Improving contrast? (1 Viewer)

Hi, Another newbie question, I guess.

I am considering an upgrade my scope/eyepiece set to gain a little better contrast. Does the eyepiece contribute to the contrast of the view, or is this more a feature of the body?
My current set is an Opticron Imagic 65 (discontinued 2007) with the HR2 40933 zoom eyepiece. Wondering if an HDF (or even the SDL) zoom eyepiece would be a useful improvement.

For info, the eyepiece fitted has a zoom range from 20 to 60 (varies slightly between scope models), of which the higher mag seems not particulary suited to the smaller scopes like the 65. I find the range up to around x35 useful. (I'm not asking why my scope is not-so-great at 60x).

Dave

Dave,

Speaking "in general", yes, the eyepiece utilized can have an effect on the perceived contrast of the image. I am speaking specifically in reference to different eyepieces I have utilized on several of my scopes. Some give off "warm" and "cool" color representations which affect perceived contrast with the image.

I cannot specifically say for the eyepieces you listed for your particular model.

There is the odd post here about zoom vs fixed eyepiece. I too would think that a good fixed lens would be possible for less than a good zoom, wider FOV perhaps, even as sharp maybe more contrast?
I will take the scope to an Opticron stockist and try one out and compare with the HR zoom.

Dave

I tried a fixed magnification (27x) Opticron eyepiece from the same range (HR) to compare with the HR zoom version I had. At 27x on my particular scope the view on the zoom lens is pretty good , much further past 30x the view becomes less comfortable (I guess smaller EP) and beginning to lose definition).
I can report that between these eyepieces from the same range there is little difference in contrast. My expectation that the fixed version would be sharper than the zoom was not realised as the zoom (at a similar mag) was not less sharp, possibly a little sharper).

So, no improvement in contrast. Not too much of a failed trial as the contrast perhaps is not bad (I've been trying a few other makes of scope recently at RSPB sites and this scope holds its own well enough). The FOV using the fixed eyepiece, however, is vastly improved. There is more CA in the wider view and it might not be as sharp off centre as the narrower zoom, but what an extensive view. Looking again at the FOV of the zoom feels immediately narrow and restricted. I think that the fixed eyepiece will stay on the scope and also lead to a search for a better (HDF) and slightly lower mag eyepiece.

Dave..

In general, unless we are dealing with an obviously defective eyepiece, and assuming that magnification does not change, it is the scope and not the eyepiece that determines the sharpness of the system and most of the contrast of the system as well. There can be small differences in contrast between different eyepiece designs due to different coatings, baffling and number of air/glass surfaces, but the visible effect of these is very slight when compared to the visible effects of the quality of the scope body.

Kimmo

Hi Dave

Just wanted to clarify something regarding your scope.

The HR2 zoom provides 18-54x magnification on your 65mm scope (it's 20-60x on the 80mm Imagic).

Cheers, Pete

pete_gamby said:

Hi Dave

Just wanted to clarify something regarding your scope.

The HR2 zoom provides 18-54x magnification on your 65mm scope (it's 20-60x on the 80mm Imagic).

Cheers, Pete

Click to expand...

You are quite right, Pete. I used the scale as printed on the side, too lazy to work out the real, but close, mag. I think that the scale 20-60 refers to an HR66, as printed on the eyepiece. Doesn't the IM80 range run to around 69 on this eyepiece?

Dave

Just a post to round off my "search" and questions.

I recently acquired an HDF eypeice that gives 25x on this scope. It is good. Compared to the HR40931 (27x) it is sharper across the field and is sharp to the field edge. Far less CA off axis on my IM65 too.

To add to the new eyepiece, I snagged a used SDL eyepiece. (I'm weak willed and spend too much time on the Bay) This is just as sharp and free of CA as the HDF, but a narrower AFOV.

One of the recent eyepieces came with a GS665GAED body attached, so my equipment aspirations have changed a little.

One thing has become apparent from my upgrade path, this is that the IM65 is a very creditable performer for its value.

Dave (Hopefully set up with a scope that will suit me for a few years to come....)