for money but performance wise it's just not worth it.

[RobertI]

I guess if you are regularly doing critical viewing of the planets at high magnifications and it’s the difference between seeing that microscopic feature and not seeing it, then the extra spend might be worth it for some!

Edited December 8, 2021 by RobertI

[Mark at Beaufort]

10 hours ago, paulastro said:

I think you'd love this Mark.  I have another version, and I hate to say it, but its noticeably better than the AstroTech ED non-FPL 53 version we both used to own.

Thanks Paul it does look tempting and thanks for the comparison with the Astro Tech. I recently observed with Stu and I viewed the Sun through his Tak and it was incredible.

 

[John]

2 hours ago, Mr Spock said:

I've had a look through a Tak and can say it is slightly better - slightly. When you add in a decent focuser it's nearly three times the price. Only the owner can decide if it's value for money but performance wise it's just not worth it.

Well that's the thing isn't it. The difference in price can get you a nice 10 inch dob AND some nice eyepieces and a lunt solar wedge to add to your fine 4 inch refractor so you can have an observational setup that can last a lifetime for the price of one "poodle".

 

 

 

Edited December 8, 2021 by John

[mikeDnight]

2 hours ago, paulastro said:

Well, by the sound of it then Mike, you'll be selling your DZ 😊.

You never know! It does say in the Tak manual that fluorite is superior by many orders of magnitude to any ED glass. What that means in reality I'm not certain, but I suspect its more to do with spectral range beyond the visual?? I can't tell the difference between the DC/DF and the DZ visually, but I had to find out for myself at great expense. I'd be more than happy with a Starfield 102ED, and am pretty certain it would do everything my Tak could do, even at the silly high powers I sometimes like to use. Though I do believe the writing on the Tak's lens cell goes all the way through the tube, like the writing on a stick of Blackpool rock. I'm not sawing it in half to prove it though!