DayStar Filters 140mm-Aperture Energy Rejection Filter (170mm Cap Diameter)

DayStar Filters 140mm-Aperture Energy Rejection Filter (170mm Cap Diameter)

DayStar Filters 140mm-Aperture Energy Rejection Filter (170mm Cap Diameter)

B&H # DAE170N140 MFR # E-170N140
Special Order
Expected availability: 7-14 business days

Product Highlights

  • For Use on Refractor and Maksutov OTAs
  • Reduces Heat Load on Filter Assembly
  • Absorbs or Reflects UV and/or IR Light
  • For H-alpha, Sodium, Helium D3 Filters
  • Inside Diameter of Cap: 17 cm (6.692")
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SAFETY FIRST: Observing the Sun without the proper protection may result in serious personal injury, including permanent eye damage and blindness, and/or damage to equipment. Never point an optic at the sun without an approved solar filter on the front of the optic. For direct solar viewing, viewing the sun through an optic, or when using cameras with an optical viewfinder, ensure your filter is ISO 12312-2 (also written as ISO 12312-2:2015) certified. Never use photographic neutral density filters for direct solar viewing, viewing the sun through an optic, or when using cameras with an optical viewfinder.

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DayStar Filters E-170N140 overview

  • 1Description

Daystar Filters' 140mm-Aperture Energy Rejection Filter is designed for on-axis use with Refractor and Maksutov-style OTAs to reduce the heat load on your filter assembly by absorbing or reflecting UV and/or IR light while transmitting light in the desired spectrum. This ERF can be used with H-alpha, Sodium, and Helium D3 solar filters, but is incompatible with calcium wavelengths.

Choose the ERF aperture size to approximately match your refractor's objective aperture or Maksutov corrector plate. Select the correct filter cap size by measuring the outside diameter of the OTA's dew shield and choose the ERF with the smallest inside diameter that will fit over the dew shield. A set of screws is included to secure the ERF into place. This ERF's cap has an inside diameter of 17 cm (6.692").

UPC: 724696425533
In the Box
DayStar Filters 140mm-Aperture Energy Rejection Filter (170mm Cap Diameter)
  • 3 x Set Screws
  • Limited 5-Year Warranty
  • Table of Contents
    • 1Description

    DayStar Filters E-170N140 reviews

    140mm-Aperture Energy Rejection Filter (170mm Cap Diameter) is rated 4.0 out of 5 by 1.
    Rated 4 out of 5 by from I use the 140mm ERF aperture model with an Astro-Tech 130EDT The 140mm aperture (170mm cap diameter) will fit the dew shield of an Astro-Tech 130 EDT. I know what you're thinking: with a large aperture refractor (100mm+) and a Daystar Quark eyepiece, you can obtain an aperture advantage over a dedicated solar scope, which tend to exist in the 40-60mm range, and so perhaps you can possess a large aperture refractor, adapted for solar, and save some money at the same time. Well, sort of. The bad: This one took a while to arrive. In my case the time from order to arrival was a little over six weeks. Not unbearable, but you may need to plan your season of solar viewing in advance if the filter size that you need is special order. After a while I stopped asking B&H Photo for updates and just called Daystar directly. They did admit that my order was delayed - and in their defense it was over the holiday season - though for a while I wondered if it would ever show up, especially since my credit card had already been charged in full at the time of order. To be fair, Daystar were polite and transparent about what was going on. The metal cell on my unit (the thing that holds the glass) was delivered slightly out of round. By this I mean that the cell is perfectly round except along one side where it has obviously been dropped. I would blame the shippers but there is absolutely no indication of damage to the shipping box or packing materials. In other words I am fairly sure that the drop occurred at Daystar. It can be damaged easily this way since the filter is quite heavy - about 3 lbs. As it happens, the damage is not bad enough to cause a fitting problem, but it only just fits over my dew shield. The filter attaches to the front end of the dew shield. This has the effect of making the heaviest part of your scope even heavier. This is quite a problem when it comes to balancing. You will likely need a substantial mount to carry the filter and your telescope. For example, you'd probably be at the limit of utility on an Orion Atlas, especially for imaging. In my case I use the ERF filter with the dew shield completely retracted to assist in balancing, riding on an Astro-Physics 1100 GTO. So this ERF filter is not cheap to accommodate. To attach the filter to your dew shield, you are supplied with three nylon screws and some pieces of felt. I can't help but feel the nylon screws are laughably inadequate for holding something so heavy to the front of the telescope. Rather than test this assertion, I taped up the filter to the dew shield in addition to using the nylon screws. See photos. Keep in mind that the smaller diameter ERF units are going to be less heavy. The weight of the filter is problematic in another regard - it's heavy enough to tug on the dew shield and move it, even if the dew shield is secured with its own grub screws. Again, more tape can mitigate this. Avoid pointing the telescope towards the ground. The good: The filter arrives with a nice note from the owner at Daystar. While there are no 'instructions' there is at least a sense that you've bought something made to order and of professional grade. You are reliably informed that the filter does not in fact filter infrared rays, but only ultra-violet. I can't decide if this is a good or bad thing. For the money, I would like both types of radiation to be filtered before entering the telescope. To this end, I use a 2" UV/IR cut-off filter inside the telescope, in addition to the ERF, though this is probably redundant. Doing this doesn't seem to affect the image of the sun (I say this since I have tested the Quark eyepiece without the ERF, and only the 2" filter, through a 4" refractor. It looks the same). So the filter does appear to work. I have detected no heat issues or other problems since using it in combination with my Daystar Quark eyepiece. I expect that I could go without the ERF altogether and rely entirely on the internal 2" cut-off filter, but I'd rather be safe than melted. For this review I had considered testing my system without the 2" filter, but I just don't want to risk doing that. I feel that Daystar could provide some more specific information about when an ERF is required, and when it is not, besides the general guidelines that I can find on forums. The other effect of the filter is that it is a visual indicator that you have a filter on the front of your telescope while otherwise appearing to ignore all the warnings about pointing optics directly at the sun. This is comforting for those about to look through it. It's difficult to recommend this expensive ERF filter, but it's difficult to recommend not having one if your refractor is 5" or greater and you want to be absolutely on the safe side while observing the sun. It does allow you to concentrate on imaging or viewing the sun without worry, with a large aperture (for solar) and work on the various other imaging issues, such as focusing, lucky imaging, or achieving a full solar disk, if desired. So in this regard I am happy with mine and will be keep it.
    Date published: 2018-06-12
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