Explore Scientific 2-inch Adapter for FFFR507X-00 Field Flattener Focal Reducer

Product Overview

This is the Explore Scientific 2-inch adapter, item number 510364, which connects Explore Scientific's 3-inch 0.7X Field Flattener Focal Reducer (FFFR507X-00) to a telescope fitted with a 2-inch focuser. It also works in the other direction of the same problem: it allows a 3-inch diagonal to be mounted on a 2-inch focuser drawtube.

Explore Scientific gives its dimensions in the product description rather than in a specification table: 76mm in diameter, 36mm in height, and a weight of .15lb (.08kg). It is a purely mechanical part — there is no glass in it — and its function is to let a 3-inch accessory work on a telescope that was never built with a 3-inch focuser.

The value of a piece like this is that it changes what an existing telescope can carry without changing the telescope. A 0.7X reducer and flattener is a substantial upgrade to a refractor's imaging performance, and this adapter is what puts one on a tube whose focuser is 2 inches.

Who It's For

• Owners of the FFFR507X-00 3-inch 0.7X field flattener focal reducer whose telescope has a 2-inch focuser rather than a 3-inch one.
• Imagers upgrading an existing refractor who would rather add a reducer and flattener than replace the focuser or the tube.
• Owners of a 3-inch diagonal looking to use it on a telescope with a 2-inch focuser drawtube.
• Anyone building an imaging train across two Explore Scientific size standards and needing the mechanical link between them.
• Observers who have moved a flattener or diagonal between telescopes and now need the fitting for the second tube.

Key Features & Design

• Connects 3-inch accessories to a 2-inch focuser: the specific job it exists to do, and the reason a 3-inch flattener is not limited to 3-inch focusers.
• Made for the FFFR507X-00 0.7X field flattener focal reducer, which is the accessory Explore Scientific names for it.
• Also takes a 3-inch diagonal onto a 2-inch focuser drawtube, so the same part covers a visual as well as an imaging case.
• 76mm diameter, 36mm height: a compact connector that adds as little as possible to the optical train.
• .15lb (.08kg) published weight: negligible next to the flattener or diagonal it carries, so it does not change the balance of a setup.
• No optical elements: nothing in the light path to add reflections, scatter or aberration — it is a mechanical coupling only.

Recommended Uses

• Fitting the Explore Scientific 3-inch 0.7X field flattener focal reducer to a refractor with a 2-inch focuser.
• Mounting a 3-inch diagonal on a 2-inch focuser drawtube for visual observing.
• Building an imaging train that spans Explore Scientific's 2-inch and 3-inch fittings.
• Moving a 3-inch flattener between a 3-inch-focuser telescope and a 2-inch-focuser telescope as your setup changes.

Compatibility and Accessory Notes

• Named accessory: Explore Scientific specifies this adapter for the FFFR507X-00 3-inch 0.7X Field Flattener Focal Reducer.
• Focuser side: it is made for a 2-inch focuser, which covers the majority of refractors above about 80mm.
• Diagonal use: Explore Scientific also lists it for mounting a 3-inch diagonal to a 2-inch focuser drawtube.
• Height in the train: the published height is 36mm. Every component in an imaging train consumes part of the available backfocus, so 36mm is the figure to work with when you are adding up the distance from the focuser to the sensor.
• Thread and fitting specification: Explore Scientific does not publish the thread sizes or the clamping method for this adapter. If you are matching it to something outside the two applications they name, send us the parts involved and we will confirm the fit with our Explore Scientific representative before you order.
• Spacing: the reducer's optimum sensor spacing is a property of the reducer rather than of this adapter, and Explore Scientific does not state how the adapter's 36mm figures into it. Send us the camera and any spacers you have and we will work the numbers through with you.

Good to Know Before You Order

• This is an adapter only. The FFFR507X-00 field flattener focal reducer, the diagonal and any camera-side spacers are separate items. We stock the flattener and can quote the pair together.
• It contains no optics, so it does not change magnification, field or image quality on its own. It changes what mechanically fits, which is a different and equally necessary thing.
• It adds 36mm of length to the optical path. On a visual setup that is rarely an issue; in an imaging train, backfocus is a budget and 36mm is part of it. If you are close to the limit of your focuser travel, that is worth checking first.
• Explore Scientific publishes no thread specification, material or finish detail for this part, so those rows read as not published in the table below rather than being estimated. Anything you need confirmed, we can ask them directly.
• Its published weight is .15lb (.08kg), which is the part itself. That figure is worth having when you are totalling up an imaging train, and it is small enough not to affect balance.

Frequently Asked Questions

Is it difficult to set up?

No. It is a mechanical connector that goes between the 2-inch focuser and the 3-inch accessory, and it takes seconds to fit. Where care is worthwhile is in the imaging train as a whole, because the 36mm of height it adds is part of the total spacing between the reducer and the camera sensor — and we are glad to work that sum out with you.

What exactly does it connect?

Explore Scientific lists two applications: the 3-inch 0.7X Field Flattener Focal Reducer (FFFR507X-00) onto a telescope with a 2-inch focuser, and a 3-inch diagonal onto a 2-inch focuser drawtube.

Does it include the field flattener?

No. This listing is the adapter alone. The FFFR507X-00 is a separate item, and we can put the two together on one order if that is easier.

Will it change the image?

Not by itself — it has no glass in it. The reducer does the optical work; this part is what lets the reducer attach.

How much room does it take up?

76mm across and 36mm tall, at .15lb (.08kg). The 36mm is the number that matters when you are counting backfocus.

Will it fit my telescope?

If your telescope has a 2-inch focuser, that is the side this adapter is made for. For anything unusual, send us the make and model of the telescope and the accessory you want to attach and we will confirm it before you order.

Bottom Line

In short: a 76mm by 36mm, .15lb mechanical adapter that puts Explore Scientific's 3-inch 0.7X field flattener focal reducer — or a 3-inch diagonal — onto a telescope with a 2-inch focuser. If you tell us the telescope, the camera and the accessories you are joining up, we will check the spacing and the fit with you before anything ships.