barlow with the Bushnell Mak 90 Northsatr

opticsplanet.com · Posted: Mon Jun 06, 2005 3:19 pm Post subject:

Hi

Bushnell 90 mm Mak Update

When this telescope came out just before Christmas, Bushnell supplied it with a 25mm (48x) eyepiece and a 4mm (300x) eyepiece. No barlow lens was included.

Unfortunately, the manual supplied with this telescope listed a barlow lens as one of the items included. This was a misprint on Bushnell's part. The 90mm Mak, 788890, does not come with a barlow and has never been supplied with a barlow lens.

To remedy this error, Bushnell for a time supplied a barlow with this scope to any customer who called in and complained. When combined with the 4mm eyepiece, however, the barlow produced much more magnification than the telescope could handle. Image quality was totally unusable with this combination. In fact, even with the 4mm eyepiece alone, magnification is still more than this scope can handle. Bushnell should not have supplied a 4mm eyepiece with this scope in the first place.

To make matters worse, some customers are now reporting that Bushnell claims you should not or must not use a barlow lens with this scope. This is incorrect. When used with a low-power eyepiece, a barlow can definitely be used with the Mak 90 and is still a good way to increase magnification and maintain the longer eye relief of a low power eyepiece. Bottom line here is that any eyepiece or eyepiece plus barlow combination that does not produce more than roughly 150x, is a good choice for this 90mm telescope, or any 90mm telescope, regardless of the design. (Note: For daytime use, keep magnification less than 80x for best results.) If you are not sure what eyepiece to add or use with your Mak 90, this will help

25mm eyepiece = 48x w/o a barlow and 96x with a 2x barlow
22mm eyepiece = 55x w/0 a barlow and 110x with a 2x barlow
20mm eyepiece = 60x w/o a barlow and 120x with a 2x barlow
17mm eyepiece = 71x w/o a barlow and 142x with a 2x barlow
15mm eyepiece = 80x w/o a barlow and 160x with a 2x barlow
12mm eyepiece = 100x w/o a barlow
10mm eyepiece = 120x w/o a barlow
8mm eyepiece = 150x w/o a barlow
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BobY · Guest

I just got the Meade 8-24mm zoom eyepiece for this scope and I am very glad I took your advice!

OK, it's pricey, but still significantly cheaper than the scope itself and the optical quality is outstanding. This one eyepiece pretty much covers the usable range of the scope, it has great eye relief (better than both the 4mm and 25mm eyepieces included with the scope) and it stays in focus as you zoom. (I was a bit surprised it didn't come with any dust caps and only a ziplock bag for storage, though.)

I couldn't be happier...well, at least until my credit card bill comes Smile

Maybe you should offer a package deal on this scope/eyepiece combo?