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Altair Astro 1.25" Dielectric Star Diagonal

Price:  £49.99 (Inc. 20% VAT)Earn 49 Loyalty Points

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Generally In Stock, Please Confirm Before Ordering  

Generally In Stock, Please Confirm Before Ordering

Model:  DIAG-125IN-DIEL
Brand:  Altair

Altair Astro 1.25'' Dielectric Star Diagonal
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A high quality 1.25" Star Diagonal with multi layer dielectric coatings offering 99% reflectance and extreme durability.

Perfect for small portable refractors where transport space is limited.

Aluminium CNC machined casing.

Non-marring brass compression ring.

2x protective dust caps.

Presentation box with foam inner cut-out.
Cleaning instructions:

Dust will enter the diagonal after opening it, and during normal use. This is inevitable and a little dust will have no effect on image quality. As a general guide, the product should be cleaned only when it gets very dusty usually once per a year or two. It is important to note you can use a diagonal for years with dust on it and it will not noticeably degrade the image. We have found that sometimes the translucent dust cap on the 1.25" end of the diagonal is so tight fitting, that the edge of the barrel can scrape the plastic off the inside of the dust cap, which can end up inside the diagonal the first few times you use it. If this is the case, you can just blow the dust off using a photographic blower (squeeze bulb type) which is quite handy to have around for eyepieces and suchlike, and it's no big problem. For stubborn dust and moisture spots from condensation, gently wipe the mirror with optical cleaning fluid and a cotton wool bud. There is no need to flood the diagonal with fluid, only a little is required. Tescos sell cheap eyeglass cleaning fluid which some customers have recommended works well (use the coated-lens type), or you can use Baader fluid which is designed for optics. Most camera shops also stock optical cleaning fluid for coated lenses. Isopropyl alcohol can also be used (90% or more concentration).

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Some items that are showing as in stock are in stock at our holding warehouses, not at the shop. To double check the stock levels at the shop, please contact us on 01909774369 or

The delivery times for most items is 1 - 2 days but again, please double check stock levels on important orders before placing an order via the website.

The delivery costs for courier next day are for mainland UK only. If you live in the Scottish Highlands/Islands, Channel Islands or Northern Ireland, then a shipping surchage will apply. please contact us for prices. Smaller items can still go 1st class via Royal Mail.

Please note that if you are wanting to take advantage of our Saturday and Sunday timed services or next day pre 12 or pre 10:30 services, you MUST check that the stock is here at the shop before placing orders. Also, orders using the Saturday and Sunday services must be placed before 2pm the previous working day. Also, please remember to check that the stock is here at the shop before placing orders. If the stock is not at the shop, we won't be able to ship on any of the timed services. 

Please note International customers will need to contact us for a shipping price prior to ordering via the website. This all depends on the size and weight of the items. Please get in touch with us for any postage costs. Please note we do NOT ship telescopes or heavy items outside of the UK. This is due to massive postage costs and problems regarding returns.

If you have any questions regarding stock levels or delivery, please get in touch.

Rother Valley Optics now have a loyalty point scheme active on the website. As you can see from the products, every item has a point value. Each pound you spend with us, you will receive 1 loyalty point. 1 point is worth 1p. You can accumulate these points as you shop with us, then when you are over £5, you can spend them on the website! Easy as that.

Even if you collect most of your items from our shop, you can still order via the website and select the "shop collection" delivery option. Then you can come to our shop, collect your item and still get your points!

Please note this scheme is online only. Customers who order via the telephone can still be added to the scheme manually. Please ask for more details on this. Before placing orders online, please make sure you are registered with us first otherwise your points won't be allocated.

So happy shopping and if you have any questions about the scheme or any other queries, please get in touch.

Rother Valley Optics


Finance is now available on most products above £250! We offer 12, 24, 36 and 48 months with a fixed 15.9% typical APR. Please note this can't be done through the website at this moment in time. You will need to email us or drop into the shop to sort out finance. As long as the item is above £250, finance is generally available!

Please note some items are NOT eligible for finance. Please contact us for eligibility first. 

Please get in touch with us today to find out if you're applicable.

You must be over 18 years to apply, live in the UK, have a valid UK bank account and not be bankrupt. Your credit file will be searched on application to see if you are eligible.

Rother Valley Optics Ltd is registered in England and Wales 04762707. Registered Office: 21 Station Road, Kiveton Park, Rotherham, S26 6QP. Rother Valley Optics Ltd acts as a credit broker only. Rother Valley Optics Ltd are authorised and regulated by the Financial Conducts Authority. Credit provided subject to age and status..

If you have any questions about this, simply give us a ring or drop into the shop for a chat.

- - - Rother Valley Optics Ltd

01909 774 369