Awful flare in Pentax PF 80ED (1 Viewer)

Hi All

Back in 2002 I bought the Pentax Straight pf 80 on the strength of glowing BVD reviews. This was pre BF sadly. When I tried it out in sunny conditions I noticed awful flare, which caused me to return the scope to the retailer and eventually gain a refund, though I had to go to the County court and make a claim. See the attached pictures.

Prior to this drastic action it was returned to Pentax Japan and the retailer both of whom said there was no probem. This was despite my detailed explanation but before I took SLR pictures of the problem (I didn't have a digital camera at the time).

In March 02 the scope was sent to Pentax and and finally in January 03 Pentax admitted a problem with the scope "under the unusually demanding conditions you describe". This was a victory of sorts though it had taken about a year and lots of hassle to get a refund.

My question is has anyone else noticed this problem with the scope or was it modified in some way? At the time I just couldn't understand why no one else could see it. or how a scope could be designed with such an inherent flaw.

I don't understand what the flaw was. Your photo seems to show bright sunlight reflecting off the inside of the lens cell? Was the dew shield retracted? What was the effect through the telescope? What did you see and under what conditions did this show up?

Clear skies, Alan

I have to confess that I've never experienced this problem with my PF80-ED. Under difficult lighting conditions I extend the lens shade and flare seems well-controlled.

The one problem I've had with my PF80-ED is that when eyepieces are used that don't have a locking notch (as with the 20-60x zoom) the grip of the lens collar is insufficient to prevent rotation. This becomes a problem sometimes when I am digiscoping. Pentax will fix the problem on warranty, but I'll have to be without the scope for 6-8 weeks, which is a kind of hardship. So I have not addressed the matter yet.

The flaw was the fact with a low sun it would catch the metal ring the lens rests against and reflect a bright spot which was then magnified by the eyepiece which was then part of the scopes view. I have seen flare in most scopes but never to the extent that it showed in this one, with the coloured effects it produced depending on the angle the sun caught the the ring. The lens hood only helped up to a point, I could still get the effect if the sun was shining directly on the ring.

I had a look inside the scope with no eyepiece and could see the sun hitting the ring and glinting so as far as I was concerned this was the problem.

Do you think (Alan) to see this level of flare is acceptable in a scope then? What I saw was what you see in the bottom 2 photos - that was the effect, various coloured crescent shapes which for me interfered with my viewing pleasure.

Dipped,

I'm not second-quessing you about the flare issue on your particular Pentax, but I would like to point out that when viewing right towards a setting or rising sun, any and every scope I have ever tried will show more or less prominent reflections.

Now, some do show much more prominent reflections, and some significantly less. The very best, in fact show quite little. With any scope, the objectionability of them will be dramatically influenced by minute changes in viewing angle, position of the sun in the sky, amount of scattered light in the air etc. Therefore making relevant comparisons is not very easy at all unless you have two scopes set up side-by-side aimed at exactly the same target. Additionally, we are most likely to encounter difficult light conditions (and, hence, bad reflections) with the very scope we have paid dearly to own. I still remember the first time I happened to hit upon the "sour spot for reflections" with my first ever premium scope. These kinds of reflections also cannot be prevented with the lens shades, since they occur when the sun is so close to the viewed target that one would need an unrealistically long shade for it to make any meaningfull difference.

I don't know how it is with the best astronomical scopes, but with spotting scopes we still need to accept some level of imperfection when it comes to reflection control under difficult light conditions.

Kimmo

I have the 100 , 80a & 65a pf.s & have never noticed that problem .
Brian.

There is an easy cheap fix for this problem. A knife edged baffle placed just behind the objective cell so that the reflection from the cell is completely blocked. Alas, this simple measure is seldom done properly.

kabsetz said:

Dipped,

I'm not second-quessing you about the flare issue on your particular Pentax, but I would like to point out that when viewing right towards a setting or rising sun, any and every scope I have ever tried will show more or less prominent reflections.

Now, some do show much more prominent reflections, and some significantly less. The very best, in fact show quite little. With any scope, the objectionability of them will be dramatically influenced by minute changes in viewing angle, position of the sun in the sky, amount of scattered light in the air etc. Therefore making relevant comparisons is not very easy at all unless you have two scopes set up side-by-side aimed at exactly the same target. Additionally, we are most likely to encounter difficult light conditions (and, hence, bad reflections) with the very scope we have paid dearly to own. I still remember the first time I happened to hit upon the "sour spot for reflections" with my first ever premium scope. These kinds of reflections also cannot be prevented with the lens shades, since they occur when the sun is so close to the viewed target that one would need an unrealistically long shade for it to make any meaningfull difference.

I don't know how it is with the best astronomical scopes, but with spotting scopes we still need to accept some level of imperfection when it comes to reflection control under difficult light conditions.

Kimmo

Click to expand...

I agree that all scopes (birding), show some some flare. However in this model in my opinion it was off the scale. To me it would not seem too difficult to stop reflections from the objective lens metal ring, it is just a case of designing it carefully and with a non-reflective edge.

After I returned the scope I tested the Zeiss 85 diascope, old Swarovski 80mm and a Viking clone of the Pentax. I took a small penlight torch to shine at the lens ring to see if there was any bright reflection to simulate a low sun and also directly compared the zeiss and swaro under identical conditions against the sun.

My findings were it is possible to predict flare from the obj. lens area with the torch. The Viking did reflect from the obj. ring but didn't interact with the lens in the way the Pentax did to produce the colours seen in my pictures.
The swaro showed no flare in the sun, the zeiss did in identical conditions. I put the Zeiss flare down to the design at the obj. lens end as it is possible to view what's happening with the eyepiece off, and see where the sun catches and is then magnified, with the eyepiece.

I have since used a Swaro 65 and the only flare (and it is minimal), I can detect appears to come not from the objective end but much deeper inside the scope at the circumference of a small lens. In other words there is no need for any flare to come from the objective end of things. At least that's how I see it.

I suppose that once I saw it in my Pentax I became sensitive to it and to its cause in the scope and in other models. I know it is possible to move your eye position in some models to get rid of it but I kind of feel I shouldn't have to. Nothing is perfect but some designs are better than others in respect of flare it appears.

dipped said:

The flaw was the fact with a low sun it would catch the metal ring the lens rests against and reflect a bright spot which was then magnified by the eyepiece which was then part of the scopes view. I have seen flare in most scopes but never to the extent that it showed in this one, with the coloured effects it produced depending on the angle the sun caught the the ring. The lens hood only helped up to a point, I could still get the effect if the sun was shining directly on the ring.

I had a look inside the scope with no eyepiece and could see the sun hitting the ring and glinting so as far as I was concerned this was the problem.

Do you think (Alan) to see this level of flare is acceptable in a scope then? What I saw was what you see in the bottom 2 photos - that was the effect, various coloured crescent shapes which for me interfered with my viewing pleasure.

Click to expand...

I simply didn't understand what you were seeing, and under what conditions. If the flare was a problem while you were using the scope, then it wasn't acceptable.

Clears skies, Alan

After I returned the scope I tested the Zeiss 85 diascope, old Swarovski 80mm and a Viking clone of the Pentax

Click to expand...

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I have recently been looking for a scope and am interested in both Pentax and Viking. The only Viking scope with an 80mm objective lens I can find is the AV80 ED which is considerably cheaper than the equivalent Pentax. Is this the scope you're referring to? Just to add to the confusion, I have been told today that Viking scopes are made by Opticron and "badged" Viking. Can anybody shed some light on the above?????????

Ta

Eddie