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SDL eyepieces (1 Viewer)

graham_t

Well-known member
I've had a GS52 scope with an HDF eyepiece for a while now but (although I'm veryhappy with it) was curious to know whether an SDL would give a significant improvement.
I've read the comments on here, but have just realised that there are 2 SDL zooms both with the same magnification range but with differing fields of view and, it is claimed, different eye reliefs and differing resolutions. The part numbers are different 40935G and 40936G but otherwise they are hard to distinguish.
This proabably exxplains why, when I look up the prices for SDL zooms I get very different prices from different retailers. So, if you are trying to buy one, be sure that you are getting what you think you are.
I find this very confusing, couldn't they have been called something different? Is one being phased out and the other in?
Also, any comments on their relative merits?

Another question -field of view. Is the field of view proportional to magnification in a zoom? I was trying to compare the fields of view of a 24WW (40858G) with that of an HDF zoom at a similar magnification. If it is proportional, then there should not be a huge difference. 45.5(zoom0 to 49 fixed. The reason I'm curious is that I've preferred fixed eyepieces in the past but tried a zoom on the GS52. I did try both before I bought, but since the magnification on the barrel of a HDF zoom is not given for a 52 dia scope it was hard to accurately compare the 2
 
The short answer is if you are happy with the HDF stick with it. I have a very old SDL and as far as I can tell (with my eyesight) there is not a significant improvement over the HDF
 
The SDL you have is probably the old one 40935G

http://www.opticron.co.uk/Pages/gs52_scope.htm

shows the new one as well.

If you go to the images, you will find they look different. The old one was stumpier, whilst the new one has more proportions of the HDF eyepiece.

What I find strange is even in the new RSPB magazine packages are advertised including an SDL zoom, but they don't specify which one.
 
Hi Graham,

The website is now also showing the new SDL v2 (40936) It will be in shops in around early September but before that we will be launching it at the British Birdfair (Tent OD10)

The new SDL Zoom v2 will be sharper, have a wider field of view and also the eyerelief will be more constant, meaning you will not need to adjust the eyecup as much when viewing over different magnifications.

Eyerelief;

40936 New SDL 20-18mm
40935 Current SDL 27-22mm

For a short time both SDL Zooms will be running together as we phase the old one out, so sorry for the confusion. Although it will be easy to tell the two apart price wise, with the new SDL Zoom v2 SRP at £259.00 and the current SDL Zoom at £229.00

The SDL Zoom advertised currently in the RSPB Birds magazine would be the current 40935.

In terms of whether it would be worth your while upgrading, it is hard to say. The only main difference you will see is the wider field of view. In the end it will probably boil down to what price you can upgrade for and whether you think it is worth the investment for you.

So to clear that all up;

40936 New SDL Zoom v2 SRP £259.00
40935 SDL Zoom SRP £229.00

I hope this helps,

Rob
Opticron
 
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