Magnification

A place for all thermal spotter and riflescope questions and info
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wiiawiwb
Posts: 26
Joined: 16 Sep 2017, 17:34
Location: In the forest

Magnification

Post by wiiawiwb » 27 Oct 2017, 11:57

I want to be absolutely sure I am clear about how magnification affects ultimately what I see. There are two factors to consider...clarity and FOV.

If I have a thermal unit that has a low native magnification, say a Pulsar HD19S with 1.1, I will benefit from its wide FOV but, if I need to see more clearly what it is, then I will need to use digital magnification which then begins to degrade the image. Contrast with a Pulsar Helion 50F that has a native magnification of 4.1. The FOV will be significantly smaller but at the optically-magnified size of 3.1 it will be clear and not degraded.

So, I need to choose which is more important when choosing a unit. To have a more optically-clear picture or a more optically-wide FOV. If the FOV, is narrow, can't I recover or make up for that by sweeping the thermal unit so as to take in more of what I am viewing? There is no way make up for clarity. The native is what the native is and once I begin to digitally magnify, I will be degrading the clarity.

I'm speaking now of handheld spotters only. Wouldn't it always make sense to err on the size of too much native magnification than too much FOV? I can recover from too much magnification by physically sweeping the unit to take in more of the landscape but I can never recover the clarity once digital magnification begins.

phoenix
BRUCE ALMIGHTY
Posts: 4872
Joined: 09 May 2012, 14:40
Location: Aberdeen

Re: Magnification

Post by phoenix » 27 Oct 2017, 14:34

Your point is well made and with reference to thermals I agree with you.
However, higher optical magnification requires longer focal length lenses and, to keep the lens aperture as low as possible, this means larger diameter lenses.
Since the lenses are made from Germanium, which is uber expensive, the difference in price between, say, a thermal with a 38mm objective and a 50mm objective is all down to the extra cost of the larger lens on the 50mm model.
That difference in price may well be the deciding factor in the purchase of a thermal unit and it would still be far better to have a thermal with a small lens and low optical magnification than not having a thermal at all.
You are also correct in saying that digital magnification does not improve the resolution of the image, however, it can help with target identification.
I spot with a roof mounted 75mm thermal spotter which does not use digital magnification, but also have another 75mm hand held thermal spotter in the vehicle which is used to try to identify targets seen on the roof mounted spotter, but not immediately identifiable. Using x4 digtal zoom on the hand held spotter allows positive identification of the target in approx half the cases when it's used.
Typically, a target which is not moving and is close to the ground could be (in my area) a fox, a hare, a badger or a roe deer. If the target doesn't get up and walk around (which would make it much more easy to identify) then movements of the head or body of the target when viewed using digital zoom can often eliminate one or more of the possible species.

Cheers

Bruce
LAND ROVER - THE WORLD'S WORST 4X4 BY FAR

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sunndog
ADMINISTRATOR
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Joined: 10 Jun 2012, 17:51
Location: buxton, derbyshire

Re: Magnification

Post by sunndog » 27 Oct 2017, 19:23

If you can afford it go for the bigger lens. I went from a 20mm to a 38mm lens and the difference in target i'd was night and day
oslon black drivers
http://nightvisionforumuk.com/viewtopic.php?f=35&t=2333

when asking for advice, please include what n.v device and/or illumination you already have (if any) and what rifles you intend to use them on...cheers

Davesniper
Posts: 134
Joined: 18 Mar 2016, 00:38
Location: Knutsford

Re: Magnification

Post by Davesniper » 27 Oct 2017, 23:25

I have the HD19S when they came out and soon relized I bought wrong ...foxing ID was a problem so last year got the XQ38 absolutely brilliant! Plan was to sell the 19s but because I do a lot of ratting I could not bring myself to sell them as the wider field of view is excellent. ..when we shoot over bait for fox I use a Lilliput screen from landy my buddy has the HD 38s but insist we use the HD 19s mounted on top as the field of view is better, expensive cock up on my part but I have the best of both a bit like one gun will not do all jobs and one fishing rod will not do all types of fishing.

wiiawiwb
Posts: 26
Joined: 16 Sep 2017, 17:34
Location: In the forest

Re: Magnification

Post by wiiawiwb » 28 Oct 2017, 01:07

I can not speak for others but will speak for myself and say that my limited time on this forum has been a delight. Everyone has been wonderfully helpful and accommodating and I really do appreciate it. In particular, I can't help but tip my hat to both Bruce and Mini Mag who both possess a world of knowledge and are graciously willing to share it. Kudos to them and kudos to all of you.

I wish circumstance allowed me the fortune to buy nothing but the best and not fret about the consequence. Circumstance is other than that so I do fret about spending such a large sum and hoping beyond hope that it was a prudent choice. For me, anything that calls itself Helion is a stretch of the wallet. I do hope you kind folks don't mind my journey here as I redouble my efforts to be sure that when I step off the plank it will be one I don't regret.

Thank you all.

C.J
Posts: 17
Joined: 07 Feb 2016, 20:35
Location: Devon

Re: Magnification

Post by C.J » 28 Oct 2017, 10:40

I have used a Quantum XD19S and a Helion XQ50F.

When atmospheric conditions allow the Helion is incredible but if it's a bit misty you can easily miss heat sources especially if the focus is off.

The Quantum XQ38 and the Helion XP38 are probably the best compromise but I've yet to try a Quantum Lite.
Last edited by C.J on 28 Oct 2017, 12:58, edited 1 time in total.

wiiawiwb
Posts: 26
Joined: 16 Sep 2017, 17:34
Location: In the forest

Re: Magnification

Post by wiiawiwb » 28 Oct 2017, 10:52

Here is a video put out by Pulsar showing one of the Quantums. They don't say what model it is.

I was drawn to this particular video because it takes place in the woods. To my eyes, it is very clear both at base magnification and with digital zoom.

Any thoughts Pulsar model this is?


Muskett
Posts: 566
Joined: 17 Nov 2012, 12:52
Location: East Sussex Rabbit Warren

Re: Magnification

Post by Muskett » 28 Oct 2017, 17:19

Many of us can't justify the huge costs to get the best kit.
A Helion XQ38F seems to me the best compromise. The negative is that its a bit focus fussy close in and you will need to pan more compared to say XP50.
The XQ50 FOV isn't helping it at all, even with its bigger lens.

The Helion XP50 is the best performance wise but the price is horrendous. It can do it because of the larger sensor size and lens. Start mag and FOV being good. It can be digi magged up to give similar performance to the XQ38F. Raw base setting then I doubt the picture can be bettered for spotting when panning without a bigger lens which isn't available. Lots to like but the price; that price taking it to rifle sight WT1 budget.

The budget Quantums may well have a really large field of view but small sensor, small lens, and less expensive parts suggest its not really doing it. Makes second hand better units look the sensible option.

A larger 75mm lens would be nice but then thats not going to fit into a pocket.

So its pretty frustrating. An under £2.5k XP50 performance from a competitor, if it could be done, would take the market.

Sussexsteve
Posts: 118
Joined: 06 Oct 2013, 11:43
Location: Sussex

Re: Magnification

Post by Sussexsteve » 29 Oct 2017, 07:22

Forget about Field of view. Buy the biggest lens you can get both spotter and scope. The higher the base magnification the better. No point having an xp50 spotter with 2.5 mag when the xq50 with its 4.5 mag makes ID easier. Don’t get sucked into the 640 sensors either.

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